The Sydney Memory and Ageing Study (MAS): methodology and baseline medical and neuropsychiatric characteristics of an elderly epidemiological non-demented cohort of Australians aged 70-90 years

Associations between fruit and vegetable intakes and incident depression in middle-aged and older adults from 10 diverse international longitudinal cohorts

BACKGROUND

Emerging observational evidence supports a role for higher fruit and vegetable intake in protecting against the development of depression. However, there is a scarcity of research in older adults or in low- to middle-income countries (LMICs).

METHODS

Participants were 7801 community-based adults (mean age 68.6 ± 8.0 years, 55.8 % female) without depression, from 10 diverse cohorts, including four cohorts from LMICs. Fruit and vegetable intake was self-reported via comprehensive food frequency questionnaire, short food questionnaire or diet history. Depressive symptoms were assessed using validated measures, and depression defined applying validated cut-offs. The associations between baseline fruit and vegetable intakes and incident depression over a follow-up period of three to nine years were examined using Cox regression. Analyses were performed by cohort with results meta-analysed.

RESULTS

There were 1630 cases of incident depression (21 % of participants) over 40,258 person-years of follow-up. Higher intake of fruit was associated with a lower risk of incident depression (HR 0.87, 95%CI [0.77, 0.99], I2 = 4 %). No association was found between vegetable intake and incident depression (HR 0.93, 95%CI [0.84, 1.04], I2 = 0 %).

LIMITATIONS

Diverse measures used across the different cohorts and the modest sample size of our study compared with prior studies may have prevented an association being detected for vegetable intake.

CONCLUSIONS

Our study supports a role for fruit, but not vegetable intake in protecting against depression. Research investigating different types of fruits and vegetables using standardised measures in larger cohorts of older adults from low- and middle-income countries is warranted.

The contribution of cumulative blood pressure load to dementia, cognitive function and mortality in older adults

BACKGROUND

Few studies evaluated the contribution of long-term elevated blood pressure (BP) towards dementia and deaths. We examined the association between cumulative BP (cBP) load and dementia, cognitive decline, all-cause and cardiovascular deaths in older Australians. We also explored whether seated versus standing BP were associated with these outcomes.

METHODS

The Sydney Memory and Aging Study included 1037 community-dwelling individuals aged 70-90 years, recruited from Sydney, Australia. Baseline data was collected in 2005-2007 and the cohort was followed for seven waves until 2021. cSBP load was calculated as the area under the curve (AUC) for SBP ≥140 mmHg divided by the AUC for all SBP values. Cumulative diastolic BP (cDBP) and pulse pressure (cPP) load were calculated using thresholds of 90 mmHg and 60 mmHg. Cox and mixed linear models were used to assess associations.

RESULTS

Of 527 participants with both seated and standing BP data (47.7% men, median age 77), 152 (28.8%) developed dementia over a mean follow-up of 10.5 years. Higher cPP load was associated with a higher risk of all-cause deaths, and cSBP load was associated with a higher risk of cardiovascular deaths in multivariate models (P for trend < 0.05). Associations between cPP load, dementia and cognitive decline lost statistical significance after adjustment for age. Differences between sitting and standing BP load were not associated with the outcomes.

CONCLUSION

Long-term cPP load was associated with a higher risk of all-cause deaths and cSBP load associated with a higher risk of cardiovascular deaths in older Australians.

Growth differentiation factor 15 (GDF15) levels are associated with malnutrition in acutely admitted older adults

BACKGROUND AND AIMS

The aging process is often accompanied by high risk of malnutrition and elevated levels of growth differentiation factor 15 (GDF15). GDF15 is an increasingly recognized biomarker for regulation of metabolism, but few studies have investigated the connection between GDF15 and malnutrition in older age and how it relates to other features of aging such as decreased appetite and physical function. Therefore, we investigated the associations between GDF15 levels and nutritional status, appetite, and physical function in acutely admitted older adults.

METHODS

Plasma GDF15 levels were measured using immunoassays in 302 older adults (≥65 years) admitted to the emergency department (ED). Nutritional status was evaluated with the Mini Nutritional Assessment Short-Form (MNA®-SF), appetite was evaluated with the Simplified Nutritional Appetite Questionnaire (SNAQ), and physical function was evaluated with handgrip strength (HGS), 30-s chair stand test (30s-RSS), and gait speed (GS). Associations between GDF15 and each outcome was determined by logistic regression adjusted for age, sex, and C-reactive protein (CRP).

RESULTS

Each doubling in plasma GDF15 level was associated with an adjusted odds ratio (OR) (95% confidence interval) of 1.59 (1.10-2.29, P = 0.01) for risk of malnutrition compared to normal nutrition and 1.19 (0.85-1.69, P = 0.3)) for malnutrition compared to risk of malnutrition. Each doubling in GDF15 was associated with an adjusted OR of 1.63 (1.21-2.23)) for having poor appetite, 1.46 (1.07-1.99) for having low HGS, 1.74 (1.23-2.51) for having low 30s-RSS, and 1.99 (1.39-2.94) for having low GS.

CONCLUSION

Among older adults admitted to the ED, higher GDF15 levels were significantly associated with malnutrition, poor appetite, and low physical function independent of age, sex, and CRP.

Lifestyle and incident dementia: A COSMIC individual participant data meta‐analysis

INTRODUCTION

The LIfestyle for BRAin Health (LIBRA) index yields a dementia risk score based on modifiable lifestyle factors and is validated in Western samples. We investigated whether the association between LIBRA scores and incident dementia is moderated by geographical location or sociodemographic characteristics.

METHODS

We combined data from 21 prospective cohorts across six continents (N = 31,680) and conducted cohort-specific Cox proportional hazard regression analyses in a two-step individual participant data meta-analysis.

RESULTS

A one-standard-deviation increase in LIBRA score was associated with a 21% higher risk for dementia. The association was stronger for Asian cohorts compared to European cohorts, and for individuals aged ≤75 years (vs older), though only within the first 5 years of follow-up. No interactions with sex, education, or socioeconomic position were observed.

DISCUSSION

Modifiable risk and protective factors appear relevant for dementia risk reduction across diverse geographical and sociodemographic groups.

HIGHLIGHTS

A two-step individual participant data meta-analysis was conducted. This was done at a global scale using data from 21 ethno-regionally diverse cohorts. The association between a modifiable dementia risk score and dementia was examined. The association was modified by geographical region and age at baseline. Yet, modifiable dementia risk and protective factors appear relevant in all investigated groups and regions.

Poor mobility and lower limb weakness are associated with three distinct depressive symptom trajectories over 6 years in older people

OBJECTIVES

Physical decline can be associated with the onset of depressive symptoms in later life. This study aimed to identify physical and lifestyle risk factors for depressive symptom trajectories in community-dwelling older adults.

METHODS

Participants were 553 people aged 70-90 years who underwent baseline physical, psychological and lifestyle assessments. Group-based trajectory analysis was used to identify patterns of depressive symptom development over 6 years of follow-up. Strengths of associations between baseline functional test performances and depressive symptom trajectories were evaluated with univariable ordinal models. Subsequently, the adjusted cumulative odds ratio for the association between identified risk factors, demographic factors and baseline anti-depressant use were measured using multivariable ordinal logistic regression.

RESULTS

Three distinct depressive symptom trajectories were identified: a low-and-stable course (10% of participants), a low-and-increasing course (81%) and a moderate-and-increasing course (9%). Timed Up and Go test time was the strongest risk factor of depressive symptom trajectory, followed by Five Times Sit-to-Stand test performance, planned physical activity levels, and knee extension strength (adjusted standardised ORs 1.65, 95% CI 1.34-2.04; 1.44, 95% CI 1.16-1.77; 1.44, 95% CI 1.17-1.76 and 1.41, 95% CI 1.15-1.73 respectively). After adjusting for age, sex, body mass index and baseline anti-depressant use, Timed Up and Go test performance and knee extension strength were independently and significantly associated with depressive trajectories.

CONCLUSIONS

Timed Up and Go test times, Five Times Sit-to-Stand test performance, planned physical activity levels and knee extension strength are associated with three discrete depressive symptom trajectories. These clinical tests may help identify older adults aged 70-90 years at risk of developing depressive symptoms and help guide subsequent strength and mobility interventions.

Longitudinal alcohol-related brain changes in older adults: The Sydney Memory and Ageing Study

Increases in harmful drinking among older adults indicate the need for a more thorough understanding of the relationship between later-life alcohol use and brain health. The current study investigated the relationships between alcohol use and progressive grey and white matter changes in older adults using longitudinal data. A total of 530 participants (aged 70 to 90 years; 46.0% male) were included. Brain outcomes assessed over 6 years included total grey and white matter volume, as well as volume of the hippocampus, thalamus, amygdala, corpus callosum, orbitofrontal cortex and insula. White matter integrity was also investigated. Average alcohol use across the study period was the main exposure of interest. Past-year binge drinking and reduction in drinking from pre-baseline were additional exposures of interest. Within the context of low-level average drinking (averaging 11.7 g per day), higher average amount of alcohol consumed was associated with less atrophy in the left (B = 7.50, pFDR = 0.010) and right (B = 5.98, pFDR = 0.004) thalamus. Past-year binge-drinking was associated with poorer white matter integrity (B = -0.013, pFDR = 0.024). Consuming alcohol more heavily in the past was associated with greater atrophy in anterior (B = -12.73, pFDR = 0.048) and posterior (B = -17.88, pFDR = 0.004) callosal volumes over time. Across alcohol exposures and neuroimaging markers, no other relationships were statistically significant. Within the context of low-level drinking, very few relationships between alcohol use and brain macrostructure were identified. Meanwhile, heavier drinking was negatively associated with white matter integrity.

Critical periods for cognitive reserve building activities for late life global cognition and cognitive decline: the Sydney memory and aging cohort study

Cognitive, social, and physical activities, collectively linked to cognitive reserve, are associated with better late-life cognitive outcomes. To better understand the building of cognitive reserve, we investigated which of these activities, during which stages of life, had the strongest associations with late-life cognitive performance. From the Sydney Memory and Aging Study, 546 older Australians, who were community-dwelling and without a dementia diagnosis at recruitment (Mage 80.13 years, 52.2% female), were asked about their engagement in social, physical, and cognitive activities throughout young adulthood (YA), midlife (ML), and late-life (LL). Comprehensive neuropsychological testing administered biennially over 6 years measured baseline global cognition and cognitive decline. In our study, YA, but not ML nor LL, cognitive activity was significantly associated with late-life global cognition (β = 0.315, p < .001). A follow-up analysis pointed to the formal education component of the YA cognitive activity measure, rather than YA cognitive leisure activities, as a significant predictor of better late-life global cognition (β = 0.146, p = .003). YA social activity and LL cognitive activity were significantly associated with less cognitive decline (β = 0.023, p < .001, and β = 0.016, p = .022, respectively). Physical activity was not found to be associated with global cognition or cognitive decline. Overall, YA cognitive activity was associated with better late-life cognition, and YA social and LL cognitive activities were associated with less cognitive decline. Formal education emerges as the key contributor in the association between YA cognitive activity and late-life global cognition.

Cognitive and physical declines and falls in older people with and without mild cognitive impairment: a 7-year longitudinal study

OBJECTIVES

We examined longitudinal changes in cognitive and physical function and associations between change in function and falls in people with and without mild cognitive impairment (MCI).

DESIGN

Prospective cohort study with assessments every 2 years (for up to 6 years).

SETTING

Community, Sydney, Australia.

PARTICIPANTS

Four hundred and eighty one people were classified into three groups: those with MCI at baseline and MCI or dementia at follow-up assessments (n = 92); those who fluctuated between cognitively normal and MCI throughout follow-up (cognitively fluctuating) (n = 157), and those who were cognitively normal at baseline and all reassessments (n = 232).

MEASUREMENTS

Cognitive and physical function measured over 2-6 years follow-up. Falls in the year following participants' final assessment.

RESULTS

In summary, 27.4%, 38.5%, and 34.1% of participants completed 2, 4, and 6 years follow-up of cognitive and physical performance, respectively. The MCI and cognitive fluctuating groups demonstrated cognitive decline, whereas the cognitively normal group did not. The MCI group had worse physical function than the cognitively normal group at baseline but decline over time in physical performance was similar across all groups. Decline in global cognitive function and sensorimotor performance were associated with multiple falls in the cognitively normal group and decline in mobility (timed-up-and-go test) was associated with multiple falls across the whole sample.

CONCLUSIONS

Cognitive declines were not associated with falls in people with MCI and fluctuating cognition. Declines in physical function were similar between groups and decline in mobility was associated with falls in the whole sample. As exercise has multiple health benefits including maintaining physical function, it should be recommended for all older people. Programs aimed at mitigating cognitive decline should be encouraged in people with MCI.

Examining the validity of the Mini-Mental State Examination (MMSE) and its domains using network analysis

BACKGROUND

The Mini-Mental State Examination (MMSE) is the most widely used standardised screener for impairments across a range of cognitive domains. However, the degree to which its domains (orientation, registration, attention, recall, language, and visuospatial) capture cognitive functioning measured using standardised neuropsychological tests is unclear.

METHOD

A longitudinal research design with four biannual assessments over a 6-year period was used with an initial sample of 1037 older adults (aged above 70 years). Participants completed MMSE and neuropsychological tests at each assessment. Network analysis was utilised to investigate unique associations among the MMSE and its domains and neuropsychological test performance at each time point.

RESULTS

The total MMSE and two of its domains, language and recall, were associated with neuropsychological memory performance. The MMSE orientation, registration and visuospatial domains did not have any unique associations with neuropsychological performance. No stable internal interconnections between MMSE domains were found over time. The association of total MMSE as well as its recall domain with neuropsychological memory performance remained very similar over the 6-year period.

CONCLUSIONS

The present study adds evidence to the validity of the MMSE and supports the clinical usage of the MMSE, whereby the total score is used for screening patients with or without cognitive impairments, with repeated administration to monitor cognitive changes over time, to inform intervention. However, the tool is not able to diagnose the cases for changes in specific cognitive domains and as such, should not replace a complete neuropsychological assessment.

Enhancing precision of the 16-item Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE-16) using Rasch methodology

OBJECTIVE

This study aimed to investigate psychometric properties and enhance precision of the 16-item Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE-16) up to interval-level scale using Rasch methodology.

DESIGN

Partial Credit Rasch model was applied to the IQCODE-16 scores using longitudinal data spanning 10 years of biennial follow-up.

SETTING

Community-dwelling older adults aged 70-90 years and their informants, living in Sydney, Australia, participated in the longitudinal Sydney Memory and Ageing Study (MAS).

PARTICIPANTS

The sample included 400 participants of the MAS aged 70 years and older, 109 out of those were diagnosed with dementia 10 years after the baseline assessment.

MEASUREMENTS

The IQCODE-16.

RESULTS

Initial analysis indicated excellent reliability of the IQCODE-16, Person Separation Index (PSI) = 0.92, but there were four misfitting items and local dependency issues. Combining locally dependent items into four super-items resulted in the best Rasch model fit with no misfitting or locally dependent items, strict unidimensionality, strong reliability, and invariance across person factors such as participants' diagnosis and relationship to their informants, as well as informants' age and sex. This permitted the generation of conversion algorithms to transform ordinal scores into interval data to enhance precision of measurement.

CONCLUSIONS

The IQCODE-16 demonstrated strong reliability and satisfied expectations of the unidimensional Rasch model after minor modifications. Ordinal-to-interval transformation tables published here can be used to increase accuracy of the IQCODE-16 without altering its current format. These findings could contribute to enhancement of precision in assessing clinical conditions such as cognitive decline in older people.

Associations of Osteoarthritis with Prevalence and Incidence of Cardiovascular Disease over 10 Years in Community-Dwelling Older Adults: The Sydney Memory and Ageing Study

INTRODUCTION

The data are limited for the association between osteoarthritis (OA) and cardiovascular disease (CVD) in community-based older populations and whether there is sex difference. This study aimed to examine the relationship between OA and prevalence and incidence of CVD over 10 years in community-dwelling older adults.

METHODS

Data on self-reported OA, high cholesterol, hypertension, and type 2 diabetes were collected from 1,025 community-dwelling participants aged 70-90 years in the Sydney Memory and Ageing Study. The presence of CVD at baseline was defined as self-reported presence of stroke, heart attack, transient ischaemic attack, angina, aortic aneurysm, or claudication. The incidence of CVD was defined by a combination of incident self-reported CVD or CVD mortality at different follow-up timepoints over 10 years.

RESULTS

At baseline, 395 (38.5%) participants self-reported OA (252 [44.6%] women, 143 [31.1%] men). Self-reported OA was associated with increased prevalence of CVD in women (OR 1.67, 95% CI 1.12-2.47) but not men (1.26, 0.80-1.98). In the total population, self-reported OA at baseline was associated with increased incidence of CVD at 4 years (OR 1.77, 95% CI 1.10-2.83), 6 years (1.59, 1.03-2.46), 8 years (1.56, 1.02-2.38), and 10 years (1.66, 1.10-2.50), but not at 2 years (1.43, 0.79-2.57). Significant associations were observed in female participants at 4, 8, and 10 years, with no significant associations seen in male participants.

CONCLUSION

OA was associated with increased prevalence at baseline and incidence of CVD over 10 years in community-based older adults, especially women. Identifying those with OA to target their cardiovascular risk factors while managing their OA has the potential to reduce the burden of CVD in older people, particularly women.

The combination of olfactory dysfunction and depression increases the risk of incident dementia in older adults

OBJECTIVES

Olfactory dysfunction and depression are common in later life, and both have been presented as risk factors for dementia. Our purpose was to investigate the associations between these two risk factors and determine if they had an additive effect on dementia risk.

DESIGN

Olfactory function was assessed using the Brief Smell Identification Test (BSIT), and depression was classified using a combination of the 15-item Geriatric Depression Scale (GDS) score and current antidepressant use. Cross-sectional associations between depression and olfactory function were examined using correlations. Cox regression analyses were conducted to examine the longitudinal relationship between olfaction and depression and incident dementia across 12-years of follow-up.

PARTICIPANTS

Participants were 780 older adults (aged 70-90 years; 56.5% female) from the Sydney Memory and Ageing Study (MAS) without a diagnosis of dementia at baseline.

RESULTS

Partial correlation revealed a nonsignificant association between baseline depression and olfactory function after accounting for covariates (r = -.051, p = .173). Cox regression showed that depression at baseline (hazard ratio = 1.706, 95% CI 1.185-2.456, p = .004) and lower BSIT scores (HR = .845, 95%CI .789-.905, p < .001) were independently associated with a higher risk of incident dementia across 12 years. Entering both predictors together improved the overall predictive power of the model.

CONCLUSIONS

Lower olfactory identification scores and depressive symptoms predict incident dementia over 12 years. The use of BSIT scores and depression in conjunction provides a greater ability to predict dementia than either used alone. Assessment of olfactory function and depression screening may provide clinical utility in the early detection of dementia.

Risk factors and cognitive correlates of white matter hyperintensities in ethnically diverse populations without dementia: The COSMIC consortium

INTRODUCTION

White matter hyperintensities (WMHs) are an important imaging marker for cerebral small vessel diseases, but their risk factors and cognitive associations have not been well documented in populations of different ethnicities and/or from different geographical regions.

METHODS

We investigated how WMHs were associated with vascular risk factors and cognition in both Whites and Asians, using data from five population-based cohorts of non-demented older individuals from Australia, Singapore, South Korea, and Sweden (N = 1946). WMH volumes (whole brain, periventricular, and deep) were quantified with UBO Detector and harmonized using the ComBat model. We also harmonized various vascular risk factors and scores for global cognition and individual cognitive domains.

RESULTS

Factors associated with larger whole brain WMH volumes included diabetes, hypertension, stroke, current smoking, body mass index, higher alcohol intake, and insufficient physical activity. Hypertension and stroke had stronger associations with WMH volumes in Whites than in Asians. No associations between WMH volumes and cognitive performance were found after correction for multiple testing.

CONCLUSION

The current study highlights ethnic differences in the contributions of vascular risk factors to WMHs.

Correlates of Gait Speed Among Older Adults From 6 Countries: Findings From the COSMIC Collaboration

BACKGROUND

Few studies have compared gait speed and its correlates among different ethnogeographic regions. The goals of this study were to describe usual and rapid gait speed, and identify their correlates across Australian, Asian, and African countries.

METHODS

We used data from 6 population-based cohorts of adults aged 65+ from 6 countries and 3 continents (N = 6 472), with samples ranging from 231 to 1 913. All cohorts are members of the Cohort Studies of Memory in an International Consortium collaboration. We investigated whether clinical (body mass index [BMI], hypertension, stroke, apolipoprotein status), psychological (cognition, mood, general health), and behavioral factors (smoking, drinking, physical activity) correlated with usual (N = 4 cohorts) and rapid gait speed (N = 3 cohorts) similarly across cohorts. Regression models were controlled for age, sex, and education, and were sex-stratified.

RESULTS

Age- and sex-standardized usual gait speed means ranged from 0.61 to 1.06 m/s and rapid gait speed means ranged from 1.16 to 1.64 m/s. Lower BMI and better cognitive function consistently correlated with faster gait speed in all cohorts. Less consistently, not having hypertension and greater physical activity engagement were associated with faster gait speed. Associations with mood, smoking, and drinking were largely nonsignificant. These patterns were not attenuated by demographics. There was limited evidence that the associations differed by sex, except physical activity, where the greater intensity was associated with usual gait among men but not women.

CONCLUSIONS

This study is among the first to describe the usual and rapid gait speeds across older adults in Africa, Asia, and Australia.

Frequency of cognitive "super-aging" in three Australian samples using different diagnostic criteria

OBJECTIVES

To investigate the frequency of exceptional cognition (cognitive super-aging) in Australian older adults using different published definitions, agreement between definitions, and the relationship of super-aging status with function, brain imaging markers, and incident dementia.

DESIGN

Three longitudinal cohort studies.

SETTING

Participants recruited from the electoral roll, Australian Twins Registry, and community advertisements.

PARTICIPANTS

Older adults (aged 65-106) without dementia from the Sydney Memory and Ageing Study (n = 1037; median age 78), Older Australian Twins Study (n = 361; median age 68), and Sydney Centenarian Study (n = 217; median age 97).

MEASUREMENTS

Frequency of super-aging was assessed using nine super-aging definitions based on performance on neuropsychological testing. Levels of agreement between definitions were calculated, and associations between super-aging status for each definition and functioning (Bayer ADL score), structural brain imaging measures, and incident dementia were explored.

RESULTS

Frequency of super-aging varied between 2.9 and 43.4 percent with more stringent definitions associated with lower frequency. Agreement between different criteria varied from poor (K = 0.04, AC1 = .24) to very good (K = 0.83, AC1 = .91) with better agreement between definitions using similar tests and cutoffs. Super-aging was associated with better functional performance (4.7-11%) and lower rates of incident dementia (hazard ratios 0.08-0.48) for most definitions. Super-aging status was associated with a lower burden of white matter hyperintensities (3.8-33.2%) for all definitions.

CONCLUSIONS

The frequency of super-aging is strongly affected by the demographic and neuropsychological testing parameters used. Greater consistency in defining super-aging would enable better characterization of this exceptional minority.

Social connections and risk of incident mild cognitive impairment, dementia, and mortality in 13 longitudinal cohort studies of ageing

INTRODUCTION

Previous meta-analyses have linked social connections and mild cognitive impairment, dementia, and mortality. However, these used aggregate data from North America and Europe and examined a limited number of social connection markers.

METHODS

We used individual participant data (N = 39271, Mage  = 70.67 (40-102), 58.86% female, Meducation  = 8.43 years, Mfollow-up  = 3.22 years) from 13 longitudinal ageing studies. A two-stage meta-analysis of Cox regression models examined the association between social connection markers with our primary outcomes.

RESULTS

We found associations between good social connections structure and quality and lower risk of incident mild cognitive impairment (MCI); between social structure and function and lower risk of incident dementia and mortality. Only in Asian cohorts, being married/in a relationship was associated with reduced risk of dementia, and having a confidante was associated with reduced risk of dementia and mortality.

DISCUSSION

Different aspects of social connections - structure, function, and quality - are associated with benefits for healthy aging internationally.

HIGHLIGHTS

Social connection structure (being married/in a relationship, weekly community group engagement, weekly family/friend interactions) and quality (never lonely) were associated with lower risk of incident MCI. Social connection structure (monthly/weekly friend/family interactions) and function (having a confidante) were associated with lower risk of incident dementia. Social connection structure (living with others, yearly/monthly/weekly community group engagement) and function (having a confidante) were associated with lower risk of mortality. Evidence from 13 longitudinal cohort studies of ageing indicates that social connections are important targets for reducing risk of incident MCI, incident dementia, and mortality. Only in Asian cohorts, being married/in a relationship was associated with reduced risk of dementia, and having a confidante was associated with reduced risk of dementia and mortality.

Apathy as a determinant of health behaviors in older adults: Implications for dementia risk reduction

INTRODUCTION

Long-term improvements in physical inactivity and other behavioral risk factors are integral to dementia risk reduction; however, sustained behavior change is challenging. Apathy, depression, and fatigue may impact engagement in health behaviors, but their presentation overlaps. This study investigates whether these symptoms are differentially associated with multiple health behaviors.

METHODS

In 1037 community-dwelling older adults without dementia (aged 70-90, 55% women), regression analyses examined apathy, depression, and fatigue as predictors of health behaviors (physical activity, diet, alcohol, smoking) and a behavioral risk index.

RESULTS

Apathy was associated with reduced physical activity and alcohol use, and one or multiple behavioral risk factors. No or inconsistent relations were found between depression or fatigue and health behaviors.

DISCUSSION

Apathy is relevant to multiple health behaviors and should be considered when designing health promotion for older adults, including interventions for dementia risk reduction. Findings highlight the importance of distinguishing apathy from comorbid symptoms.

Highlights

Novel theory-based perspective on behavioural risk factors for dementia.Higher apathy predicted less physical activity and alcohol use, and increased odds of lifestyle risk factors.Depressive symptoms were not associated with any health behavior.Apathy may be a determinant of multiple health behaviors in older adults, distinct from depression and fatigue.Considering apathy in precision prevention of dementia appears warranted.

Study protocol for development and validation of a single tool to assess risks of stroke, diabetes mellitus, myocardial infarction and dementia: DemNCD-Risk

INTRODUCTION

Current efforts to reduce dementia focus on prevention and risk reduction by targeting modifiable risk factors. As dementia and cardiometabolic non-communicable diseases (NCDs) share risk factors, a single risk-estimating tool for dementia and multiple NCDs could be cost-effective and facilitate concurrent assessments as compared with a conventional single approach. The aim of this study is to develop and validate a new risk tool that estimates an individual's risk of developing dementia and other NCDs including diabetes mellitus, stroke and myocardial infarction. Once validated, it could be used by the public and general practitioners.

METHODS AND ANALYSIS

Ten high-quality cohort studies from multiple countries were identified, which met eligibility criteria, including large representative samples, long-term follow-up, data on clinical diagnoses of dementia and NCDs, recognised modifiable risk factors for the four NCDs and mortality data. Pooled harmonised data from the cohorts will be used, with 65% randomly allocated for development of the predictive model and 35% for testing. Predictors include sociodemographic characteristics, general health risk factors and lifestyle/behavioural risk factors. A subdistribution hazard model will assess the risk factors' contribution to the outcome, adjusting for competing mortality risks. Point-based scoring algorithms will be built using predictor weights, internally validated and the discriminative ability and calibration of the model will be assessed for the outcomes. Sensitivity analyses will include recalculating risk scores using logistic regression.

ETHICS AND DISSEMINATION

Ethics approval is provided by the University of New South Wales Human Research Ethics Committee (UNSW HREC; protocol numbers HC200515, HC3413). All data are deidentified and securely stored on servers at Neuroscience Research Australia. Study findings will be presented at conferences and published in peer-reviewed journals. The tool will be accessible as a public health resource. Knowledge translation and implementation work will explore strategies to apply the tool in clinical practice.

Use of Antihypertensives, Blood Pressure, and Estimated Risk of Dementia in Late Life: An Individual Participant Data Meta-Analysis

Importance

The utility of antihypertensives and ideal blood pressure (BP) for dementia prevention in late life remains unclear and highly contested.

Objectives

To assess the associations of hypertension history, antihypertensive use, and baseline measured BP in late life (age >60 years) with dementia and the moderating factors of age, sex, and racial group.

Data Source and Study Selection

Longitudinal, population-based studies of aging participating in the Cohort Studies of Memory in an International Consortium (COSMIC) group were included. Participants were individuals without dementia at baseline aged 60 to 110 years and were based in 15 different countries (US, Brazil, Australia, China, Korea, Singapore, Central African Republic, Republic of Congo, Nigeria, Germany, Spain, Italy, France, Sweden, and Greece).

Data Extraction and Synthesis

Participants were grouped in 3 categories based on previous diagnosis of hypertension and baseline antihypertensive use: healthy controls, treated hypertension, and untreated hypertension. Baseline systolic BP (SBP) and diastolic BP (DBP) were treated as continuous variables. Reporting followed the Preferred Reporting Items for Systematic Review and Meta-Analyses of Individual Participant Data reporting guidelines.

Main Outcomes and Measures

The key outcome was all-cause dementia. Mixed-effects Cox proportional hazards models were used to assess the associations between the exposures and the key outcome variable. The association between dementia and baseline BP was modeled using nonlinear natural splines. The main analysis was a partially adjusted Cox proportional hazards model controlling for age, age squared, sex, education, racial group, and a random effect for study. Sensitivity analyses included a fully adjusted analysis, a restricted analysis of those individuals with more than 5 years of follow-up data, and models examining the moderating factors of age, sex, and racial group.

Results

The analysis included 17 studies with 34 519 community dwelling older adults (20 160 [58.4%] female) with a mean (SD) age of 72.5 (7.5) years and a mean (SD) follow-up of 4.3 (4.3) years. In the main, partially adjusted analysis including 14 studies, individuals with untreated hypertension had a 42% increased risk of dementia compared with healthy controls (hazard ratio [HR], 1.42; 95% CI 1.15-1.76; P = .001) and 26% increased risk compared with individuals with treated hypertension (HR, 1.26; 95% CI, 1.03-1.53; P = .02). Individuals with treated hypertension had no significant increased dementia risk compared with healthy controls (HR, 1.13; 95% CI, 0.99-1.28; P = .07). The association of antihypertensive use or hypertension status with dementia did not vary with baseline BP. There was no significant association of baseline SBP or DBP with dementia risk in any of the analyses. There were no significant interactions with age, sex, or racial group for any of the analyses.

Conclusions and Relevance

This individual patient data meta-analysis of longitudinal cohort studies found that antihypertensive use was associated with decreased dementia risk compared with individuals with untreated hypertension through all ages in late life. Individuals with treated hypertension had no increased risk of dementia compared with healthy controls.

Measuring Empathy Across the Adult Lifespan: A Comparison of Three Assessment Types

Empathy is a core component of social cognition that can be indexed via behavioral, informant-report, or self-report methods of assessment. However, concerns have been raised regarding the lack of convergence between these assessment approaches for cognitive empathy. Here, we provided the first comparison of all three measurement approaches for cognitive and affective empathy in a large adult sample (N = 371) aged 18 to 101 years. We found that poor convergence was more of a problem for cognitive empathy than affective empathy. While none of the cognitive empathy measures correlated with each other, for affective empathy, self-report was significantly associated with both behavioral and informant-report assessments. However, for both cognitive and affective empathy, there was evidence for poor discriminant validity within the measures. Out of the three assessment approaches, only the informant-report measures were consistently associated with indices of social functioning. Importantly, age did not moderate any of the tested relationships, indicating that both the strengths and the limitations of these different types of assessment do not appear to vary as a function of age. These findings highlight the variation that exists among empathy measures and are discussed in relation to their practical implications for the assessment of empathy.

Using network analysis to validate domains of the modified telephone interview for cognitive status

BACKGROUND

The modified Telephone Interview for Cognitive Status (TICS-M) is a widely used tool for assessing global cognitive functions and screening for cognitive impairments. The tool was conceptualised to capture various cognitive domains, but the validity of such domains has not been investigated against comprehensive neuropsychological assessments tools. Therefore, this study aimed to explore the associations between the TICS-M domains and neuropsychological domains to evaluate the validity of the TICS-M domains using network analysis.

MATERIALS AND METHODS

A longitudinal research design was used with a large sample of older adults (aged above 70 years; n = 1037 at the baseline assessment) who completed the TICS-M and comprehensive neuropsychological assessments biennially. We applied network analysis to identify unique links between the TICS-M domains and neuropsychological test scores.

RESULTS

At baseline, there were weak internal links between the TICS-M domains. The TICS-M memory and language domains were significantly related to their corresponding neuropsychological domains. The TICS-M attention domain had significant associations with executive function and visuospatial abilities. The TICS-M orientation domain was not significantly associated with any of the five neuropsychological domains. Despite an attrition of almost 50% at wave four, weak internal links between the TICS-M domains and most associations between TICS-M and neuropsychological domains that were found initially, remained stable at least over two waves within the 6-year period.

CONCLUSIONS

This study supports the overall structural validity of the TICS-M screener in assessing enduring global cognitive function. However, separate TICS-M cognitive domains should not be considered equivalent to the analogous neuropsychological domains.

Risk factors and cognitive correlates of white matter hyperintensities in ethnically diverse populations without dementia: the COSMIC consortium

INTRODUCTION

White matter hyperintensities (WMH) are an important imaging marker for cerebral small vessel diseases, but their risk factors and cognitive associations have not been well-documented in populations of different ethnicities and/or from different geographical regions.

METHOD

Magnetic resonance imaging data of five population-based cohorts of non-demented older individuals from Australia, Singapore, South Korea, and Sweden (N = 1,946) were examined for WMH and their associations with vascular risk factors and cognition.

RESULT

Factors associated with larger whole brain WMH volumes included diabetes, hypertension, stroke, current smoking, body mass index, higher alcohol intake and insufficient physical activity. Participants with moderate or higher physical activity had less WMH than those who never exercised, but the former two groups did not differ. Hypertension and stroke had stronger associations with WMH volumes in the White, compared to Asian subsample.

DISCUSSION

The current study highlighted the ethnic differences in the contributions of vascular risk factors to WMH.

Parental history of dementia and the risk of dementia: A cross-sectional analysis of a global collaborative study

BACKGROUND

Parental history of dementia appears to increase the risk of dementia, but there have been inconsistent results. We aimed to investigate whether the association between parental history of dementia and the risk of dementia are different by dementia subtypes and sex of parent and offspring.

METHODS

For this cross-sectional study, we harmonized and pooled data for 17,194 older adults from nine population-based cohorts of eight countries. These studies conducted face-to-face diagnostic interviews, physical and neurological examinations, and neuropsychological assessments to diagnose dementia. We investigated the associations of maternal and paternal history of dementia with the risk of dementia and its subtypes in offspring.

RESULTS

The mean age of the participants was 72.8 ± 7.9 years and 59.2% were female. Parental history of dementia was associated with higher risk of dementia (odds ratio [OR] = 1.47, 95% confidence interval [CI] = 1.15-1.86) and Alzheimer's disease (AD) (OR = 1.72, 95% CI = 1.31-2.26), but not with the risk of non-AD. This was largely driven by maternal history of dementia, which was associated with the risk of dementia (OR = 1.51, 95% CI = 1.15-1.97) and AD (OR = 1.80, 95% CI = 1.33-2.43) whereas paternal history of dementia was not. These results remained significant when males and females were analyzed separately (OR = 2.14, 95% CI = 1.28-3.55 in males; OR = 1.68, 95% CI = 1.16-2.44 for females).

CONCLUSIONS

Maternal history of dementia was associated with the risk of dementia and AD in both males and females. Maternal history of dementia may be a useful marker for identifying individuals at higher risk of AD and stratifying the risk for AD in clinical trials.

Risk Factors for Falls and Fall-Related Fractures in Community-Living Older People with Pain: A Prospective Cohort Study

(1) Background: This prospective study aimed to identify predictors of falls and fall-related fractures in community-dwelling older people with pain; (2) Methods: Participants comprised 389 community-dwelling older people aged 70+ years who had musculoskeletal pain in the neck, back, hip, leg/knee and/or feet. Demographic, anthropometric, balance, mobility, cognitive function, psychological status and physical activity level measures were obtained at baseline. Falls were monitored with monthly falls calendars for 12 months. Logistic regression analyses were performed to identify predictors of falls and fall-related fractures during a 12-month follow-up; (3) Results: Of the 389 participants, 175 (45.0%) and 20 (5.1%) reported falls and fall-related fractures during the 12-month follow-up, respectively. Greater postural sway on foam, more depressive symptoms and lower physical activity levels at baseline were associated with falls during the 12-month follow-up. Slower walking speed at baseline was associated with fall-related fractures during the 12-month follow-up. These associations remained significant after adjusting for age, sex, body mass index, comorbidities and medication use; (4) Conclusions: This study suggests poor balance, low mood and a less active lifestyle are predictors of falls, and slower walking speed predicts fall-related fractures among community-dwelling older people with pain.

Vitamin D supplementation and cognition-Results from analyses of the D-Health trial

BACKGROUND

Observational studies have consistently found a link between low serum 25-hydroxyvitamin D concentration and higher risk of cognitive impairment. Results from randomized controlled trials have been mixed, and few have been conducted in the general population.

METHODS

We recruited 21,315 community-dwelling Australians aged between 60 and 84 years to participate in the D-Health Trial, a randomized, double-blind, placebo-controlled trial. The intervention was monthly oral doses of 60,000 international units of vitamin D or placebo for 5 years. We assessed cognitive function in a randomly sampled group of participants aged ≥70 years using the Telephone Interview for Cognitive Status (TICS) at 2 and 5 years after randomization. The primary outcome for this analysis was TICS score; the secondary outcome was the proportion of people who had cognitive impairment (defined as TICS score ≤25). We analyzed data using mixed models (linear and logistic).

RESULTS

We interviewed 3887 participants at year 2 and 3614 participants at year 5. The mean TICS score at these time points was 32.3 and 32.2, respectively. Vitamin D supplementation did not affect cognitive function as measured by TICS score (mean difference between vitamin D and placebo groups 0.04; 95% CI -0.14 to 0.23), or alter risk of cognitive impairment (odds ratio 1.00; 95% CI 0.75 to 1.33).

CONCLUSIONS

Monthly bolus doses of vitamin D supplementation neither enhanced nor hindered cognitive function among older adults. Population-wide vitamin D supplementation of older adults that are largely vitamin D replete is unlikely to substantially benefit cognition.

Network of mental activities, cognitive function and depression in older men and women

BACKGROUND

Evidence suggests that lifestyle activities impact cognitive and mental health in older populations. However, how lifestyle factors are associated with one another, and which factors are most important for cognitive function and mental health has received comparatively little attention.

DESIGN

Bayesian-Gaussian network analysis was used to investigate unique associations between mental activities (MA; i.e., activities involving cognitive engagement), global cognition, and depression at three time-points in a large sample of older adults (baseline, 2 years, and 4 years follow-up).

SETTING

This study used longitudinal data from participants living in Australia and participating in the Sydney Memory and Ageing Study.

PARTICIPANTS

The sample included 998 participants (55% female) aged between 70 and 90, without a diagnosis of dementia at baseline.

MEASUREMENTS

Neuropsychological assessment of global cognition, self-reported depressive symptoms, and self-reported information about daily MA.

RESULTS

Cognitive functioning was positively associated with playing tabletop games and using the internet in both sexes at all time-points. MA were differentially linked in men and women. Depression was not consistently associated with MA in men across the three time-points; women who visited artistic events consistently had lower depression scores.

CONCLUSIONS

Engaging with tabletop games and using the internet was associated with better cognition in both sexes, however sex acted as a modifier for other associations. These findings are useful for future investigations that consider interactive associations between MA, cognition, and mental health in older adults, and their possible roles in promoting healthy aging.

The relationship between alcohol use and dementia in adults aged more than 60 years: a combined analysis of prospective, individual-participant data from 15 international studies

AIM

To synthesize international findings on the alcohol-dementia relationship, including representation from low- and middle-income countries.

METHODS

Individual participant data meta-analysis of 15 prospective epidemiological cohort studies from countries situated in six continents. Cox regression investigated the dementia risk associated with alcohol use in older adults aged over 60 years. Additional analyses assessed the alcohol-dementia relationship in the sample stratified by sex and by continent. Participants included 24 478 community dwelling individuals without a history of dementia at baseline and at least one follow-up dementia assessment. The main outcome measure was all-cause dementia as determined by clinical interview.

RESULTS

At baseline, the mean age across studies was 71.8 (standard deviation = 7.5, range = 60-102 years), 14 260 (58.3%) were female and 13 269 (54.2%) were current drinkers. During 151 636 person-years of follow-up, there were 2124 incident cases of dementia (14.0 per 1000 person-years). When compared with abstainers, the risk for dementia was lower in occasional [hazard ratio (HR) = 0.78; 95% confidence interval (CI) = 0.68-0.89], light-moderate (HR = 0.78; 95% CI = 0.70-0.87) and moderate-heavy drinkers (HR = 0.62; 95% CI = 0.51-0.77). There was no evidence of differences between life-time abstainers and former drinkers in terms of dementia risk (HR = 0.98; 95% CI = 0.81-1.18). In dose-response analyses, moderate drinking up to 40 g/day was associated with a lower risk of dementia when compared with lif-time abstaining. Among current drinkers, there was no consistent evidence for differences in terms of dementia risk. Results were similar when the sample was stratified by sex. When analysed at the continent level, there was considerable heterogeneity in the alcohol-dementia relationship.

CONCLUSIONS

Abstinence from alcohol appears to be associated with an increased risk for all-cause dementia. Among current drinkers, there appears to be no consistent evidence to suggest that the amount of alcohol consumed in later life is associated with dementia risk.

Measuring distress in older population: Rasch analysis of the Kessler Psychological Distress Scale

OBJECTIVES

The 10-item Kessler Psychological Distress Scale (K-10) is a widely applied distress measure; however, its psychometric properties were not established with older populations using advanced methodology. The aim of this study was to examine psychometric properties of the K-10 through application of Rasch methodology and if possible, develop an ordinal-to-interval conversion to improve its reliability in older populations.

METHOD

The Partial Credit Rasch Model was applied to analyse K-10 scores of the sample including 490 participants (56.3 % females) aged 70 to 90 years and without dementia from the Sydney Memory and Ageing Study (MAS).

RESULTS

The initial analysis of the K-10 showed poor reliability and significant deviation from the expectations of the Rasch model. The best model fit was evident after correcting disordered thresholds and creating two testlet models to address local dependency between items (χ²(35) = 29.87, p = 0.71). The modified K-10 demonstrated strict unidimensionality, enhanced reliability and scale invariance across personal factors, such as sex, age, and education and permitted development of ordinal-to-interval transformation algorithms.

LIMITATIONS

Ordinal-to-interval conversion can only be applied for older adults with complete data.

CONCLUSIONS

The K-10 satisfied principles of fundamental measurement defined by Rasch model after minor modifications. Clinicians and researchers can transform K-10 raw scores into interval-level data using converging algorithms published here without altering the original scale response format, which increases reliability of the K-10.

Establishing conversion of the 16-item Informant Questionnaire on Cognitive Decline in the Elderly scores into interval-level data across multiple samples using Rasch methodology

BACKGROUND

The 16-item Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE-16) is a well-validated and widely-used measure of cognitive changes (CCs) among older adults. This study aimed to use Rasch methodology to establish psychometric properties of the IQCODE-16 and validate the existing ordinal-to-interval transformation algorithms across multiple large samples.

METHODS

A Partial Credit Rasch model was employed to examine psychometric properties of the IQCODE-16 using data (n = 918) from two longitudinal studies of participants aged 57-99 years: the Older Australian Twins Study (n = 450) and the Canberra Longitudinal Study (n = 468), and reusing the Sydney Memory and Ageing Study (MAS) sample (n = 400).

RESULTS

Initial analyses indicated good reliability for the IQCODE-16 (Person Separation Index range: 0.82-0.90). However, local dependency was identified between items, with several items showing misfit to the model. Replicating the existing Rasch solution could not reproduce the best Rasch model fit for all samples. Combining locally dependent items into three testlets resolved all misfit and local dependency issues and resulted in the best Rasch model fit for all samples with evidence of unidimensionality, strong reliability, and invariance across person factors. Accordingly, new ordinal-to-interval transformation algorithms were produced to convert the IQCODE-16 ordinal scores into interval data to improve the accuracy of its scores.

CONCLUSIONS

The findings of this study support the reliability and validity of the IQCODE-16 in measuring CCs among older adults. New ordinal-to-interval conversion tables generated using samples from multiple independent datasets are more generalizable and can be used to enhance the precision of the IQCODE-16 without changing its original format. An easy-to-use converter has been made available for clinical and research use.

High polygenic risk score for exceptional longevity is associated with a healthy metabolic profile

Healthy metabolic measures in humans are associated with longevity. Dysregulation leads to metabolic syndrome (MetS) and negative health outcomes. Recent exceptional longevity (EL) genome wide association studies have facilitated estimation of an individual's polygenic risk score (PRS) for EL. We tested the hypothesis that individuals with high ELPRS have a low prevalence of MetS. Participants were from five cohorts of middle-aged to older adults. The primary analyses were performed in the UK Biobank (UKBB) (n = 407,800, 40-69 years). Replication analyses were undertaken using three Australian studies: Hunter Community Study (n = 2122, 55-85 years), Older Australian Twins Study (n = 539, 65-90 years) and Sydney Memory and Ageing Study (n = 925, 70-90 years), as well as the Swedish Gothenburg H70 Birth Cohort Studies (n = 2273, 70-93 years). MetS was defined using established criteria. Regressions and meta-analyses were performed with the ELPRS and MetS and its components. Generally, MetS prevalence (22-30%) was higher in the older cohorts. In the UKBB, high EL polygenic risk was associated with lower MetS prevalence (OR = 0.94, p = 1.84 × 10^-42) and its components (p < 2.30 × 10^-8). Meta-analyses of the replication cohorts showed nominal associations with MetS (p = 0.028) and 3 MetS components (p < 0.05). This work suggests individuals with a high polygenic risk for EL have a healthy metabolic profile promoting longevity.

Ensemble feature selection with data-driven thresholding for Alzheimer's disease biomarker discovery

BACKGROUND

Feature selection is often used to identify the important features in a dataset but can produce unstable results when applied to high-dimensional data. The stability of feature selection can be improved with the use of feature selection ensembles, which aggregate the results of multiple base feature selectors. However, a threshold must be applied to the final aggregated feature set to separate the relevant features from the redundant ones. A fixed threshold, which is typically used, offers no guarantee that the final set of selected features contains only relevant features. This work examines a selection of data-driven thresholds to automatically identify the relevant features in an ensemble feature selector and evaluates their predictive accuracy and stability. Ensemble feature selection with data-driven thresholding is applied to two real-world studies of Alzheimer's disease. Alzheimer's disease is a progressive neurodegenerative disease with no known cure, that begins at least 2-3 decades before overt symptoms appear, presenting an opportunity for researchers to identify early biomarkers that might identify patients at risk of developing Alzheimer's disease.

RESULTS

The ensemble feature selectors, combined with data-driven thresholds, produced more stable results, on the whole, than the equivalent individual feature selectors, showing an improvement in stability of up to 34%. The most successful data-driven thresholds were the robust rank aggregation threshold and the threshold algorithm threshold from the field of information retrieval. The features identified by applying these methods to datasets from Alzheimer's disease studies reflect current findings in the AD literature.

CONCLUSIONS

Data-driven thresholds applied to ensemble feature selectors provide more stable, and therefore more reproducible, selections of features than individual feature selectors, without loss of performance. The use of a data-driven threshold eliminates the need to choose a fixed threshold a-priori and can select a more meaningful set of features. A reliable and compact set of features can produce more interpretable models by identifying the factors that are important in understanding a disease.

Dose-response relationship between late-life physical activity and incident dementia: A pooled analysis of 10 cohort studies of memory in an international consortium

INTRODUCTION

Though consistent evidence suggests that physical activity may delay dementia onset, the duration and amount of activity required remains unclear.

METHODS

We harmonized longitudinal data of 11,988 participants from 10 cohorts in eight countries to examine the dose-response relationship between late-life physical activity and incident dementia among older adults.

RESULTS

Using no physical activity as a reference, dementia risk decreased with duration of physical activity up to 3.1 to 6.0 hours/week (hazard ratio [HR] 0.88, 95% confidence interval [CI] 0.67 to 1.15 for 0.1 to 3.0 hours/week; HR 0.68, 95% CI 0.52 to 0.89 for 3.1 to 6.0 hours/week), but plateaued with higher duration. For the amount of physical activity, a similar pattern of dose-response curve was observed, with an inflection point of 9.1 to 18.0 metabolic equivalent value (MET)-hours/week (HR 0.92, 95% CI 0.70 to 1.22 for 0.1 to 9.0 MET-hours/week; HR 0.70, 95% CI 0.53 to 0.93 for 9.1 to 18.0 MET-hours/week).

DISCUSSION

This cross-national analysis suggests that performing 3.1 to 6.0 hours of physical activity and expending 9.1 to 18.0/MET-hours of energy per week may reduce dementia risk.

Longitudinal changes in participant and informant reports of subjective cognitive complaints are associated with dementia risk

Background

Individuals with subjective cognitive complaints (SCCs) are at an increased risk of dementia. Questions remain about participant-reported versus informant-reported SCCs as indicators of future dementia and about longitudinal changes in participant-and informant-reported SCCs and risk of incident dementia.

Method

Participants were 873 older adults (M = 78.65-years; 55% female) and 849 informants from the Sydney Memory and Ageing Study. Comprehensive assessments occurred biennially, and clinical diagnoses were made by expert consensus for 10-years. SCCs were participants' and informants' responses to a single binary question concerning their/the participant's memory decline (Yes/No) over the first 6-years. Categorical latent growth curve analyses, using the logit transformation, were used to model SCC change over time. Associations of initial propensity to report SCCs at baseline, and change in propensity to report SCCs over time, with dementia risk were examined using Cox regression.

Results

70% of participants reported SCCs at baseline, with a proportional increase in the odds of reporting by 11% for each additional year in the study. In contrast, 22% of informants reported SCCs at baseline, with a proportional increase by 30% in the odds of reporting per year. Participants' initial level of (p = 0.007), but not change in SCC reporting (p = 0.179), was associated with risk of dementia controlling for all covariates. Both informants' initial level of (p < 0.001), and change in (p < 0.001), SCCs significantly predicted incident dementia. When modelled together, informants' initial level of, and change in, SCCs were still independently associated with increased dementia risk (p's < 0.001).

Conclusion

These data suggest that informants' initial impressions, and increased reporting, of SCCs appear to be uniquely prognostic of future dementia compared to participants', even based on a single SCC question.

Applying generalizability theory to examine assessments of subjective cognitive complaints: whose reports should we rely on - participant versus informant?

OBJECTIVES

This study aimed to apply the generalizability theory (G-theory) to investigate dynamic and enduring patterns of subjective cognitive complaints (SCC), and reliability of two widely used SCC assessment tools.

DESIGN

G-theory was applied to assessment scales using longitudinal measurement design with five assessments spanning 10 years of follow-up.

SETTING

Community-dwelling older adults aged 70-90 years and their informants, living in Sydney, Australia, participated in the longitudinal Sydney Memory and Ageing Study.

PARTICIPANTS

The sample included 232 participants aged 70 years and older, and 232 associated informants. Participants were predominantly White Europeans (97.8%). The sample of informants included 76 males (32.8%), 153 females (65.9%), and their age ranged from 27 to 86 years, with a mean age of 61.3 years (SD = 14.38).

MEASUREMENTS

The Memory Complaint Questionnaire (MAC-Q) and the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE).

RESULTS

The IQCODE demonstrated strong reliability in measuring enduring patterns of SCC with G = 0.86. Marginally acceptable reliability of the 6-item MAC-Q (G = 0.77-0.80) was optimized by removing one item resulting in G = 0.80-0.81. Most items of both assessments were measuring enduring SCC with exception of one dynamic MAC-Q item. The IQCODE significantly predicted global cognition scores and risk of dementia incident across all occasions, while MAC-Q scores were only significant predictors on some occasions.

CONCLUSIONS

While both informants' (IQCODE) and self-reported (MAC-Q) SCC scores were generalizable across sample population and occasions, self-reported (MAC-Q) scores may be less accurate in predicting cognitive ability and diagnosis of each individual.

Comparison of Computerised and Pencil-and-Paper Neuropsychological Assessments in Older Culturally and Linguistically Diverse Australians

OBJECTIVES

Computerised neuropsychological assessments (CNAs) are proposed as an alternative method of assessing cognition to traditional pencil-and-paper assessment (PnPA), which are considered the "gold standard" for diagnosing dementia. However, limited research has been conducted with culturally and linguistically diverse (CALD) individuals. This study investigated the suitability of PnPAs and CNAs for measuring cognitive performance in a heterogenous sample of older, Australian CALD English-speakers compared to a native English-speaking background (ESB) sample.

METHODS

Participants were 1037 community-dwelling individuals aged 70-90 years without a dementia diagnosis from the Sydney Memory and Ageing Study (873 ESB, 164 CALD). Differences in the level and pattern of cognitive performance in the CALD group were compared to the ESB group on a newly developed CNA and a comprehensive PnPA in English, controlling for covariates. Multiple hierarchical regression was used to identify the extent to which linguistic and acculturation variables explained performance variance.

RESULTS

CALD participants' performance was consistently poorer than ESB participants on both PnPA and CNA, and more so on PnPA than CNA, controlling for socio-demographic and health factors. Linguistic and acculturation variables together explained approximately 20% and 25% of CALD performance on PnPA and CNA respectively, above demographics and self-reported computer use.

CONCLUSIONS

Performances of CALD and ESB groups differed more on PnPAs than CNAs, but caution is needed in concluding that CNAs are more culturally-appropriate for assessing cognitive decline in older CALD individuals. Our findings extend current literature by confirming the influence of linguistic and acculturation variables on cognitive assessment outcomes for older CALD Australians.

Associations between social connections and cognition: a global collaborative individual participant data meta-analysis

BACKGROUND

Poor social connections (eg, small networks, infrequent interactions, and loneliness) are modifiable risk factors for cognitive decline. Existing meta-analyses are limited by reporting aggregate responses, a focus on global cognition, and combining social measures into single constructs. We aimed to investigate the association between social connection markers and the rate of annual change in cognition (ie, global and domain-specific), as well as sex differences, using an individual participant data meta-analysis.

METHODS

We harmonised data from 13 longitudinal cohort studies of ageing in North America, South America, Europe, Africa, Asia, and Australia. Studies were eligible for inclusion if they had baseline data for social connection markers and at least two waves of cognitive scores. Follow-up periods ranged from 0 years to 15 years across cohorts. We included participants with cognitive data for at least two waves and social connection data for at least one wave. We then identified and excluded people with dementia at baseline. Primary outcomes were annual rates of change in global cognition and cognitive domain scores over time until final follow-up within each cohort study analysed by use of an individual participant data meta-analysis. Linear mixed models within cohorts used baseline social connection markers as predictors of the primary outcomes. Effects were pooled in two stages using random-effects meta-analyses. We assessed the primary outcomes in the main (partially adjusted) and fully adjusted models. Partially adjusted models controlled for age, sex, and education; fully adjusted models additionally controlled for diabetes, hypertension, smoking, cardiovascular risk, and depression.

FINDINGS

Of the 40 006 participants in the 13 cohort studies, we excluded 1392 people with dementia at baseline. 38 614 individual participants were included in our analyses. For the main models, being in a relationship or married predicted slower global cognitive decline (b=0·010, 95% CI 0·000-0·019) than did being single or never married; living with others predicted slower global cognitive (b=0·007, 0·002-0·012), memory (b=0·017, 0·006-0·028), and language (b=0·008, 0·000-0·015) decline than did living alone; and weekly interactions with family and friends (b=0·016, 0·006-0·026) and weekly community group engagement (b=0·030, 0·007-0·052) predicted slower memory decline than did no interactions and no engagement. Never feeling lonely predicted slower global cognitive (b=0·047, 95% CI 0·018-0·075) and executive function (b=0·047, 0·017-0·077) decline than did often feeling lonely. Degree of social support, having a confidante, and relationship satisfaction did not predict cognitive decline across global cognition or cognitive domains. Heterogeneity was low (I2=0·00-15·11%) for all but two of the significant findings (association between slower memory decline and living with others [I2=58·33%] and community group engagement, I2=37·54-72·19%), suggesting robust results across studies.

INTERPRETATION

Good social connections (ie, living with others, weekly community group engagement, interacting weekly with family and friends, and never feeling lonely) are associated with slower cognitive decline.

FUNDING

EU Joint Programme-Neurodegenerative Disease Research grant, funded by the National Health and Medical Research Council Australia, and the US National Institute on Aging of the US National Institutes of Health.

An accelerated degeneration of white matter microstructure and networks in the nondemented old-old

The nondemented old-old over the age of 80 comprise a rapidly increasing population group; they can be regarded as exemplars of successful aging. However, our current understanding of successful aging in advanced age and its neural underpinnings is limited. In this study, we measured the microstructural and network-based topological properties of brain white matter using diffusion-weighted imaging scans of 419 community-dwelling nondemented older participants. The participants were further divided into 230 young-old (between 72 and 79, mean = 76.25 ± 2.00) and 219 old-old (between 80 and 92, mean = 83.98 ± 2.97). Results showed that white matter connectivity in microstructure and brain networks significantly declined with increased age and that the declined rates were faster in the old-old compared with young-old. Mediation models indicated that cognitive decline was in part through the age effect on the white matter connectivity in the old-old but not in the young-old. Machine learning predictive models further supported the crucial role of declines in white matter connectivity as a neural substrate of cognitive aging in the nondemented older population. Our findings shed new light on white matter connectivity in the nondemented aging brains and may contribute to uncovering the neural substrates of successful brain aging.

Aging Is Associated With Multidirectional Changes in Social Cognition: Findings From an Adult Life-Span Sample Ranging From 18 to 101 Years

OBJECTIVES

Normal adult aging is associated with changes in social cognition. Although 4 social cognitive domains have been identified (social perception, theory of mind [ToM], affective empathy, and social behavior), no study has tested all 4 domains concurrently in a life-span sample, limiting understanding of the relative magnitude of age-related changes across domains. This study addresses this gap by providing the first assessment of all 4 social cognitive domains in an adult life-span sample.

METHODS

Three hundred and seventy-two participants ranging from 18 to 101 years of age took part in this study. Participants completed a testing battery that assessed social perception, ToM, affective empathy, and social behavior, as well as broader cognitive function and well-being.

RESULTS

The results showed that adult aging is associated with multidirectional changes in social cognitive abilities, with ToM and social perception showing nonlinear decline across much of the life-span, and affective empathy and social behavior showing improvement. Age remained a significant predictor of all 4 social cognitive domains, even after accounting for broader cognitive function. Weak associations emerged between some of the social cognitive abilities and and indices of broader well-being.

DISCUSSION

These findings provide novel and important evidence that normative aging is associated with both gains and losses in social cognition that occur at distinct points of the adult life-span, and that are at least partially independent of general age-related cognitive decline.

Networks of inflammation, depression, and cognition in aging males and females

BACKGROUND

Prioritizing the maintenance of healthy cognitive aging and personalizing preventive interventions to enhance their effectiveness is crucial as the global population ages. Systemic inflammation and depression in older people have been associated with decreased levels of cognition but results have been inconsistent.

AIMS

To explore the interactive network of inflammation, depression and cognition by sex in older people.

METHODS

We used novel network analysis to explore the unique associations between inflammatory biomarkers, depression, cognition, and somatic, genetic, and lifestyle risk factors in an older (aged 70-90 years), non-demented, community-dwelling sample from the longitudinal Sydney Memory and Aging Study (N = 916) at baseline and at a two-year follow-up.

RESULTS

The networks of biomarkers, depression, cognition, and relevant covariates were significantly different between males and females. A stable negative link between depression and cognition was found in females only; a stable positive association between biomarker interleukin-6 and depression was found in females only; and a stable positive association between biomarker interleukin-8 and alcohol was found in females only. For both males and females, a stable, positive relationship was found between the presence of APOE-ε4 gene and biomarker C-reactive protein; between education and cognition; and between biomarker interleukin-6 and all other biomarkers.

CONCLUSIONS

These findings suggest different psychophysiological mechanisms underlie the interactive network of biomarkers, depression and cognition in males and females that should be considered when designing personalized preventive interventions to maintain cognitively healthy aging.

Instrumental Activities of Daily Living by Subjective and Objective Measures: The Impact of Depression and Personality

Objective

Previous research shows that depression and personality are independently associated with self- and informant-reports of the ability to perform instrumental activities of daily living (IADLs). However, less is known about the association between depression and personality and performance-based measures of IADLs. We aimed to determine how depression and personality predict self-and informant-reports of IADL compared to performance-based measures of IADLs in a sample of older adults with normal cognition (NC) and Mild Cognitive Impairment (MCI).

Methods

Participants consisted of 385 older adults with NC (n = 235), or a diagnosis of MCI (n = 150), aged between 76 and 99-years from the Sydney Memory and Ageing Study. Participants underwent comprehensive neuropsychological and clinical assessments to determine global cognition and clinical diagnoses. Personality traits were measured by the NEO Five-Factor Inventory (NEO-FFI) and depression by the Geriatric Depression Scale (GDS). Subjective IADLs were self- and informant-reported Bayer Activities of Daily Living (B-ADL) scales and objective IADL was the Sydney Test of Activities of Daily Living in Memory Disorders (STAM). Linear regressions examined the relationship between depression and personality and the three types of IADL measures, controlling for all covariates and global cognition.

Results

Participant-reported IADL, although associated with global cognition, was more strongly associated with GDS and NEO-FFI scores (conscientiousness and neuroticism). Informant-reported IADL was strongly associated with both global cognition and participants' GDS scores. STAM scores were not associated with participants' GDS or NEO-FFI scores; instead, they were predicted by demographics and global cognition.

Conclusion

These results suggest that performance-based measures of IADL may provide more objective and reliable insight into an individual's underlying functional ability and are less impacted by the participants' mood and personality compared to subjectively reported IADL. We argue that performance-based IADL measures are preferable when trying to accurately assess everyday functional ability and its relationship to cognitive status. Where performance-based measures are not available (e.g., in some clinical settings), informant ratings should be sought as they are less influenced by the participant's personality and mood compared to self-reports.

Cognitive decline is associated with frequency-specific resting state functional changes in normal aging

Resting state low-frequency brain activity may aid in our understanding of the mechanisms of aging-related cognitive decline. Our purpose was to explore the characteristics of the amplitude of low-frequency fluctuations (ALFF) in different frequency bands of fMRI to better understand cognitive aging. Thirty-seven cognitively normal older individuals underwent a battery of neuropsychological tests and MRI scans at baseline and four years later. ALFF from five different frequency bands (typical band, slow-5, slow-4, slow-3, and slow-2) were calculated and analyzed. A two-way ANOVA was used to explore the interaction effects in voxel-wise whole brain ALFF of the time and frequency bands. Paired-sample t-test was used to explore within-group changes over four years. Partial correlation analysis was performed to assess associations between the altered ALFF and cognitive function. Significant interaction effects of time × frequency were distributed over inferior frontal gyrus, superior frontal gyrus, right rolandic operculum, left thalamus, and right putamen. Significant ALFF reductions in all five frequency bands were mainly found in the right hemisphere and the posterior cerebellum; whereas localization of the significantly increased ALFF were mainly found in the cerebellum at typical band, slow-5 and slow-4 bands, and left hemisphere and the cerebellum at slow-3, slow-2 bands. In addition, ALFF changes showed frequency-specific correlations with changes in cognition. These results suggest that changes of local brain activity in cognitively normal aging should be investigated in multiple frequency bands. The association between ALFF changes and cognitive function can potentially aid better understanding of the mechanisms underlying normal cognitive aging.

Risk factors for falls in community-dwelling older people with mild cognitive impairment: a prospective one-year study

Objective

Mild cognitive impairment (MCI) is considered an intermediate stage between normal cognitive function and dementia. Fall risk is increased in this group, but there is limited literature exploring specific fall risk factors that may be addressed in fall prevention strategies. The aim of this study was to examine risk factors for falls in older people with MCI, focusing on cognitive, psychological and physical factors.

Methods

Participants (n = 266, 45% women) were community-dwelling older people aged 70-90 years who met the criteria for MCI. Cognitive, psychological, sensorimotor and physical assessments, physical activity levels, medication use, general health and disability were ascertained at baseline. Falls were monitored prospectively for 12 months.

Results

During follow-up, 106 (40%) participants reported one or more falls. Poorer visual contrast sensitivity, increased postural sway, lower levels of weekly walking activity, higher levels of depressive symptoms and psychotropic medication use were significantly associated with faller status (≥1 falls) in univariable analyses. Of these factors, poor visual contrast sensitivity, increased postural sway and psychotropic medication use were found to be significant independent predictors of falls in multivariable analysis while controlling for age and sex. No measures of cognitive function were associated with falls.

Conclusions

Poor visual contrast sensitivity, impaired balance and psychotropic medication use predicted falls in community-dwelling people with MCI. These risk factors may be amenable to intervention, so these factors could be carefully considered in fall prevention programs for this population.

Memory decline in older individuals predicts an objective indicator of oral health: findings from the Sydney Memory and Ageing Study

Background

Growing evidence suggests that there is an association between poor oral health and cognitive function in late adulthood. However, most studies to date have relied on cross-sectional research methods that do not permit inferences about the temporality of any association. Moreover, the few longitudinal studies that do exist have typically relied on small samples and quite limited cognitive or oral health assessments. The aim of the present study was therefore designed to provide the first direct evaluation of whether cognitive function is predictive of poor oral health in older adults.

Methods

This longitudinal research included data from 339 participants aged 70 years or older from The Sydney Memory and Ageing Study (MAS), a large cohort of healthy community-dwelling older adults. Cognitive function was assessed using a battery of tests at baseline (Wave 1) in 2005 and six years later (Wave 4) in 2011. In 2015 (Wave 6), participants were assessed for oral health using the Oral Health Assessment Tool (OHAT), number of functional occluding pairs of natural teeth and sublingual resting saliva pH (SRSpH). Ordinal least squares regression analysis was used to model the effect of cognitive function on total OHAT score, and binomial logistic regression used for SRSpH and occluding pairs of functional teeth.

Results

Two models were tested. In the partially adjusted model, age, gender and years of education were included. The fully adjusted model additionally included medical conditions, general health, depression, smoking, alcohol consumption, functionality, and dental care utilization. The key finding to emerge was that a six-year change in memory (from Wave 1 to Wave 4) was associated with lower sublingual resting saliva pH at Wave 6 in partially (Odds Ratio (OR) = 0.65) and fully adjusted model (OR = 0.63).

Conclusions

This longitudinal study provides further evidence that a relationship between cognitive function and oral health exists, and also points to this relationship potentially being bi-directional, as previous evidence suggests. The findings from the study also suggest that older adults who present with greater than normal memory decline at an earlier point in life were more likely to experience poor oral health when this was evaluated at a later time-point, four years later.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-022-02128-y.

Surgical Hospitalization Is Not Associated With Cognitive Trajectory Over 6 Years in Healthy Older Australians

OBJECTIVE

The aim was to investigate the association of cognitive trajectories and overnight surgical hospitalization in older adults, while controlling for and comparing with the association with acute medical hospitalizations.

DESIGN

This is a secondary analysis of data from a population-based, longitudinal cohort study of older Australians.

SETTING AND PARTICIPANTS

Cognition was assessed with 4 biennial waves of prospective neuropsychological data from 1026 Sydney Memory and Aging Study participants age 70 to 90 years at baseline. Hospitalization exposure was obtained from 10 years of electronically linked data from the New South Wales Admitted Patient Data Collection.

METHODS

Latent growth curve modeling estimated global cognition z score baseline and slope over 6 years, and the effects of contemporaneous surgical and medical hospitalization predictors while controlling for potential demographic and comorbidity confounders.

RESULTS

After controlling for confounding variables, this analysis showed that overnight surgical hospitalizations were not associated with worse baseline global cognition or accelerated cognitive decline over 6 years. This was despite this cohort having more surgeries and more complex surgeries compared with Australian data for overnight hospitalizations in over 70-year-olds. Conversely, recent medical hospitalizations were associated with accelerated cognitive decline.

CONCLUSIONS AND IMPLICATIONS

This analysis finds that surgery and anesthesia are unlikely to be risk factors for medium to long-term global cognitive decline in healthy older adults, while controlling for contemporaneous medical hospitalizations. These findings are contrary to prior conclusions from several surgical studies that may have been impeded by insufficient comparison groups. They are, however, consistent with recent population-based studies suggesting surgery has minimal association with cognitive decline in the medium to long-term. Future research needs to clarify the association of surgical hospitalization with the full spectrum of cognitive outcomes including subjective cognitive complaints and dementia, and importantly, how these cognitive outcomes correlate with clinically significant functional changes.

Machine learning, artificial intelligence and the prediction of dementia

PURPOSE OF REVIEW

Artificial intelligence and its division machine learning are emerging technologies that are increasingly applied in medicine. Artificial intelligence facilitates automatization of analytical modelling and contributes to prediction, diagnostics and treatment of diseases. This article presents an overview of the application of artificial intelligence in dementia research.

RECENT FINDINGS

Machine learning and its branch Deep Learning are widely used in research to support in diagnosis and prediction of dementia. Deep Learning models in certain tasks often result in better accuracy of detection and prediction of dementia than traditional machine learning methods, but they are more costly in terms of run times and hardware requirements. Both machine learning and Deep Learning models have their own strengths and limitations. Currently, there are few datasets with limited data available to train machine learning models. There are very few commercial applications of machine learning in medical practice to date, mostly represented by mobile applications, which include questionnaires and psychometric assessments with limited machine learning data processing.

SUMMARY

Application of machine learning technologies in detection and prediction of dementia may provide an advantage to psychiatry and neurology by promoting a better understanding of the nature of the disease and more accurate evidence-based processes that are reproducible and standardized.

Clinical investigation of dynamic and enduring aspects of global cognition in aged population

BACKGROUND

A major issue in evaluating the cognitive status of ageing populations is a clear distinction between enduring and dynamic aspects of global cognition necessary for evaluating risks of dementia and effectiveness of preventive interventions.

MATERIALS AND METHODS

Generalizability Theory was applied to investigate dynamic and enduring aspects of global cognition using longitudinal data over 10 years of follow-up. Measures included the Mini-Mental Status Examination (MMSE) and the Telephone Interview for Cognitive Status-modified (TICS-M). The sample (N = 238) included 154 females, mean age = 76.54 years, SD = 3.94 from the Sydney Memory and Ageing Study.

RESULTS

The MMSE measured dynamic and enduring aspects of cognition to a comparable degree with 56% of variance explained by enduring aspects and 44% by dynamic aspects and showed low sensitivity/high specificity in detecting dementia. A shortened version of the MMSE (MMSE-D8) better captured dynamic aspects of cognition after removing three items less sensitive to change. The TICS-M predominantly measured enduring aspects of cognition (72%) with the remaining 28% due to dynamic aspects and displayed high sensitivity/high specificity for dementia screening.

CONCLUSIONS

The MMSE measures both dynamic and enduring cognitive aspects and is suitable for general clinical assessments, while the MMSE-D8 can be used to monitor transitory changes of global cognition over time. The TICS-M is more useful for measuring enduring features of cognition and screening for dementia. Our findings highlight the value of generalizability theory to distinguish dynamic and enduring features of cognition, which may contribute to preventive interventions and monitoring cognitive ability over time.

Can detection and prediction models for Alzheimer's Disease be applied to Prodromal Parkinson's Disease using explainable artificial intelligence? A brief report on Digital Neuro Signatures

Parkinson's disease (PD) is the fastest growing neurodegeneration and has a prediagnostic phase with a lot of challenges to identify clinical and laboratory biomarkers for those in the earliest stages or those 'at risk'. Despite the current research effort, further progress in this field hinges on the more effective application of digital biomarker and artificial intelligence applications at the prediagnostic stages of PD. It is of the highest importance to stratify such prediagnostic subjects that seem to have the most neuroprotective benefit from drugs. However, current initiatives to identify individuals at risk or in the earliest stages that might be candidates for future clinical trials are still challenging due to the limited accuracy and explainability of existing prediagnostic detection and progression prediction solutions. In this brief paper, we report on a novel digital neuro signature (DNS) for prodromal-PD based on selected digital biomarkers previously discovered on preclinical Alzheimer's disease. (AD). Our preliminary results demonstrated a standard DNS signature for both preclinical AD and prodromal PD, containing a ranked selection of features. This novel DNS signature was rapidly repurposed out of 793 digital biomarker features and selected the top 20 digital biomarkers that are predictive and could detect both the biological signature of preclinical AD and the biological mechanism of a-synucleinopathy in prodromal PD. The resulting model can provide physicians with a pool of patients potentially eligible for therapy and comes along with information about the importance of the digital biomarkers that are predictive, based on SHapley Additive exPlanations (SHAP). Similar initiatives could clarify the stage before and around diagnosis, enabling the field to push into unchartered territory at the earliest stages of the disease.

Education, Occupational Complexity, and Incident Dementia: A COSMIC Collaborative Cohort Study

BACKGROUND

Education and occupational complexity are main sources of mental engagement during early life and adulthood respectively, but research findings are not conclusive regarding protective effects of these factors against late-life dementia.

OBJECTIVE

This project aimed to examine the unique contributions of education and occupational complexity to incident dementia, and to assess the mediating effects of occupational complexity on the association between education and dementia across diverse cohorts.

METHOD

We used data from 10,195 participants (median baseline age = 74.1, range = 58∼103), representing 9 international datasets from 6 countries over 4 continents. Using a coordinated analysis approach, the accelerated failure time model was applied to each dataset, followed by meta-analysis. In addition, causal mediation analyses were performed.

RESULT

The meta-analytic results indicated that both education and occupational complexity were independently associated with increased dementia-free survival time, with 28%of the effect of education mediated by occupational complexity. There was evidence of threshold effects for education, with increased dementia-free survival time associated with 'high school completion' or 'above high school' compared to 'middle school completion or below'.

CONCLUSION

Using datasets from a wide range of geographical regions, we found that both early life education and adulthood occupational complexity were independently predictive of dementia. Education and occupational experiences occur during early life and adulthood respectively, and dementia prevention efforts could thus be made at different stages of the life course.

Assay of Fatty Acids and Their Role in the Prevention and Treatment of COVID-19

Since the emergence of COVID-19, concerted worldwide efforts have taken place to minimize global spread of the contagion. Its widespread effects have also facilitated evolution of new strains, such as the delta and omicron variants, which emerged toward the end of 2020 and 2021, respectively. While these variants appear to be no more deadly than the previous alpha, beta, and gamma strains, and widespread population vaccinations notwithstanding, greater virulence makes the challenge of minimizing spread even greater. One of the peculiarities of this virus is the extreme heath impacts, with the great majority of individuals minimally affected, even sometimes unaware of infection, while for a small minority, it is deadly or produces diverse long-term effects. Apart from vaccination, another approach has been an attempt to identify treatments, for those individuals for whom the virus represents a threat of particularly severe health impact(s). These treatments include anti-SARS-CoV-2 monoclonal antibodies, anticoagulant therapies, interleukin inhibitors, and anti-viral agents such as remdesivir. Nutritional factors are also under consideration, and a variety of clinical trials are showing promise for the use of specific fatty acids, or related compounds such as fat-soluble steroid vitamin D, to mitigate the more lethal aspects of COVID-19 by modulating inflammation and by anti-viral effects. Here we explore the potential protective role of fatty acids as a potential prophylactic as well as remedial treatment during viral infections, particularly COVID-19. We present a multiplexed method for the analysis of free and phospholipid bound fatty acids, which may facilitate research into the role of fatty acids as plasma biomarkers and therapeutic agents in minimizing pre- and post-infection health impacts.