Late-Life Body Mass Index, Rapid Weight Loss, Apolipoprotein E ε4 and the Risk of Cognitive Decline and Incident Dementia

The impact of exercise on blood-based biomarkers of Alzheimer's disease in cognitively unimpaired older adults

Physical activity is a promising preventative strategy for Alzheimer's disease: it is associated with lower dementia risk, better cognition, greater brain volume and lower brain beta-amyloid. Blood-based biomarkers have emerged as a low-cost, non-invasive strategy for detecting preclinical Alzheimer's disease, however, there is limited literature examining the effect of exercise (a structured form of physical activity) on blood-based biomarkers. The current study investigated the influence of a 6-month exercise intervention on levels of plasma beta-amyloid (Aβ42, Aβ40, Aβ42/40), phosphorylated tau (p-tau181), glial fibrillary acidic protein (GFAP) and neurofilament light (NfL) chain in cognitively unimpaired older adults, and as a secondary aim, whether blood-based biomarkers related to cognition. Ninety-nine community-dwelling older adults (69.1 ± 5.2) were allocated to an inactive control, or to moderate or high intensity exercise groups where they cycled twice weekly for six months. At baseline and six months (post-intervention), fasted blood was collected and analysed using single molecule array (SIMOA) assays, and cognition was assessed. Results demonstrated no change in levels of any plasma biomarker from pre- to post-intervention. At baseline, higher NfL was associated with poorer cognition (β = -0.33, SE = 0.13, adjusted p = .042). Exploratory analyses indicated higher cardiorespiratory fitness was associated with higher NfL and GFAP levels in apolipoprotein E (APOE) ε4 non-carriers compared to ε4 carriers (NfL, β = -0.43, SE = 0.19, p = .029; GFAP, β = -0.41, SE = 0.20, p = .044), though this association was mediated by body mass index (BMI). These results highlight the importance of considering BMI in analysis of blood-based biomarkers, especially when investigating differences between APOE ε4 carriers and non-carriers. Our results also indicate that longer follow-up periods may be required to observe exercise-induced change in blood-based biomarkers.

Sarcopenia is a predictor for Alzheimer's continuum and related clinical outcomes

Low body mass index is closely related to a high risk of Alzheimer's disease (AD) and related biomarkers including amyloid-β (Aβ) deposition. However, the association between sarcopenia and Aβ-confirmed AD remains controversial. Therefore, we investigated the relationship between sarcopenia and the AD continuum. We explored sarcopenia's association with clinical implications of participants on the AD continuum. We prospectively enrolled 142 participants on the AD continuum (19 with preclinical AD, 96 with mild cognitive impairment due to AD, and 28 with AD dementia) and 58 Aβ-negative cognitively unimpaired participants. Sarcopenia, assessed using dual-energy X-ray absorptiometry and hand grip measurements, was considered a predictor. AD continuum, defined by Aβ deposition on positron emission tomography served as an outcome. Clinical severity in participants on the AD continuum assessed using hippocampal volume, Mini-Mental State Examination (MMSE), Seoul Verbal Learning Test (SVLT), and Clinical Dementia Rating Scale Sum of Boxes Scores (CDR-SOB) were also considered an outcome. Sarcopenia (odds ratio = 4.99, p = 0.004) was associated independently with the AD continuum after controlling for potential confounders. Moreover, sarcopenia was associated with poor downstream imaging markers (decreased hippocampal volume, β = - 0.206, p = 0.020) and clinical outcomes (low MMSE, β = - 1.364, p = 0.025; low SVLT, β = - 1.077, p = 0.025; and high CDR-SOB scores, β = 0.783, p = 0.022) in participants on the AD continuum. Sarcopenia was associated with the AD continuum and poor clinical outcome in individuals with AD continuum. Therefore, our results provide evidence for future studies to confirm whether proper management of sarcopenia can effective strategies are required for sarcopenia management to prevent the AD continuum and its clinical implications.

How are APOE4, changes in body weight, and longevity related? Insights from a causal mediation analysis

The ε4 allele of the APOE gene (APOE4) is known for its negative association with human longevity; however, the mechanism is unclear. APOE4 is also linked to changes in body weight, and the latter changes were associated with survival in some studies. Here, we explore the role of aging changes in weight in the connection between APOE4 and longevity using the causal mediation analysis (CMA) approach to uncover the mechanisms of genetic associations. Using the Health and Retirement Study (HRS) data, we tested a hypothesis of whether the association of APOE4 with reduced survival to age 85+ is mediated by key characteristics of age trajectories of weight, such as the age at reaching peak values and the slope of the decline in weight afterward. Mediation effects were evaluated by the total effect (TE), natural indirect effect, and percentage mediated. The controlled direct effect and natural direct effect are also reported. The CMA results suggest that APOE4 carriers have 19%-22% (TE p = 0.020-0.039) lower chances of surviving to age 85 and beyond, in part, because they reach peak values of weight at younger ages, and their weight declines faster afterward compared to non-carriers. This finding is in line with the idea that the detrimental effect of APOE4 on longevity is, in part, related to the accelerated physical aging of ε4 carriers.

Sex-Specific Association of Body Mass Index with Hippocampal Subfield Volume and Cognitive Function in Non-Demented Chinese Older Adults

Recent research suggests a possible association between midlife obesity and an increased risk of dementia in later life. However, the underlying mechanisms remain unclear. Little is known about the relationship between body mass index (BMI) and hippocampal subfield atrophy. In this study, we aimed to explore the associations between BMI and hippocampal subfield volumes and cognitive function in non-demented Chinese older adults. Hippocampal volumes were assessed using structural magnetic resonance imaging. Cognitive function was evaluated using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). A total of 66 participants were included in the final analysis, with 35 females and 31 males. We observed a significant correlation between BMI and the hippocampal fissure volume in older females. In addition, there was a negative association between BMI and the RBANS total scale score, the coding score, and the story recall score, whereas no significant correlations were observed in older males. In conclusion, our findings revealed sex-specific associations between BMI and hippocampal subfield volumes and cognitive performance, providing valuable insights into the development of effective interventions for the early prevention of cognitive decline.

Patterns of Aging Changes in Bodyweight May Predict Alzheimer's Disease

Relationships between patterns of aging-changes in bodyweight and AD are not fully understood. We compared mean age-trajectories of weight between those who did and did not develop late-onset-AD, and evaluated impact of age at maximum weight (AgeMax), and slope of decline in weight, on AD risk. Women with late-onset-AD had lower weight three or more decades before AD onset, and ∼10 years younger AgeMax, compared to AD-free women. APOE4 carriers had younger AgeMax and steeper slope. Older AgeMax and flatter slope predicted lower AD risk. Premature decline in weight could be a sign of accelerated physical aging contributing to AD.

Exogenous exposures shape genetic predisposition to lipids, Alzheimer's, and coronary heart disease in the MLXIPL gene locus

Associations of single nucleotide polymorphisms (SNPs) of the MLXIPL lipid gene with Alzheimer's (AD) and coronary heart disease (CHD) and potentially causal mediation effects of their risk factors, high-density lipoprotein cholesterol (HDL-C) and triglycerides (TG), were examined in two samples of European ancestry from the US (22,712 individuals 587/2,608 AD/CHD cases) and the UK Biobank (UKB) (232,341 individuals; 809/15,269 AD/CHD cases). Our results suggest that these associations can be regulated by several biological mechanisms and shaped by exogenous exposures. Two patterns of associations (represented by rs17145750 and rs6967028) were identified. Minor alleles of rs17145750 and rs6967028 demonstrated primary (secondary) association with high TG (lower HDL-C) and high HDL-C (lower TG) levels, respectively. The primary association explained ~50% of the secondary one suggesting partly independent mechanisms of TG and HDL-C regulation. The magnitude of the association of rs17145750 with HDL-C was significantly higher in the US vs. UKB sample and likely related to differences in exogenous exposures in the two countries. rs17145750 demonstrated a significant detrimental indirect effect through TG on AD risk in the UKB only (βIE = 0.015, pIE = 1.9 × 10-3), which suggests protective effects of high TG levels against AD, likely shaped by exogenous exposures. Also, rs17145750 demonstrated significant protective indirect effects through TG and HDL-C in the associations with CHD in both samples. In contrast, rs6967028 demonstrated an adverse mediation effect through HDL-C on CHD risk in the US sample only (βIE = 0.019, pIE = 8.6 × 10-4). This trade-off suggests different roles of triglyceride mediated mechanisms in the pathogenesis of AD and CHD.

Associations of lifestyle with physical, hearing, visual, and mental functional impairments among older adults: Findings from two prospective cohort studies

OBJECTIVE

To examine the associations between lifestyle habits and functional impairments among older adults.

METHODS

The study includes 20,545 women and 14,374 men aged 70 years or older at the time of the function assessment. Participants were from two prospective cohort studies: the Shanghai Women's Health Study (SWHS, enrollment from 1996 to 2000) and the Shanghai Men's Health Study (SMHS, enrollment from 2002 to 2006). Lifestyle information was collected at study enrollment and a healthy lifestyle score (HLS) was derived. Functional impairment information was collected at the follow-up survey conducted in 2012-2017. Logistic regression analyses were applied to estimate the associations of HLS with functional impairments.

RESULTS

The average age at lifestyle and functional impairment assessment was 62.3 (range: 49.9-70.9) and 77.7 (range: 70.0-89.4) for women and 67.5 (range: 55.1-74.9) and 77.4 (range: 70.0-88.6) for men. After a median follow-up of 14.4 years, we found that the HLS was inversely associated with overall severe functional impairment: odds ratio (95% confidence interval), 0.78(0.71-0.86) and individual severe functional impairment: 0.67(0.62-0.73) for independent walking, 0.85(0.77-0.94) for hearing/vision, 0.79(0.70-0.88) for memory, and 0.74(0.67-0.82) for decision-making impairment, comparing the highest with the lowest HLS categories. Such associations were similar among individuals with/without cardiometabolic diseases at baseline. The associations between each lifestyle factor and functional impairments differed.

CONCLUSION

A healthy lifestyle was associated with reduced odds of physical and mental impairment among older Chinese adults, emphasizing the importance of promoting and maintaining a healthy lifestyle to prevent or postpone age-related functional impairments.

Cognitive trajectories preluding the imminent onset of Alzheimer's disease dementia in individuals with normal cognition: results from the HELIAD cohort

BACKGROUND

The cognitive trajectories of cognitively normal (CN) individuals rapidly progressing to Alzheimer's disease dementia (AD) have not been investigated.

AIM

To explore the preclinical pattern of cognitive performance heralding the rapid progression from normal cognition to AD.

METHODS

The HELIAD cohort underwent comprehensive neuropsychological assessments (memory, language, attention, executive and visuo-perceptual functions) at baseline and after approximately 3-year intervals. The cognitive trajectories of those with normal cognition at baseline were explored according to the follow-up diagnosis using adjusted generalised estimating equations analyses.

RESULTS

A total of 932 predominantly female (61%), older (72.9 ± 4.9), CN participants were followed for 3.09 (± 0.83) years. Among them, 761 individuals remained CN, 29 progressed to AD and 142 developed MCI (33 single-domain amnestic, 41 multidomain amnestic, 37 single-domain non-amnestic and 31 multidomain non-amnestic). Those progressing to AD were already performing worse than the healthy reference in every single cognitive domain at baseline. Cognitive deficits ranged between ~ 0.5SD (attention, executive function and language) and ~ 1.0SD (memory and visuo-perceptual skills). Throughout the 3-year follow-up, memory constantly exhibited the most prominent impairment compared to the remaining cognitive domains while executive function diminished in the most abrupt fashion (~ 0.19SD yearly) separating from the remaining three cognitive functions before the development of full-blown AD. Heterogeneous patterns of cognitive decline clearly differentiated those progressing to MCI from those rapidly converting to AD, as well.

DISCUSSION

Poor performance in every cognitive domain may characterise cognitively normal individuals at high risk of fast progression to AD.

CONCLUSION

Strict neuropsychological cut-offs fail to detect a considerable number of individuals at high risk of rapid progression to AD.

Body Mass Index Trajectories Preceding Incident Mild Cognitive Impairment and Dementia

Importance

Body mass index (BMI) trajectories before the onset of mild cognitive impairment (MCI) and during the progression from MCI to dementia remain unclear.

Objective

To assess the long-term BMI trajectories preceding incident MCI and dementia and explore whether they are associated with brain pathologies.

Design, Setting, and Participants

The Rush Memory and Aging Project (MAP) was an ongoing community-based cohort study. This study included cognitively intact participants aged 60 to 90 years at baseline with annual follow-up from October 1997 to December 2020 (maximum follow-up of 22 years). During the follow-up, participants underwent brain autopsies. Data were analyzed from August 2021 to February 2022 using mixed-effect models.

Exposures

BMI was calculated using height and weight measured at baseline and follow-ups.

Main Outcomes and Measures

Incident MCI and dementia were diagnosed following standard criteria. Neuropathological assessments (including global Alzheimer disease and vascular pathology) were performed for autopsies.

Results

A total of 1390 participants (mean [SD] age, 78.4 [6.5] years; 1063 female [76.5%]) were included in the study. In the analysis of BMI trajectories before MCI (n = 939), during the follow-up (median [IQR] duration, 6 [3-9] years), 371 participants (39.5%) developed MCI, of whom 88 (23.7%) progressed to dementia. Those who developed MCI were older (mean [SD] age, 79.6 [5.9] years vs 76.9 [6.6] years), consumed less alcohol (median [IQR] consumption, 0 [0-5.8] g/day vs 1.1 [0-6.9] g/day), had a lower BMI (mean [SD], 27.2 [4.9] vs 28.2 [5.9]), and were more likely to be apolipoprotein E (APOE) ε4 carriers (89 of 371 [24.0%] vs 98 of 568 [17.3%]) compared with those who remained cognitively intact over follow-up. Those who developed dementia were older (mean [SD] age, 81.0 [5.2] years vs 79.1 [6.0] years), had a lower level of physical activity (median [IQR] activity, 1.0 [0-2.5] h/week vs 1.8 [0.2-3.8] h/week), and were more likely to be APOE ε4 carriers than those who were dementia-free (33 of 88 [37.5%] vs 56 of 283 [19.8%]). Compared with participants who remained cognitively intact, in those with incident MCI, BMI tended to decline earlier and faster. From 7 years before diagnosis, people with incident MCI had an associated significantly lower BMI (mean difference, -0.96; 95% CI, -1.85 to -0.07) than those who were cognitively intact. Among people with incident MCI, the slopes of BMI decline did not differ significantly between those who did and did not develop dementia (β, -0.03; 95% CI, -0.21 to 0.15). In the analysis of BMI trajectories before autopsy (n = 358), BMI was associated with a faster declination among participants with a high burden of global Alzheimer disease pathology (β for pathology × time highest vs lowest tertile, -0.14; 95% CI, -0.26 to -0.02) or vascular pathology (β for pathology × time2 highest vs lowest tertile, 0.02; 95% CI, 0-0.05).

Conclusions and Relevance

Results of this cohort study suggest that among cognitively intact people, significantly lower BMI occurs beginning approximately 7 years before MCI diagnosis. After MCI diagnosis, BMI declines at the same pace in people who develop dementia and those who do not. High brain pathologies may underly the BMI decline preceding dementing disorders.

Gender-specific relationship between thigh muscle and fat mass and brain amyloid-β positivity

BACKGROUND

The relationship of specific body composition in the thighs and brain amyloid-beta (Aβ) deposition remained unclear, although there were growing evidence that higher muscle and fat mass in thighs had a protective effect against cardiometabolic syndromes. To determine whether muscle mass and fat mass in the thighs affected amyloid-beta (Aβ) positivity differently in relation to gender, we investigated the association of muscle mass and fat mass with Aβ positivity using positron emission tomography (PET) in individuals without dementia.

METHODS

We recruited 240 participants (134 [55.8%] males, 106 [44.2%] females) without dementia ≥45 years of age who underwent Aβ PET, bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DEXA) scans of the hip in the health promotion center at Samsung Medical Center in Seoul, Korea. Lower extremity skeletal muscle mass index (LASMI) was measured using BIA, and gluteofemoral fat percentage (GFFP) was estimated using DEXA scans of the hip. We investigated the associations of LASMI and GFFP with Aβ positivity using logistic regression analyses after controlling for age, APOE4 genotype, and cognitive stage.

RESULTS

Higher muscle mass in the thighs, measured as LASMI (odds ratio [OR]=0.27, 95% confidence interval [CI] 0.08 to 0.84, p=0.031) was associated with a lesser risk of Aβ positivity in only females. Higher fat mass in the thighs, measured as GFFP (OR=0.84, 95% CI 0.73 to 0.95, p=0.008) was associated with a lesser risk of Aβ positivity in only males. However, the association between LAMSI (p for interaction= 0.810), GFFP (p for interaction= 0.075) and Aβ positivity did not significantly differ by gender. Furthermore, LAMSI only negatively correlated with centiloid (CL) values in females (r=-0.205, p=0.037), and GFFP only negatively correlated with CL values only in males (r=-0.253, p=0.004).

CONCLUSIONS

Our findings highlight the importance of recognizing that gender differences exist with respect to the specific body composition to potentially protect against Aβ deposition. Therefore, our results may help in designing gender-specific strategies for controlling body composition to prevent Aβ deposition.

Potential modifiable factors associated with late-life cognitive trajectories

Objective

There is variability across individuals in cognitive aging. To investigate the associations of several modifiable factors with high and low cognitive performance.

Methods

Data came from 17,724 community-dwelling individuals aged 65-98 years. Global cognition, verbal fluency, episodic memory, and psychomotor speed were assessed over up to seven years. Group-based multi-trajectory modeling identified distinct cognitive trajectories. Structural equation modeling examined the direct/indirect associations of social/behavioral factors and several chronic conditions with cognitive trajectories.

Results

Seven trajectory subgroups were identified. In the structural equation modeling we compared two subgroups-participants with the highest (14.2%) and lowest (4.1%) cognitive performance with the average subgroup. Lower education, never alcohol intake, and frailty directly predicted increased risk of low performance, and decreased likelihood of high performance. Hypertension (RR: 0.69, 95%CI: 0.60-0.80), obesity (RR: 0.84, 95%CI: 0.73-0.97), diabetes (RR: 0.69, 95%CI: 0.56-0.86) and depression (RR: 0.68, 95%CI: 0.54-0.85) only predicted lower likelihood of high cognitive performance, while dyslipidemia was only associated with low performance (RR: 1.30, 95%CI: 1.07-1.57). Living alone predicted increased risk of low cognitive performance and several comorbidities. Smoking did not predict cognitive trajectories but was associated with increased risk of diabetes, obesity and frailty. Findings were similar when examining the direct associations between modifiable risk factors and all seven cognitive subgroups.

Conclusions

Although several modifiable factors were associated with high performance, and reversely with low performance, this was not observed for obesity, hypertension and dyslipidemia. Further, health behaviors may affect cognitive function indirectly, via geriatric conditions. This indicates that strategies to promote healthy cognitive aging, may be distinct from those targeting dementia prevention.

Independent effect of body mass index variation on amyloid-β positivity

Objectives

The relationship of body mass index (BMI) changes and variability with amyloid-β (Aβ) deposition remained unclear, although there were growing evidence that BMI is associated with the risk of developing cognitive impairment or AD dementia. To determine whether BMI changes and BMI variability affected Aβ positivity, we investigated the association of BMI changes and BMI variability with Aβ positivity, as assessed by PET in a non-demented population.

Methods

We retrospectively recruited 1,035 non-demented participants ≥50 years of age who underwent Aβ PET and had at least three BMI measurements in the memory clinic at Samsung Medical Center. To investigate the association between BMI change and variability with Aβ deposition, we performed multivariable logistic regression. Further distinctive underlying features of BMI subgroups were examined by employing a cluster analysis model.

Results

Decreased (odds ratio [OR] = 1.68, 95% confidence interval [CI] 1.16–2.42) or increased BMI (OR = 1.60, 95% CI 1.11–2.32) was associated with a greater risk of Aβ positivity after controlling for age, sex, APOE e4 genotype, years of education, hypertension, diabetes, baseline BMI, and BMI variability. A greater BMI variability (OR = 1.73, 95% CI 1.07–2.80) was associated with a greater risk of Aβ positivity after controlling for age, sex, APOE e4 genotype, years of education, hypertension, diabetes, baseline BMI, and BMI change. We also identified BMI subgroups showing a greater risk of Aβ positivity.

Conclusion

Our findings suggest that participants with BMI change, especially those with greater BMI variability, are more vulnerable to Aβ deposition regardless of baseline BMI. Furthermore, our results may contribute to the design of strategies to prevent Aβ deposition with respect to weight control.

Long-term Weight Change and its Temporal Relation to Later-life Dementia in the Health and Retirement Study

CONTEXT

Weight loss among middle-aged and older adults has been associated with a higher risk of subsequent dementia. However, most studies have limited follow-up durations or suboptimal control for the potential influence of physical frailty (PF).

OBJECTIVE

Our study aimed to investigate the long-term and temporal relations of weight change to risk of dementia among middle-aged and older adults in the United States.

METHODS

A total of 5985 participants aged 65 years and older were included from the Health and Retirement Study. History of long-term weight change was calculated using 9 repeated body mass index measurements during 1992-2008. We then followed participants' dementia status from 2008 to 2018. Multivariable Cox proportional hazard models were used.

RESULTS

During the study follow-up period (mean = 7.54 years), a total of 682 (11.40%) dementia cases were documented. After adjustment for basic demographic and lifestyle factors, participants with weight loss (median: -0.23 kg/m2 per year) were at a significantly higher risk of dementia (HR = 1.60; 95% CI, 1.33, 1.92), compared with the stable weight group (median: 0.11 kg/m2 per year). This association was attenuated but remained strong and significant after further adjustment for PF (HR = 1.57; 95% CI, 1.30, 1.89). Significant association was observed for weight loss assessed approximately 14 to 18 years preceding dementia diagnosis (HR = 1.30; 95% CI, 1.07, 1.58), and was consistent closer to diagnosis.

CONCLUSION

Both recent and remote weight loss were associated with a higher risk of later-life dementia among middle-aged and older adults independent of PF status.

Sex-Differential Associations Between Body Mass Index and the Incidence of Dementia

BACKGROUND

Little is known about the sex differences in the association between body mass index (BMI) and dementia in late life.

OBJECTIVE

Therefore, this retrospective cohort study aimed to analyze associations between BMI and dementia in older women and men separately in general practices in Germany.

METHODS

This study included patients followed in one of 832 general practices in Germany between 2006 and 2019 (index date: first visit date). Study variables included dementia (dependent variable), BMI (independent variable), age, sex, and comorbidities (control variables). Kaplan-Meier curves and adjusted Cox regression analyses were conducted to analyze associations between BMI and the 10-year incidence of dementia in women and men, separately.

RESULTS

There were 296,767 patients included in this study (mean [standard deviation] age 70.2 [5.9] years; 54.3% women). The proportion of underweight, normal weight, overweight, and obesity was 0.9%, 25.5%, 41.5%, and 32.1%, respectively. The 10-year incidence of dementia significantly decreased with increasing BMI, from 11.5% in women with underweight to 9.1% in those with obesity (log-rank p <  0.001). Respective figures in men were 12.0% and 8.2% (log-rank p <  0.001). In women, only overweight (versus normal weight) was significantly associated with dementia (HR = 0.93, 95% CI = 0.88-0.97). In contrast, in men, the only BMI category significantly associated with the incidence of dementia was underweight (HR = 1.58, 95% CI = 1.11-2.25).

CONCLUSION

In this study conducted in Germany, overweight was negatively associated with dementia in women, whereas there was a positive underweight-dementia relationship in men. More data are needed to confirm or refute these findings in other settings.

ApoE4 Is Associated with Lower Body Mass, Particularly Fat Mass, in Older Women with Cognitive Impairment

A lower body mass is associated with the progression of Alzheimer’s disease (AD) and the risk of mortality in patients with AD; however, evidence of genetic determinants of decreased body mass in cognitively impaired older adults is limited. We therefore investigated the genetic effect of APOE-ε4 on body composition in older adults with mild cognitive impairment (MCI) and early-to-moderate-stage AD. A total of 1631 outpatients (aged 65–89 years) with MCI and early-to-moderate-stage AD were evaluated for the association between body composition and APOE-ε4 status. After adjusting for covariates, including cognitive function evaluated with the Mini-Mental State Examination, the presence of the APOE-ε4 was associated with lower weight (β = −1.116 ± 0.468 kg per presence, p = 0.017), fat mass (β = −1.196 ± 0.401 kg per presence, p = 0.003), and percentage of body fat (β = −1.700 ± 0.539% per presence, p = 0.002) in women but not in men. Additionally, the impact of APOE-ε4 on measures of body composition in women was more remarkable in MCI than in AD patients. The presence of the APOE-ε4 allele was associated with lower fat mass, particularly in women with MCI, independent of cognitive decline.

Associations of Body Mass Index-Metabolic Phenotypes with Cognitive Decline in Parkinson's Disease

BACKGROUND

Growing evidence suggests important effects of body mass index (BMI) and metabolic status on neurodegenerative diseases. However, the roles of BMI and metabolic status on cognitive outcomes in Parkinson's disease (PD) may vary and are yet to be determined.

METHODS

In total, 139 PD patients from the whole PD cohort in Parkinson's Progression Markers Initiative database underwent complete laboratory measurements, demographic and anthropometric parameters at baseline, and were enrolled in this study. Further, they were categorized into 4 different BMI-metabolic status phenotypes using Adult Treatment Panel-III criteria. Motor and cognition scales at baseline and longitudinal changes after a 48-month follow-up were compared among the 4 groups. Repeated-measure linear mixed models were performed to compare PD-related biomarkers among BMI-metabolic status phenotypes across time.

RESULTS

We found that PD patients in the metabolically unhealthy normal weight group showed more cognitive decline in global cognition and visuospatial perception after a 48-month follow-up than those in the other 3 groups (p < 0.05). No difference was found in motor scales among different BMI-metabolic status phenotypes. Finally, compared to the metabolically healthy normal weight group, the metabolically healthy obesity group had lower CSF Aβ42 and serum neurofilament levels in repeated-measure linear mixed models adjusting for age, gender, APOE e4 carrier status, and years of education (p = 0.031 and 0.046, respectively).

CONCLUSION

The MUNW phenotype was associated with a rapid cognitive decline in PD.

Body Mass Index and Polygenic Risk for Alzheimer's Disease Predict Conversion to Alzheimer's Disease

Body mass index (BMI) is a risk factor for Alzheimer's disease (AD) although the relationship is complex. Obesity in midlife is associated with increased risk for AD, whereas evidence supports both higher and lower BMI increasing risk for AD in late life. This study examined the influence of individual differences in genetic risk for AD to further clarify the relationship between late-life BMI and conversion to AD. Participants included 52 individuals diagnosed as having mild cognitive impairment (MCI) at baseline who converted to AD within 24 months and 52 matched MCI participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort. BMI was measured at baseline. Genetic risk for AD was assessed via genome-wide polygenic risk scores. Conditional logistic regression models were run to determine if BMI and polygenic risk predicted conversion to AD. Results showed an interaction between BMI and genetic risk, such that individuals with lower BMI and higher polygenic risk were more likely to convert to AD relative to individuals with higher BMI. These results remained significant after adjusting for cerebrospinal fluid biomarkers of AD. Exploratory sex-stratified analyses revealed this relationship only remained significant in males. These results show that higher genetic risk in the context of lower BMI predicts conversion to AD in the next 24 months, particularly among males. These findings suggest that genetic risk for AD in the context of lower BMI may serve as a prodromal risk factor for future conversion to AD.

Weight Loss and the Risk of Dementia: A Meta-analysis of Cohort Studies

BACKGROUND

Weight loss is a common phenomenon among the elderly and is identified as an important indicator of health status. Many epidemiology studies have investigated the association between weight loss and dementia, but the results were inconsistent.

OBJECTIVE

To examine and determine the association between weight loss and the risk of dementia.

METHODS

Eligible cohort studies involving weight loss and dementia were searched from PubMed, Embase, and Ovid databases through October 2018. Pooled relative risks (RRs) with its 95% confidence intervals (CIs) were used to estimate the effects of weight loss on the risk of dementia. Subgroup and sensitivity analyses were performed to explore the potential sources of heterogeneity. The Begg's test and Egger's test were used to assess the publication bias.

RESULTS

A total of 20 cohort studies with 38,141 participants were included in this meta-analysis. Weight loss was significantly associated with the risk of dementia (RR=1.26, 95% CI=1.15-1.38). BMI decline ≥0.8 units (RR=1.31, 95% CI=1.10-1.56) and ≥4% (RR=1.19, 95% CI=1.03-1.38) could increase the risk of dementia. The risk of all-cause dementia for people with weight loss increased by 31% (RR=1.31, 95% CI=1.15-1.49), and 25% higher for incident Alzheimer's disease (RR=1.25, 95% CI=1.07-1.46). Weight loss in participants with normal weight had a similar dementia risk (RR=1.21, 95% CI=1.06-1.38) with the overweight individuals (RR=1.22, 95% CI=1.11-1.34).

CONCLUSION

Weight loss may be associated with an increased risk of dementia, especially for Alzheimer's disease. Maintaining weight stability may help prevent dementia.

Life Course Adiposity and Alzheimer's Disease: A Mendelian Randomization Study

BACKGROUND

Several studies showed that life course adiposity was associated with Alzheimer's disease (AD). However, the underlying causality remains unclear.

OBJECTIVE

We aimed to examine the causal relationship between life course adiposity and AD using Mendelian randomization (MR) analysis.

METHODS

Instrumental variants were obtained from large genome-wide association studies (GWAS) for life course adiposity, including birth weight (BW), childhood body mass index (BMI), adult BMI, waist circumference (WC), waist-to-hip ratio (WHR), and body fat percentage (BFP). A meta-analysis of GWAS for AD including 71,880 cases and 383,378 controls was used in this study. MR analyses were performed using inverse variance weighted (IVW), weighted median, and MR-Egger regression methods. We calculated odds ratios (ORs) per genetically predicted standard deviation (1-SD) unit increase in each trait for AD.

RESULTS

Genetically predicted 1-SD increase in adult BMI was significantly associated with higher risk of AD (IVW: OR = 1.03, 95% confidence interval [CI] = 1.01-1.05, p = 2.7×10-3) after Bonferroni correction. The weighted median method indicated a significant association between BW and AD (OR = 0.94, 95% CI = 0.90-0.98, p = 1.8×10-3). We also found suggestive associations of AD with WC (IVW: OR = 1.03, 95% CI = 1.00-1.07, p = 0.048) and WHR (weighted median: OR = 1.04, 95% CI = 1.00-1.07, p = 0.029). No association was detected of AD with childhood BMI and BFP.

CONCLUSION

Our study demonstrated that lower BW and higher adult BMI had causal effects on increased AD risk.

The dynamic association between body mass index and cognition from midlife through late-life, and the effect of sex and genetic influences

Body mass index (BMI) is associated with cognitive abilities, but the nature of the relationship remains largely unexplored. We aimed to investigate the bidirectional relationship from midlife through late-life, while considering sex differences and genetic predisposition to higher BMI. We used data from 23,892 individuals of European ancestry from the Health and Retirement Study, with longitudinal data on BMI and three established cognitive indices: mental status, episodic memory, and their sum, called total cognition. To investigate the dynamic relationship between BMI and cognitive abilities, we applied dual change score models of change from age 50 through 89, with a breakpoint at age 65 or 70. Models were further stratified by sex and genetic predisposition to higher BMI using tertiles of a polygenic score for BMI (PGSBMI). We demonstrated bidirectional effects between BMI and all three cognitive indices, with higher BMI contributing to steeper decline in cognitive abilities in both midlife and late-life, and higher cognitive abilities contributing to less decline in BMI in late-life. The effects of BMI on change in cognitive abilities were more evident in men compared to women, and among those in the lowest tertile of the PGSBMI compared to those in the highest tertile, while the effects of cognition on BMI were similar across groups. In conclusion, these findings highlight a reciprocal relationship between BMI and cognitive abilities, indicating that the negative effects of a higher BMI persist from midlife through late-life, and that weight-loss in late-life may be driven by cognitive decline.

Sex differences in brain aging among adults with family history of Alzheimer's disease and APOE4 genetic risk

Emerging evidence suggests that Alzheimer's Disease (AD) risk factors may differentially contribute to disease trajectory in women than men. Determining the effect of AD risk factors on brain aging in women, compared to men, is critical for understanding whether there are sex differences in the pathways towards AD in cognitively intact but at-risk adults. Brain Age Gap (BAG) is a concept used increasingly as a measure of brain health; BAG is defined as the difference between predicted age (based on structural MRI) and chronological age, with negative values reflecting preserved brain health with age. Using BAG, we investigated whether there were sex differences in the brain effects of AD risk factors (i.e., family history of AD, and carrying an apolipoprotein E ε4 allele [+APOE4]) in cognitively intact adults, and if this relationship was moderated by modifiable factors (i.e. body mass index [BMI], blood pressure and physical activity). We undertook a cross-sectional study of structural MRIs from 1067 cognitively normal adults across four neuroimaging datasets. An elastic net regression model found that women with a family history of AD and +APOE4 genotype had more advanced brain aging than their male counterparts. In a sub-cohort of women with those risk factors, higher BMI was associated with less brain aging whereas lower BMI was not. In a sub-cohort of women and men with +APOE4, engaging in physical activity was more beneficial to men's brain aging than women's. Our results demonstrate that AD risk factors are associated with greater brain aging in women than men, although there may be more unexplored modifiable factors that influence this relationship. These findings suggest that the complex interplay between unmodifiable and modifiable AD risk factors can potentially protect against brain aging in women and men.

Body weight changes and longitudinal associations with cognitive decline among community-dwelling older adults

INTRODUCTION

We aim to investigate the longitudinal associations between changes in body weight (BW) and declines in cognitive function and risk of mild cognitive impairment (MCI)/dementia among cognitively normal individuals 65 years or older.

METHODS

Data from the Age Gene/Environment Susceptibility-Reykjavik Study (AGES-Reykjavik Study) including 2620 participants, were examined using multiple logistic regression models. Cognitive function included speed of processing (SP), executive function (EF), and memory function (MF). Changes in BW were classified as; weight loss (WL), weight gain (WG), and stable weight (SW).

RESULTS

Mean follow-up time was 5.2 years and 61.3% were stable weight. Participants who experienced WL (13.4%) were significantly more likely to have declines in MF and SP compared to the SW group. Weight changes were not associated with EF. WL was associated with a higher risk of MCI, while WG (25.3%) was associated with a higher dementia risk, when compared to SW.

DISCUSSION

Significant BW changes in older adulthood may indicate impending changes in cognitive function.

Gut microbiota in dementia. Critical review of novel findings and their potential application

There is a great deal of impetus for the comprehensive understanding of the complete pathological function, genetic information, and functional diversity of the gut microbiota that favors the development of dementia. It has been reported that patients with mild cognitive impairment and Alzheimer's disease present with several metabolic and immune-inflammatory alterations. The recently highlighted aspects of human health linked to cognitive decline include insulin-resistance, obesity, and chronic low-grade inflammation. Gut microbiota is known to produce neurotransmitters, such as GABA, acetylcholine, dopamine or serotonin, vitamins, intestinal toxins, and modulate nerve signaling - with emphasis on the vagus nerve. Additionally, gut dysbiosis results in impaired synthesis of signaling proteins affecting metabolic processes relevant to the development of Alzheimer's disease. Due to numerous links of gut microbiota to crucial metabolic and inflammatory pathways, attempts aimed at correcting the gut microflora composition may affect dementia pathology in a pleiotropic manner. Taking advantage of the metabolic effects of cold exposure on organisms by the introduction of whole-body cryostimulation in dementia patients could lead to alterations in gut microbiota and, therefore, decrease of an inflammatory response and insulin resistance, which remain one of the critical metabolic features of dementia. Further studies are needed in order to explore the potential application of recent findings and ways of achieving the desired goals.

Five-Year Change in Body Mass Index Predicts Conversion to Mild Cognitive Impairment or Dementia Only in APOE ɛ4 Allele Carriers

BACKGROUND

Body mass index (BMI) has been identified as an important modifiable lifestyle risk factor for dementia, but less is known about how BMI might interact with Apolipoprotein E ɛ4 (APOE ɛ4) carrier status to predict conversion to mild cognitive impairment (MCI) and dementia.

OBJECTIVE

The aim of this study was to investigate the interaction between APOE ɛ4 status and baseline (bBMI) and five-year BMI change (ΔBMI) on conversion to MCI or dementia in initially cognitively healthy older adults.

METHODS

The associations between bBMI, ΔBMI, APOE ɛ4 status, and conversion to MCI or dementia were investigated among 1,289 cognitively healthy elders from the National Alzheimer's Coordinating Center (NACC) database.

RESULTS

After five years, significantly more carriers (30.6%) converted to MCI or dementia than noncarriers (17.6%), p < 0.001, OR = 2.06. Neither bBMI (OR = 0.99, 95%CI = 0.96-1.02) nor the bBMI by APOE interaction (OR = 1.02, 95%CI = 0.96-1.08) predicted conversion. Although ΔBMI also did not significantly predict conversion (OR = 0.90, 95%CI = 0.78-1.04), the interaction between ΔBMI and carrier status was significant (OR = 0.72, 95%CI = 0.53-0.98). For carriers only, each one-unit decline in BMI over five years was associated with a 27%increase in the odds of conversion (OR = 0.73, 95%CI = 0.57-0.94).

CONCLUSION

A decline in BMI over five years, but not bBMI, was strongly associated with conversion to MCI or dementia only for APOE ɛ4 carriers. Interventions and behaviors aimed at maintaining body mass may be important for long term cognitive health in older adults at genetic risk for AD.

Association between the occurrence of albuminuria and the risk of early dementia among older people upon health examination: a community-based cohort study in Taiwan

OBJECTIVES

This study aimed to investigate the associations between biochemical markers, renal function, health behaviours and dementia among older people.

DESIGN

A retrospective cohort study.

SETTING

Community-based health examination database from Taipei city.

PARTICIPANTS

In total, 35 434 older people were included from February 2005 to December 2012. To assess changes in renal function, we selected participants who attended health examinations at least twice and responded to the AD8 questionnaire in 2012. We excluded those with dementia at baseline.

PRIMARY OUTCOME MEASURES

Early dementia was assessed using the AD8 questionnaire in 2012. Explanatory variables included demographic factors, health behaviours, biochemical markers and renal function. We used a Cox proportional hazard model to estimate the HR for early dementia onset.

RESULTS

Individuals with mild albuminuria (HR 1.228; 95% CI 1.066 to 1.414), lower eGFR (HR 1.549; 95% CI 1.319 to 1.820) and higher age (HR 1.022; 95% CI 1.015 to 1.028) were associated with a high risk of early dementia. Older people with no alcohol intake (HR 0.872; 95% CI 0.794 to 0.958), and higher education levels (HR 0.647; 95% CI 0.589 to 0.710) were at a low risk of early dementia.

CONCLUSIONS

Elevated mild albuminuria and low eGFR were associated with a high risk of early dementia in this community-based cohort. Routine health examinations for older people can help screen out the high-risk population, and clinical management might reduce or delay the risk of early dementia.

Polymorphism rs11867353 of Tyrosine Kinase Non-Receptor 1 (TNK1) Gene Is a Novel Genetic Marker for Alzheimer's Disease

Several single-nucleotide polymorphisms (SNPs) and rare variants of non-receptor tyrosine kinase 1 gene (TNK1) have been associated with Alzheimer's disease (AD). To date, none of the associations have proven to be of practical importance in predicting the risk of AD either because the evidence is not conclusive, or the risk alleles occur at very low frequency. In the present study, we are evaluating the associations between rs11867353 polymorphism of TNK1 gene and both AD and mild cognitive impairment (MCI) in a group of 1656 persons. While the association with AD was found to be highly statistically significant (p < 0.0001 for the risk genotype CC), no statistically significant association with MCI could be established. Possible explanation of the apparent discrepancy could be rapid progression of MCI to AD in persons with the CC genotype. Additional findings of the study are statistically significant associations of rs11867353 polymorphism with body mass index, body weight, and body height. The patients with AD and CC genotype had significantly lower values of body mass index and body weight compared with patients with other genotypes. The main outcome of the study is the finding of a previously never described association between the rs11867353 polymorphism of the TNK1 gene and AD. The rs11867353 polymorphism has a potential to become a significant genetic marker when predicting the risk of AD.

The type 2 diabetes-specific dementia risk score (DSDRS) is associated with frailty, cognitive and functional status amongst Mexican community-dwelling older adults

Background

The type 2 diabetes (T2D) specific dementia-risk score (DSDRS) was developed to evaluate dementia risk in older adults with T2D. T2D-related factors have been shown increase the risk of age-related conditions, which might also increase dementia risk. Here, we investigate the associations of DSDRS with frailty, disability, quality of life (QoL) and cognition in community-dwelling older adults with T2D.

Methods

We included 257 community-dwelling older adults with T2D to evaluate the association between DSDRS and Mini-mental state examination (MMSE), Isaac’s set-test (IST), clock drawing test (CDT), quality of life (SF-36), risk of malnutrition (Mini-Nutritional Assessment or MNA), as well as frailty, Katz’ and Lawton-Brody scores. We also assessed the phenotype and correlates of high-estimated dementia risk by assessing individuals with DSDRS >75th age-specific percentiles.

Results

Mean age of participants was 78.0 ± 6.2 years. DSDRS showed a significant correlation with MMSE test, IST, CDT, SF-36, MNA, Lawton-Brody and Katz scores, and an increasing number of frailty components. DSDRS was higher among frail, pre-frail, and subjects with limited ADL and IADL (p < 0.001). Participants with DSDRS >75th age-specific percentiles had lower education, MMSE, IST, SF-36, MNA, Katz, Lawton-Brody, and higher frailty scores. High-estimated 10-year dementia risk was associated with ADL and IADL disability, frailty and risk of malnutrition. When assessing individual components of DSDRS, T2D-related microvascular complications were associated to all outcome measures.

Conclusion

The DSDRS is associated with frailty, disability, malnutrition and lower cognitive performance. These findings support that T2D-related factors have significant burden on functional status, QoL, disability and dementia risk.

Association of body mass index with risk of cognitive impairment and dementia: A systematic review and meta-analysis of prospective studies

Controversies persist about the associations of body mass index (BMI) with risk of cognitive impairment and dementia. This study aimed to evaluate these associations from various aspects, in which Embase, PubMed and Cochrane databases were searched to identify prospective studies up to May 2019. Random-effects meta-analyses and dose-response meta-analysis were conducted, involving twenty-nine of 20,083 identified literatures. Meta-analysis showed that midlife underweight, obesity and late-life underweight conferred 1.39-, 1.31- and 1.64-fold excess risk for cognitive impairment and dementia, while late-life overweight and obesity conferred 21% and 25% reduced risk. In dose-response meta-analysis, all cause dementia (ACD), Alzheimer's disease (AD) and vascular dementia (VaD) risk in midlife was significantly elevated when BMI surpassed 29, 30 and 32 kg/m². AD risk in late-life was decreased when BMI was under 27 kg/m², while this protection for VaD was absent when BMI surpassed 39 kg/m². Higher BMI produced opposite exerted opposite effects on dementia in mid- and late-age population. Firstly reported, a dose-response relationship further supports the guideline from the standpoint of dementia prevention.

Nativity, Neighborhoods, and Body Composition in the Sacramento Area Latino Study on Aging

BACKGROUND AND OBJECTIVES

Globally, obesity influences the risk of many major chronic diseases. Our study examines the association between individual nativity and neighborhood level concentration of immigrants with 10-year changes in weight, body mass index (BMI), and waist circumference (WC) among older Latinos.

RESEARCH DESIGN AND METHODS

The Sacramento Area Latino Study on Aging (SALSA) is a population-based prospective study of community-dwelling older adults of Mexican origin (baseline ages 58-101 years). The primary outcome was repeated measures of weight over a 10-year period for 1,628 respondents. Nativity was defined by participants' reported place of birth (US-born or Latin American foreign born). Neighborhood immigrant concentration was measured as the percentage of foreign born at census tract level (2000 US Census). We used linear mixed models with repeated measures of weight, height, BMI, and WC as dependent variables (level 1), clustered within individuals (level 2) and neighborhood migrant concentration (level 3).

RESULTS

Foreign born (FB) respondents had lower baseline weight than the US-born (mean, 160 vs. 171 lbs, p < .0001). Over time, weight differences between the FB and the US-born decreased by 1.7 lbs/5 years as US-born weight decreased more rapidly. We observed a significant interaction between individual nativity and neighborhood immigrant concentration (p = .012). We found similar patterns for BMI, but did not find statistically significant differences in WC trajectories.

DISCUSSION AND IMPLICATIONS

Our study observed significant differences by foreign born vs. US nativity in baseline weight/BMI and in their trajectories over time. Additionally, we found weight/BMI differences in neighborhood immigrant concentration for the FB, but not for the US-born.

Late-life obesity is a protective factor for prodromal Alzheimer's disease: a longitudinal study

Higher body mass index (BMI) in late-life has recently been considered as a possible protective factor for Alzheimer's disease (AD), which yet remains conflicting. To test this hypothesis, we have evaluated the cross-sectional and longitudinal associations of BMI categories with CSF biomarkers, brain β-amyloid (Aβ) load, brain structure, and cognition and have assessed the effect of late-life BMI on AD risk in a large sample (n = 1,212) of non-demented elderly from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database. At baseline, higher late-life BMI categories were associated with higher levels of CSF Aβ42 (p=0.037), lower levels of CSF total-tau (t-tau, p=0.026) and CSF t-tau/Aβ42 (p=0.008), lower load of Aβ in the right hippocampus (p=0.030), as well as larger volumes of hippocampus (p<0.0001), entorhinal cortex (p=0.009) and middle temporal lobe (p=0.040). But no association was found with CSF phosphorylated-tau (p-tau) or CSF p-tau/Aβ42. Longitudinal studies showed that higher BMI individuals experienced a slower decline in cognitive function. In addition, Kaplan–Meier survival analysis revealed that higher late-life BMI had a reduced risk of progression to AD over time (p = 0.009). Higher BMI in late-life decreased the risk of AD, and this process may be driven by AD-related biomarkers.

Internal Lipid Profile and Body Lipid Profile in Relation to Cognition: A Cross-Sectional Study in Southern China

AIM

There are currently no established, clinically relevant, non-invasive markers of cognitive impairment, except for age and APOE genotype.

METHODS

A cross-sectional study of 1,296 participants from Nanchang, China, has been conducted. We collected data from Mini-Mental State Examination (MMSE) scores, internal lipid profiles and body lipid profiles, age and other factors that may have an effect on cognitive impairment.

RESULTS

Internal lipid profiles (OR = 1.03 [95%CI, 1.00-1.06], P = 0.024), body lipid profiles (OR = 1.05 [95%CI, 1.01-1.09], P = 0.014), and age (OR = 1.03 [95%CI, 1.01-1.05], P < 0.001) were all positively correlated with cognitive impairment.

CONCLUSIONS

Cognitive impairment was more frequent in female patients with high internal lipid profiles or body lipid profiles, and these characteristics were related to age and education.

Dementia risk by combinations of metabolic diseases and body mass index: Japan Gerontological Evaluation Study Cohort Study

AIMS/INTRODUCTION

To compare the dementia risk associated with pre-existing diabetes, hypertension, dyslipidemia, obesity (body mass index [BMI] ≥25 kg/m2 ) and underweight (BMI <18.5 kg/m2 ) among older adults. We also explored the dementia risk associated with combinations of metabolic diseases and BMI.

MATERIALS AND METHODS

We used data from the Japan Gerontological Evaluation Study. Participants completed a health checkup in 2010 and were followed for 5.8 years on average. Dementia was measured by municipal long-term care insurance registration. Diabetes, hypertension, dyslipidemia, obesity and underweight were diagnosed by medication use or health examination results. We calculated the incidence of dementia and adjusted hazard ratios (HRs).

RESULTS

Among 3,696 participating older adults, 338 developed dementia. Adjusted HRs (95% confidence intervals) in men and women (reference: those without corresponding disease of normal weight) were as follows: 2.22 (1.26-3.90) and 2.00 (1.07-3.74) for diabetes; 0.56 (0.29-1.10) and 1.05 (0.64-1.71) for hypertension; 1.30 (0.87-1.94) and 0.73 (0.49-1.08) for dyslipidemia; 0.73 (0.42-1.28) and 0.82 (0.49-1.37) for BMI of 25-29.9 kg/m2 ; and 1.04 (0.51-2.10) and 1.72 (1.05-2.81) for underweight. Dementia risk was significantly higher in underweight men with dyslipidemia (HR 4.15, 95% CI 1.79-9.63) compared with normal-weight men without dyslipidemia, and in underweight women with hypertension (HR 3.79, 1.55-9.28) compared with normal-weight women without hypertension. Dementia incidence was highest among underweight older adults with hypertension followed by dyslipidemia.

CONCLUSIONS

Among Japanese older adults, underweight and prevalent diabetes are risk factors for developing dementia. Lower BMI is also associated with a higher incidence of dementia.

Social network types and cognitive decline among older Korean adults: A longitudinal population-based study

OBJECTIVES

Social network (SN) has been known to impact on cognitive function in late life. However, knowledge regarding the link between SN of various types and cognitive decline (CD) is limited. This study's aim was to investigate which types of SN are associated with reduced risk of CD 2 years later among community-dwelling older adults.

METHODS

Secondary analysis of data from 1960 cognitively intact adults 65 years of age or older who participated in the Korean Longitudinal Study of Aging (KLoSA) was employed. K-means cluster analysis was conducted to derive SN types using seven common SN characteristics (marital status, living with children, number of children, frequency of contact with children, frequency of contact with friends, frequency of participation in religious activities, and frequency of participation in social groups). Multivariable linear regression analysis regarding the effects of SN type on CD between 2012 and 2014 was conducted, controlling for covariates.

RESULTS

K-means cluster analyses identified a model with five types of SN as being most optimal, and they were named diverse/couple, diverse/family, congregant, restricted/married, and widowed. The average CD 2 years later was most pronounced in those in the widowed network. Compared with the widowed, older adults in the diverse/couple network and the congregant network at baseline had a lower risk of CD 2 years after initial assessment.

CONCLUSIONS

Findings show that older Korean adults embedded in widowed network types are at risk for CD and suggest the importance of having a spouse and religious group activities in maintaining cognitive function in later life.

High levels of plasma fibrinogen are related to post-stroke cognitive impairment

INTRODUCTION

Studies have shown that high levels of the fibrinogen (FIB) are related to cognitive deficits. However, the relationship between fibrinogen and cognitive deficit after stroke remains unclear. Therefore, we explored the relationship between plasma fibrinogen and post-stroke cognitive impairment (PSCI).

METHODS

This study is carried out in the First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang Province, China. A total of 210 patients with acute ischemic stroke were enrolled in this study. Ultimately, 134 patients completed 3-month follow-up. Blood samples were collected at hospital admission. Cognitive function was evaluated 3 months after stroke. All patients underwent the Mini-Mental State Examination (MMSE) after 3 months.

RESULTS

Higher levels of fibrinogen were observed in patients with post-stroke cognitive impairment compared with the non-PSCI group (p < .001). Additionally, elevated plasma fibrinogen levels were independently associated with PSCI (odds ratio [OR] = 2.000, 95% CI 1.062-3.770 p = .032). The plasma fibrinogen levels were negatively correlated with the 3-month MMSE scores (r = -.171, p = .048). In a multivariate linear regression, FIB was negatively associated with the 3-month MMSE scores after adjustment for the other variables (β = -0.782, p = .035).

CONCLUSION

High levels of plasma fibrinogen were associated with the presence and severity of PSCI.

Body Weight Variation Patterns as Predictors of Cognitive Decline over a 5 Year Follow-Up among Community-Dwelling Elderly (MAPT Study)

This study aimed to analyze associations between weight variation patterns and changes in cognitive function and hippocampal volume among non-demented, community-dwelling elderly. Sample was formed of 1394 adults >70 years (63.9% female), all volunteers from the Multidomain Alzheimer Preventive Trial (MAPT). Weight loss was defined as ≥5% of body weight decrease in the first year of follow-up; weight gain as ≥5% of weight increase; and stability if <5% weight variation. Cognition was examined by a Z-score combining four tests. Measures were assessed at baseline, 6, 12, 24, 36, 48, and 60 months of follow-up. Hippocampal volume was evaluated with magnetic resonance imaging in 349 subjects in the first year and at 36 months. Mixed models were performed. From the 1394 participants, 5.5% (n = 76) presented weight loss, and 9.0% (n = 125) presented weight gain. Cognitive Z-score decreased among all groups after 5 years, but decline was more pronounced among those who presented weight loss (adjusted between-group mean difference vs. stable: -0.24, 95%CI: -0.41 to -0.07; p = 0.006). After 3 years, hippocampal atrophy was observed among all groups, but no between-group differences were found. In conclusion, weight loss ≥5% in the first year predicted higher cognitive decline over a 5 year follow-up among community-dwelling elderly, independently of body mass index.

Mind the gaps: What we don't know about cognitive impairment in essential tremor

INTRODUCTION

Although the hallmark feature of essential tremor (ET) is tremor, there is growing appreciation that cognitive impairment also occurs, including increased prevalence of mild cognitive impairment (MCI) and increased prevalence and incidence of dementia. With emerging knowledge of ET-cognitive impairment, come fundamental questions regarding its course, bases, predictors and clinical outcomes. Studies in the general population and in Parkinson's disease (PD), a related movement disorder, offer a starting point from which to begin filling these clinically important knowledge gaps.

METHODS

A PubMed search (June 2018) identified articles for this review.

RESULTS

Much of our knowledge of cognitive impairment in ET is of the static condition (e.g., prevalence of cognitive impairment in ET), with nearly no information on its bases, predictors and dynamics (i.e., course, and clinical outcomes). In PD, where such data have been published, rates of cognitive decline and conversion to MCI/dementia are higher than in the general population. Predictors of cognitive change in PD and the general population have also been identified, yet they only partially overlap one another.

CONCLUSION

The predictors and dynamics of cognitive impairment have been investigated fairly extensively in the general population, to a somewhat lesser extent in PD, and are emerging only now in ET. We suggest that longitudinal studies specific to ET are needed, and we outline variables to be considered in these investigations. Increased knowledge of ET-cognitive impairment will facilitate meaningful counseling of patients and their families.

Neuropsychological Functioning in Older Adults with Obesity: Implications for Bariatric Surgery

Bariatric surgery is the most effective approach to treating morbid obesity, resulting in decreased morbidity, mortality, and improved quality of life. Research on outcomes has generally been restricted to young and middle-aged adults, despite a growing epidemic of obesity in older adults. The use of bariatric surgery has been limited in older individuals, in part due to concerns that preexisting cognitive dysfunction increases the risk of poor post-surgical outcomes, including cognitive decline. The literature on the relationship between obesity and cognition in older adults is emerging, but fraught by several methodological limitations. While there is insufficient research to determine the nature of cognitive outcomes following bariatric surgery in older adults, the aim of this paper is to review the existing evidence and make the case for further study.

The Role of Leptin and Adiponectin in Obesity-Associated Cognitive Decline and Alzheimer's Disease

Cross-talk between adipose tissue and central nervous system (CNS) underlies the increased risk of obese people to develop brain diseases such as cognitive and mood disorders. Detailed mechanisms for how peripheral changes caused by adipose tissue accumulation in obesity impact the CNS to cause brain dysfunction are poorly understood. Adipokines are a large group of substances secreted by the white adipose tissue to regulate a wide range of homeostatic processes including, but not limited to, energy metabolism and immunity. Obesity is characterized by a generalized change in the levels of circulating adipokines due to abnormal accumulation and dysfunction of adipose tissue. Altered adipokine levels underlie complications of obesity as well as the increased risk for the development of obesity-related comorbidities such as type 2 diabetes, cardiovascular and neurodegenerative diseases. Here, we review the literature for the role of adipokines as key mediators of the communication between periphery and CNS in health and disease. We will focus on the actions of leptin and adiponectin, two of the most abundant and well studied adipokines, in the brain, with particular emphasis on how altered signaling of these adipokines in obesity may lead to cognitive dysfunction and augmented risk for Alzheimer's disease. A better understanding of adipokine biology in brain disorders may prove of major relevance to diagnostic, prevention and therapy.

Cognitive Functioning of Geriatric Patients: Is Hypovitaminosis D the Next Marker of Cognitive Dysfunction and Dementia?

The study objective is to investigate whether vitamin D is associated with the cognitive function of geriatric patients. This cross-sectional study involved 357 patients hospitalized in the geriatric ward who complained of memory problems (mean age: 82.3 years). The level of cognitive function was measured with the Mini-Mental State Examination (MMSE) and the clinical diagnosis of dementia was established according to the International Classification of Diseases (ICD-10) criteria. The serum 25-hydroxy vitamin D was measured with liquid chromatography-tandem mass spectrometry. The iterative Bayesian model averaging (BMA) procedure was applied to linear and logistic regression models in order to identify the best set of factors describing cognitive dysfunction and dementia, respectively. According to BMA, there is strong evidence that higher vitamin D levels, higher body mass index (BMI), and higher mobility function measured with the Timed Up and Go (TUG) test are independently associated with better cognitive performance and lower risk of dementia. Additionally, there is strong evidence that fewer years of education and lower vitamin B12 plasma levels independently describe worse cognitive performance. However, vitamin B12 levels higher than 800 pg/mL is negatively associated with the MMSE performance. Hypovitaminosis D in geriatric patients is an underrated marker of cognitive dysfunction and dementia.