Influence of family history of dementia in the development and progression of late-onset Alzheimer's disease

Does having a family member with dementia affect health beliefs about changing lifestyle and health behaviour for dementia risk reduction?

BACKGROUND

Dementia is a worldwide public health concern. Implementing lifestyle changes that target modifiable risk factors is crucial for reducing the risk of dementia. The aim of this study was to investigate the effect of having family members with dementia on individuals' health beliefs and tendencies towards adopting healthier lifestyles and behaviours.

METHODS

A cross-sectional, comparative study was conducted with 338 people aged 40 years and older, of whom 168 have the experience of having family members with dementia, and 170 have no such experience. Data were collected using a characteristics form, the Motivation to Change Lifestyle and Health Behaviours for Dementia Risk Reduction scale, and the modified Charlson comorbidity index. Descriptive statistics, Pearson's chi-square and independent t-tests, were used.

RESULTS

Those with family members with dementia were more likely to have greater motivation to modify their lifestyle (perceived susceptibility, severity, benefits, and cues to action) to reduce their risk of developing dementia. Additionally, they had greater perceived barriers to gain by adopting a healthy lifestyle, in contrast to those without such family members.

CONCLUSION

The presence of family members with dementia could be an important factor to consider when designing initiatives targeting health beliefs related to dementia prevention behaviours and lifestyle changes.

Sex differences in the associations of socioeconomic factors and cognitive performance with family history of Alzheimer's disease

INTRODUCTION

While higher socioeconomic factors (SEF) and cognitive performance (CP) have been associated with reduced Alzheimer's disease (AD) risk, recent evidence highlighted that these factors may have opposite effects on family history of AD (FHAD).

METHODS

Leveraging data from the UK Biobank (N=448,100) and the All of Us Research Program (N=240,319), we applied generalized linear regression models, polygenic risk scoring (PRS), and one-sample Mendelian randomization (MR) to test the sex-specific SEF and CP associations with AD and FHAD.

RESULTS

Observational and genetically informed analyses highlighted that higher SEF and CP were associated with reduced AD and sibling-FHAD, while these factors were associated with increased parent-FHAD. We also observed that population minorities may present different patterns with respect to sibling-FHAD vs. parent-FHAD. Sex differences in FHAD associations were identified in ancestry-specific and SEF PRS and MR results.

DISCUSSION

This study contributes to understanding the sex-specific relationships linking SEF and CP to FHAD, highlighting the potential role of reporting, recall, and surviving-related dynamics.

Entorhinal-based path integration selectively predicts midlife risk of Alzheimer's disease

INTRODUCTION

Entorhinal cortex (EC) is the first cortical region to exhibit neurodegeneration in Alzheimer's disease (AD), associated with EC grid cell dysfunction. Given the role of grid cells in path integration (PI)-based spatial behaviors, we predicted that PI impairment would represent the first behavioral change in adults at risk of AD.

METHODS

We compared immersive virtual reality (VR) PI ability to other cognitive domains in 100 asymptomatic midlife adults stratified by hereditary and physiological AD risk factors. In some participants, behavioral data were compared to 7T magnetic resonance imaging (MRI) measures of brain structure and function.

RESULTS

Midlife PI impairments predicted both hereditary and physiological AD risk, with no corresponding multi-risk impairment in episodic memory or other spatial behaviors. Impairments associated with altered functional MRI signal in the posterior-medial EC.

DISCUSSION

Altered PI may represent the transition point from at-risk state to disease manifestation in AD, prior to impairment in other cognitive domains.

Cognitive Functioning of Unaffected First-degree Relatives of Individuals With Late-onset Alzheimer's Disease: A Systematic Literature Review and Meta-analysis

First-degree relatives of individuals with late-onset Alzheimer's disease (LOAD) are at increased risk for developing dementia, yet the associations between family history of LOAD and cognitive dysfunction remain unclear. In this quantitative review, we provide the first meta-analysis on the cognitive profile of unaffected first-degree blood relatives of LOAD-affected individuals compared to controls without a family history of LOAD. A systematic literature search was conducted in PsycINFO, PubMed /MEDLINE, and Scopus. We fitted a three-level structural equation modeling meta-analysis to control for non-independent effect sizes. Heterogeneity and risk of publication bias were also investigated. Thirty-four studies enabled us to estimate 218 effect sizes across several cognitive domains. Overall, first-degree relatives (n = 4,086, mean age = 57.40, SD = 4.71) showed significantly inferior cognitive performance (Hedges' g = -0.16; 95% CI, -0.25 to -0.08; p < .001) compared to controls (n = 2,388, mean age = 58.43, SD = 5.69). Specifically, controls outperformed first-degree relatives in language, visuospatial and verbal long-term memory, executive functions, verbal short-term memory, and verbal IQ. Among the first-degree relatives, APOE ɛ4 carriership was associated with more significant dysfunction in cognition (g = -0.24; 95% CI, -0.38 to -0.11; p < .001) compared to non-carriers (g = -0.14; 95% CI, -0.28 to -0.01; p = .04). Cognitive test type was significantly associated with between-group differences, accounting for 65% (R23 = .6499) of the effect size heterogeneity in the fitted regression model. No evidence of publication bias was found. The current findings provide support for mild but robust cognitive dysfunction in first-degree relatives of LOAD-affected individuals that appears to be moderated by cognitive domain, cognitive test type, and APOE ɛ4.

Subclinical memory impairment in unaffected siblings of patients with dementia

Objective: Family history of dementia is a known risk factor for dementia. The cognitive performance of unaffected siblings of dementia patients has been poorly studied. We aimed to determine whether clinically unaffected siblings of dementia patients have significant cognitive impairment compared to individuals who do not have first-degree relatives with dementia. Methods: We compared the cognitive performance of 67 patients with dementia (24 males; mean age 69.5), 90 healthy siblings of those patients (34 males; mean age 61.56) and 92 healthy adults (35 males; mean age 60.96) who have no first-degree relatives with dementia. We assessed learning and memory (Rey Auditory Verbal Learning Test (RAVLT)), short-term/working memory (Digit Span) executive functions (Stroop Test) and general intelligence (Raven Progressive Matrices). Test scores were compared among three groups, with regression-based adjustments for age, sex, and education. Results: As expected, the patients with dementia were impaired in all cognitive domains. In the Sibling Group, RAVLT total learning was significantly lower compared to controls (B = -3.192, p = .005). In a subgroup analysis, compared to controls, RAVLT delayed recall was poorer in the siblings of patients with early-onset (<65 years) dementia. No significant differences were observed in other cognitive domains. Conclusion: Clinically unaffected siblings of dementia patients seem to have a selective subclinical impairment in memory encoding. This impairment seems to be more prominent in siblings of patients with early-onset dementia who also have deficits in delayed recall. Future studies are needed to determine if the observed cognitive impairment deteriorates to dementia.

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.

Exploratory Longitudinal Study of Ocular Structural and Visual Functional Changes in Subjects at High Genetic Risk of Developing Alzheimer's Disease

This study aimed to analyze the evolution of visual changes in cognitively healthy individuals at risk for Alzheimer's disease (AD). Participants with a first-degree family history of AD (FH+) and carrying the Ε4+ allele for the ApoE gene (ApoE ε4+) underwent retinal thickness analysis using optical coherence tomography (OCT) and visual function assessments, including visual acuity (VA), contrast sensitivity (CS), color perception, perception digital tests, and visual field analysis. Structural analysis divided participants into FH+ ApoE ε4+ and FH- ApoE ε4- groups, while functional analysis further categorized them by age (40-60 years and over 60 years). Over the 27-month follow-up, the FH+ ApoE ε4+ group exhibited thickness changes in all inner retinal layers. Comparing this group to the FH- ApoE ε4- group at 27 months revealed progressing changes in the inner nuclear layer. In the FH+ ApoE ε4+ 40-60 years group, no progression of visual function changes was observed, but an increase in VA and CS was maintained at 3 and 12 cycles per degree, respectively, compared to the group without AD risk at 27 months. In conclusion, cognitively healthy individuals at risk for AD demonstrated progressive retinal structural changes over the 27-month follow-up, while functional changes remained stable.

Path integration selectively predicts midlife risk of Alzheimer's disease

The entorhinal cortex (EC) is the first cortical region to exhibit neurodegeneration in Alzheimer's disease (AD), associated with EC grid cell dysfunction. Given the role of grid cells in path integration, we predicted that path integration impairment would represent the first behavioural change in adults at-risk of AD. Using immersive virtual reality, we found that midlife path integration impairments predicted both hereditary and physiological AD risk, with no corresponding impairment on tests of episodic memory or other spatial behaviours. Impairments related to poorer angular estimation and were associated with hexadirectional grid-like fMRI signal in the posterior-medial EC. These results indicate that altered path integration may represent the transition point from at-risk state to disease onset in AD, prior to impairment in other cognitive domains.

Modifiable Lifestyle Activities Affect Cognition in Cognitively Healthy Middle-Aged Individuals at Risk for Late-Life Alzheimer's Disease

BACKGROUND

It is now acknowledged that Alzheimer's disease (AD) processes are present decades before the onset of clinical symptoms, but it remains unknown whether lifestyle factors can protect against these early AD processes in mid-life.

OBJECTIVE

We asked whether modifiable lifestyle activities impact cognition in middle-aged individuals who are cognitively healthy, but at risk for late life AD. Participants (40-59 years) completed cognitive and clinical assessments at baseline (N = 206) and two years follow-up (N = 174).

METHODS

Mid-life activities were measured with the Lifetime of Experiences Questionnaire. We assessed the impact of lifestyle activities, known risk factors for sporadic late-onset AD (Apolipoprotein E ɛ4 allele status, family history of dementia, and the Cardiovascular Risk Factors Aging and Dementia score), and their interactions on cognition.

RESULTS

More frequent engagement in physically, socially, and intellectually stimulating activities was associated with better cognition (verbal, spatial, and relational memory), at baseline and follow-up. Critically, more frequent engagement in these activities was associated with stronger cognition (verbal and visuospatial functions, and conjunctive short-term memory binding) in individuals with family history of dementia. Impaired visuospatial function is one of the earliest cognitive deficits in AD and has previously associated with increased AD risk in this cohort. Additionally, conjunctive memory functions have been found impaired in the pre-symptomatic stages of AD.

CONCLUSION

These findings suggest that modifiable lifestyle activities offset cognitive decrements due to AD risk in mid-life and support the targeting of modifiable lifestyle activities for the prevention of AD.

Modifiable and non-modifiable risk factors of dementia on midlife cerebral small vessel disease in cognitively healthy middle-aged adults: the PREVENT-Dementia study

Background

Considerable overlap exists between the risk factors of dementia and cerebral small vessel disease (SVD). However, studies remain limited to older cohorts wherein pathologies of both dementia (e.g. amyloid) and SVD (e.g. white matter hyperintensities) already co-exist. In younger asymptomatic adults, we investigated differential associations and interactions of modifiable and non-modifiable inherited risk factors of (future) late-life dementia to (present-day) mid-life SVD.

Methods

Cognitively healthy middle-aged adults (aged 40–59; mean 51.2 years) underwent 3T MRI (n = 630) as part of the PREVENT-Dementia study. To assess SVD, we quantified white matter hyperintensities, enlarged perivascular spaces, microbleeds, lacunes, and computed composite scores of SVD burden and subtypes of hypertensive arteriopathy and cerebral amyloid angiopathy (CAA). Non-modifiable (inherited) risk factors were APOE4 status and parental family history of dementia. Modifiable risk factors were derived from the 2020 Lancet Commission on dementia prevention (early/midlife: education, hypertension, obesity, alcohol, hearing impairment, head injuries). Confirmatory factor analysis (CFA) was used to evaluate the latent variables of SVD and risk factors. Structural equation modelling (SEM) of the full structural assessed associations of SVD with risk factors and APOE4*risk interaction.

Results

In SEM, the latent variable of global SVD related to the latent variable of modifiable midlife risk SVD (β = 0.80, p = .009) but not non-modifiable inherited risk factors of APOE4 or family history of dementia. Interaction analysis demonstrated that the effect of modifiable risk on SVD was amplified in APOE4 non-carriers (β = − 0.31, p = .009), rather than carriers. These associations and interaction effects were observed in relation to the SVD subtype of hypertensive arteriopathy, rather than CAA. Sensitivity analyses using separate general linear models validated SEM results.

Conclusions

Established modifiable risk factors of future (late-life) dementia related to present-day (mid-life) SVD, suggesting that early lifestyle modifications could potentially reduce rates of vascular cognitive impairment attributed to SVD, a major ‘silent’ contributor to global dementia cases. This association was amplified in APOE4 non-carriers, suggesting that lifestyle modifications could be effective even in those with genetic predisposition to dementia.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13195-022-01095-4.

Machine learning for comprehensive prediction of high risk for Alzheimer's disease based on chromatic pupilloperimetry

Currently there are no reliable biomarkers for early detection of Alzheimer's disease (AD) at the preclinical stage. This study assessed the pupil light reflex (PLR) for focal red and blue light stimuli in central and peripheral retina in 125 cognitively normal middle age subjects (45–71 years old) at high risk for AD due to a family history of the disease (FH+), and 61 age-similar subjects with no family history of AD (FH−) using Chromatic Pupilloperimetry coupled with Machine Learning (ML). All subjects had normal ophthalmic assessment, and normal retinal and optic nerve thickness by optical coherence tomography. No significant differences were observed between groups in cognitive function and volumetric brain MRI. Chromatic pupilloperimetry-based ML models were highly discriminative in differentiating subjects with and without AD family history, using transient PLR for focal red (primarily cone-mediated), and dim blue (primarily rod-mediated) light stimuli. Features associated with transient pupil response latency (PRL) achieved Area Under the Curve Receiver Operating Characteristic (AUC-ROC) of 0.90 ± 0.051 (left-eye) and 0.87 ± 0.048 (right-eye). Parameters associated with the contraction arm of the rod and cone-mediated PLR were more discriminative compared to parameters associated with the relaxation arm and melanopsin-mediated PLR. Significantly shorter PRL for dim blue light was measured in the FH+ group in two test targets in the temporal visual field in right eye that had highest relative weight in the ML algorithm (mean ± standard error, SE 0.449 s ± 0.007 s vs. 0.478 s ± 0.010 s, p = 0.038). Taken together our study suggests that subtle focal changes in pupil contraction latency may be detected in subjects at high risk to develop AD, decades before the onset of AD clinical symptoms. The dendrites of melanopsin containing retinal ganglion cells may be affected very early at the preclinical stages of AD.

Longitudinal analysis of the retina and choroid in cognitively normal individuals at higher genetic risk for Alzheimer disease

PURPOSE

To assess baseline differences and longitudinal rate of change in retinal and choroidal imaging parameters between APOE ε4 carriers and non-carriers with normal cognition.

DESIGN

Prospective study.

SUBJECTS

413 eyes of 218 individuals with normal cognition aged ≥55 years with known APOE status (98 ε4 carriers, 120 non-carriers). Exclusion criteria included diabetes mellitus, uncontrolled hypertension, glaucoma, and vitreoretinal or neurodegenerative disease.

METHODS

Optical coherence tomography (OCT) and OCT angiography (OCTA) was performed at baseline and at 2 years [Zeiss Cirrus HD-OCT 5000 with AngioPlex (Zeiss Meditec, Dublin, CA)]. Groups were compared using sex- and age-adjusted generalized estimating equations.

MAIN OUTCOME MEASURES

OCT: retinal nerve fiber layer thickness, macular ganglion cell-inner plexiform layer thickness, central subfield thickness (CST), choroidal vascularity index. OCTA: foveal avascular zone area, perfusion density (PD), vessel density, peripapillary capillary perfusion density and capillary flux index (CFI). Rate of change per year was calculated.

RESULTS

At baseline, ε4 carriers demonstrated decreased CST (p=0.018), PD in the 6mm Early Treatment Diabetic Retinopathy Study (ETDRS) circle (p=0.049), and temporal CFI (p=0.047). Seventy-one ε4 carriers and 78 non-carriers returned at 2 years; at follow-up, the 6mm ETDRS circle (p=0.05) and outer ring (p=0.049) showed decreased PD in ε4 carriers, with no differences in rates of change between groups (all p>0.05).

CONCLUSIONS

There were measured differences in CST, PD, and peripapillary CFI between APOE ε4 carriers and non-carriers with normal cognition. Larger and longer-term studies may further elucidate the potential prognostic value of these findings.

Association between having a family member with dementia and perceptions of dementia preventability

BACKGROUND

One's experience with dementia may affect their perceptions about dementia preventability, which in turn could influence preventive health behaviors. We aimed to examine how having a family history of dementia and caregiving experience are associated with perceptions about and self-efficacy for dementia preventability.

METHODS

Cross-sectional, self-administered survey. Participants reported whether they have had a family member with dementia and, among those who reported having a family member with dementia, whether they served as a caregiver. Outcomes were perceptions about the likelihood of dementia preventability, self-efficacy for dementia prevention, and benefits of specific dementia prevention strategies. Associations were assessed via partial proportional odds model for ordinal outcome variables and logistic regression for binary outcome variables.

RESULTS

Of 1,575 respondents, 71% had a family member with dementia, of which 42% served as a caregiver. People with a family member with dementia were less likely to believe that dementia is preventable (aOR = 0.75, 95% CI: 0.58, 0.96) and had lower self-efficacy for dementia prevention (aOR = 0.71, 95% CI: 0.56, 0.90). The subgroup analysis among those with caregiving experience was consistent with the primary findings, showing less belief in the likelihood of dementia preventability (aOR = 0.69, 95% CI: 0.46, 1.03) and self-efficacy (aOR = 0.75, 95% CI: 0.56, 1.00).

CONCLUSION

Having a family member with dementia is associated with unfavorable perceptions about dementia preventability. Incorporating family history of dementia into communication efforts about dementia risk reduction may help address potential barriers to preventive health behaviors.

Evidence of plasma biomarkers indicating high risk of dementia in cognitively normal subjects

Subjects with comorbidities are at risk for neurodegeneration. There is a lack of a direct relationship between comorbidities and neurodegeneration. In this study, immunomagnetic reduction (IMR) assays were utilized to assay plasma Aβ_1-42 and total tau protein (T-Tau) levels in poststroke (PS, n = 27), family history of Alzheimer's disease (ADFH, n = 35), diabetes (n = 21), end-stage renal disease (ESRD, n = 41), obstructive sleep apnea (OSA, n = 20), Alzheimer's disease (AD, n = 65). Thirty-seven healthy controls (HCs) were enrolled. The measured concentrations of plasma Aβ_1-42 were 14.26 ± 1.42, 15.43 ± 1.76, 15.52 ± 1.60, 16.15 ± 1.05, 16.52 ± 0.59, 15.97 ± 0.54 and 20.06 ± 3.09 pg/mL in HC, PS, ADFH, diabetes, ESRD, OSA and AD groups, respectively. The corresponding concentrations of plasma T-Tau were 15.13 ± 3.62, 19.29 ± 8.01, 17.93 ± 6.26, 19.74 ± 2.92, 21.54 ± 2.72, 20.17 ± 2.77 and 41.24 ± 14.64 pg/mL. The plasma levels of Aβ_1-42 and T-Tau in were significantly higher in the PS, ADFH, diabetes, ESRD and OSA groups than controls (Aβ_1-42 in PS: 15.43 ± 1.76 pg/mL vs. 14.26 ± 1.42 pg/mL, p < 0.005; T-Tau in PS: 19.29 ± 8.01 vs. 15.13 ± 3.62 pg/mL, p < 0.005, Aβ_1-42 in ADFH: 15.52 ± 1.60 pg/mL vs. 14.26 ± 1.42 pg/mL, p < 0.001; T-Tau in ADFH: 17.93 ± 6.26 vs. 15.13 ± 3.62 pg/mL, p < 0.005, Aβ_1-42 in diabetes: 16.15 ± 1.05 pg/mL vs. 14.26 ± 1.42 pg/mL, p < 0.001; T-Tau in diabetes: 19.74 ± 2.92 vs. 15.13 ± 3.62 pg/mL, p < 0.001, Aβ_1-42 in ESRD: 16.52 ± 0.59 pg/mL vs. 14.26 ± 1.42 pg/mL, p < 0.001; T-Tau in ESRD: 21.54 ± 2.72 vs. 15.13 ± 3.62 pg/mL, p < 0.001, Aβ_1-42 in OSA: 15.97 ± 0.54 pg/mL vs. 14.26 ± 1.42 pg/mL, p < 0.001; T-Tau in OSA: 20.17 ± 2.77 vs. 15.13 ± 3.62 pg/mL, p < 0.001). This evidence indicates the high risk for dementia in these groups from the perspective of plasma biomarkers.

Association between dementia parental family history and mid-life modifiable risk factors for dementia: a cross-sectional study using propensity score matching within the Lifelines cohort

OBJECTIVE

Individuals with a parental family history (PFH) of dementia have an increased risk to develop dementia, regardless of genetic risks. The aim of this study is to investigate the association between a PFH of dementia and currently known modifiable risk factors for dementia among middle-aged individuals using propensity score matching (PSM).

DESIGN

A cross-sectional study.

SETTING AND PARTICIPANTS

A subsample of Lifelines (35-65 years), a prospective population-based cohort study in the Netherlands was used.

OUTCOME MEASURES

Fourteen modifiable risk factors for dementia and the overall Lifestyle for Brain Health (LIBRA) score, indicating someone's potential for dementia risk reduction (DRR).

RESULTS

The study population included 89 869 participants of which 10 940 (12.2%) had a PFH of dementia (mean (SD) age=52.95 (7.2)) and 36 389 (40.5%) without a PFH of dementia (mean (SD) age=43.19 (5.5)). Of 42 540 participants (47.3%), PFH of dementia was imputed. After PSM, potential confounding variables were balanced between individuals with and without PFH of dementia. Individuals with a PFH of dementia had more often hypertension (OR=1.19; 95% CI 1.14 to 1.24), high cholesterol (OR=1.24; 95% CI 1.18 to 1.30), diabetes (OR=1.26; 95% CI 1.11 to 1.42), cardiovascular diseases (OR=1.49; 95% CI 1.18 to 1.88), depression (OR=1.23; 95% CI 1.08 to 1.41), obesity (OR=1.14; 95% CI 1.08 to 1.20) and overweight (OR=1.10; 95% CI 1.05 to 1.17), and were more often current smokers (OR=1.20; 95% CI 1.14 to 1.27) and ex-smokers (OR=1.21; 95% CI 1.16 to 1.27). However, they were less often low/moderate alcohol consumers (OR=0.87; 95% CI 0.83 to 0.91), excessive alcohol consumers (OR=0.93; 95% CI 0.89 to 0.98), socially inactive (OR=0.84; 95% CI 0.78 to 0.90) and physically inactive (OR=0.93; 95% CI 0.91 to 0.97). Having a PFH of dementia resulted in a higher LIBRA score (RC=0.15; 95% CI 0.11 to 0.19).

CONCLUSION

We found that having a PFH of dementia was associated with several modifiable risk factors. This suggests that middle-aged individuals with a PFH of dementia are a group at risk and could benefit from DRR. Further research should explore their knowledge, beliefs and attitudes towards DRR, and whether they are willing to assess their risk and change their lifestyle to reduce dementia risk.

The effect of Alzheimer's disease risk factors on brain aging in normal Chineses: Cognitive aging and cognitive reserve

Aging has been recognized as a major driving force of the Alzheimer's disease's (AD) progression, however, the relationship between brain aging and AD is still unclear. There is also a lack of studies investigating the influence of AD risk factors on brain aging in cognitively normal people. Here, the "Brain Age Gap Estimation" (BrainAGE) framework was applied to investigate the effects of AD risk factors on individual brain aging. Across a total of 165 cognitively normal elderly subjects, although no significant difference was observed in the BrainAGE scores among the three groups, AD risk dose (i.e., the number of AD risk factors) is tend to associated with an increased BrainAGE scores (high-risk > middle risk > low risk). Female exhibited more advanced brain aging (P = 0.004), and higher education years were associated with preserved brain aging (P < 0.001). APOE-ɛ4 (P = 0.846) and family history (FH) of dementia (P = 0.209) did not increase BrainAGE scores. When comparing 52 aMCI patients with 38 cognitively normal controls from ADNI dataset, aMCI patients showed significantly increased BrainAGE scores. BrainAGE scores were negatively correlated with CSF Aβ42 levels in the aMCI group (r = -0.275, P = 0.048). With an accuracy of 68.9%, BrainAGE outperformed APOE-ɛ4 and hippocampus gray matter volume (GMV) in predicting aMCI. In conclusion, AD is independently associated with structural changes in the brain that reflect advanced aging. Potentially, BrainAGE combined with APOE-ɛ4 and hippocampus GMV could be used as a pre-screening tool in early-stage AD.

Knowledge, health beliefs and attitudes towards dementia and dementia risk reduction among descendants of people with dementia: a qualitative study using focus group discussions

Background

Individuals with a parental family history of dementia have an increased risk of developing dementia because they share their genes as well as their psychosocial behaviour. Due to this increased risk and their experience with dementia, they may be particularly eager to receive information regarding dementia risk reduction (DRR). This study evaluated the knowledge, beliefs and attitudes towards dementia and DRR among descendants of people with dementia.

Method

Using a semi-structured topic guide, three focus group discussions were conducted consisting of 12 female (80%) and 3 male (20%) descendants of people with dementia with a mean (± SD) age of 48.8 (± 12) years. Focus group discussions were audio recorded and transcribed. Each transcript was analysed thoroughly, and where appropriate, a code was generated and assigned by two researchers independently. Then, similar codes were grouped together and categorized into themes.

Results

The items in the topic guide could only be addressed after participants had been given the opportunity to share their experiences of having a parent with dementia. Participants were unaware or uncertain about the possibility of reducing the risk of developing dementia and therefore hesitant to assess their dementia risk without treatment options in sight. Moreover, participants indicated that their general practitioner only gave some information on heritability, not on DRR. Although participants identified a large number of modifiable risk factors as a group during the group discussions, they were eager to receive more information on dementia and DRR. In the end, participants adopted a more positive attitude towards a DRR programme and provided suggestions for the development of future DRR programmes.

Conclusions

Although the research aim was to evaluate the knowledge, beliefs and attitudes towards dementia and DRR, sharing experiences of having a parent with dementia seemed a prerequisite for considering participants’ own risk of developing dementia and participating in a DRR programme. Knowledge of dementia and DRR was limited. Due to unawareness of the possibility of reducing dementia risk, participants were hesitant about assessing their dementia risk. Group discussions positively changed the perception of dementia risk assessment and participants’ willingness to participate in a DRR programme.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-11415-2.

Inherited risk of dementia and the progression of cerebral small vessel disease and inflammatory markers in cognitively healthy midlife adults: the PREVENT-Dementia study

Cerebral small vessel disease (SVD) and inflammation are increasingly recognized as key contributors to Alzheimer's disease (AD), although the timing, trajectory, and relation between them early in the disease process is unclear. Therefore, to investigate very early-stage changes, we compared 158 healthy midlife adults with and without inherited AD predisposition (APOE4 carriership (38% positive), parental family history (FH) of dementia (54% positive)) on markers of SVD (white matter hyperintensities (WMH), cerebral microbleeds), and inflammation (C-reactive protein (CRP), fibrinogen), cross-sectionally and longitudinally over two years. While WMH severity was comparable between groups at baseline, longitudinal progression of WMH was greater in at-risk groups (APOE4+ and FH+). Topographically, APOE4 was associated exclusively with deep, but not periventricular, WMH progression after adjusting for FH. Conversely, APOE4 carriers displayed lower CRP levels than noncarriers, but not fibrinogen. Furthermore, interaction analysis showed that FH moderated the effect of SVD and inflammation on reaction time, an early feature of SVD, but not episodic memory or executive function. Findings suggest that vascular and inflammatory changes could occur decades before dementia onset, and may be of relevance in predicting incipient clinical progression.

Modifiable, Non-Modifiable, and Clinical Factors Associated with Progression of Alzheimer's Disease

There is an extensive literature relating to factors associated with the development of Alzheimer's disease (AD), but less is known about factors which may contribute to its progression. This review examined the literature with regard to 15 factors which were suggested by PubMed search to be positively associated with the cognitive and/or neuropathological progression of AD. The factors were grouped as potentially modifiable (vascular risk factors, comorbidities, malnutrition, educational level, inflammation, and oxidative stress), non-modifiable (age at clinical onset, family history of dementia, gender, Apolipoprotein E ɛ4, genetic variants, and altered gene regulation), and clinical (baseline cognitive level, neuropsychiatric symptoms, and extrapyramidal signs). Although conflicting results were found for the majority of factors, a positive association was found in nearly all studies which investigated the relationship of six factors to AD progression: malnutrition, genetic variants, altered gene regulation, baseline cognitive level, neuropsychiatric symptoms, and extrapyramidal signs. Whether these or other factors which have been suggested to be associated with AD progression actually influence the rate of decline of AD patients is unclear. Therapeutic approaches which include addressing of modifiable factors associated with AD progression should be considered.

Proximity to dementia onset and multi-modal neuroimaging changes: The prevent-dementia study

BACKGROUND

First-degree relatives of people with dementia (FH+) are at increased risk of developing Alzheimer's disease (AD). Here, we investigate "estimated years to onset of dementia" (EYO) as a surrogate marker of preclinical disease progression and assess its associations with multi-modal neuroimaging biomarkers.

METHODS

89 FH+ participants in the PREVENT-Dementia study underwent longitudinal MR imaging over 2 years. EYO was calculated as the difference between the parental age of dementia diagnosis and the current age of the participant (mean EYO = 23.9 years). MPRAGE, ASL and DWI data were processed using Freesurfer, FSL-BASIL and DTI-TK. White matter lesion maps were segmented from FLAIR scans. The SPM Sandwich Estimator Toolbox was used to test for the main effects of EYO and interactions between EYO, Time, and APOE-ε4+. Threshold free cluster enhancement and family wise error rate correction (TFCE _FWER) was performed on voxelwise statistical maps.

RESULTS

There were no significant effects of EYO on regional grey matter atrophy or white matter hyperintensities. However, a shorter EYO was associated with lower white matter Fractional Anisotropy and elevated Mean/Radial Diffusivity, particularly in the corpus callosum (TFCE_FWERp < 0.05). The influence of EYO on white matter deficits were significantly stronger compared to that of normal ageing. APOE-ε4 carriers exhibited hyperperfusion with nearer proximity to estimated onset in temporo-parietal regions. There were no interactions between EYO and time, suggesting that EYO was not associated with accelerated imaging changes in this sample.

CONCLUSIONS

Amongst cognitively normal midlife adults with a family history of dementia, a shorter hypothetical proximity to dementia onset may be associated with incipient brain abnormalities, characterised by white matter disruptions and perfusion abnormalities, particularly amongst APOE-ε4 carriers. Our findings also confer biological validity to the construct of EYO as a potential stage marker of preclinical progression in the context of sporadic dementia. Further clinical follow-up of our longitudinal sample would provide critical validation of these findings.

Uptake and effectiveness of a tailor-made online lifestyle programme targeting modifiable risk factors for dementia among middle-aged descendants of people with recently diagnosed dementia: study protocol of a cluster randomised controlled trial (Demin study)

INTRODUCTION

Descendants of patients with dementia have a higher risk to develop dementia. This study aims to investigate the uptake and effectiveness of an online tailor-made lifestyle programme for dementia risk reduction (DRR) among middle-aged descendants of people with recently diagnosed late-onset dementia.

METHODS AND ANALYSIS

Demin is a cluster randomised controlled trial, aiming to include 21 memory clinics of which 13 will be randomly allocated to the passive (poster and flyer in a waiting room) and 8 to the active recruitment strategy (additional personal invitation by members of the team of the memory clinic). We aim to recruit 378 participants (40-60 years) with a parent who is recently diagnosed with Alzheimer's disease or vascular dementia at one of the participating memory clinics. All participants receive a dementia risk assessment (online questionnaire, physical examination and blood sample) and subsequently an online tailor-made lifestyle advice regarding protective (Mediterranean diet, low/moderate alcohol consumption and high cognitive activity) and risk factors (physical inactivity, smoking, loneliness, cardiovascular diseases (CVD), hypertension, high cholesterol, diabetes, obesity, renal dysfunction and depression) for dementia. The primary outcome is the difference in uptake between the two recruitment strategies. Secondary outcomes are change(s) in (1) the Lifestyle for Brain Health score, (2) individual health behaviours, (3) health beliefs and attitudes towards DRR and (4) compliance to the tailor-made lifestyle advice. Outcomes will be measured at 3, 6, 9 and 12 months after baseline. The effectiveness of this online tailor-made lifestyle programme will be evaluated by comparing Demin participants to a matched control group (lifelines cohort).

ETHICS AND DISSEMINATION

This study has been approved by the Dutch Ministry of Health, Welfare and Sport according to the Population Screening Act. All participants have to give online informed consent using SMS-tan (transaction authentication number delivered via text message). Findings will be disseminated through peer-reviewed journals and (inter)national conferences.

TRIAL REGISTRATION NUMBER

NTR7434.

The Role of Nutrition and Inflammation on Cognition in a High-Risk Group for Alzheimer's Disease

Background:

Alzheimer’s disease (AD) is a prevalent neurodegenerative disease. Treatments are necessary to target people at high risk for AD. Inflammation, particularly tumor necrosis factor alpha (TNFα), appears to be an important marker associated with the development of AD pathophysiology. Consuming a high-fat diet induces tissue expression of TNFα.

Objective:

This study investigates the relationship between nutrition, circulating inflammation, and cognition in African American women (age: M = 59.5 (±8.20) [42–73] years) at risk for developing AD.

Methods:

Participants were split into high-fat and low-fat groups based on total dietary fat consumption self-reported on the Lower Mississippi Delta Nutrition Intervention Research Initiative Food Frequency Questionnaire (Delta NIRI FFQ).

Results:

A high-fat diet was associated with increased blood serum TNFα (p = 0.02) compared to the low-fat diet. In addition, global cognition scores were 9.0% better in those who consumed a higher fat diet (p = 0.04). No significant differences across groups were noted for executive function, dual-tasking, and visuospatial performance.

Conclusion:

These results indicate that there may be multiple biological pathways involved in AD development, suggesting the need for more holistic approaches to mitigate AD-development risk.

The effect of physical activity on cognition relative to APOE genotype (PAAD-2): study protocol for a phase II randomized control trial

BACKGROUND

By 2050, the prevalence of Alzheimer's disease (AD) in the United States is predicted to reach 13.8 million. Despite worldwide research efforts, a cure for AD has not been identified. Thus, it is critical to identify preventive strategies that can reduce the risk of or delay the onset of AD. Physical activity (PA) has potential in this regard. This randomized clinical trial aims to (a) test the causal relationship between PA and AD-associated cognitive function for persons with a family history of AD (FH+), (b) determine the moderating role of apolipoprotein epsilon 4 (APOE4) carrier status on cognition, and (c) assess cerebral structure, cerebral function, and putative biomarkers as mediators of the effects of PA on cognition.

METHODS

We are recruiting cognitively normal, middle aged (40-65 years) sedentary adults with FH+. Participants are randomly assigned to a 12-month PA intervention for 3 days/week or to a control group maintaining their normal lifestyle. Saliva samples are taken at pre-test to determine APOE genotype. At pre-, mid-, and post-tests, participants complete a series of cognitive tests to assess information-processing speed, verbal and visual episodic memory, constructional praxis, mnemonic discrimination, and higher-order executive functions. At pre- and post-tests, brain imaging and blood biomarkers are assessed.

DISCUSSION

We hypothesize that 1) the PA group will demonstrate improved cognition compared with controls; 2) PA-derived cognitive changes will be moderated by APOE4 status; and 3) PA-induced changes in neural and blood biomarkers will contribute to cognitive changes and differ as a function of APOE4 status. Our results may provide important insights into the potential of PA to preserve neurocognitive function in people with a heightened risk of AD due to FH+ and as moderated by APOE4 status. By using sophisticated analytic techniques to assess APOE as a moderator and neurobiological mechanisms as mediators across trajectories of cognitive change in response to PA, we will advance our understanding of the potential of PA in protecting against AD.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03876314. Registered March 15, 2019.

"Choosing Wisely": Apolipoprotein E Genetic Testing for the Diagnosis of Alzheimer's Disease in Dementia Clinics

BACKGROUND

Apolipoprotein E (APOE) ɛ4 allele carriers have an increased risk of late-onset Alzheimer's disease (AD). However, in the "Choosing Wisely" campaign for avoiding unnecessary medical tests, treatments, and procedures, APOE genetic testing is not recommended as a predictive test for AD.

OBJECTIVE

The aim of this study was to investigate the potential value of APOE genetic testing in a specific clinical context.

METHODS

Subjects with poor performance in the Korean version of the Mini-Mental Status Examination for dementia screening (MMSE-DS) with a Z-score of less than -1.5 were recruited from the public health centers. All participants underwent APOE genetic testing. Family history of dementia (FHx) was confirmed if one or more first-degree relatives had dementia.

RESULTS

Among 349 subjects, 162 (46.4%) were diagnosed with AD. APOEɛ4 allele carriers had a much higher risk of AD in the group with FHx than in the group without FHx (OR = 15.81, 95% CI = 2.74-91.21 versus OR = 1.82, 95% CI = 1.00-3.27, z = 2.293, p = 0.011). The sensitivity, specificity, positive predictive value, and negative predictive value for the APOEɛ4 allele were 47.7%, 90.9%, 91.3%, and 46.5% in the group with FHx.

CONCLUSION

It would be a wise choice to perform the APOE genetic testing for the diagnosis of AD in subjects with poor performance in a screening test and a family history of dementia.

Association of Acquired and Heritable Factors With Intergenerational Differences in Age at Symptomatic Onset of Alzheimer Disease Between Offspring and Parents With Dementia

IMPORTANCE

Acquired and heritable traits are associated with dementia risk; however, how these traits are associated with age at symptomatic onset (AAO) of Alzheimer disease (AD) is unknown. Identifying the associations of acquired and heritable factors with variability in intergenerational AAO of AD could facilitate diagnosis, assessment, and counseling of the offspring of parents with AD.

OBJECTIVE

To quantify the associations of acquired and heritable factors with intergenerational differences in AAO of AD.

DESIGN, SETTING, AND PARTICIPANTS

This nested cohort study used data from the Knight Alzheimer Disease Research Center that included community-dwelling participants with symptomatic AD, parental history of dementia, and available DNA data who were enrolled in prospective studies of memory and aging from September 1, 2005, to August 31, 2016. Clinical, biomarker, and genetic data were extracted on January 17, 2017, and data analyses were conducted from July 1, 2017, to August 20, 2019.

MAIN OUTCOMES AND MEASURES

The associations of acquired (ie, years of education; body mass index; history of cardiovascular disease, hypertension, hypercholesterolemia, diabetes, active depression within 2 years, traumatic brain injury, tobacco use, and unhealthy alcohol use; and retrospective determination of AAO) and heritable factors (ie, ethnicity/race, paternal or maternal inheritance, parental history of early-onset dementia, APOE ε4 allele status, and AD polygenic risk scores) to intergenerational difference in AAO of AD were quantified using stepwise forward multivariable regression. Missense or frameshift variants within genes associated with AD pathogenesis were screened using whole-exome sequencing.

RESULTS

There were 164 participants with symptomatic AD, known parental history of dementia, and available DNA data (mean [SD] age, 70.9 [8.3] years; 90 [54.9%] women) included in this study. Offspring were diagnosed with symptomatic AD a mean (SD) 6.1 (10.7) years earlier than their parents (P < .001). The adjusted R2 for measured acquired and heritable factors for intergenerational difference in AAO of AD was 0.29 (F8,155 = 9.13; P < .001). Paternal (β = -9.52 [95% CI, -13.79 to -5.25]) and maternal (β = -6.68 [95% CI, -11.61 to -1.75]) history of dementia, more years of education (β = -0.58 [95% CI -1.08 to -0.09]), and retrospective determination of AAO (β = -3.46 [95% CI, -6.40 to -0.52]) were associated with earlier-than-expected intergenerational difference in AAO of AD. Parental history of early-onset dementia (β = 21.30 [95% CI, 15.01 to 27.59]), presence of 1 APOE ε4 allele (β = 5.00 [95% CI, 2.11 to 7.88]), and history of hypertension (β = 3.81 [95% CI, 0.88 to 6.74]) were associated with later-than-expected intergenerational difference in AAO of AD. Missense or frameshift variants within genes associated with AD pathogenesis were more common in participants with the greatest unexplained variability in intergenerational AAO of AD (19 of 48 participants [39.6%] vs 26 of 116 participants [22.4%]; P = .03).

CONCLUSIONS AND RELEVANCE

Acquired and heritable factors were associated with a substantial proportion of variability in intergenerational AAO of AD. Variants in genes associated with AD pathogenesis may contribute to unexplained variability, justifying further study.

Allocentric and Egocentric Spatial Processing in Middle-Aged Adults at High Risk of Late-Onset Alzheimer's Disease: The PREVENT Dementia Study

Impairments in spatial processing due to hippocampal degeneration have been observed in the years immediately preceding the diagnosis of Alzheimer's disease (AD) dementia. The demonstration of changes in spatial processing in preceding decades would provide a cognitive marker for pre-clinical AD and an outcome measure for early intervention trials. The present study examined allocentric and egocentric spatial processing in relation to future dementia risk in a middle-aged cohort. The CAIDE Dementia Risk Score (DRS) was calculated for 188 persons aged 40 to 59, of whom 94 had a parent with dementia. Participants underwent the Four Mountains Test (4MT) of allocentric spatial processing, the Virtual Reality Supermarket Trolley Task (VRSTT) of egocentric spatial processing, and 3T MRI scans. A significant negative association was found between the DRS and 4MT (Spearman correlation - 0.26, p = 0.0006), but not with the VRSTT. The 4MT was also found to be a better predictor of risk than tests of episodic memory, verbal fluency, or executive functioning. The results suggest that allocentric rather than egocentric processing may be a potential indicator of risk for late-onset AD, consistent with the hypothesis that the earliest cognitive changes in AD are driven by tau-related degeneration in the medial temporal lobe rather than amyloid-only deposition in the medial parietal lobe.

Association between blood lead level and subsequent Alzheimer's disease mortality

Background:

Previous studies suggest that cumulative lead exposure is associated with cognitive decline, but its relation with Alzheimer’s disease (AD) remains unclear. Therefore, this study investigated the longitudinal association between blood lead level (BLL) and AD mortality.

Methods:

This study included 8,080 elders (60 years or older) with BLL data from the 1999 to 2008 US National Health and Nutrition Examination Survey. Mortality was determined from linked 1999–2014 National Death Index data. A causal diagram presented causal assumptions and identified a sufficient set of confounders: age, sex, poverty, race/ethnicity, and smoking. Cox proportional hazard models were used to determine the association between BLL and subsequent AD mortality. Impacts of competing risks and design effect were also assessed. Adjusted hazard rate ratio (HRR) and 95% confidence interval (CI) were reported.

Results:

Follow-up ranged from <1 to 152 months (median, 74). Eighty-one participants died from AD over 632,075 total person-months at risk. An increase in BLL was associated with an increase in AD mortality after adjusting for identified confounders. We estimated that those with BLL of 1.5 and 5 μg/dl had 1.2 (95% CI = 0.70, 2.1) and 1.4 (95% CI = 0.54, 3.8) times the rate of AD mortality compared to those with BLL of 0.3 μg/dl, respectively, after accounting for competing risks. Adjusted HRRs were 1.5 (95% CI = 0.81, 2.9) and 2.1 (95% CI = 0.70, 6.3), respectively, after considering design effect.

Conclusions:

This longitudinal study demonstrated a positive, albeit not statistically significant, association between BLL and AD mortality after adjustment for competing risks or design effect.

AD molecular: PET amyloid imaging across the Alzheimer's disease spectrum: From disease mechanisms to prevention

The advent of amyloid-beta (Aβ) positron emission tomography (PET) imaging has transformed the field of Alzheimer's disease (AD) by enabling the quantification of cortical Aβ accumulation and propagation in vivo. This revolutionary tool has made it possible to measure direct associations between Aβ and other AD biomarkers, to identify factors that influence Aβ accumulation and to redefine entry criteria into clinical trials as well as measure drug target engagement. This chapter summarizes the main findings on the associations of Aβ with other biomarkers of disease progression across the AD spectrum. It discusses investigations of the timing at which Aβ pathology starts to accumulate, demonstrates the clinical utility of Aβ PET imaging and discusses some ethical implications. Finally, it presents genetic and potentially modifiable lifestyle factors that might influence Aβ accumulation and therefore be targets for AD prevention.

Social support and verbal interaction are differentially associated with cognitive function in midlife and older age

Social engagement is associated with healthy aging and preserved cognition. Two dimensions of engagement, verbal interactions and perceived support, likely impact cognition via distinct mechanistic pathways. We explored the cognitive benefit of each construct among enrollees (N = 1,052, mean age = 60.2 years) in the Wisconsin Registry for Alzheimer's Prevention study, who provide neuropsychological and sociobehavioral data at two-year intervals. Outcomes included six cognitive factor scores representing key domains of executive function and memory. Key predictors included self-reported perceived social support and weekly verbal interaction. Results indicated that after adjusting for lifestyle covariates, social support was positively associated with Speed and Flexibility and that verbal interactions were associated with Verbal Learning and Memory. These findings suggest that support, which may buffer stress, and verbal interaction, an accessible, aging-friendly form of environmental enrichment, are uniquely beneficial. Both are integral in the design of clinical and community interventions and programs that promote successful aging.

Synergistic interaction between APOE and family history of Alzheimer's disease on cerebral amyloid deposition and glucose metabolism

Background

Recently, the field of gene-gene or gene-environment interaction research appears to have gained growing interest, although it is seldom investigated in Alzheimer’s disease (AD). Hence, the current study aims to investigate interaction effects of the key genetic and environmental risks—the apolipoprotein ε4 allele (APOE4) and family history of late-onset AD (FH)—on AD-related brain changes in cognitively normal (CN) middle-aged and older adults.

Methods

[¹¹C] Pittsburg compound-B (PiB) positron emission tomography (PET) imaging as well as [¹⁸F] fluoro-2-deoxyglucose (FDG) PET that were simultaneously taken with T1-weighted magnetic resonance imaging (MRI) were obtained from 268 CNs from the Korean Brain Aging Study for Early Diagnosis and Prediction of AD (KBASE). Composite standardized uptake value ratios were obtained from PiB-PET and FDG-PET images in the AD signature regions of interests (ROIs) and analyzed. Voxel-wise analyses were also performed to examine detailed regional changes not captured by the ROI analyses.

Results

A significant synergistic interaction effect was found between the APOE4 and FH on amyloid-beta (Aβ) deposition in the AD signature ROIs as well as other regions. Synergistic interaction effects on cerebral glucose metabolism were observed in the regions not captured by the AD signature ROIs, particularly in the medial temporal regions.

Conclusions

Strong synergistic effects of APOE4 and FH on Aβ deposition and cerebral glucose metabolism in CN adults indicate possible gene-to-gene or gene-to-environment interactions that are crucial for pathogenesis of AD involving Aβ. Other unspecified risk factors—genes and/or environmental—that are captured by the positive FH status might either coexpress or interact with APOE4 to alter AD-related brain changes in CN. Healthy people with both FH and APOE4 need more attention for AD prevention.

Electronic supplementary material

The online version of this article (10.1186/s13195-018-0411-x) contains supplementary material, which is available to authorized users.

Considerations on accuracy, pattern and possible underlying factors of brain microbleed progression in older adults with absence or mild presence of vascular pathology

Objective To analyse brain microbleed (BMB) progression, its possible underlying factors, and the influence of inter-observer differences, in older individuals with none or mild vascular pathology. Methods This study analysed magnetic resonance images, cognitive, demographic and laboratory data from all individuals from the Alzheimer's Disease (AD) Neuroimaging Initiative database who had the required sequences for identifying BMBs over three consecutive years at the time the database was accessed (January 2016). BMBs were assessed independently by two observers with similar levels of experience. Results A total of 291 patients were included in the study. The number of individuals with BMBs and the number of BMBs per individual slightly and nonsignificantly increased across three consecutive years (Y1: 55/291 [19%]; Y2: 61/291 [21%]; Y3: 66/291 [23%]) with 1-2 BMBs and (Y1: 11/291 [4%]; Y2: 12/291 [4%]; Y3: 14/291 [5%]) with ≥ 3 BMBs. Both observers identified a similar pattern of BMB prevalence and progression in each cognitive group (normal < early/late mild cognitive impairment (MCI) > AD patients) despite inter-observer differences (1.5 BMBs, 95% confidence interval -3.7, 6.2], κ=0.543), which were mainly in the cortex. Serum cholesterol was the main predictor of change in BMB count between time-points but did not predict overall progression. Conclusions Inter-observer differences are always present and it is difficult to ascertain their influence in the analysis of BMB progression, which was observed in cognitively normal and MCI individuals, but not in AD patients. This should be confirmed in further studies.

Background and distribution of lobar microbleeds in cognitive dysfunction

OBJECTIVES

Cerebral microbleeds (CMBs) are often observed in memory clinic patients. It has been generally accepted that deep CMBs (D-CMBs) result from hypertensive vasculopathy (HV), whereas strictly lobar CMBs (SL-CMBs) result from cerebral amyloid angiopathy (CAA) which frequently coexists with Alzheimer's disease (AD). Mixed CMBs (M-CMBs) have been partially attributed to HV and also partially attributed to CAA. The aim of this study was to elucidate the differences between SL-CMBs and M-CMBs in terms of clinical features and regional distribution.

MATERIALS

We examined 176 sequential patients in our memory clinic for clinical features and CMB location using susceptibility-weighted images obtained on a 3T-MRI. The number of lobar CMBs in SL-CMBs and M-CMBs was counted in each cerebral lobe and their regional density was adjusted according to the volume of each lobe.

RESULTS

Of the total 176 patients, 111 patients (63.1%) had CMBs. Within the patients who had CMBs, M-CMBs were found in 54 patients (48.6%), followed by SL-CMBs in 35 (31.5%) and D-CMBs in 19 (17.1%). The SL-CMB group showed a significantly higher prevalence of family history of dementia, whereas the M-CMB group showed an increasing trend toward hypertension and smoking. The prevalence of AD was significantly higher in the SL-CMBs group, whereas the prevalence of AD with cerebrovascular disease was higher in the M-CMBs group. The regional density of lobar CMBs was significantly higher in the occipital lobe in the M-CMB group, whereas the SL-CMB group showed higher regional density between regions an increasing tendency in the parietal and occipital lobe.

CONCLUSION

The between-group differences in clinical features and regional distribution indicate there to be an etiological relationship of SL-CMBs to AD and CAA, and M-CMBs to both HV and CAA.

Family history and TOMM40 '523 interactive associations with memory in middle-aged and Alzheimer's disease cohorts

INTRODUCTION

Family history (FH) of Alzheimer's disease (AD) affects mitochondrial function and may modulate effects of translocase of the outer mitochondrial membrane 40 kDa (TOMM40) rs10524523 ('523) poly-T length on memory decline.

METHODS

For 912 nonapolipoprotein ε4 middle-aged adults and 365 aged adults across the AD spectrum, linear mixed models gauged FH and TOMM40 '523 interactions on memory and global cognition between baseline and up to 10 years later. A cerebrospinal fluid mitochondrial function biomarker was also assessed.

RESULTS

For FH negative participants, gene-dose preservation of memory and global cognition was seen for "very long" versus "short" carriers. For FH positive, an opposite gene-dose decline was seen for very long versus short carriers. Maternal FH was a stronger predictor in aged, but not middle-aged, participants. Similar gene-dose effects were seen for the mitochondrial biomarker aspartate aminotransferase.

DISCUSSION

These results may clarify conflicting findings on TOMM40 poly-T length and AD-related decline.

The midlife cognitive profiles of adults at high risk of late-onset Alzheimer's disease: The PREVENT study

INTRODUCTION

Although biomarker studies of late-onset Alzheimer's disease suggest pathology to be present decades before diagnosis, little is known about cognitive performance at this stage.

METHODS

A sample of 210 adults (aged 40-59) of whom 103 have a parent diagnosed with dementia (family history subgroup) underwent computerized cognitive testing. Apolipoprotein E (apoE) status was determined, and 193 subjects had magnetic resonance imaging. Distance from dementia onset was estimated in relation to age of parental diagnosis, and Cardiovascular Risk Factors, Aging, and Incidence of Dementia Risk Scores were calculated.

RESULTS

Lower hippocampal volumes (P = .04) were associated with poorer spatial location recall and higher Dementia Risk Scores with poorer visual recognition (P = .0005), and lower brain and hippocampal volume (P < .0001, P = .04, respectively). Family history subgroup participants closer to dementia onset had lower scores on visual working memory (P = .05), whereas those with an APOE ε4 allele performed better on form perception (P = .005).

DISCUSSION

Middle-aged adults at risk of dementia show evidence of poorer cognitive performance, principally in visuospatial functions.

From Brain Disease to Brain Health: Primary Prevention of Alzheimer's Disease and Related Disorders in a Health System Using an Electronic Medical Record-Based Approach

BACKGROUND

Alzheimer's disease and aging brain disorders are progressive, often fatal neurodegenerative diseases. Successful aging, modern lifestyles and behaviors have combined to result in an expected epidemic. Risks for these diseases include genetic, medical, and lifestyle factors; over 20 modifiable risks have been reported.

OBJECTIVES

We aim to primarily prevent Alzheimer's disease and related disorders through electronic medical record (EMR)-based screening, risk assessments, interventions, and surveillance.

DESIGN

We identified modifiable risks; developed human, systems and infrastructural resources; developed interventions; and targeted at-risk groups for the intervention.

SETTING

A Community Based Health System.

PARTICIPANTS

In year one (June 2015 to May 2016), 133 at-risk patients received brain health services with the goal of delaying or preventing Alzheimer's disease and related disorders.

MEASUREMENTS

We created mechanisms to identify patients at high risk of neurodegenerative disease; EMR-based structured clinical documentation support tools to evaluate risk factors and history; evidence-based interventions to modify risk; and the capacity for annual surveillance, pragmatic trials, and practice-based and genomic research using the EMR.

RESULTS

This paper describes our Center for Brain Health, our EMR tools, and our first year of healthy but at-risk patients.

CONCLUSION

We are translating research into primary prevention of Alzheimer's disease and related disorders in our health system and aim to shift the paradigm in Neurology from brain disease to brain health.

Cerebrospinal fluid mitochondrial DNA in the Alzheimer's disease continuum

Low levels of cell-free mitochondrial DNA (mtDNA) in the cerebrospinal fluid (CSF) of Alzheimer's disease (AD) patients have been identified and proposed as a novel biomarker for the disease. The lack of validation studies of previous results prompted us to replicate this finding in a comprehensive series of patients and controls. We applied droplet digital polymerase chain reaction in CSF specimens from 124 patients representing the AD spectrum and 140 neurologically healthy controls. The following preanalytical and analytical parameters were evaluated: the effect of freeze-thaw cycles on mtDNA, the linearity of mtDNA load across serial dilutions, and the mtDNA levels in the diagnostic groups. We found a wide range of mtDNA copies, which resulted in a high degree of overlap between groups. Although the AD group presented significantly higher mtDNA counts, the receiver-operating characteristic analysis disclosed an area under the curve of 0.715 to distinguish AD patients from controls. MtDNA was highly stable with low analytical variability. In conclusion, mtDNA levels in CSF show a high interindividual variability, with great overlap within phenotypes and presents low sensitivity for AD.

Meta-analysis of the Association between Alzheimer Disease and Variants in GAB2, PICALM, and SORL1

The genetic variants play a crucial role in the pathogenesis of Alzheimer's disease (AD), while the relationships of specific single nucleotide polymorphisms (SNPs) with AD are still controversial. We performed the meta-analysis to obtain a more precise estimation of whether growth factor receptor-bound protein-associated binding protein 2 (GAB2), phosphatidylinositol binding clathrin assembly protein (PICALM), and sortilin-related receptor (SORL1) variants are associated with AD. Databases including PubMed, Embase, and Cochrane Library were searched to find relevant studies. Cochran's Q-statistic and I ² were used to assess the heterogeneity among the included studies. Odds ratios (OR) and 95 % confidence intervals (95 % CIs) were conducted to evaluate the association between the SNP and the susceptibility to AD. Publication bias was estimated by funnel plots. All of the statistical analyses were implemented using R Version 3.2.1 software. A total of 35 case-control studies involving 15 SNPs were included. There was no significant association between SNPs of GAB2 rs2373115 (G > T) and PICALM rs541458 (C > T) and AD. The allele T of rs3851179 in PICALM was associated with a 13 % increase in the risk of AD. Seven SNPs on SORL1 were significantly associated with AD. Four SNPs, including rs1010159*T, rs641120*A, rs668387*T, and rs689021*A, were associated with a decreased risk of AD, while the other three SNPs, including rs12285364*T, rs2070045*G, and rs2282649*T, were all associated with an increased risk of AD. The results of the present study suggested that multiple gene variants were associated with AD. The SNP of rs3851179 (PICALM), rs12285364 (SORL1), rs2070045 (SORL1), and rs2282649 (SORL1) was associated with an increased risk of AD, whereas SORL1 rs1010159, rs641120, rs668387, and rs689021 were associated with a decreased risk of AD.