Women have a greater lifetime risk of developing Alzheimer’s disease (AD) dementia than men, a sex/gender disparity that cannot be explained by female longevity alone. There is substantial evidence for sex differences in the effects of APOE £4 on risk for AD. While APOE e4 increases AD risk in both sexes, women who carry APOE e4 are disproportionately vulnerable to cognitive impairment and AD compared to their counterpart men. In contrast to APOE e4, APOE £2 is associated with slower cognitive decline and a lower risk of AD. Although a less robust literature, APOE e2 may also have sex-specific effects. Because APOE e2 is the rarest major APOE allele, well-powered studies are needed to examine sex-specific effects. The objective of the present study was to examine sex-specific associations of APOE e2 carriage with longitudinal cognitive decline in a large cohort of clinically unimpaired adults.

We used observational data from two sources: the National Alzheimer’s Coordinating Center (NACC) and the Rush Alzheimer’s Disease Center (ROS/MAP/MARS) studies. We included data from clinically unimpaired adults who were >50 years old at baseline who self-identified as non-Hispanic White (NHW) or non-Hispanic Black (NHB). Participants were categorized as APOE £2, £4, or £3/e3 carriers. APOE e2/e4 carriers were excluded. The same battery of neuropsychological tests was used to assess global cognition in participants from both data sources. Linear mixed models examined interactive associations of genotype (£2 or £4 vs. £3/£3), sex, and time on longitudinal cognition in NHW and NHB participants separately. Analyses were first performed in a pooled sample of NACC and ROS/MAP/MARS participants and if significant they were repeated separately in each data source.

Across both data sources, 9,766 NHW (mean (SD) age=73.0(9.00) years, mean (SD) education=16.3(2.83) years, n(%) women=6,344(65.0)) and 2,010 NHB participants (mean(SD) age=71.3(7.59) years, mean(SD) education=14.9(3.10) years, n(%) women=1,583(78.8)) met inclusion criteria. Sex modified the association between APOE £2 and cognitive decline in NHW (ß=0.097, 95% CI: 0.023-0.172, pint=.01) but not NHB participants (ß=-0.011, 95% CI: -0.153-0.131, pint=.9). In sex-stratified analyses of NHW participants, APOE £2 (vs. £3/£3) carriage was associated with attenuated cognitive decline in men (ß=0.096, 95% CI: 0.037-0.155, p=.001), but not women (ß=-0.001, 95% CI: -0.044-0.043, p=.97). In analyses comparing men and women APOE £2 carriers, men exhibited slower cognitive decline than women (ß=0.120, 95% CI: 0.051-0.190, p=.001). Analyses performed separately in NACC and ROS/MAP revealed the same pattern of male-specific APOE £2 protection in NHW participants in both data sources.

In light of the longstanding view that APOE £2 protects against AD and dementia, our results provide evidence that APOE £2 is associated with attenuated cognitive decline in men but not women among NHW adults. This male-specific protection may contribute to sex differences in AD-related cognitive decline. Our findings have important implications for understanding the biological drivers of sex differences in AD risk, which is crucial for developing sex-specific strategies to prevent and treat AD dementia.

Alterations in cerebral blood flow (CBF) are associated with risk of cognitive decline and Alzheimer’s disease (AD). Although apolipoprotein E (APOE) ε4 and greater vascular risk burden have both been linked to reduced CBF in older adults, less is known about how APOE ε4 status and vascular risk may interact to influence CBF. We aimed to determine whether the effect of vascular risk on CBF varies by gene dose of APOE ε4 alleles (i.e., number of e4 alleles) in older adults without dementia.

144 older adults without dementia from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) underwent arterial spin labeling (ASL) and T1-weighted MRI, APOE genotyping, fluorodeoxyglucose positron emission tomography (FDG-PET), lumbar puncture, and blood pressure assessment. Vascular risk was assessed using pulse pressure (systolic blood pressure -diastolic blood pressure), which is thought to be a proxy for arterial stiffening. Participants were classified by number of APOE ε4 alleles (n0 alleles = 87, m allele = 46, n2 alleles = 11). CBF in six FreeSurfer-derived a priori regions of interest (ROIs) vulnerable to AD were examined: entorhinal cortex, hippocampus, inferior temporal cortex, inferior parietal cortex, rostral middle frontal gyrus, and medial orbitofrontal cortex. Linear regression models tested the interaction between categorical APOE ε4 dose (0, 1, or 2 alleles) and continuous pulse pressure on CBF in each ROI, adjusting for age, sex, cognitive diagnosis (cognitively unimpaired vs. mild cognitive impairment), antihypertensive medication use, cerebral metabolism (FDG-PET composite), reference CBF region (precentral gyrus), and AD biomarker positivity defined using the ADNI-optimized phosphorylated tau/ß-amyloid ratio cut-off of > 0.0251 pg/ml.

A significant pulse pressure X APOE ε4 dose interaction was found on CBF in the entorhinal cortex, hippocampus, and inferior parietal cortex (ps < .005). Among participants with two e4 alleles, higher pulse pressure was significantly associated with lower CBF (ps < .001). However, among participants with zero or one ε4 allele, there was no significant association between pulse pressure and CBF (ps > .234). No significant pulse pressure X APOE ε4 dose interaction was found in the inferior temporal cortex, rostral middle frontal gyrus, or medial orbitofrontal cortex (ps > .109). Results remained unchanged when additionally controlling for general vascular risk assessed via the modified Hachinski Ischemic Scale.

These findings demonstrate that the cross-sectional association between pulse pressure and region-specific CBF differs by APOE ε4 dose. In particular, a detrimental effect of elevated pulse pressure on CBF in AD-vulnerable regions was found only among participants with the e4/e4 genotype. Our findings suggest that pulse pressure may play a mechanistic role in neurovascular unit dysregulation for those genetically at greater risk for AD. Given that pulse pressure is just one of many potentially modifiable vascular risk factors for AD, future studies should seek to examine how these other factors (e.g., diabetes, high cholesterol) may interact with APOE genotype to affect cerebrovascular dysfunction.

There is limited and inconsistent research exploring diagnosis, treatment, and prevention of dementias amongst Black Indigenous People of Color (BIPOC). By 2050, it is suspected that the White population will significantly decrease and BIPOC groups will comprise the majority of the US population yet BIPOC are historically underrepresented in dementia research. Prior research indicates apolipoprotein 4 allele (APOE-4) status is associated with a greater risk of developing Alzheimer’s disease in Black individuals when compared to non-Hispanic Whites. Investigating the racial disparities in dementia will expand our knowledgebase of risk for dementia types in the Black community to better meet the evergrowing population needs. The current study explored the impact of racial identity on global cognitive functioning, independent of age, education, and APOE e4 status.

Participants were drawn from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) study and consisted of five pairs of Black and White individuals (n = 10) matched based on age, education, and APOE status. Global cognitive performance was measured by the total Mini Mental Status Examination (MMSE) score. Notably, only five Black individuals in phase 1 of ADNI met inclusion criteria. It was hypothesized Black individuals would be more cognitively impaired than their White counterparts. A matched pairs t-test was utilized to examine the relationship between global cognitive performance and race.

Black and White individuals’ MMSE scores did not significantly differ (p > .05). The mean MMSE performance of White participants (26.40) was less robust than Black participants (27.80). Findings are inconsistent with current research, indicating that BIPOC individuals are disproportionately impacted by AD, with increased severity of cognitive impairment. There is a profound need for more research in preventative interventions and recruitment of BIPOC individuals who have been historically marginalized in cognitive research trials to help better understand diagnosis, treatment, and prevention of AD in BIPOC.

The observed commensurate global cognitive functioning performance between matched Black and White individuals is not consistent with prior research findings demonstrating increased risk of developing dementia amongst BIPOC. This study’s small sample size reflects a significant barrier to detecting clinically meaningful differences. Efforts to address the recruitment crisis, underreporting, cultural influences, and overall mistrust of research among BIPOC is warranted. Inclusive research is critical to dismantling health disparities.

White matter microstructure (WMM) potentially mediates the relation between APOE4 and memory performance. This study’s purpose was to understand whether p-tau effects this mediation model and whether education level differentially impacts the relations between these genetic and biological biomarkers’ influence on memory.

Participants included 161 older adults (M=74 years, 40.4% female, 92% White, 74 e4 non-carriers, 87 e4 carriers) with subjective and objective cognitive impairment from the Alzheimer’s Disease Neuroimaging Initiative (ADNI). A composite memory score created by ADNI was used as the outcome variable. Mean fractional anisotropy (FA) and radial diffusivity (RD) values of white matter tracts within regions of interest (i.e., fornix (FX), hippocampal cingulum (CGH)) were individually used as the measures of WMM. A moderated mediation was run to examine whether p-tau was a moderator of the mediation between APOE4, white matter microstructure, and memory. An exploratory dual moderated mediation analysis examined education as a moderator of the moderated mediation. Indirect effects were tested using bootstrapping procedures.

In the FA moderated mediation model, APOE4 was significantly related to FA of the fornix and memory performance. FA of the CGH and FX were also related to memory performance. With FA of the fornix as the mediator, the conditional indirect effect was not significant (95% CI[-.0009, .0070]). There was a trend suggesting at low (95% CI[-.2421, -.0140]) and average (95% CI[-.1658, -.0083]) levels of p-tau, FA of the fornix was a significant mediator but was non-significant at high levels of p-tau (95% CI [-.1322, .0341]). The RD moderated mediation model was non-significant. The FA and RD exploratory dual moderated mediation models were non-significant. However, the APOE4 x p-tau interaction with FA of the fornix as the mediator suggested a trend. At low levels of p-tau, increased education was related to a significant moderated mediation.

Results suggest that FA of the fornix is a significant mediator between the relation of APOE4 and memory, and this may be dependent upon p-tau levels. When p-tau burden load was high, the path by which APOE4 impacts memory performance was not through white matter microstructure degradation. Additionally, the potential buffering effects of education may be most robust at lower levels of p-tau burden.

The Apolipoprotein E (APOE) gene has been established in the Alzheimer’s disease (AD) literature to impact brain structure and function and may also show congruent effects in healthy older adults, although findings in this population are much less consistent. Magnetic Resonance Imaging (MRI), Diffusion Tensor Imaging (DTI), and neuropsychological measures present as useful, non-invasive tools to investigate the impact of APOE-e allele status on grey matter structure, white matter integrity, and cognitive functioning, respectively. Nonetheless, studies to date have revealed mix findings and few studies have taken a multimodal approach to investigating APOE’s effects. Thus, the objective of the current study was to replicate and expand upon the multimodal neuroimaging study conducted by Honea et al. (2009), that examined the impact of APOE-e4 presence on brain structure and cognitive function in healthy older adults, with the addition of APOE-e2 carriers and cognitive composite measures. The aim of the current replication study was to identify reliable changes to grey matter volume and white matter integrity in healthy older adults as it relates to APOE-e allele presence and cognitive performance. This represents one of the first studies to investigate both the risk and protective effects of APOE-e alleles (e4 and e2 respectively) on measures of cognitive performance, GMV and white matter integrity in healthy older adults.

Data were obtained from the Alzheimer’s Disease Initiative phase 3 (ADNI3) database. Baseline MRI, DTI and cognitive composite scores for memory (ADNI-Mem) and executive function (ADNI-EF) were acquired from 116 healthy controls. Participants were grouped according to APOE allele presence (APOE-e2+ N= 17, APOE-e3e3 N= 64, APOE-e4+ N=35). Voxel-based morphometry (VBM) and tract based spatial statistics (TBSS) were used to compare grey matter volume (GMV) and white matter integrity respectively between APOE-e2+ and APOE-e3e3 controls, and again between APOE-e4+ and APOE-e3e3 controls. Multivariate analysis of covariance (MANCOVA) was used to examine the effects of APOE polymorphism on memory and EF across all APOE groups with covariates of age, sex, education, and cognitive scores were correlated with imaging metrics within groups (Pearson r) to examine associations between cognitive performance and brain structure.

Consistent with findings from Honea et al. (2009), no significant differences were seen across APOE groups, within-groups in MRI metrics, or cognitive performance (p>0.05, corrected for multiple comparisons). Taking a similar approach to Honea and company, nonsignificant, trend-level results were examined (p<0.2, corrected for multiple comparisons) and suggested: 1) Decreased GMV and increased mean diffusivity (MD) were present in APOE-e4+ compared to APOE-e3e3 and 2) Increased GMV and fractional anisotropy (FA) were present in APOE-e2+ compared to APOE-e3e3.

The current study replicated and extended previous findings. Trend-level findings across both the current and replicated study suggests there may be subtle neurostructural differences in healthy aging as a function of APOE-e4 status. The current study additionally found potential subtle differences in GMV and white matter integrity in APOE-e2 carriers at the trend-level, consistent with previous reports of APOE-e2 's protective effects against neurodegeneration. Although these findings should be interpreted with caution, trend-level effects seen in the current study are consistent with previous research and may hold important implications for APOE neuromechanisms.

Prior studies have determined the Apolipoprotein-E (ApoE) ε4 allele presents a greater risk for developing Alzheimer's disease and for earlier onset of cognitive decline compared to individuals without the gene. Research has also recognized that traumatic brain injuries (TBIs) with loss of consciousness increase the risk for earlier development of the disease. This study sought to determine the moderating factor of TBI history on ApoE-ε4 risk associated with earlier Alzheimer's disease onset.

Participants included 9,585 individuals with autopsy confirmed Alzheimer's disease pathology, that had available ApoE genotype data, TBI data, and clinician determined age of cognitive decline, representing disease onset. A 2x3 factorial ANOVA was conducted to compare the main effects of ApoE-ε4 status and TBI history and the interaction effect between the two on disease onset. The analyses used three ApoE-ε4 groups and two TBI groups. The groups included: (1) no ApoE-ε4 allele; (2) one ApoE-ε4 allele; (3) two ApoE-ε4 alleles; (4) no TBI history, (5) positive TBI history.

Results indicated a significant interaction effect between ApoE-ε4 status and TBI history. Secondary analyses determined the driving force behind the interaction was the effect of ApoE-ε4, which had a significant impact on the age of onset in both TBI groups, while TBI history only significantly impacted onset in individuals without an ApoE-ε4 allele.

Contrary to prior research, these findings did not indicate TBI was significant in determining earlier onset. However, it is important to consider the large variability within the TBI group from the lack of differentiation between mild, moderate, and severe TBIs. Overall, these findings underline the greater risk and stronger impact that ApoE-ε4 poses for Alzheimer's disease onset compared to TBI. The results of this study emphasize the importance of evaluating ApoE-ε4 status for determining risk of earlier onset AD. Clinicians can better determine risk by considering patients' ApoE-ε4 status alongside TBI history.

Both Apolipoprotein z4 (APOz4) and Brain-Derived Neurotropic Factor val66met (BDNF-met) have been implicated as cognitive risk polymorphisms and may signal a more rapid trajectory of cognitive decline (Boots et al., 2017; Lim et al., 2015). The presence of both risk alleles may additively result in greater cognitive difficulties (Cechova et al., 2020), specifically executive functioning (Sapkota et al., 2017). As executive functioning difficulties can be associated with Posttraumatic Stress Disorder (PTSD; Woon et al., 2017), individuals with PTSD who carry these polymorphisms may be at higher risk for decline in executive functioning. In this study, we examined the cross-sectional and longitudinal impact of these alleles on executive functioning performance in Veterans with PTSD.

Seventy community-dwelling male Veterans were enrolled as part of a larger study at VAPAHCS and consented to genetic analysis. A current or lifetime history of PTSD (score > 40 on the CAPS-IV; Blake et al., 1995) was required for study participation. Trail Making Test B (TMT-B; Army Individual Test Battery, 1994) was used to assess executive functioning. TMT-B was part of a comprehensive neuropsychological battery administered at baseline and yearly over the following three years. Mean age and education were 61 years old (SD = 4.5; range = 55-78) and 14 years (SD = 2.3; range = 8-20), respectively.

The majority of the sample was White (71%) and were from the Korean and Vietnam War eras.

APOz4 and BDNF-met were present in 29% and 27% of the sample, respectively; both were present in six participants. Regression models were fitted separately for TMT-B raw time-to-complete and number of errors, both cross-sectionally at screening and then longitudinally. The presence of BDNF-met was a significant predictor of TMT-B time and number of errors in both models (Time: ß = 0.09, p = 0.03 and ß = 0.11, p < 0.01; Errors: IRR = 2.4, p = 0.01 and IRR = 1.9, p = 0.01), while APOz4 only predicted errors longitudinally (IRR = 1.8, p = 0.03). There was no significant allelic interaction; however, the presence of both alleles additively multiplied TMT-B errors by approximately 3.7 times at screening (IRR = 3.7; p = 0.01) and 3.3 times longitudinally (IRR = 3.3; p < 0.01).

Altogether, these results are suggestive of an adverse, additive, effect of the APOz4 and BDNF-met polymorphisms on executive functioning, in particular error-proneness, with their combined presence tripling the errors made on TMT-B cross-sectionally and longitudinally. Consistent with previous research, the TMT-B error analysis increases detection of cognitive impairment, similar to other clinical samples (Varjacic et al., 2018). While TMT-B errors are typically interpreted qualitatively, the strong effect of these established risk alleles on error rates further support this metric as a clinically useful indicator of executive dysfunction in a PTSD population. In keeping with the Boston Process approach, these findings support the importance of error analysis in clinical interpretation of neuropsychological performance.

The apolipoprotein E (APOE) gene has been identified as a major risk factor for the development of Alzheimer’s disease in late life. Research has shown that APOE e4 allele carriers demonstrate poorer memory performance and accelerated cognitive decline relative to non-carriers, and there is a need to identify potential factors of resiliency against the negative effects of e4 on cognition. Social support may represent one potential mechanism given that higher levels of social support have been linked to better cognitive and functional outcomes in older adults. Thus, the current study sought to examine whether social support moderates the relationship between APOE e4 status and subjective and objective memory performance in a large community-based sample of Hispanic/Latino (H/L) and Non-Hispanic White (NHW) older adults residing in Texas.

Participants included 1,564 (H/L = 808, NHW = 756) older adults (mean age = 66.36±8.68) without dementia that had enrolled in the Health and Aging Brain Study-Health Disparities. Participants completed study questionnaires and a comprehensive neuropsychological battery. Apolipoprotein e4 status (e4 carriers vs. non-carriers) was determined by possession of at least one e4 allele. Perceived social support was measured using the total score from the abbreviated 12-item version of the Interpersonal Support Evaluation List. Objective memory performance was assessed using a z-score composite of Story A and B from the Weschler Memory Scale (WMS)-III and immediate and delayed recall trials from the Spanish-English Verbal Learning Test. Subjective memory was assessed using the total score from the Subject Memory Complaints Questionnaire. Race stratified multiple linear regression models, controlling for age, sex, and years of education, examined APOE e4 positivity x social support interactions on subjective and objective memory performance.

There was a significant APOE e4 genotype x social support interaction on objective memory performance (ß = -1.10, p = 0.003) in H/Ls such that higher levels of social support were associated with better memory performance in non-e4 carriers (ß = 0.14, p < .001), but not in e4 carriers (ß = -0.13, p = 0.9). In contrast, no significant APOE e4 status x social support interaction was observed on subjective memory (ß = -0.39, p = 0.35) in H/Ls. Finally, results revealed no significant APOE e4 genotype x social support interactions on subjective memory (ß = 0.14 p = 0.77) or objective memory (ß = 0.67, p = 0.11) performance in NHWs. Conclusions: Findings revealed that social support did not mitigate against the negative effects of e4 on subjective and objective memory performance in H/Ls or NHWs. However, results demonstrate that higher levels of social support are associated with better objective, but not subjective memory performance in H/Ls without the e4 genotype. These findings suggest that social support may protect against cognitive decline and enhance cognitive reserve in non-e4 carriers. Future studies should explore other potential factors of resiliency (e.g., diet, exercise) and examine the association between genetic risk and social support on neural markers (e.g., cortical thinning, hippocampal atrophy).

The presence of an e4 allele of the apolipoprotein E gene (APOE ε4) is considered the strongest genetic risk factor for Alzheimer’s disease (AD) in the US. Evidence suggests that APOE ε4 carriers have worse memory performances compared to APOE ε4 non-carriers in cognitively normal older adults and that female APOE ε4 carriers are at greater risk of AD compared to male carriers. Recent advancements in estimating biological age using DNA methylation markers may enhance understanding of the associations between sex and APOE ε4 on cognitive aging. Thus, the current study aimed to investigate whether associations between APOE ε4 status and memory vary according to rates of biological aging, using a DNA methylation age biomarker, in older men and women without dementia.

Cross-sectional data were obtained from 1771 older adults enrolled in the 2016 wave of the Health and Retirement Study (Mean age = 75, SD = 7; 57% female; 76% non-Hispanic white). The standardized residual from regressing chronological age on the epigenetic clock “DNAGrimAge” was used as a measure of the aging rate. A series of ANCOVAs with Bonferroni corrected post hoc pairwise tests, adjusting for education, white blood cell count, chronological age, and depressive symptoms were used to test the main and interaction effects of APOE ε4 status (non-carriers = 0; carriers = 1) and aging rates, defined as 1 standard deviation below (i.e., slow rate), or above (i.e., fast rate) sex-specific mean rate (i.e., average) of aging, on a standardized composite measure of verbal memory. Alpha was set at .05 and all raw scores were converted to z-score metric prior to analyses.

APOE ε4 female carriers with slow rates of aging (n = 34) had significantly better memory performances compared to APOE ε4 female carriers with fast rates of aging (n = 41), mean difference = .61, p = .006, and average rates of aging (n = 170), mean difference = .44, p = .017. There was no effect of aging rate on memory in the female non-carriers and there were no significant differences in memory performances based on rates of aging in either male APOE ε4 carriers or non-carriers.

Although the presence of the APOE ε4 has previously been shown to represent a stronger risk of AD for women compared to men, results from the current study suggest that slower rates of aging in this high-risk group may confer protection against clinical symptoms (i.e., memory impairment). Conversely, faster than average aging in female APOE ε4 carriers may represent a group at greater risk of memory impairment due to AD. However, longitudinal studies with larger sample sizes are needed to evaluate the risk of dementia/memory impairment based on rates of aging in female APOE ε4 carriers.

To evaluate the association between neuropsychiatric symptoms and apolipoprotein E (APOE) ϵ4 allele among older people in Central African Republic (CAR) and the Republic of Congo (ROC).

Multicenter population-based study following a two-phase design.

From 2011 to 2012, rural and urban areas of CAR and ROC.

People aged 65 and over.

Following screening using the Community Screening Interview for Dementia, participants with low cognitive scores (CSI-D ≤ 24.5) underwent clinical assessment. Dementia diagnosis followed the DSM-IV criteria and Peterson’s criteria were considered for Mild Cognitive Impairment (MCI). Neuropsychiatric symptoms were evaluated through the brief version of the Neuropsychiatric Inventory (NPI-Q). Blood samples were taken from all consenting participants before APOE genotyping was performed by polymerase chain reaction (PCR). Logistic regression models were used to evaluate the association between the APOE ϵ4 allele and neuropsychiatric symptoms.

Overall, 322 participants had complete information on both neuropsychiatric symptoms and APOE status. Median age was 75.0 years and 81.1% were female. Neuropsychiatric symptoms were reported by 192 participants (59.8%) and at least 1 APOE ϵ4 allele was present in 135 (41.9%). APOE ϵ4 allele was not significantly associated with neuropsychiatric symptoms but showed a trend toward a protective effect in some models.

This study is the first one investigating the association between APOE ϵ4 and neuropsychiatric symptoms among older people in sub-Saharan Africa (SSA). Preliminary findings indicate that the APOE ϵ4 allele was not associated with neuropsychiatric symptoms. Further research seems, however, needed to investigate the protective trend found in this study.

Recent research has revealed that cognitively unimpaired older adults who are at higher risk for developing Alzheimer’s disease (AD) dementia often exhibit subtle cognitive alterations in their neuropsychological profiles. Emerging evidence suggests that autobiographical memory, which is memory for personal events and knowledge, may be sensitive to early AD-related cognitive alterations. In the present study, we investigated whether the rapid generation of autobiographical memory category exemplars, a retrieval process that taxes the neural network that is vulnerable to early AD, is compromised in cognitively unimpaired middle-aged and older carriers of the e4 allele of the apolipoprotein E gene (APOE4), which increases risk for AD dementia.

In addition to standard neuropsychological tests, we administered a fluency task that requires generating exemplars for two types of autobiographical memory, namely episodic memories and personal semantics, to a group of cognitively unimpaired middle-aged and older adults (n = 45) enriched with APOE4 carriers (n = 20).

While no APOE4 deficits were found on standard neuropsychological tests, episodic and personal semantic exemplar generation was reduced in the APOE4 group.

Autobiographical memory aberrations associated with a higher risk for AD are evident in fluency and affect both episodic memory and personal semantics.

Apolipoprotein E (APOE) E4 is the main genetic risk factor for Alzheimer’s disease (AD). Due to the consistent association, there is interest as to whether E4 influences the risk of other neurodegenerative diseases. Further, there is a constant search for other genetic biomarkers contributing to these phenotypes, such as microtubule-associated protein tau (MAPT) haplotypes. Here, participants from the Ontario Neurodegenerative Disease Research Initiative were genotyped to investigate whether the APOE E4 allele or MAPT H1 haplotype are associated with five neurodegenerative diseases: (1) AD and mild cognitive impairment (MCI), (2) amyotrophic lateral sclerosis, (3) frontotemporal dementia (FTD), (4) Parkinson’s disease, and (5) vascular cognitive impairment.

Genotypes were defined for their respective APOE allele and MAPT haplotype calls for each participant, and logistic regression analyses were performed to identify the associations with the presentations of neurodegenerative diseases.

Our work confirmed the association of the E4 allele with a dose-dependent increased presentation of AD, and an association between the E4 allele alone and MCI; however, the other four diseases were not associated with E4. Further, the APOE E2 allele was associated with decreased presentation of both AD and MCI. No associations were identified between MAPT haplotype and the neurodegenerative disease cohorts; but following subtyping of the FTD cohort, the H1 haplotype was significantly associated with progressive supranuclear palsy.

This is the first study to concurrently analyze the association of APOE isoforms and MAPT haplotypes with five neurodegenerative diseases using consistent enrollment criteria and broad phenotypic analysis.

This study investigated the characteristics of subjective memory complaints (SMCs) and their association with current and future cognitive functions.

A cohort of 209 community-dwelling individuals without dementia aged 47–90 years old was recruited for this 3-year study. Participants underwent neuropsychological and clinical assessments annually. Participants were divided into SMCs and non-memory complainers (NMCs) using a single question at baseline and a memory complaints questionnaire following baseline, to evaluate differential patterns of complaints. In addition, comprehensive assessment of memory complaints was undertaken to evaluate whether severity and consistency of complaints differentially predicted cognitive function.

SMC and NMC individuals were significantly different on various features of SMCs. Greater overall severity (but not consistency) of complaints was significantly associated with current and future cognitive functioning.

SMC individuals present distinctive features of memory complaints as compared to NMCs. Further, the severity of complaints was a significant predictor of future cognition. However, SMC did not significantly predict change over time in this sample. These findings warrant further research into the specific features of SMCs that may portend subsequent neuropathological and cognitive changes when screening individuals at increased future risk of dementia.

Default mode network (DMN) is vulnerable to the effects of APOE genotype. Given the reduced brain volumes and APOE ε 4-related brain changes in elderly carriers, it is less known that whether these changes would influence the functional connectivity and to what extent. This study aimed to examine the functional connectivity within DMN, and its diagnostic value with age-related morphometric alterations considered.

Whole brain and seed-based resting-state functional connectivity (RSFC) analysis were conducted in cognitively normal APOE ε 4 carriers and matched non-carriers (N=38). The absolute values of mean correlation coefficients (z-values) were used as a measure of functional connectivity strength (FCS) between DMN subregions, which were also used to estimate their diagnostic value by receiver-operating characteristic (ROC) curves.

APOE ε 4 carriers demonstrated decreased interhemispheric FCS, particularly between right hippocampal formation (R.HF) and left inferior parietal lobular (L.IPL) (t=3.487, p<0.001). ROC analysis showed that the FCS of R.HF and L.IPL could differentiate APOE ε 4 carriers from healthy counterparts (AUC value=0.734, p=0.025). Moreover, after adjusting the impact of morphometry, the differentiated value of FCS of R.HF and L.IPL was markedly improved (AUC value=0.828, p=0.002).

Our findings suggest that APOE ε 4 allele affects the functional connectivity within posterior DMN, particularly the atrophy-corrected interhemispheric FCS before the clinical expression of neurodegenerative disease.