Gender-Based Pathways to Cognitive Aging in the Mexican-Origin Population in the United States: The Significance of Work and Family

The Association of Neighborhood Socioeconomic Status with Executive Function and Processing Speed in Cognitively Normal Mexican American Elders from the Health and Aging Brains Study: Health Disparities Cohort

INTRODUCTION

Neighborhood socioeconomic status (NSES) has been linked with overall health, and this study will evaluate whether NSES is cross-sectionally associated with cognition in non-Hispanic whites (NHWs) and Mexican Americans (MAs) from the Health and Aging Brain: Health Disparities Study (HABS-HD).

METHODS

The HABS-HD is a longitudinal study conducted at the University of North Texas Health Science Center. The final sample analyzed (n = 1,312) were 50 years or older, with unimpaired cognition, and underwent an interview, neuropsychological examination, imaging, and blood draw. NSES was measured using the national area deprivation index (ADI) percentile ranking, which considered socioeconomic variables. Executive function and processing speed were assessed by the trail making tests (A and B) and the digit-symbol substitution test, respectively. Linear regression was used to assess the association of ADI and cognitive measures.

RESULTS

MAs were younger, more likely to be female, less educated, had higher ADI scores, performed worse on trails B (all p < 0.05), and had lower prevalence of APOE4 + when compared to NHWs (p < 0.0001). A higher percentage of MAs lived in the most deprived neighborhoods than NHWs. For NHWs, ADI did not predict trails B or DSS scores, after adjusting for demographic variables and APOE4. For MAs, ADI predicted trails A, trails B, and DSS after adjusting for demographic covariates and APOE4 status.

CONCLUSION

Our study revealed that living in an area of higher deprivation was associated with lower cognitive function in MAs but not in NHWs, which is important to consider in future interventions to slow cognitive decline.

Associations of Nativity and the Role of the Hispanic Paradox on the Cognitive Health of Older Latinos Living in the United States

Background

US-based Latinos have lower education and income combined with higher health risks than non-Latino whites, but often 'paradoxically' evidence better health-related outcomes. Less work has investigated this paradox for cognitive-related outcomes despite nativity diversity.

Objective

We evaluated cognitive aging within older Latinos of diverse nativity currently living in the US and participating in Rush Alzheimer's Disease Center studies.

Methods

Participants without baseline dementia, who completed annual neuropsychological assessments (in English or Spanish) were grouped by US-born (n = 117), Mexico-born (n = 173), and born in other Latin American regions (LAr-born = 128). Separate regression models examined associations between nativity and levels of (N = 418) or change in (n = 371; maximum follow-up ∼16 years) global and domain-specific cognition.

Results

Demographically-adjusted linear regression models indicated that foreign-born nativity was associated with lower levels of global cognition and select cognitive domains compared to US-born Latinos. No associations of nativity with cognitive decline emerged from demographically-adjusted mixed-effects models; however, Mexico-born nativity appeared associated with slower declines in working memory compared to other nativity groups (p-values ≥ 0.051). Mexico-born Latinos had relatively higher vascular burden and lower education levels than other nativity groups; however, this did not alter results.

Conclusions

Nativity differences in baseline cognition may be due, in part, to accumulated stressors related to immigration and acculturation experienced by foreign-born Latinos which may hasten meeting criteria for dementia later in life. In contrast, Mexico-born participants' slower working memory declines, taken in the context of other participant characteristics including vascular burden, suggests the Hispanic Paradox may relate to factors with the potential to affect cognition.

Parity and Risk of Dementia in Women: The Atherosclerosis Risk in Communities Study

Objective: Reproductive factors, including parity, may contribute to dementia risk, due to hormonal, physiological, social, and demographic factors. We hypothesized that higher parity would be associated with increased dementia risk. Materials and Methods: We utilized data from the Atherosclerosis Risk in Communities (ARIC) community-based cohort study. Participants were recruited in 1987-1989 and followed through 2017. Participants, all born between 1921 and 1945, were from four U.S. communities in Forsyth County, NC; Jackson, MS; Minneapolis, MN; and Washington County, MD. We included all female participants seen at ARIC visit three or five for whom parity and dementia outcomes were available (N = 7,921). The primary exposure was self-reported number of live births. Our primary outcome was dementia, diagnosed via neurocognitive assessments, informant interviews, and expert adjudication. We created Cox proportional hazards models to evaluate the association between parity and incident dementia, adjusting for demographic factors, education level, apolipoprotein E allele status, and vascular risk factors. We tested for interactions by race and birth cohort. Results: The adjusted hazard ratio was 0.82 (95% confidence intervals [CI] 0.69-0.99) for dementia in women with 0-1 births and 0.85 (95% CI 0.72-0.99) for women with 5+ births, compared to women with 2 births (reference group). This association was present in women born from 1924 to 1934, but not in women born in 1935 or later (p-interaction <0.001). Conclusion: We found an inverted U-shaped association of parity with dementia risk. This effect was modified by birth cohort, suggesting that the association may depend on demographic and sociocultural factors.

Prospective Effects of Discrimination, Depressive Symptoms, and Cognitive Control Among Mexican-Origin Women

OBJECTIVES

Cognitive control predicts functional independence and cognitive health outcomes, but is yet to be known the extent to which social stress, like discrimination, may diminish cognitive control capacities in Mexican-origin women. We evaluated the prospective associations between everyday and ethnic discrimination on cognitive control and examined the mediating effects of depressive symptoms on these links. We further examined the extent to which associations varied by age and financial strain.

METHODS

We used data from 596 Mexican-origin women (average age = 38.89, standard deviation = 5.74) who participated in a 3-wave longitudinal study spanning 8 years (from 2012 to 2020). Participants completed measures of everyday and ethnic discrimination at Wave 1, depressive symptoms in Waves 1 and 2, and completed computer-based tasks of cognitive control at Wave 3. Self-reported assessments of financial strain were completed at Wave 2. Moderated mediation structural equation models were implemented to test hypotheses.

RESULTS

Depressive symptoms significantly mediated the prospective association between everyday/ethnic discrimination to cognitive control. Higher levels of everyday and ethnic discrimination at baseline were associated with more depressive symptoms at Wave 2, which were then related to poorer cognitive control (i.e., longer reaction time in congruent and/or incongruent trials) at Wave 3. There was no significant moderation of age. Among those with low financial strain, higher levels of everyday discrimination were related to faster response times.

DISCUSSION

Results revealed the long-term consequences of experiences with discrimination on cognitive control that operate through increased depressive symptoms and that may have some subtle differential effects across levels of financial strain.

Associations Between Parity and Cognition: Race/Ethnic Differences

BACKGROUND

Race/ethnicity is associated with differences in reproductive history and cognition individually, yet it remains an understudied factor in the relationship between parity and later-life cognition.

OBJECTIVE

To evaluate if the association between parity and cognition differs between racial/ethnic groups.

METHODS

Participants included 778 older, postmenopausal women from the Health and Nutrition Examination Survey (Latina: n = 178, Non-Latino Black [NLB]: n = 169, Non-Latino White [NLW]: n = 431) who self-reported at least one birth. Cognitive outcomes included working memory, learning memory, and verbal fluency. Covariates included age, education, cardiovascular and other reproductive health factors, adult socioeconomic status (SES) and depressive symptoms. We fit a series of linear models to examine a) whether parity was associated with cognitive functioning, b) if this association varied by race/ethnicity through parity by race/ethnicity interactions, and c) individual parity with cognition associations stratified by race/ethnicity.

RESULTS

In the full sample, parity was significantly negatively associated with Digit Symbol Substitution Test (DSST) performance (b = -0.70, p = 0.024) but not Animal Fluency or word-list learning and memory. Tests of race/ethnicity-by-parity interactions were not statistically significant (ps > 0.05). However, stratified analyses by race/ethnicity showed a differential effect of parity on DSST performance, such that parity was significantly negatively associated with DSST performance (b = -1.66, p = 0.007) among Latinas but not in NLWs (b = -0.16, p = 0.74) or NLBs (b = -0.81, p = 0.191).

CONCLUSION

Among Latina, but not NLB or NLW women, greater parity was associated with worse processing speed/executive functioning later in life. Further research is needed to understand the mechanisms driving racial/ethnic differences.

Duration of Dementia and Social Service Use in the U.S.-Born and Foreign-Born Mexican-American Population

Objective

The study estimates the number of years after age 65 that Mexican Americans live with likely dementia and the impact of dementia on community-based services (CBS) use by nativity.

Methods

Using the Hispanic Established Populations for the Epidemiologic Studies of the Elderly Sullivan methods are employed to predict duration of dementia and logistic regressions identify the predictors of service utilization.

Results

Foreign-born women spend more years than other groups with dementia. The foreign-born are more likely to use out-of-home services, whereas U.S.-born are more likely to use in-home services. The foreign-born with dementia of relatively recent onset had the highest probability of service use.

Discussion

Given the high cost of institutional care and availability of family caregivers, community-based services are a potentially useful alternative for the growing Mexican-American population living with dementia. Expanded Medicaid and CBS programs could be an equitable and cost-effective alternative that should be investigated.

Mitochondrial DNA oxidative mutations are elevated in Mexican American women potentially implicating Alzheimer's disease

Mexican Americans (MAs) are the fastest-growing Hispanic population segment in the US; as this population increases in age, so will the societal burden of age-related diseases such as Alzheimer's disease (AD). Mitochondrial DNA (mtDNA) damage may be implicated in MA AD risk since metabolic comorbidities are more prevalent in this group. Oxidative damage to guanosine (8oxoG) is one of the most prevalent DNA lesions and a putative indicator of mitochondrial dysfunction. Testing blood samples from participants of the Texas Alzheimer's Research and Care Consortium, we found mtDNA 8oxoG mutational load to be significantly higher in MAs compared to non-Hispanic whites and that MA females are differentially affected. Furthermore, we identified specific mtDNA haplotypes that confer increased risk for oxidative damage and suggestive evidence that cognitive function may be related to 8oxoG burden. Our understanding of these phenomena will elucidate population- and sex-specific mechanisms of AD pathogenesis, informing the development of more precise interventions and therapeutic approaches for MAs with AD in the future.