Late-life Memory Research Articles

Life course financial mobility and later-life memory function and decline by gender, and race and ethnicity: an intersectional analysis of the US KHANDLE and STAR cohort studies

Intersectionality has rarely been considered in research studies of cognitive ageing. We investigated whether life-course financial mobility is differentially associated with later-life memory function and decline across intersectional identities defined by gender, and race and ethnicity. Data were from two harmonised multiethnic cohorts (the Kaiser Healthy Aging and Diverse Life Experiences cohort and the Study of Healthy Aging in African Americans cohort) in northern California, USA (n=2340). Life-course financial mobility, measured using a combination of self-reported financial capital measures in childhood (from birth to age 16years) and later adulthood (at the cohort baseline) was defined as consistently high, upwardly mobile, downwardly mobile, or consistently low. We clustered individuals into 32strata representing intersectional identities defined by life-course financial mobility combined with gender, and race and ethnicity. Verbal episodic memory was assessed using the Spanish and English Neuropsychological Assessment Scales over four waves from 2017to 2023. Adjusted mixed-effects linear regression models were estimated with and without fixed effects of gender, race and ethnicity, and financial mobility, to evaluate whether the random effects of the intersectional identity strata contributed variance to memory beyond individual fixed effects. Mean age was 73·6years (SD 8·1). Of 2340individuals, 1460 (62·4%) were women, 880 (37·6%) were men, 388 (16·6%) were Asian, 1136 (48·5%) were Black, 334 (14·3%) were Latinx, and 482 (20·6%) were White. Consistently low and downwardly mobile financial capital were strongly negatively associated with later-life memory at baseline (-0·162SD units [95% CI -0·273to -0·051] for consistently low and -0·171 [-0·250to -0·092] for downwardly mobile), but not rate of change over time. Intersectional identities contributed 0·2% of memory variance after accounting for the fixed effects of gender, race and ethnicity, and financial mobility. Consistently low and downward life-course financial mobility are associated with lower later-life memory function. Intersectional identities defined by financial mobility in addition to gender, and race and ethnicity, contribute negligible additional variance to later-life memory in this study setting. US National Institute on Aging, US National Institutes of Health.

Life-course financial mobility shapes later-life memory function

Life-course financial mobility shapes later-life memory function

Childhood adversities and memory function in later life: the mediating role of activity participation

BackgroundChildhood adversities may lead to decreased activity participation in later life, impacting memory health in ageing adults. Childhood adversities related to deprivation and threat, as conceptualized by the Dimensional Model of Adversity, can exhibit distinct impacts on cognitive and emotional outcomes in children and younger adults. This study examined the potential influence of childhood deprivation and threat on memory function in later life and the mediating role of activity participation in these relationships.MethodsThis study used data from the first wave of Panel Study of Active Ageing and Society (PAAS), a representative survey of Hong Kong residents aged 50 or above (N = 1,005). Key variables included late-life memory function measured by delayed recall test, deprivation- and threat-related childhood adversities, and the frequency of participation in informal and formal types of activities. Mediation tests were used for analysis.ResultsChildhood deprivation was associated with a lower late-life memory function, whereas threat was not. The negative effects of childhood deprivation and its subdomain, economic hardship, on memory function were mediated by activity participation. Total participation scores presented the strongest mediating effect (17.3–20.6%), with formal activities playing a more substantial mediating role than informal activities in mitigating the effect of childhood deprivation.ConclusionsThese findings expand the applicability of the Dimensional Model of Adversity to ageing populations, highlighting the influence of deprivation on life-long cognitive development. Furthermore, this study revealed an indirect mechanism by which childhood deprivation affects memory health in old age through diverse activity participation.

Mid-Life Household Food Insecurity and Subsequent Memory Function and Rate of Decline in Rural South Africa, 2004-2022.

We aimed to investigate mid-life food insecurity over time in relation to subsequent memory function and rate of decline in Agincourt, rural South Africa. Data from the longitudinal Agincourt Health and Socio-Demographic Surveillance System (Agincourt HDSS) were linked to the population-representative Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community in South Africa (HAALSI). Food insecurity (yes vs. no) and food insecurity intensity (never/rarely/sometimes vs. often/very often) in the past month were assessed every 3 years from 2004 to 2013 in Agincourt HDSS. Cumulative exposure to each food insecurity measure was operationalized as 0, 1, and ≥2 time points. Episodic memory was assessed from 2014/15 to 2021/22 in HAALSI. Mixed-effects linear regression models were fitted to investigate the associations of each food insecurity measure with memory function and rate of decline over time. A total of 3,186 participants (mean age [SD] in 2004: 53 [12.87]; range: 30-96) were included and 1,173 (36%) participants experienced food insecurity in 2004, while this figure decreased to 490 (15%) in 2007, 489 (15%) in 2010, and 150 (5%) in 2013. Experiencing food insecurity at one time point (vs. never) from 2004 to 2013 was associated with lower baseline memory function (β = -0.095; 95% CI: -0.159 to -0.032) in 2014/15 but not rate of memory decline. Higher intensity of food insecurity at ≥2 time points (vs. never) was associated with lower baseline memory function (β = -0.154, 95% CI: -0.338 to 0.028), although the estimate was imprecise. Other frequencies of food insecurity and food insecurity intensity were not associated with memory function or decline in the fully adjusted models. In this setting, mid-life food insecurity may be a risk factor for lower later-life memory function, but not decline.

Exercise-induced cortical disinhibition mediates the relationship between fitness and memory in older adults.

Regular exercise benefits learning and memory in older adults, but the neural mechanisms mediating these effects remain unclear. Evidence in young adults indicates that acute exercise creates a favourable environment for synaptic plasticity by enhancing cortical disinhibition. As such, we investigated whether plasticity-related disinhibition mediated the relationship between cardiorespiratory fitness and memory function in healthy older adults (n=16, mean age=66.06). Participants completed a graded maximal exercise test and assessments of visual and verbal memory, followed by two counterbalanced sessions involving 20min of either high-intensity interval training exercise or rest. Disinhibition was measured following intermittent theta burst stimulation via paired-pulse transcranial magnetic stimulation. In line with our hypotheses, we observed a positive correlation between cardiorespiratory fitness and verbal memory, which was mediated by plasticity-related cortical disinhibition. Our novel finding implicates cortical disinhibition as a mechanism through which the effects of acute bouts of exercise may translate to improved memory in older adults. This finding extends current understanding of the physiological mechanisms underlying the positive influence of cardiorespiratory fitness for memory function in older adults, and further highlights the importance of promoting exercise engagement to maintain cognitive health in later life. KEY POINTS: There are well established benefits of regular exercise for memory function in older adults, but the mechanisms are unclear. Cortical disinhibition is important for laying down new memories, and is enhanced following acute exercise in young adults, suggesting it is a potential mechanism underlying these benefits in ageing. Older adults completed a fitness test and assessments of memory, followed by two sessions involving either 20min of exercise or rest. Disinhibition was measured following intermittent theta burst stimulation via paired-pulse transcranial magnetic stimulation. Cardiorespiratory fitness was positively associated with memory performance. Higher fitness was associated with enhanced cortical disinhibition following acute exercise. Cortical disinhibition completely mediated the relationship between fitness and memory. This novel finding provides a mechanistic account for the positive influence of cardiorespiratory fitness on memory in later life, and emphasises the importance of regular exercise for cognitive health in older populations.

Mid-life employment trajectories and subsequent memory function and rate of decline in rural South Africa, 2000-22.

To investigate mid-life employment trajectories in relation to later-life memory function and rate of decline in rural South Africa. Data from the Agincourt Health and Socio-Demographic Surveillance System were linked to the 'Health and Ageing in Africa: A Longitudinal Study of an INDEPTH Community in South Africa' (HAALSI) in rural Agincourt, South Africa (N = 3133). Employment was assessed every 4 years over 2000-12 as being employed (0, 1, 2 and ≥3 time points), being employed in a higher-skill occupation (0, 1, 2 and ≥3 time points) and dynamic employment trajectories identified using sequence analysis. Latent memory z-scores were assessed over 2014-22. Mixed-effects linear regression models were fitted to examine the associations of interest. Sustained mid-life employment from 2000-12 (β = 0.052, 95% CI: -0.028 to 0.132, 1 vs 0 time points; β = 0.163, 95% CI: 0.077 to 0.250, 2 vs 0 time points; β = 0.212, 95% CI: 0.128 to 0.296, ≥3 vs 0 time points) and greater time spent in a higher-skill occupation (β = 0.077, 95% CI: -0.020 to 0.175, 1 vs 0 time points; β = 0.241, 95% CI: 0.070 to 0.412, 2 vs 0 time points; β = 0.361, 95% CI: 0.201 to 0.520, ≥3 vs 0 time points) were associated with higher memory scores in 2014/15, but not subsequent rate of memory decline. Moving from a lower-skill to higher-skill occupation was associated with higher memory function, but a faster rate of decline over 2014-22. Sustained mid-life employment, particularly in higher-skill occupations, may contribute to later-life memory function in this post-Apartheid South African setting.

TRANSETHNIC META-ANALYSIS OF INTERACTIONS BETWEEN GENETICS AND EARLY-LIFE SOCIOECONOMIC CONTEXT ON COGNITION

Abstract Later-life cognitive function is influenced by genetics as well as early- and later-life socioeconomic context. However, few studies have examined the interaction between genetics and early childhood factors. Using gene-based tests (interaction sequence kernel association test [iSKAT]/iSKAT optimal unified test), we examined whether common and rare variants in 39 gene regions previously associated with cognitive performance, dementia, and related traits had an interaction with childhood socioeconomic context (parental education and financial strain) on memory performance or decline in European ancestry (EA, N = 10,468) and African ancestry (AA, N = 2,252) participants from the Health and Retirement Study. Of the 39 genes, 22 in EA and 19 in AA had nominally significant interactions with at least one childhood socioeconomic measure on memory performance and/or decline; however, only one, SLC24A4 x father’s education, remained significant after multiple testing correction (false discovery rate [FDR] < .05). In trans-ethnic meta-analysis, 2 genes interacted with childhood socioeconomic context: MS4A4A x mother’s education on memory performance, and SLC24A4 x father’s education on memory decline. Both interactions remained significant after adjusting for respondent’s own education, apolipoprotein-ε4 allele status, lifestyle factors, body mass index, and comorbidities. For both interactions in EA and AA, the genetic effect was stronger in participants with low parental education. Examination of common and rare variants in genes discovered through genome-wide association studies shows that childhood context may interact with gene regions to jointly impact later-life memory function and decline. Genetic effects may be more salient for those with lower childhood socioeconomic status.

MEDIATING EFFECTS OF QUALITY OF LIFE IN THE ASSOCIATION OF DEBTS AND LATER MEMORY FUNCTION IN CHINA, ENGLAND, AND THE US

Abstract Non-mortgage debts were linked to negative cognitive health outcomes in later-life older adults. It is unclear how they may be associated with later-life memory function through psychosocial pathways, and whether the associations vary by health care system and policy environment. We examined the mediating effects of depressive symptoms and dissatisfaction with life in the association between non-mortgage debts and subsequent memory function among adults aged 65-101 years in the US, China, and England. Data were from harmonized, nationally representative longitudinal studies of aging in the US (Health and Retirement Study; n=8,388), China (China Health and Retirement Longitudinal Study; n=1,180), and England (English Longitudinal Study of Aging; n=3,390). Non-mortgage debt burden was defined as any pre-existing or new non-mortgage debts in two years (2010-2012 for the US and England; 2011-2013 for China). Memory function was measured by 20-point immediate and delayed word recall summary scores over a subsequent 5- or 6-year follow-up period. Within each country, we used sampling-weighted, multivariable-adjusted causal mediation analysis (product method) to estimate the total and direct effects of non-mortgage debts on memory function, and the indirect effects mediated by depressive symptoms and dissatisfaction with life. We observed significant mediating effects of depressive symptoms on the association between non-mortgage debts and memory function in China only. Dissatisfaction with life had a significant mediating effect on this association in US and China, not in England. Although more investigation is needed, the relationships between non-mortgage debts and later-life memory function through psychosocial pathways may differ across macro-level socioeconomic structures.

Longitudinal change in memory performance as a strong endophenotype for Alzheimer's disease.

Although large-scale genome-wide association studies (GWAS) have been conducted on AD, few have been conducted on continuous measures of memory performance and memory decline. We conducted a cross-ancestry GWAS on memory performance (in 27,633 participants) and memory decline (in 22,365 participants; 129,201 observations) by leveraging harmonized cognitive data from four aging cohorts. We found high heritability for two ancestry backgrounds. Further, we found a novel ancestry locus for memory decline on chromosome 4 (rs6848524) and three loci in the non-Hispanic Black ancestry group for memory performance on chromosomes 2 (rs111471504), 7 (rs4142249), and 15 (rs74381744). In our gene-level analysis, we found novel genes for memory decline on chromosomes 1 (SLC25A44), 11 (BSX), and 15 (DPP8). Memory performance and memory decline shared genetic architecture with AD-related traits, neuropsychiatric traits, and autoimmune traits. We discovered several novel loci, genes, and genetic correlations associated with late-life memory performance and decline. Late-life memory has high heritability that is similar across ancestries. We discovered four novel variants associated with late-life memory. We identified four novel genes associated with late-life memory. Late-life memory shares genetic architecture with psychiatric/autoimmune traits.

Sex-specific genetic architecture of late-life memory performance.

Women demonstrate a memory advantage when cognitively healthy yet lose this advantage to men in Alzheimer's disease. However, the genetic underpinnings of this sex difference in memory performance remain unclear. We conducted the largest sex-aware genetic study on late-life memory to date (Nmales =11,942; Nfemales =15,641). Leveraging harmonized memory composite scores from four cohorts of cognitive aging and AD, we performed sex-stratified and sex-interaction genome-wide association studies in 24,216 non-Hispanic White and 3367 non-Hispanic Black participants. We identified three sex-specific loci (rs67099044-CBLN2, rs719070-SCHIP1/IQCJ-SCHIP), including an X-chromosome locus (rs5935633-EGL6/TCEANC/OFD1), that associated with memory. Additionally, we identified heparan sulfate signaling as a sex-specific pathway and found sex-specific genetic correlations between memory and cardiovascular, immune, and education traits. This study showed memory is highly and comparably heritable across sexes, as well as highlighted novel sex-specific genes, pathways, and genetic correlations that related to late-life memory. Demonstrated the heritable component of late-life memory is similar across sexes. Identified two genetic loci with a sex-interaction with baseline memory. Identified an X-chromosome locus associated with memory decline in females. Highlighted sex-specific candidate genes and pathways associated with memory. Revealed sex-specific shared genetic architecture between memory and complex traits.

Association between Loneliness and Memory Function through White Matter Hyperintensities in Older Adults: The Moderating Role of Gender.

Loneliness has an important impact on memory function in late life. However, the neural mechanism by which loneliness detrimentally influences memory function remains elusive. Furthermore, it remains unclear whether the association between loneliness and memory function varies by gender. The current study aimed to investigate the neural mechanism underlying the association between loneliness and episodic memory function and explore whether it varies with gender among cognitively normal older adults. A total of 173 community-dwelling adults aged 60 years or older from the Korean Social Life, Health, and Aging Project (KSHAP) study (mean age = 71.87) underwent an assessment of loneliness, neuropsychological testing, and structural magnetic resonance imaging. The association between loneliness and episodic memory function was mediated by the volume of white matter hyperintensities (WMHs), but not by hippocampal or gray matter volumes. In addition, the association between loneliness and memory function through WMHs was significantly moderated by gender; specifically, the indirect effect was significant among men but not among women. The study suggests that WMHs may be a potential neurological mechanism that causes late-life memory dysfunction associated with loneliness in older men. The findings underscore the need for gender-specific interventions to mitigate memory impairment associated with late-life loneliness, with significant public health implications.

The integrity of dopaminergic and noradrenergic brain regions is associated with different aspects of late-life memory performance

Changes in dopaminergic neuromodulation play a key role in adult memory decline. Recent research has also implicated noradrenaline in shaping late-life memory. However, it is unclear whether these two neuromodulators have distinct roles in age-related cognitive changes. Here, combining longitudinal MRI of the dopaminergic substantia nigra–ventral tegmental area (SN-VTA) and noradrenergic locus coeruleus (LC) in younger (n = 69) and older (n = 251) adults, we found that dopaminergic and noradrenergic integrity are differentially associated with memory performance. While LC integrity was related to better episodic memory across several tasks, SN-VTA integrity was linked to working memory. Longitudinally, we found that older age was associated with more negative change in SN-VTA and LC integrity. Notably, changes in LC integrity reliably predicted future episodic memory. These differential associations of dopaminergic and noradrenergic nuclei with late-life cognitive decline have potential clinical utility, given their degeneration in several age-associated diseases.

Does education moderate gender disparities in later-life memory function? A cross-national comparison of harmonized cognitive assessment protocols in the United States and India.

We compared gender disparities in later-life memory, overall and by education, in India and the United States (US). Data (N=7443) were from harmonized cognitive assessment protocols (HCAPs) in the Longitudinal Aging Study of India-Diagnostic Assessment of Dementia (LASI-DAD; N=4096; 2017-19) and US Health and Retirement Study HCAP (HRS-HCAP; N=3347; 2016-17). We derived harmonized memory factors from each study using confirmatory factor analysis. We used multivariable-adjusted linear regression to compare gender disparities in memory function between countries, overall and by education. In the United States, older women had better memory than older men (0.28 SD-unit difference; 95% CI: 0.22, 0.35). In India, older women had worse memory than older men (-0.15 SD-unit difference; 95% CI: -0.20, -0.10), which attenuated with increasing education and literacy. We observed gender disparities in memory in India that were not present in the United States, and which dissipated with education and literacy.

FV 12 The integrity of dopaminergic and noradrenergic brain regions is associated with different aspects of late-life memory performance

FV 12 The integrity of dopaminergic and noradrenergic brain regions is associated with different aspects of late-life memory performance

Reproductive Markers in Alzheimer's Disease Progression: The Framingham Heart Study.

Reproductive status, such as the age of menarche or menopause, may be linked to cognitive abilities and risk for incident Alzheimer's disease (AD) but the evidence is conflicting. It is also not fully known if these factors interact with cortical beta-amyloid deposition. To study the relationship between reproductive risks, sex hormone markers and risk for decline in specific cognitive domains in women. We analyzed the association of reproductive markers (age at menarche, number of births, age at menopause, sex hormone-binding globulin, estradiol, estrone, total testosterone, free testosterone) with incident AD and annualized cognitive decline in the community-based longitudinal Framingham Heart Study (FHS) Offspring women 60 years and older (n=772, mean age 68 years, mean follow-up 10.7 ± 3 years). We used the Cox proportional hazards regression model and linear regression model, adjusting for covariates. Incident AD dementia as well as the annualized change in memory, language, attention and executive functions. Older age at menopause was associated with a lower risk of incident AD dementia (p = 0.047, 6% lower risk per older year) after adjusting for baseline age, education, hormone therapy status, and MMSE score. Older age at menopause was significantly associated with a slower annualized decline in memory (beta = 0.085, p = 0.00059). The lower level of plasma Aβ42 was also associated with a higher risk of incident AD (HR = 0.97, 95% CI = 0.95, 0.99; p = 0.0039) but there was no significant interaction effect with age at menarche, age at menopause or plasma sex hormone levels. Younger age at menopause is a risk factor for late-life memory decline and incident AD. This risk appears to be independent of Aβ42 pathology. Further studies to understand the biological and social mechanisms underlying the differential effects of reproductive risks are warranted.

New insights on later-life memory decline over time with a variable-centered approach.

New insights on later-life memory decline over time with a variable-centered approach.

CROSS-NATIONAL VARIABILITY IN SEX/GENDER DIFFERENCES AND LATER-LIFE MEMORY: INDIA AND THE UNITED STATES

Abstract Little is known about the extent of sex/gender differences in later-life cognitive health in low-income countries such as India. We compared sex/gender differences in later-life memory, overall and by educational attainment, across men and women aged ≥65 years in India and the United States. Data were from Harmonized Cognitive Assessment Protocols (HCAP) in the population-representative Longitudinal Study of Aging in India (LASI; N=4,096;) and U.S. Health and Retirement Study (HRS; N=3,345). Multiple-group models estimated interactions between sex/gender and educational attainment on harmonized episodic memory scores across countries. In the U.S., women had a memory performance advantage compared to men across all education levels. In India, men had a memory performance advantage compared to women overall, interactions revealed that this advantage was only present among those with no formal education. Among those with at least lower secondary education, women demonstrated an advantage that increased with increasing education.

Virtual navigation in healthy aging: Activation during learning and deactivation during retrieval predicts successful memory for spatial locations

Spatial navigation and spatial memory are two important skills for independent living, and are known to be compromised with age. Here, we investigate the neural correlates of successful spatial memory in healthy older adults in order to learn more about the neural underpinnings of maintenance of navigation skill into old age. Healthy older adults watched a video shot by a person navigating a route and were asked to remember objects along the route and then attempted to remember object locations by virtually pointing to the location of hidden objects from several locations along the route. Brain activity during watching and pointing was recorded with functional MRI. Larger activations in temporal and frontal regions during watching, and larger deactivations in superior parietal cortex and intraparietal sulcus during pointing, were associated with smaller location errors. These findings suggest that larger evoked responses during learning of spatial information coupled with larger deactivation of canonical spatial memory regions at retrieval are important for effective spatial memory in late life.

0334 The Role of Race-Gender Intersectionality in Associations between Insomnia Patterns and Late-Life Memory Trajectories

Abstract Introduction Difficulty initiating sleep (DIS) may be a stronger predictor of neurodegenerative risk than other insomnia symptoms. This study examined whether longitudinal patterns of DIS are associated with subsequent memory trajectories, and whether associations differ across non-Hispanic Black and White men and women. Methods 12,565 participants in the Health and Retirement Study (Mage=67.8±9.1, 59.1% women) who self-identified as non-Hispanic Black (14.5%) or non-Hispanic White were included. DIS (“How often do you have trouble falling asleep?”) at three biennial waves (2002-2006) was dichotomized (“never/rarely/sometimes”=0, “often”=1). Participants were categorized into three mutually exclusive groups: low (reference group), persistent, and variable DIS. Episodic memory was assessed using a 10-item word list recall test at five biennial waves (2008-2016). Latent growth curves modeled associations between DIS patterns and subsequent memory level and change, adjusting for sociodemographics (model 1), health conditions (model 2), and depressive symptoms (model 3) in 2002. Stratified models compared associations across White men, Black men, White women, and Black women. Results Compared to low DIS, persistent (β=-0.03, p<.001) or variable (β=-0.07, p<.001) DIS was associated with worse subsequent memory in models 1 and 2. The effect of variable (β=-0.05, p<.001), but not persistent (β=-0.01, p=.271), DIS remained in model 3. Persistent DIS was most prevalent among White women (5.4% vs. 2.4-4%), and variable DIS was most prevalent among Black women (24.1% vs. 14-22.2%). Persistent DIS was only significantly associated with memory among White women (β=-0.04, p=.003 vs. β=-0.04, p=.324 for Black Men; β=-0.03, p=.087 for White men; and β=0.01, p=.859 for Black women). Variable DIS was most strongly associated with memory among Black men (β=-0.141, p=.003), followed by White men (β=-0.09, p<.001), White women (β=-0.06, p<.001) and Black women (β=-0.06, p=.064). There were no associations between DIS patterns and memory change. Conclusion While links between persistent DIS and subsequent memory may reflect negative cognitive effects of depression, variable DIS may presage worse memory above and beyond depression. Race/gender differences in the prevalence and predictive value of DIS patterns for subsequent cognitive function highlight the value of an intersectional lens. Gender disparities in DIS may be more prominent than racial disparities. Support (If Any) NIA F31AG067717 (PI: Zaheed)

Childhood Socioeconomic Disadvantage and Pathways to Memory Performance in Mid to Late Adulthood: What Matters Most?

ObjectivesChildhood socioeconomic disadvantage is consistently associated with lower cognitive function in later life. This study aims to distinguish the contribution of specific aspects of childhood socioeconomic disadvantage for memory performance in mid to late adulthood, with consideration for direct and indirect effects through education and occupation.MethodsData were from adults aged 50 to 80 years who completed the life history module in the 2006/2007 wave of the English Longitudinal Study of Aging (n = 4,553). The outcome, memory score, was based on word recall tests (range: 0–20 points). We used the g-formula to estimate direct and indirect effects of a composite variable for childhood socioeconomic disadvantage and its 4 individual components: lower-skilled occupation of the primary breadwinner, having few books in the home, overcrowding in the home, and lack of water and heating facilities in the home.ResultsFew books were the most consequential component of childhood socioeconomic disadvantage for later-life memory (total effect: −0.82 points for few books; 95% confidence interval [CI]: −1.04, −0.60), with roughly half being a direct effect. The total effect of a breadwinner in lower-skilled occupations was smaller but not significantly different from a few books (−0.67 points; 95% CI: −0.88, −0.46), while it was significantly smaller with overcrowding (−0.31 points; 95% CI: −0.56, −0.06). The latter 2 total effects were mostly mediated by education and occupation.DiscussionA literate environment in the childhood home may have lasting direct effects on memory function in mid to later life, while parental occupation and overcrowding appear to influence memory primarily through educational and occupational pathways.