Memory profiles predict dementia over 23-28 years in normal but not successful aging

Physical, cognitive, and social activities as mediators between personality and cognition: evidence from four prospective samples

OBJECTIVES

The present study examined how activity engagement mediates the association between personality and cognition.

METHODS

Participants were middle-aged and older adults (Age range: 24-93 years; N > 16,000) from the Midlife in the United States Study, the Health and Retirement Study, the English Longitudinal Study of Ageing, and the Wisconsin Longitudinal Study of Aging. In each sample, personality traits and demographic factors were assessed at baseline, engagement in cognitive, physical, and social activities was assessed in a second wave, and cognition was measured in a third wave, 8 to 20 years later.

RESULTS

Random-effect meta-analyses indicated that lower neuroticism and higher extraversion, openness, and conscientiousness were prospectively associated with better cognition. Most of these associations were partly mediated by greater engagement in physical and cognitive activities but not social activities. Physical activity accounted for 7% (neuroticism) to 50% (extraversion) and cognitive activity accounted for 14% (neuroticism) to 45% (extraversion) of the association with cognition.

CONCLUSION

The present study provides replicable evidence that physical and cognitive activities partly mediate the prospective association between personality traits and cognitive functioning.

Rey Auditory Verbal Learning Test in idiopathic normal pressure hydrocephalus and Alzheimer's disease

Objective: This study aims to evaluate the ability of the Rey Auditory Verbal Learning Test (RAVLT), to separate the early stages of idiopathic normal pressure hydrocephalus (iNPH) from Alzheimer's disease (AD), both in comparison to each other and to healthy individuals (HI). Method: The RAVLT performance regarding learning, recall and recognition, was analyzed in three matched samples comprising 30 HI, 84 participants with AD and 84 with iNPH. The clinical samples were divided into two subgroups based on scores on the MMSE, High performers (27-30 points, n = 30) and Medium performers (18-26 points, n = 54). Results: Memory performance was significantly impaired in both clinical samples relative to HI, even in the comparisons with the subgroups consisting of only High-MMSE performers. Despite similar results on measures capturing learning, the iNPH patients outperformed AD patients on measures of recall and recognition. Conclusions: Learning impairment occurs early in iNPH and AD alike, when MMSE performance is still within normal limits. RAVLT measures of delayed recall and recognition are less affected in iNPH than in AD and may serve as differential diagnostic neuropsychological markers.

Characterising the covariance pattern between lifestyle factors and structural brain measures: a multivariable replication study of two independent ageing cohorts

Modifiable lifestyle factors have been shown to promote healthy brain ageing. However, studies have typically focused on a single factor at a time. Given that lifestyle factors do not occur in isolation, multivariable analyses provide a more realistic model of the lifestyle-brain relationship. Here, canonical correlation analyses (CCA) examined the relationship between nine lifestyle factors and seven MRI-derived indices of brain structure. The resulting covariance pattern was further explored with Bayesian regressions. CCA analyses were first conducted on a Danish cohort of older adults (n = 251) and then replicated in a British cohort (n = 668). In both cohorts, the latent factors of lifestyle and brain structure were positively correlated (UK: r = .37, p < 0.001; Denmark: r = .27, p < 0.001). In the cross-validation study, the correlation between lifestyle-brain latent factors was r = .10, p = 0.008. However, the pattern of associations differed between datasets. These findings suggest that baseline characterisation and tailoring towards the study sample may be beneficial for achieving targeted lifestyle interventions.

Measures of physical performance as mediators between personality and cognition in two prospective studies

Few studies have examined the pathways linking personality to cognition. This study aimed to examine whether measures of physical performance (gait speed, peak expiratory flow (PEF), and grip strength) mediated the association between five-factor model personality traits and cognition (memory performance, subjective memory, and informant-rated cognition). Participants were aged 57 to 95 years from the Health and Retirement Study (HRS, N = 4,109) and the English Longitudinal Study of ageing (ELSA, N = 3,584). In HRS, personality and demographic factors were assessed in 2008/2010, physical performance in 2012/2014, and memory performance and subjective memory in 2016/2018. Informant-rated cognition was obtained in 2016 for an HRS subsample. In ELSA, personality and demographic factors were assessed in 2010/2011, physical performance in 2012/2013, and objective and subjective memory in 2014/2015. Informant-rated cognition was obtained in 2018 for an ELSA subsample. With a few exceptions, replicable patterns of mediation were found across HRS and ELSA. Slower gait speed partially mediated the association between higher neuroticism, lower conscientiousness and worse scores on all three cognitive measures (memory performance, subjective memory, and informant-rated cognition). Slower gait also partially mediated the association between openness and both objective and subjective memory. There was less replicable evidence for a mediating role of PEF and grip strength. The present study advances knowledge on the pathways linking personality to cognition in older adults and supports the hypothesis that personality associations with better physical function can help support healthy cognitive aging.

The mediating role of Vitamin D in the association between personality and memory: Evidence from two samples

Five-Factor Model (FFM) personality traits are consistently related to cognition in old age. However, little is known about the biological mediators of this association. The present study examined whether levels of Vitamin D mediated the association between personality and memory. Participants were adults aged 50-96 years from the Health and Retirement Study (HRS, N = 5229) and the English Longitudinal Study of Ageing (ELSA, N = 4249). In HRS, personality and demographic factors were assessed in 2012/2014, Vitamin D was assessed in 2016, and memory was assessed in 2018. In ELSA, personality and demographic factors were obtained in 2010/2011, Vitamin D was measured in 2012/2013, and memory was assessed in 2014/2015. In both samples, higher extraversion and conscientiousness were related to higher levels of Vitamin D, whereas higher neuroticism was related to lower Vitamin D. In both samples, higher Vitamin D partly mediated the association between both higher extraversion and conscientiousness and better memory. The association between higher neuroticism and worse memory at follow-up was partially mediated by lower Vitamin D in the HRS and ELSA. Vitamin D did not mediate the association between higher openness and better memory. The present study extends the personality-cognition literature by providing new replicable evidence that Vitamin D is a biological mediator.

Actor and Partner Effect of Loneliness on Episodic Memory and Verbal Fluency: A Dyadic Multilevel Analysis of Romantic Couples Across 28 Countries

OBJECTIVES

There is evidence that loneliness is detrimental to cognitive health. Most studies, however, do not consider the association between loneliness and cognition in the context of close relationships, such as a spouse or romantic partner. This study examines loneliness, experienced by both the individual and their romantic partner, and cognitive performance.

METHODS

Data were from 24,689 opposite-sex couples (49,378 participants) from 28 countries in the Survey of Health, Aging and Retirement in Europe. Each couple participant reported loneliness and completed memory and verbal fluency tasks. A multilevel sex-stratified analysis was used to account for the nested data structure and evaluate actor and partner effects of loneliness on cognitive performance for male and female partners.

RESULTS

Consistent with the literature, there were small actor effects of loneliness on memory and verbal fluency for both males and females: A person's own loneliness was associated negatively with their cognitive performance on both tasks. There were also small partner effects: A person with a partner who was lonely tended to have worse cognitive performance above and beyond their own loneliness. Actor and partners effects were similar for male and female partners, replicated in most countries, and generally held controlling for age, education, household size, and disease burden. For memory, loneliness effects were slightly stronger among older participants.

DISCUSSION

Both the experience of loneliness and loneliness of a partner have a negative association with cognitive health.

The association between purpose/meaning in life and verbal fluency and episodic memory: a meta-analysis of >140,000 participants from up to 32 countries

OBJECTIVES

Feelings of purpose and meaning in life are protective against consequential cognitive outcomes, including reduced risk of Alzheimer's disease and dementia. Purpose and meaning are likely to also be associated with cognitive functions on the pathway to dementia. The objective of the current research was to test whether both purpose in life and meaning in life are associated with higher verbal fluency and better episodic memory and whether these associations varied by sociodemographic characteristics or economic characteristics of the country.

DESIGN

Prospective meta-analysis of cross-sectional associations based on individual participant data.

SETTING

Established cohort studies with measures of either purpose in life or meaning in life and verbal fluency and episodic memory.

PARTICIPANTS

Across the cohorts, there were over 140,000 participants from 32 countries from North and South America, Europe, and the Middle East.

RESULTS

The meta-analysis indicated that purpose and meaning were associated with better performance on both the verbal fluency (meta-analytic partial r = .098, 95% confidence interval [CI] = .080, .116, p < .001) and episodic memory (r = .117, 95% CI = .100, .135, p < .001) task and that these associations were similar across measures of purpose in life and meaning in life. There was modest evidence that these associations were slightly stronger in relatively lower-income countries, and there was less consistent evidence that they varied by age, gender, or education.

DISCUSSION

These findings indicate a robust association between purpose/meaning and both verbal fluency and episodic memory across demographic groups and cultural context. Purpose/meaning may be a useful target of intervention for healthier cognitive aging.

Memory and Personality Development in Adulthood: Evidence From Four Longitudinal Studies

OBJECTIVES

Personality traits have been related to concurrent memory performance. Most studies, however, have focused on personality as a predictor of memory; comparatively less is known about whether memory is related to personality development across adulthood. Using 4 samples, the present study tests whether memory level and change are related to personality change in adulthood.

METHOD

Participants were drawn from 2 waves of the Wisconsin Longitudinal Study Graduates (WLSG; N = 3,232, mean age = 64.28, SD = 0.65) and Wisconsin Longitudinal Study Siblings (WLSS; N = 1,570, mean age = 63.52, SD = 6.69) samples, the Midlife in the United States (MIDUS; N = 1,901, mean age = 55.43, SD = 10.98), and the Health and Retirement Study (HRS; N = 6,038, mean age = 65.47, SD = 8.28). Immediate and delayed recall and the 5 major personality traits were assessed at baseline and follow-up.

RESULTS

There was heterogeneity in the associations across samples. A meta-analysis of latent change in the four samples indicated that lower baseline memory performance was related to an increase in neuroticism (B = -0.002; 95% CI = -0.004, -0.0008) and a decrease in agreeableness (B = 0.004; 95% CI = 0.002, 0.007) and conscientiousness (B = 0.005; 95% CI = 0.0008, 0.010). In addition, declines in memory were related to steeper declines in extraversion (B = 0.06; 95% CI = 0.003, 0.11), openness (B = 0.04; 95% CI = 0.007, 0.069), and conscientiousness (B = 0.05; 95% CI = 0.019, 0.09).

DISCUSSION

The present study indicates that poor memory and declines in memory over time are related to maladaptive personality change. These associations, however, were small and inconsistent across samples.

Biological and environmental predictors of heterogeneity in neurocognitive ageing: Evidence from Betula and other longitudinal studies

Individual differences in cognitive performance increase with advancing age, reflecting marked cognitive changes in some individuals along with little or no change in others. Genetic and lifestyle factors are assumed to influence cognitive performance in ageing by affecting the magnitude and extent of age-related brain changes (i.e., brain maintenance or atrophy), as well as the ability to recruit compensatory processes. The purpose of this review is to present findings from the Betula study and other longitudinal studies, with a focus on clarifying the role of key biological and environmental factors assumed to underlie individual differences in brain and cognitive ageing. We discuss the vital importance of sampling, analytic methods, consideration of non-ignorable dropout, and related issues for valid conclusions on factors that influence healthy neurocognitive ageing.