Differences In Cognitive Aging Research Articles

Progress and future challenges in aging and diversity research in the United States

In 2016, the UC Davis Latino Aging Research Resource Center and UC Davis Alzheimer's Disease Center brought together experts from across the country to consolidate current knowledge and identify future directions in aging and diversity research. This report disseminates the research priorities that emerged from this conference, building on an earlier Gerontological Society of America preconference. We review key racial/ethnic differences in cognitive aging and dementia and identify current knowledge gaps in the field. We advocate for a systems-level framework for future research whereby environmental, sociocultural, behavioral, neuropathological, genetic, and psychometric levels of analysis are examined together to identify pathways and mechanisms that influence disparities. We then discuss steps to increase the recruitment and retention of racial/ethnic minorities in aging studies, as none of the recommendations will be possible without strong collaboration between racial/ethnic minority communities and researchers. This approach is consistent with the National Institute on Aging Health Disparities Research Framework.

Predicting real-world behaviour: Cognition-emotion links across adulthood and everyday functioning at work

ABSTRACTInspired by the discovery of positive age trends in emotional well-being across adulthood, lifespan researchers have uncovered fascinating age differences in cognition–emotion interactions in healthy adult samples, for example in emotion processing, memory, reactivity, perception, and regulation. Taking stock of this body of research, I identify four trends and five remaining gaps in our understanding of emotional functioning in adulthood. In particular, I suggest that the field should pay stronger attention to the prediction of real-world behaviour. Using the sample case of work functioning, I outline gaps in current knowledge, including the lack of data on middle-aged adults, the neglect of relevant cognitive-emotional mechanisms, and the unclear role of life experience. Filling these gaps will enable progress in research on emotional aging in and beyond the work setting and enhance its practical utility for individuals, organisations, and society.

A Importância do Raciocínio Lógico Para a Metodologia da Pesquisa: Raciocínio, Planejamento e Execução

O estudo tem por objetivo reafirmar a importância de saber pensar e seus métodos, a fim de traçar um paralelo entre as formas de raciocínio ao longo do desenvolvimento da mente humana e os modelos metodológicos para planejar e executar uma pesquisa científica. Analisamos artigos e publicações que trouxeram em seu escopo tanto as fases do raciocínio e métodos, como diferenças etárias de pensamento crítico e analítico e sua progressão. Como podemos observar, os estudos ainda necessitam avançar na perspectiva do raciocínio lógico em adultos, já que há bastante material contemplando estudos em crianças e adolescentes. Contudo, temos bases suficientes para declarar que tal raciocínio sofisticado que a mente adulta produz, se apresenta complexo e completo o suficiente para ser classificado maduro e necessário ao método científico.

Deficits in category learning in older adults: Rule-based versus clustering accounts.

Memory research has long been one of the key areas of investigation for cognitive aging researchers but only in the last decade or so has categorization been used to understand age differences in cognition. Categorization tasks focus more heavily on the grouping and organization of items in memory, and often on the process of learning relationships through trial and error. Categorization studies allow researchers to more accurately characterize age differences in cognition: whether older adults show declines in the way in which they represent categories with simple rules or declines in representing categories by similarity to past examples. In the current study, young and older adults participated in a set of classic category learning problems, which allowed us to distinguish between three hypotheses: (a) rule-complexity: categories were represented exclusively with rules and older adults had differential difficulty when more complex rules were required, (b) rule-specific: categories could be represented either by rules or by similarity, and there were age deficits in using rules, and (c) clustering: similarity was mainly used and older adults constructed a less-detailed representation by lumping more items into fewer clusters. The ordinal levels of performance across different conditions argued against rule-complexity, as older adults showed greater deficits on less complex categories. The data also provided evidence against rule-specificity, as single-dimensional rules could not explain age declines. Instead, computational modeling of the data indicated that older adults utilized fewer conceptual clusters of items in memory than did young adults.

ELECTROPHYSIOLOGY DEPENDS ON SEX IN AGING AND DEMENTIA

Longitudinal studies on sex differences in cognitive decline have reported inconsistent findings where some studies show difference in decline while others not. Converging evidence suggest the role of large scale neurocognitive networks in memory and other cognitive functions of the brain. Acetycholine (Ach) serves as neuromodulator by altering the way neurocognitive networks respond to external and internal inputs. The aim of the present work was to investigate the behavior of a previously designed ACH index across progressive stages of dementia; and to investigate possible sex differences in cognitive aging in healthy individuals. The ACH activity, in terms of the index and possible role of sex in cognitive aging was examined using EEG recordings from a population ranging from 5 − 95 years including healthy controls (NRM) as well as mild cognitive impairment (MCI), mild and severe Alzheimer's disease (mAD and ADs) and Lewy body dementia (LBD) (n=1697). A significant difference was found for the ACH index between all pair of groups [F (4) = 23.8, p = 0.001] apart from the mAD and the NRM group and the LBD and ADs group. A medium positive correlation (r= 0.31, p < 0.001) was found between the ACH index and cognition as measured with MMSE. Looking at sex differences a significant difference [F (1) = 66.74, p = 0.001] was found for the ACH index between females and males in the elderly (mean age = 71.8 (sd.=10.2)) and women showed a higher positive correlation to MMSE in the ADs and LBD groups compared to the men. In conclusion, this study introduces the ACH index, developed on the basis of a scopolamine challenge trial. The ACH index reflects progressive loss of cholinergic function ranging from normal cognition through MCI and mild AD to severe AD; it correlates with cognition and a clear sex difference was found related to cognitive aging. The results also imply that sex may play a crucial role in EEG related research and application in dementia.

Cross-Sectional and Longitudinal Effects of CREB1 Genotypes on Individual Differences in Memory and Executive Function: Findings from the BLSA.

Purpose: Previously, we have shown that the SNP rs10932201 genotype of the cyclic AMP responsive element binding protein 1 gene (CREB1) contributes to individual differences in executive and memory function at the neural system and behavioral levels in healthy, young adults. However, longitudinal effects of CREB1 genotypes on cognition have not yet been addressed. Furthermore we were interested in replicating associations between CREB1 genotypes and human cognition in previous cross-sectional studies and explore whether APOE𝜀4 status might modify these relations.Materials and Methods: We investigated whether common, independent tag SNPs within CREB1 (rs2253206, rs10932201, rs6785) influence individual differences in age-related longitudinal change and level of executive function and memory performance independent of baseline age, sex, APOE𝜀4 status, and education. Our analysis included data from cognitively unimpaired older adults participating in the Baltimore Longitudinal Study of Aging. Eleven measures from six cognitive tests (sample sizes range 617–786) were analyzed using linear mixed effects and generalized estimating equations models. Mean baseline age ranged from 50 to 69 years and mean time of follow-up (interval) ranged from 8 to 22 years.Results: We found significant effects of all three CREB1 SNPs on performance level and/or longitudinal change in performance based on eight measures assessing semantic memory, episodic memory, or both executive function and semantic memory. SNP rs10932201 showed the most significant and largest effect (Cohen’s d = -0.70, p < 0.01) on age-related longitudinal decline of semantic memory. Additionally, we show interactions between all three CREB1 SNPs and APOE𝜀4 status on age-related longitudinal declines and levels of memory and executive function.Conclusion: Our results suggest that CREB1 genotypes independently and by interactions with APOE𝜀4 status contribute to individual differences in cognitive aging.

Cognition and Context: Rural-Urban Differences in Cognitive Aging Among Older Mexican Adults.

To describe differences in cognitive functioning across rural and urban areas among older Mexican adults. We include respondents aged 50+ in the 2012 Mexican Health and Aging Study (MHAS). Cognitive functioning by domain is regressed as a function of community size. The role of educational attainment in explaining rural/urban differences in cognitive functioning is examined. Respondents residing in more rural areas performed worse across five cognitive domains. The majority, but not all, of the association between community size and cognitive functioning was explained by lower education in rural areas. Respondents residing in more rural areas were disadvantaged in terms of cognitive functioning compared with those residing in more urban areas. Poorer cognitive functioning in late life may be the result of historical educational disadvantage in rural areas or selection through migration from rural to urban regions for employment.

Predictors of ageing-related decline across multiple cognitive functions

It is critical to discover why some people's cognitive abilities age better than others'. We applied multivariate growth curve models to data from a narrow-age cohort measured on a multi-domain IQ measure at age 11years and a comprehensive battery of thirteen measures of visuospatial, memory, crystallized, and processing speed abilities at ages 70, 73, and 76years (n=1091 at age 70). We found that 48% of the variance in change in performance on the thirteen cognitive measures was shared across all measures, an additional 26% was specific to the four ability domains, and 26% was test-specific. We tested the association of a wide variety of sociodemographic, fitness, health, and genetic variables with each of these cognitive change factors. Models that simultaneously included all covariates accounted for appreciable proportions of variance in the cognitive change factors (e.g. approximately one third of the variance in general cognitive change). However, beyond physical fitness and possession of the APOE e4 allele, very few predictors were incrementally associated with cognitive change at statistically significant levels. The results highlight a small number of factors that predict differences in cognitive ageing, and underscore that correlates of cognitive level are not necessarily predictors of decline. Even larger samples will likely be required to identify additional variables with more modest associations with normal-range heterogeneity in aging-related cognitive declines.

Interactive effects of subjective memory complaints and hypertension on learning and memory performance in the elderly

This study evaluated whether the relation between subjective memory complaints and cognitive performance is influenced by the presence of hypertension in the elderly. One hundred and five healthy older adults, 70–89 years of age, with and without hypertension treatment or diagnosis, completed a scale of subjective memory complaints. Participants were divided into those with mild memory concerns and those with minimal or no complaints. All participants completed a battery of neuropsychological tests including measures of verbal and nonverbal memory. After controlling for differences in age, gender, education, and overall intellectual ability, there were significant main effects for memory concerns and significant interactions for memory complaints and hypertension on several measures of memory performance. There were no main effects for hypertension on memory performance. Simple effects analyses of the interactions showed that the hypertensive complainers demonstrated poorer performance on measures of long-term memory and greater reliance on short-term recall than the hypertensive non-complainers. There were no differences in memory performance for the non-hypertensive groups. Among healthy elderly community-dwelling adults, those with mild subjective memory complaints in the context of hypertension demonstrated greater objective cognitive difficulties than those without hypertension as well as a greater reliance on a less efficient learning strategy. These findings suggest that memory concerns in the presence of hypertension may be important when evaluating treatment efficacy in these individuals and for identifying differences in cognitive aging.

Amžiaus sąsajos su paprastos ir sudėtingos informacijos apdorojimo greičiu, atmintimi bei psichinės veiklos perkėlimu

Suaugusiųjų amžius siejamas su informacijos apdorojimo greičio lėtėjimu ir daugelio kitų fluidinių gebėjimų (atmintis, psichinės veiklos perkėlimas) susilpnėjimu. Remiantis informacijos apdorojimo greičio teorija ir gausiais empiriniais įrodymais galima teigti, kad informacijos apdorojimo greitis yra amžiaus ir fluidinių gebėjimų ryšių mediatorius. Vis dėlto nėra aišku, ar mediacinis ryšys išlieka, jeigu atskiriamas paprastos ir sudėtingos informacijos apdorojimo greitis. Šiame straipsnyje aprašyto tyrimo tikslas – ištirti tiesioginius ir mediacinius ryšius tarp amžiaus, paprastos ir sudėtingos informacijos apdorojimo greičio, atminties ir psichinės veiklos perkėlimo. Tyrime dalyvavo 415 asmenų, kurių amžius – nuo 18 iki 84 metų (M = 39,05; SD = 18,34). Visi tyrimo dalyviai, naudodamiesi kompiuteriu, atliko vienuolika pažintinėms funkcijoms tirti skirtų užduočių. Užduotys suskirstytos į keturias grupes. Toks grupavimas pagrįstas patvirtinamąja faktorių analize (X2 = 83,035; df = 47; p = 0,001, RMSEA = 0,043; CFI = 0,973; TLI = 0,961). Tyrimo dalyviai taip pat užpildė klausimyną, kurį sudarė demografiniai klausimai apie šeiminę padėtį, darbą, lytį, kalbą, išsilavinimą ir amžių. Tiesiniai ir mediaciniai amžiaus ir pažintinių gebėjimų ryšiai įvertinti keturiais kelių analizės modeliais. Nustatyta, kad amžius stipriai susijęs su paprastos ir sudėtingos informacijos apdorojimo greičio lėtėjimu bei atminties prastėjimu. Paprastos informacijos apdorojimo greitis yra mediatorius, paaiškinantis amžiaus sąsają su atmintimi ir iš dalies – amžiaus sąsają su psichinės veiklos perkėlimu. Paprastos informacijos apdorojimo greitis tik iš dalies paaiškina amžiaus sąsają su sudėtingos informacijos apdorojimo greičiu. Sudėtingos informacijos apdorojimo greitis yra mediatorius, paaiškinantis paprastos informacijos apdorojimo greičio sąsają su psichinės veiklos perkėlimu ir iš dalies – sąsają su atmintimi.

Differences in cognitive aging: typology based on a community structure detection approach.

The current study investigated the extent and patterns of cognitive variability in younger and older adults. An important novelty of this study is the use of graph-based community structure detection analysis to map performance in a mixed population of 79 young and 76 older adults, without separating the age groups a-priori. We identified six subgroups, with distinct patterns of neuropsychological performance. The stability of the identified subgroups was confirmed by employing a cross-validation support vector machine based analysis. The majority of these subgroups comprised either young or older adults, confirming the expected role of aging in cognitive performance. In addition, we identified a subgroup of young and older adults who performed at a similar cognitive level of overall good cognitive performance with slightly decreased processing speed. This result showed that older age is not necessarily associated with general lower cognitive performance and that being young is not necessarily associated with superior cognitive performance. Moreover, cognitively better performing elderly had a significantly higher level of education attainment and higher crystallized intelligence than the other elderly, which suggests that older adults with higher cognitive reserve may be able to cope better with age-related neurobiological change.

Cognitive decline is associated with reduced surface GluR1 expression in the hippocampus of aged rats

Individual differences in cognitive aging exist in humans and in rodent populations, yet the underlying mechanisms remain largely unclear. Activity-dependent delivery of GluR1-containing AMPA receptor (AMPARs) plays an essential role in hippocampal synaptic plasticity, learning and memory. We hypothesize that alterations of surface GluR1 expression in the hippocampus might correlate with age-related cognitive decline. To test this hypothesis, the present study evaluated the cognitive function of young adult and aged rats using Morris water maze. After the behavioral test, the surface expression of GluR1 protein in hippocampal CA1 region of rats was determined using Western blotting. The results showed that the surface expression of GluR1 in the hippocampus of aged rats that are cognitively impaired was much lower than that of young adults and aged rats with preserved cognitive abilities. The phosphorylation levels of GluR1 at Ser845 and Ser831 sites, which promote the synaptic delivery of GluR1, were also selectively decreased in the hippocampus of aged-impaired rats. Correlation analysis reveals that greater decrease in surface GluR1 expression was associated with worse behavioral performance. These results suggest that reduced surface GluR1 expression may contribute to cognitive decline that occurs in normal aging, and different pattern of surface GluR1 expression might be responsible for the individual differences in cognitive aging.

Ageing towards meaningful work? Age, labour-market change, and attitudes to work in the Swedish workforce, 1979–2003

A central finding in earlier research on work orientation is that there are substantial age-differences regarding attitudes to work. Generally, more older workers describe their jobs as intrinsically meaningful than younger workers. This result has been interpreted in three different ways, the psychological, the cultural, and the structural hypotheses, where the first emphasizes cognitive age-differences, the second sees age-differences as outcomes of generational differences, and the third regards them as expressions of labour-market inequalities. These different approaches lead to quite different hypotheses regarding recent developments, but the relevant research is limited. Drawing on data from the Swedish survey of living conditions (ULF), this study has examined attitudinal change within the Swedish workforce during 1979–2003. Three sub-periods, 1986-1987, 1994-1996, and 2001-2003 were compared with 1979, the year of reference. The results showed that a consistently smaller share of the workforce held extrinsic work values in the subsequent periods, and that this applied to all age-groups. Further, the results did not support the assumption of broader cultural differences between generations. Rather, the results provide support for the structural hypothesis. Older workers held extrinsic work values to a lesser degree than younger workers regardless of period. Most strikingly, the gap between the youngest group on the labour market (ages 16–29) and the older groups widened during the period. Furthermore, class differences in the distribution of the extrinsic attitude were intact throughout the study period; manual employees were consistently more likely to hold an extrinsic attitude than were service-class employees. This implies that differences in the probability of extrinsic work attitudes have been identifiable regardless of period, but that their prevalence has decreased as jobs involving features related to extrinsic work values have decreased since 1979.

High-gamma activity in an attention network predicts individual differences in elderly adults' behavioral performance

The current study used a magnetoencephalogram to investigate the relationship between high-gamma (52–100Hz) activity within an attention network and individual differences in behavioral performance among healthy elderly adults. We analyzed brain activity in 41 elderly subjects performing a 3-stimulus visual oddball task. In addition to the average amplitude of event-related fields in the left intraparietal sulcus (IPS), high-gamma power in the left middle frontal gyrus (MFG), the strength of high-gamma imaginary coherence between the right MFG and the left MFG, and those between the right MFG and the left thalamus predicted individual differences in reaction time. In addition, high-gamma power in the left MFG was correlated with task accuracy, whereas high-gamma power in the left thalamus and left IPS was correlated with individual processing speed. The direction of correlations indicated that higher high-gamma power or coherence in an attention network was associated with better task performance and, presumably, higher cognitive function. Thus, high-gamma activity in different regions of this attention network differentially contributed to attentional processing, and such activity could be a fundamental process associated with individual differences in cognitive aging.

Ageing towards meaningful work? Age, labour-market change, and attitudes to work in the Swedish workforce, 1979–2003

A central finding in earlier research on work orientation is that there are substantial age-differences regarding attitudes to work. Generally, more older workers describe their jobs as intrinsically meaningful than younger workers. This result has been interpreted in three different ways, the psychological, the cultural, and the structural hypotheses, where the first emphasizes cognitive age-differences, the second sees age-differences as outcomes of generational differences, and the third regards them as expressions of labour-market inequalities. These different approaches lead to quite different hypotheses regarding recent developments, but the relevant research is limited. Drawing on data from the Swedish survey of living conditions (ULF), this study has examined attitudinal change within the Swedish workforce during 1979–2003. Three sub-periods, 1986-1987, 1994-1996, and 2001-2003 were compared with 1979, the year of reference. The results showed that a consistently smaller share of the workforce held extrinsic work values in the subsequent periods, and that this applied to all age-groups. Further, the results did not support the assumption of broader cultural differences between generations. Rather, the results provide support for the structural hypothesis. Older workers held extrinsic work values to a lesser degree than younger workers regardless of period. Most strikingly, the gap between the youngest group on the labour market (ages 16–29) and the older groups widened during the period. Furthermore, class differences in the distribution of the extrinsic attitude were intact throughout the study period; manual employees were consistently more likely to hold an extrinsic attitude than were service-class employees. This implies that differences in the probability of extrinsic work attitudes have been identifiable regardless of period, but that their prevalence has decreased as jobs involving features related to extrinsic work values have decreased since 1979.

BDNF and COMT polymorphisms have a limited association with episodic memory performance or engagement in complex cognitive activity in healthy older adults

Cognitive decline is a major factor in lowering the quality of life in older populations, and contributes substantially to social, economic, and health costs. As humans age, cognitive function decreases differentially, and individual differences in cognitive ageing are likely attributed to a range of causes, including environmental and genetic influences. The current study included 360 participants (240 females and 120 males) aged between 50 and 79years from the Tasmanian Healthy Brain Project. The brain-derived neurotrophic factor (BDNF) Val66Met and Catechol-O-Methyltransferase (COMT) Val158Met polymorphisms were examined for their association with visual and auditory episodic memory performance. The polymorphisms were also investigated for their association with reported life-long engagement in complex cognitive activity using a retrospective questionnaire. Relative to the demographic variables, the gene variations were found to have no association with episodic memory performance, with the exception of the COMT polymorphism on a single measure of auditory memory (RAVLT). Several other studies also demonstrated that these polymorphisms have no, small, or inconsistent effects on memory function. The BDNF Val66Met and COMT Val158Met polymorphisms were also found to be of little significance to active engagement in complex cognitive activity throughout most of the lifespan. An association was detected between BDNF Val66Met and engagement in cognitive activity in early life (p=.04, d=.23), however this did not reach significance when adjusted for multiple comparisons. The biological mechanisms that underlie engagement in cognitive activity are elusive, thus the potential relationship between BDNF Val66Met genotype and early life cognitive engagement warrants further investigation.

Sex differences in cognitive ageing: Testing predictions derived from life-history theory in a dioecious nematode

Life-history theory maintains that organisms allocate limited resources to different traits to maximize fitness. Learning ability and memory are costly and known to trade-off with longevity in invertebrates. However, since the relationship between longevity and fitness often differs between the sexes, it is likely that sexes will differentially resolve the trade-off between learning and longevity. We used an established associative learning paradigm in the dioecious nematode Caenorhabditis remanei, which is sexually dimorphic for lifespan, to study age-related learning ability in males and females. In particular, we tested the hypothesis that females (the shorter-lived sex) show higher learning ability than males early in life but senesce faster. Indeed, young females outperformed young males in learning a novel association between an odour (butanone) and food (bacteria). However, while learning ability and offspring production declined rapidly with age in females, males maintained high levels of these traits until mid-age. These results not only demonstrate sexual dimorphism in age-related learning ability but also suggest that it conforms to predictions derived from the life-history theory.

The Role of Social Activity in Age–Cognition Relations

The goal of the current project was to examine whether engaging in social activity may moderate or mediate the relation between age and cognitive functioning. A large age range sample of adults performed a variety of cognitive tests and completed a social activities questionnaire. Results did not support the moderator hypothesis, as age differences in cognition were similar in people who reported low and high levels of engagement in social activity. However, the data was consistent with a mediation model, which posits that age differences in social activity partly explain age differences in cognition. Furthermore, it supported a moderated mediation model, which assumes that the mediation effects of social activity were stronger at older ages.

Integrity of mGluR-LTD in the Associative/Commissural Inputs to CA3 Correlates with Successful Aging in Rats

The impact of aging on cognitive capabilities varies among individuals ranging from significant impairment to preservation of function on par with younger adults. Research on the neural basis for age-related memory decline has focused primarily on the CA1 region of the hippocampus. However, recent studies in elderly human and rodents indicate that individual differences in cognitive aging are more strongly tied to functional alterations in CA3 circuits. To examine synaptic plasticity in the CA3 region, we used aged rats behaviorally characterized in a hippocampal-dependent task to evaluate the status of long-term potentiation and long-term depression (LTP and LTD) in the associative/commissural pathway (A/C → CA3), which provides the majority of excitatory input to CA3 pyramidal neurons. We found that, unlike in CA1 synapses, in A/C → CA3 LTP is minimally affected by age. However, two forms of LTD, involving NMDA and metabotropic glutamate receptors (mGluR), are both greatly reduced in age-impaired rats. Age-unimpaired rats, in contrast, had intact mGluR LTD. These findings indicate that the integrity of mGluR-LTD at A/C → CA3 inputs may play a crucial role in maintaining the performance of CA3 circuitry in aging.

A cross-cultural perspective on aging and memory: Comparisons between Bangladesh and Sweden.

Most studies on cognitive aging have been conducted in high-income countries (mainly on Western populations). The main aim of this study was to compare the relative importance of predictors of episodic and semantic memory performance in older people (≥60 years) from Bangladesh (n = 400) and Sweden (n = 1,098). Hierarchical regression models were used in order to study the importance of some commonly used predictors in the two countries. A main finding was that variations in age did not have much impact on episodic and semantic memory performance in Bangladesh. Instead, sex was a strong predictor for semantic memory performance. In Sweden this pattern was reversed. In the Western world, chronological age is believed to be strongly associated with memory performance in cross-sectional studies, particularly in people greater than 60 years of age. This study indicates that the difference between the two countries (in relative importance of the predictors included in this study) is mainly due to the fact that years of education is connected to age in the Western world but to sex in Bangladesh. It remains to be examined whether earlier selective survival is also responsible for the relative absence of cognitive age differences in Bangladesh.