Examining Gender Differences in Neurocognitive Functioning Across Adulthood.

OBJECTIVE: Previous research has shown that women have an advantage on verbal episodic memory and processing speed tasks, while men show an advantage on spatial ability measures. Previous work has also found differences in cognition across age. The current study examines gender differences in neurocognitive functioning across adulthood, whether age moderates this effect, and whether these differences remain consistent with practice across multiple testing sessions. METHOD: Data from the Virginia Cognitive Aging Project were used, which included participants between the ages of 18 and 99 years (N = 5125). Participants completed measures assessing five cognitive domains: episodic memory, processing speed, reasoning, spatial visualization, and vocabulary. RESULTS: Results showed that gender was significantly related to memory, speed, and spatial visualization, but not to vocabulary or reasoning. Results of invariance analyses across men and women provided evidence of configural and metric invariance, along with partial scalar invariance. Additionally, there was little evidence that age or practice influenced the gender effect on neurocognition. CONCLUSIONS: Consistent with the previous research, these results suggest that there is a female advantage in episodic memory and processing speed, and a male advantage in spatial visualization. Gender was shown to influence cognition similarly across adulthood. Furthermore, the influence of gender remained the same across three sessions, which is consistent with the previous work that has shown that training does not differentially impact performance on spatial ability measures for females compared to males.

Brain biomarkers and cognition across adulthood.

Understanding the associations between brain biomarkers (BMs) and cognition across age is of paramount importance. Five hundred and sixty-two participants (19-80 years old, 16 mean years of education) were studied. Data from structural T1, diffusion tensor imaging, fluid-attenuated inversion recovery, and resting-state functional magnetic resonance imaging scans combined with a neuropsychological evaluation were used. More specifically, the measures of cortical, entorhinal, and parahippocampal thickness, hippocampal and striatal volume, default-mode network and fronto-parietal control network, fractional anisotropy (FA), and white matter hyperintensity (WMH) were assessed. z-Scores for three cognitive domains measuring episodic memory, executive function, and speed of processing were computed. Multiple linear regressions and interaction effects between each of the BMs and age on cognition were examined. Adjustments were made for age, sex, education, intracranial volume, and then, further, for general cognition and motion. BMs were significantly associated with cognition. Across the adult lifespan, slow speed was associated with low striatal volume, low FA, and high WMH burden. Poor executive function was associated with low FA, while poor memory was associated with high WMH burden. After adjustments, results were significant for the associations: speed-FA and WMH, memory-entorhinal thickness. There was also a significant interaction between hippocampal volume and age in memory. In age-stratified analyses, the most significant associations for the young group occurred between FA and executive function, WMH, and memory, while for the old group, between entorhinal thickness and speed, and WMH and speed, executive function. Unique sets of BMs can explain variation in specific cognitive domains across adulthood. Such results provide essential information about the neurobiology of aging.

Attrition in Longitudinal Data is Primarily Selective with Respect to Level Rather than Rate of Change.

OBJECTIVES: An important question in longitudinal research is whether the individuals who discontinue participation differ in their level of, or their change in, cognitive functioning relative to individuals who return for subsequent occasions. METHODS: Performance in five cognitive domains was examined in nearly 5000 participants between 18 and 85 years of age who completed between one and five longitudinal occasions. RESULTS: Little or no differences in cognitive performance were apparent between young adults who did or did not return for subsequent longitudinal occasions. However, among adults above about 45 years of age, returning participants had higher levels of cognitive performance, but approximately similar magnitude of longitudinal change, as participants completing fewer occasions. CONCLUSIONS: These results suggest that generalizability of longitudinal comparisons may be restricted to individuals with relatively high levels of cognitive functioning, but that rates of cognitive change are nearly comparable for individuals completing different numbers of longitudinal occasions.

Comparable Consistency, Coherence, and Commonality of Measures of Cognitive Functioning Across Adulthood.

Increased age is associated with lower scores in many cognitive tests, but interpretation of those results is based on the assumption that the measurement at different ages is equivalent, such that the differences reflect quantitative rather than qualitative changes. The assumption of measurement equivalence was investigated by comparing adult age differences in the relations among alternative versions of the same tests, among different tests of the same ability, and among different cognitive abilities. Results from three independent data sets revealed that only modest age differences were apparent at each level, which implies that cognitive abilities have similar measurement properties at different ages in adulthood.

Trajectories of normal cognitive aging.

Although sensitive detection of pathological cognitive aging requires accurate information about the trajectory of normal cognitive aging, prior research has revealed inconsistent patterns of age-cognition relations with cross-sectional and longitudinal comparisons. Age trends in four cognitive domains were compared in over 5,000 adults with cross-sectional data, and in almost 1,600 adults with three-occasion longitudinal data. Quasi-longitudinal comparisons, which are similar to cross-sectional comparisons in that there is no prior test experience and are similar to longitudinal comparisons in that the participants are from the same birth cohorts, were also reported. The age trends in quasi-longitudinal comparisons more closely resembled those in cross-sectional comparisons than those in longitudinal comparisons, which suggests that, at least up until about age 65, age-cognition relations in longitudinal comparisons are distorted by prior test experience. Results from cross-sectional and quasi-longitudinal comparisons, which can be assumed to have minimal test experience effects, imply that normal cognitive aging is characterized by nearly linear declines from early adulthood in speed, and accelerating declines in memory and reasoning. However, vocabulary knowledge increased until the decade of the 60's in all three types of comparisons. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Why is cognitive change more negative with increased age?

OBJECTIVE: The primary goal of the current study was to investigate factors contributing to more negative cognitive change at older ages. METHOD: Longitudinal data on 12 cognitive tests were examined in 2,637 adults ranging from 18 to 85 years of age. Because both the intervals between measurement occasions and the number of occasions varied across participants, it was possible to investigate effects of interval and number of measurement occasions on cognitive change in adults of different ages. In addition, about 1/2 of the participants performed alternate versions of the tests on a second and third session on the first occasion, which allowed change to be monitored over intervals of less than 1 week. RESULTS: Regression analyses revealed that cognitive change was more negative with increases in the interval between occasions but was more positive with additional measurement occasions. Both the effects of interval and of number of measurement occasions were similar across adulthood. Increased age was associated with more positive gains over a period of a few days but was associated with more negative declines when the intervals between occasions averaged about 3 years. CONCLUSIONS: This combination of results suggests that longitudinal change in cognitive functioning is more negative at older ages not because of greater declines with increases in the interval between measurement occasions, or because of smaller gains with additional measurements. Instead most of the age differences in change may be due to greater losses of benefits associated with the initial assessment over intervals of months or more from the initial assessment. (PsycINFO Database Record

Contributions of the Individual Differences Approach to Cognitive Aging.

OBJECTIVE: To review selected research in cognitive aging incorporating an individual differences approach. METHOD: Three contributions of the individual differences perspective in cognitive aging are illustrated with data from the Virginia Cognitive Aging Project. RESULTS: Research capitalizing on the variability among individuals has been used to: (a) improve sensitivity and validity of measurement of cognitive functioning, and evaluate possible age differences in the meaning of the measures; (b) investigate relations between age and individual cognitive measures in the context of other types of cognitive measures; and (c) examine the degree to which age-related influences on target measures are statistically independent of age-related influences on other cognitive measures. DISCUSSION: Although the primary focus of much of the research in cognitive aging has been on mean differences between people of different ages, people differ in many respects besides age. A fundamental assumption of the individual differences perspective is that at least some of those differences may be informative about the nature, and causes, of the relations between age and cognitive functioning.

Does Need for Cognition Have the Same Meaning at Different Ages?

Determining whether Need for Cognition (NC) has the same meaning across age may help understand why there are dramatically different age trends for cognitive abilities and for NC in adulthood. Data from 5,004 participants aged between 18 and 99 years were used to examine both internal relations and external relations of NC. Internal relations were investigated with measures of reliability, examination of factor invariance, and test-retest coefficients across three age groups. External relations were investigated by examining relations of NC with cognitive abilities, engagement, personality, self-rated cognition, and affect. Results suggest that NC may be a broad construct that could reflect motivation to seek out intellectual challenge. In addition, examination of both internal and external relations of NC indicated that the meaning of the construct may be the same across the life span. Finally, the current article showed that the strongest predictor of NC was Openness to Experience, at any age.

Which Aspects of Social Support Are Associated With Which Cognitive Abilities for Which People?

OBJECTIVES: To assess the relations between 11 aspects of social support and five cognitive abilities (vocabulary, reasoning, spatial visualization, memory, and speed of processing) and to determine whether these relations between social support and cognition are moderated by age or sex. METHOD: A sample of 2,613 individuals between the ages of 18 and 99 years completed a battery of cognitive tests and a questionnaire assessing aspects of social support. A measure of general intelligence was computed using principal components analysis. Multiple regressions were used to evaluate whether each aspect of support and/or its interactions with age or sex predicted each cognitive ability and g. RESULTS: Several aspects of social support were significantly related to all five cognitive abilities and to g. When g was included as a predictor, there were few relations with specific cognitive abilities. Age and sex did not moderate any of the relations. DISCUSSION: These results suggest that contact with family and friends, emotional and informational support, anticipated support, and negative interactions are related to cognition, whereas satisfaction with and tangible support were not. In addition, these aspects of support were primarily related to g, with the exception of family contact. Social support- cognition relations are comparable across the life span and the sexes.

Shared and unique influences on age-related cognitive change.

OBJECTIVE: Decompose cognitive change into influences unique to particular cognitive domains, and influences shared across different cognitive domains. METHOD: A total of 2,546 adults between 18 and 95 years of age performed a battery of 12 cognitive tests on 2 occasions separated by an average of 3 years. An estimate of general cognitive functioning based on the first principal factor was regressed from the observed cognitive scores to derive an estimate of specific influences on each measure, and this value was subtracted from the observed score to provide an estimate of general influences on the measure. Longitudinal change was assessed by the (T2 - T1) difference between scores on the 2 occasions. RESULTS: Although increased age was associated with specific influences on speed in cross-sectional comparisons, and in memory change in longitudinal comparisons among older adults, most of the relations between age and cognitive functioning in both cross-sectional and longitudinal comparisons were manifested as general influences shared with other cognitive measures. CONCLUSIONS: Differences in cognitive functioning associated with aging are often attributed to domain-specific effects, but results from this and other recent studies suggest that large proportions of the age differences are associated with general influences shared across different types of cognitive measures. (PsycINFO Database Record

Item analyses of memory differences.

OBJECTIVE: Although performance on memory and other cognitive tests is usually assessed with a score aggregated across multiple items, potentially valuable information is also available at the level of individual items. METHOD: The current study illustrates how analyses of variance with item as one of the factors, and memorability analyses in which item accuracy in one group is plotted as a function of item accuracy in another group, can provide a more detailed characterization of the nature of group differences in memory. Data are reported for two memory tasks, word recall and story memory, across age, ability, repetition, delay, and longitudinal contrasts. RESULTS: The item-level analyses revealed evidence for largely uniform differences across items in the age, ability, and longitudinal contrasts, but differential patterns across items in the repetition contrast, and unsystematic item relations in the delay contrast. CONCLUSION: Analyses at the level of individual items have the potential to indicate the manner by which group differences in the aggregate test score are achieved.

Little relation of adult age with cognition after controlling general influences.

Both general (i.e., shared across different cognitive measures) and specific (i.e., unique to particular cognitive measures) influences can be postulated to contribute to the relations between adult age and measures of cognitive functioning. Estimates of general and specific influences on measures of memory, speed, reasoning, and spatial visualization were derived in cross-sectional (N = 5,014) and 3-occasion longitudinal (N = 1,353) data in adults between 18 and 99 years of age. Increased age was negatively associated with estimates of general influences on cognitive functioning in both the cross-sectional differences and the longitudinal changes. Furthermore, after statistically controlling general influences, the relations of age on the cognitive measures were much smaller than were those in the original measures. Results from these and other analytical procedures converge on the conclusion that adult age appears to have weak relations with specific measures of cognitive functioning, defined as independent of influences shared across different types of cognitive measures, and that this is true in both cross-sectional and longitudinal comparisons. An implication of these findings is that general, as well as domain-specific, influences should be considered when attempting to explain the relations of age on cognitive functioning. (PsycINFO Database Record

Relations of Naturally Occurring Variations in State Anxiety and Cognitive Functioning.

Although effects of anxiety on cognitive performance have been extensively examined, anxiety-cognition relationships are often defined by between-person relationships. The current research investigated the effects of within-person variations in state anxiety on cognitive performance based on measures from three separate sessions in a sample of 1,769 healthy adults ranging from 18 to 99 years of age. Some of the adults in the sample exhibited a wide range of state anxiety across the three sessions, whereas others were fairly stable. Although one might have expected that cognitive performance would be low only on sessions in which the level of state anxiety was high, this pattern was not evident in any of five different cognitive abilities (vocabulary, memory, reasoning, spatial relations, or perceptual speed tasks). Instead, one's average level of anxiety was a more important determinant of cognitive performance than one's current level of state anxiety. Specifically, for memory and reasoning abilities, trait anxiety alone related to decreased cognitive function, regardless of state anxiety. For spatial relations and speed abilities, low state anxiety was related to decreased cognitive function in participants with high trait anxiety.

Spatial working memory capacity predicts bias in estimates of location.

Spatial memory research has attributed systematic bias in location estimates to a combination of a noisy memory trace with a prior structure that people impose on the space. Little is known about intraindividual stability and interindividual variation in these patterns of bias. In the current work, we align recent empirical and theoretical work on working memory capacity limits and spatial memory bias to generate the prediction that those with lower working memory capacity will show greater bias in memory of the location of a single item. Reanalyzing data from a large study of cognitive aging, we find support for this prediction. Fitting separate models to individuals' data revealed a surprising variety of strategies. Some were consistent with Bayesian models of spatial category use, however roughly half of participants biased estimates outward in a way not predicted by current models and others seemed to combine these strategies. These analyses highlight the importance of studying individuals when developing general models of cognition. (PsycINFO Database Record

Age does not matter: Memory complaints are related to negative affect throughout adulthood.

OBJECTIVES: Memory complaints are present in adults of all ages but are only weakly related to objective memory deficits, raising the question of what their presence may indicate. In older adults, memory complaints are moderately related to negative affect, but there is little research examining this relationship in young and middle-aged adults. This study examined whether memory complaints and negative affect were similarly related across the adult lifespan and in adults with varying levels of objective memory performance. METHOD: The sample included 3798 healthy adults, aged 18 to 99, and was divided into five groups: young, middle-aged, young-old, old-old, and oldest-old adults. Participants completed questionnaire measures of memory complaints and negative affect (neuroticism and depressive and anxiety symptoms), in addition to lab measures of objective memory. RESULTS: Using structural equation models, we found that the relationship between memory complaints and negative affect was moderate in all the age groups, and there was no evidence for moderation by objective memory. CONCLUSION: For adults of all ages, perceived memory decline may be distressing and/or negative affect may lead to negative self-evaluations of memory.

Aging Cognition Unconfounded by Prior Test Experience.

OBJECTIVE: Investigate time-related age differences in cognitive functioning without influences of prior test experience. METHODS: Cognitive scores were compared in different individuals from the same birth years who were tested in different years, when they were at different ages. These types of quasi-longitudinal comparisons were carried out on data from three large projects: the Seattle Longitudinal Study [Schaie, K. W. (2013). Developmental influences on adult intelligence: The Seattle Longitudinal Study (2nd ed.). New York, NY: Oxford University Press], the Betula Project [Ronnlund, M., & Nilsson, L-G. (2008). The magnitude, generality, and determinants of Flynn effects on forms of declarative memory and visuospatial ability: Time-sequential analyses of data from a Swedish cohort study. Intelligence, 36, 192-209], and the Virginia Cognitive Aging Project (this study). RESULTS: In each data set, the results revealed that the estimates of cognitive change with no prior test experience closely resembled the estimates of age relations based on cross-sectional comparisons. Furthermore, longitudinal comparisons revealed positive changes at young ages that gradually became more negative with increased age, whereas all of the estimates of change without prior test experience were negative except those for measures of vocabulary. DISCUSSION: The current results suggest that retest effects can distort the mean age trends in longitudinal comparisons that are not adjusted for experience. Furthermore, the findings can be considered robust because the patterns were similar across three data sets involving different samples of participants and cognitive tests, and across different methods of controlling experience effects in the new data set.

Continuity of cognitive change across adulthood.

Although cross-sectional (between-person) comparisons consistently reveal age-related cognitive declines beginning in early adulthood, significant declines in longitudinal (within-person) comparisons are often not apparent until age 60 or later. The latter results have led to inferences that cognitive change does not begin until late middle age. However, because mean change reflects a mixture of maturational and experiential influences whose contributions could vary with age, it is important to examine other properties of change before reaching conclusions about the relation of age to cognitive change. The present study was designed to examine measures of the stability, variability, and reliability of change, as well as correlations of changes in memory with changes in speed in 2,330 adults between 18 and 80 years of age. Despite substantial power to detect small effects, the absence of significant age differences in these properties suggests that cognitive change represents a qualitatively similar phenomenon across a large range of adulthood.

Do cognitive interventions alter the rate of age-related cognitive change?

There has recently been a great deal of interest in cognitive interventions, particularly when applied in older adults with the goal of slowing or reversing age-related cognitive decline. Although seldom directly investigated, one of the fundamental questions concerning interventions is whether the intervention alters the rate of cognitive change, or affects the level of certain cognitive measures with no effect on the trajectory of change. This question was investigated with a very simple intervention consisting of the performance of three versions (treatment) or one version (control) of the relevant cognitive tests at an initial occasion. Participants were retested at intervals ranging from less than 1 to 12 years, which allowed rates of change to be examined in the control and treatment groups. Although the intervention can be considered modest, participants in the treatment group had about .25 standard deviations less negative cognitive change over an interval of approximately three years than those in the control group, which is comparable to effect sizes reported with more intensive interventions. However, there were no interactions of the intervention with length of the interval between occasions, and thus there was no evidence that the intervention affected the course of age-related cognitive decline.

Breadth and age-dependency of relations between cortical thickness and cognition.

Recent advances in neuroimaging have identified a large number of neural measures that could be involved in age-related declines in cognitive functioning. A popular method of investigating neural-cognition relations has been to determine the brain regions in which a particular neural measure is associated with the level of specific cognitive measures. Although this procedure has been informative, it ignores the strong interrelations that typically exist among the measures in each modality. An alternative approach involves investigating the number and identity of distinct dimensions within the set of neural measures and within the set of cognitive measures before examining relations between the 2 types of measures. The procedure is illustrated with data from 297 adults between 20 and 79 years of age with cortical thickness in different brain regions as the neural measures and performance on 12 cognitive tests as the cognitive measures. The results revealed that most of the relations between cortical thickness and cognition occurred at a general level corresponding to variance shared among different brain regions and among different cognitive measures. In addition, the strength of the thickness-cognition relation was substantially reduced after controlling the variation in age, which suggests that at least some of the thickness-cognition relations in age-heterogeneous samples may be attributable to the influence of age on each type of measure.

Implications of the Flynn Effect for Age-Cognition Relations.

Many studies have documented that cognitive performance is often higher among people of the same age who are tested in more recent years, and it is sometimes suggested that this phenomenon will distort the relations between age and cognition in cross-sectional studies. This possibility was examined with data from two large projects involving adults across a wide age range. The results indicated that there were similar time-of-measurement increases in cognitive scores at different ages, which were accompanied by nearly constant cross-sectional age differences, but positively inflated estimates of longitudinal age differences. It is proposed that when the Flynn Effect is of comparable magnitude in adults of different ages, longitudinal comparisons of age-cognition relations are more subject to distortion than cross-sectional comparisons.