Karen L. Siedlecki

Construct validity and age sensitivity of prospective memory

We administered four prospective memory tasks to 330 adults between 18 and 89 years of age to investigate the relationship among the measures of performance in the four tasks, as well as the relationship of the prospective memory measures to age, other cognitive abilities, and noncognitive factors. The four prospective memory variables were found to exhibit both convergent and discriminant validity, indicating that prospective memory ability appears to represent a distinct dimension of individual differences. The prospective memory construct was significantly related to other cognitive abilities, such as executive functioning, fluid intelligence, episodic memory, and perceptual speed, but it was only weakly related to self-ratings of (primarily retrospective) memory and to personality traits. Although a substantial proportion of the age-related variance on the prospective memory construct was shared with other cognitive abilities, we also found some evidence of unique, statistically independent, age-related influences on prospective memory.

A mixed method approach to examining Facebook use and its relationship to self-esteem

The current study examined the relationship between self-esteem and Facebook use in sample of college-age participants (N=201). Online methods were used to collect data. Consistent with the social compensation hypothesis, results indicate that self-esteem level was related to engaging in different on-line behaviors. For example, lower self-esteem was associated with feelings of connectedness to Facebook, more frequently untagging oneself in photos, and accepting friend requests from individuals that one does not know well. Qualitative analyses indicated that individuals with higher self-esteem were more likely to report that a positive aspect of Facebook was the ability to share pictures, thoughts, and ideas, and to report that other posts could become annoying or bothersome.

Testing the white matter retrogenesis hypothesis of cognitive aging

The retrogenesis hypothesis postulates that late-myelinated white matter fibers are most vulnerable to age- and disease-related degeneration, which in turn mediate cognitive decline. While recent evidence supports this hypothesis in the context of Alzheimers disease, it has not been tested systematically in normal cognitive aging. In the current study, we examined the retrogenesis hypothesis in a group (n = 282) of cognitively normal individuals, ranging in age from 7 to 87 years, from the Brain Resource International Database. Participants were evaluated with a comprehensive neuropsychological battery and were imaged with diffusion tensor imaging. Fractional anisotropy (FA), radial diffusivity (RD), and axial diffusivity (DA), measures of white matter coherence, were computed in 2 prototypical early-myelinated fiber tracts (posterior limb of the internal capsule, cerebral peduncles) and 2 prototypical late-myelinated fiber tracts (superior longitudinal fasciculus, inferior longitudinal fasciculus) chosen to parallel previous studies; mean summary values were also computed for other early- and late-myelinated fiber tracts. We examined age-associated differences in FA, RD, and DA in the developmental trajectory (ages 7-30 years) and degenerative trajectory (ages 31-87 years), and tested whether the measures of white matter coherence mediated age-related cognitive decline in the older group. FA and DA values were greater for early-myelinated fibers than for late-myelinated fibers, and RD values were lower for early-myelinated than late-myelinated fibers. There were age-associated differences in FA, RD, and DA across early- and late-myelinated fiber tracts in the younger group, but the magnitude of differences did not vary as a function of early or late myelinating status. FA and RD in most fiber tracts showed reliable age-associated differences in the older age group, but the magnitudes were greatest for the late-myelinated tract summary measure, inferior longitudinal fasciculus (late fiber tract), and cerebral peduncles (early fiber tract). Finally, FA in the inferior longitudinal fasciculus and cerebral peduncles and RD in the cerebral peduncles mediated age-associated differences in an executive functioning factor. Taken together, the findings highlight the importance of white matter coherence in cognitive aging and provide some, but not complete, support for the white matter retrogenesis hypothesis in normal cognitive aging.

Is there anything special about the aging of source memory

A battery of cognitive tests designed to measure the constructs of episodic memory, perceptual speed, fluid ability, executive functioning, and vocabulary was administered to 330 adults between the ages of 18 and 89. Each participant also performed 4 different tasks designed to assess source memory. Structural equation modeling was used to evaluate the validity of a source-memory construct and to explore the relation of the source-memory construct to age and to the other cognitive variables. The variance common to the source-memory variables was strongly related to other cognitive abilities, suggesting that source memory may not have discriminant validity, and there were only small unique age-related effects on the source-memory construct after the influence of other abilities was considered.

An individual differences analysis of memory control.

Performance on a wide variety of memory tasks can be hypothesized to be influenced by processes associated with controlling the contents of memory. In this project 328 adults ranging from 18 to 93 years of age performed six tasks (e.g., multiple trial recall with an interpolated interference list, directed forgetting, proactive interference, and retrieval inhibition) postulated to yield measures of the effectiveness of memory control. Although most of the patterns from earlier studies were replicated, only a few of the measures of memory control were reliable at the level of individual differences. Furthermore, the memory control measures had very weak relations with the age of the participant. Analyses examining the relations between established cognitive abilities and variables from the experimental tasks revealed that most of the variables were related only to episodic memory ability.

Life satisfaction across adulthood: different determinants at different ages?

It is likely that with aging and changing life circumstances, individuals’ values shift in systematic ways, and that these shifts may be accompanied by shifts in the determinants of their subjective judgments of well being. To examine this possibility, the relations among the Satisfaction With Life Scale (SWLS) and a number of personality, affect, demographic, and cognitive variables were examined in a sample of 818 participants between the ages of 18 and 94. The results indicated that although many variables had significant zero-order correlations with the SWLS, only a few variables had unique utility in predicting life satisfaction. Invariance analyses indicated that while the qualitative nature of life satisfaction remains constant across adult age, the influence of fluid intelligence on judgments of life satisfaction declines with age. In contrast, negative affect is negatively associated with life satisfaction consistently across the adult age span.

Efficiency of route selection as a function of adult age

Two tasks hypothesized to assess the efficiency of route selection were administered to 328 adults ranging from 18 to 93 years of age. Increased age was associated with slower completion of mazes, even after adjusting for differences in perceptual-motor speed, and with longer and less accurate routes in a task in which participants were asked to visit designated exhibits in a zoo. The route selection measures were correlated with measures hypothesized to represent executive functioning, such as the number of categories in the Wisconsin card sorting test and the number of words generated in a category fluency test. However, most of the age-related influences on the measures from the route selection tasks were shared with age-related effects on established cognitive abilities, which implies that the same mechanisms may account for the relations of age on both sets of variables.

Executive Dysfunctions Across Adulthood: Measurement Properties and Correlates of the DEX Self-Report Questionnaire

ABSTRACT Difficulties in executive processes can disturb daily life functioning. Using data obtained from two independent community-dwelling samples (n 1 = 468, n 2 = 669, 18–97 years), we examined the factor structure of the Dysexecutive Functioning Questionnaire (DEX) and explored the frequencies and potential correlates of self-reported executive difficulties. Our results revealed that executive problems are parsimoniously described with one underlying factor. Everyday executive dysfunctions were moderately frequent throughout adulthood. Reports of executive problems were associated with individual difference characteristics including age, subjective health, personality, affect, and cognition. We also found that, although executive functions are known to decline with advancing adult age, younger age groups reported more problems than older groups, an effect that was partially mediated by a negative affect factor. We discuss implications for the validity of the instrument as well as directions for future research on executive functioning difficulties in everyday life.

Quantifying Cognitive Reserve in Older Adults by Decomposing Episodic Memory Variance: Replication and Extension

The theory of cognitive reserve attempts to explain why some individuals are more resilient to age-related brain pathology. Efforts to explore reserve have been hindered by measurement difficulties. Reed et al. (2010) proposed quantifying reserve as residual variance in episodic memory performance that remains after accounting for demographic factors and brain pathology (whole brain, hippocampal, and white matter hyperintensity volumes). This residual variance represents the discrepancy between an individual’s predicted and actual memory performance. The goals of the present study were to extend these methods to a larger, community-based sample and to investigate whether the residual reserve variable is explained by age, predicts longitudinal changes in language, and predicts dementia conversion independent of age. Results support this operational measure of reserve. The residual reserve variable was associated with higher reading ability, lower likelihood of meeting criteria for mild cognitive impairment, lower odds of dementia conversion in dependent of age, and less decline in language abilities over 3 years. Finally, the residual reserve variable moderated the negative impact of memory variance explained by brain pathology on language decline. This method has the potential to facilitate research on the mechanisms of cognitive reserve and the efficacy of interventions designed to impart reserve.

Investigating the structure and age invariance of episodic memory across the adult lifespan.

The structure of episodic memory was investigated by assessing different modalities of material (verbal, figural, and spatial) and different types of tests (recall, cued recall, and recognition). A 3-factor model that distinguished among modalities of material was found to be the best representation of memory and the verbal, figural, and spatial memory factors exhibiting construct validity. This 3-factor modality of material model also demonstrated configural, metric, and structural age invariance across a sample of adults (N = 327) between the ages of 18 and 94. There was evidence that latent constructs corresponding to recall, cued recall, and recognition could be distinguished from one another within the verbal domain but not within the figural and spatial domains. A mediation model examining the retrieval constructs was examined within the verbal domain, and there were unique age-related influences on cued recall and recall performance. This result is consistent with findings that increased age is associated with increased difficulty in retrieving information.