Exploring effects of type 2 diabetes on cognitive functioning in older adults.

Type 2 diabetes may be associated with exacerbated aging-related declines in cognitive neuropsychological performance. The authors examined whether such effects are systematic (i.e., broadly distributed across domains or domain-specific) or moderated by age (i.e., varying across age within older adults). The authors assembled recent cross-sectional data from the Victoria Longitudinal Study (VLS) Sample 3 (Wave 1; initial n = 570; initial age = 53-90 years). Using a comprehensive, multidimensional spectrum of cognitive neuropsychological tests, the authors examined performance differences by diabetes status (diabetes group vs. healthy controls) and age (young-old vs. old-old). Our results showed that healthy controls significantly outperformed the diabetes group only on markers of executive functioning and speed. Notably, the diabetes-related effects were robust across the two late-life age groups. Future research examining longitudinal changes is recommended. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive predictors of medical decision-making capacity in traumatic brain injury.

Objective: To identify cognitive predictors of medical decision-making capacity (MDC) in participants with moderate to severe traumatic brain injury (TBI). Participants: At baseline, participants were 34 adults with TBI and 20 healthy adults. At 6-month follow-up, participants were 24 adults with TBI and 20 healthy adults. Main Outcome Measures: Participants were administered the Capacity to Consent to Treatment Instrument (CCTI) and neuropsychological test measures. Multivariate cognitive predictor models were developed for CCTI consent abilities/standards (S) of understanding (S5); reasoning (S4); and appreciation (S3). Results: At baseline, short-term verbal memory and semantic fluency predicted TBI group performance on understanding (S5); short-term verbal memory and attention predicted performance on reasoning (S4); and working memory predicted performance on appreciation (S3). At 6 month follow-up, executive function, verbal processing speed, and working memory predicted TBI performance on understanding (S5); working memory and short-term memory predicted reasoning (S4); and basic executive functioning predicted appreciation (S3). Conclusions: Multiple cognitive functions are associated with acute impairment and partial recovery of MDC in patients with TBI. Short-term verbal memory predicted consent capacity of TBI participants at the time of acute inpatient hospitalization, while executive functioning and working memory predicted improved capacity at six-month follow-up. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neuropsychological correlates of ADHD symptoms in preschoolers.

The authors examined the neuropsychological status of 22 preschoolers at risk for attention-deficit/hyperactivity disorder (ADHD) and 50 matched control children, using measures of nonverbal working memory, perceptual and motor inhibition, and memory for relative time. All tasks included paired control conditions, which allowed for the isolation of discrete executive function constructs. Group differences were evident on several measures of neuropsychological functioning; however, after accounting for nonexecutive abilities, no deficits could be attributed to specific functions targeted by the tasks. Performance on executive measures was not related to objective indices of activity level or ratings of ADHD symptoms. Yet, the fact that at-risk preschoolers were highly symptomatic casts doubt on whether executive function deficits and/or frontostriatal networks contribute etiologically to early behavioral manifestations of ADHD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Prefrontal and parietal regions are involved in naming of objects seen from unusual viewpoints.

Object naming is commonly used for demonstrating semantic memory abilities, known to be affected in normal aging. Yet, neuropsychological assessments of older people do not reflect irregularities. The authors used a test with 2 levels of naming complexity by 2 kinds of stimuli: common objects pictured from a conventional viewpoint (usual condition) or from an unconventional viewpoint (unusual condition). The authors studied naming performance with 129 healthy participants, aged 20-85 years. For the usual stimuli, the success rate was high (90.9%), with no reduction in performance until 65 years of age. However, for the unusual stimuli, there was a marked reduction in performance with age. Brain activity was studied on 11 healthy young participants (20-30 years of age) using functional magnetic resonance imaging. The usual condition activated brain regions associated with visual perception, language, and memory. Additional brain regions associated with semantic searching and decision making were obtained in the unusual condition in the prefrontal cortex (Brodmann's area [BA] 9 and BA 47) and anterior cingulate (BA 32). The results suggest that the poor naming performance for unusual-viewed objects in older people might be related to the shrinkage of frontal gray matter with age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive correlates of mortality: Evidence from a population-based sample of very old adults.

The authors examined performance on memory, visuospatial, and verbal tasks and subsequent mortality in adults 75–95 years. The sample consisted of 178 living and 44 deceased participants. Mean-level analyses revealed mortality group differences for all domains of cognitive functioning. A Cox regression analysis, independent of age, gender, education, functional ability, and chronic illness, indicated that measures of word recognition and category fluency were significant predictors of mortality status. The results indicate a relationship between cognitive performance and subsequent mortality status in very old age and suggest that episodic memory and verbal skill may be particularly sensitive in predicting such effects. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Predicting medication adherence and employment status following kidney transplant: The relative utility of traditional and everyday cognitive approaches.

Objective: The authors investigated the utility of both traditional and everyday cognitive measures in predicting medication adherence and employment status among kidney transplant recipients. In addition, the role of noncognitive predictors was examined. Method: Cognitive measures of processing speed, memory, everyday problem solving, executive functioning, and questionnaires assessing mood, medication adherence, and employment status were individually administered to 108 kidney transplant recipients. Because the eligibility criteria differed for the two analyses, there were 103 participants in the medication adherence analyses and 94 participants in the employment analyses. Stepwise hierarchical regression and sequential binomial logistic regression analyses were conducted for continuous and dichotomous outcome measures, respectively. Results: Findings indicate that both poorer performance on the everyday problem-solving test and a higher number of depressive symptoms were predictive of poorer self-reported medication adherence (R2 = .19, p R2 = .29, ps     

Everyday problem solving in older adults: Observational assessment and cognitive correlates.

Older adults' ability to solve practical problems in 3 domains of daily living was assessed using a new measure of everyday problem solving, the Observed Tasks of Daily Living (OTDL). Findings showed that the OTDL formed internally consistent scales representing 3 distinct factors of everyday problem solving. Moreover, the OTDL showed convergent validity with related scales of a paper-and-pencil test. Older adults' performance on the OTDL was significantly correlated with their scores on measures of basic mental abilities. Path analysis showed that age affected older adults' performance on the OTDL directly and indirectly via cognitive abilities. Participants' education and health affected their everyday competence indirectly through cognitive abilities. The effects of perceptual speed and memory span were mediated by fluid and crystallized intelligence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Construct validity of WAIS—R factors: Neuropsychological test correlates in adults referred for evaluation of possible head injury.

A 3-factor solution of the Wechsler Adult Intelligence Scale—Revised (WAIS—R; Wechsler, 1981) in 260 adults with suspected head injury suggested relatively good construct validity for the factors, based on correlations with neuropsychological tests purported to measure similar abilities. The Verbal Comprehension factor was related to verbal ability, verbal memory, and executive functioning. The Perceptual Organization factor, although measuring primarily visual–spatial perception and visual constructional ability, was related to visual–spatial memory, visual attention, and executive functioning. The Freedom From Distractibility factor was correlated with two attention measures and was not associated with memory measures. Its association with executive functioning was inconsistent. The findings are discussed in terms of the multidimensional nature of neuropsychological tests and WAIS—R factors. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Age and working memory: The role of perceptual speed, the central executive, and the phonological loop.

In a study (N?=?61) comparing older (age range?=?60–80 years, M?=?67) and younger (age range?=?20-33 years, M?=?25) people, age deficits were observed in working memory, perceptual speed, and central executive functioning but not in phonological loop functioning. Controlling for age differences in central executive performance removed over 50% of the age-related variance in working memory span. However, controlling for perceptual speed removed all of the age-related variance in working memory span. In addition, age differences in central executive functioning were largely eliminated after controlling for age deficits in perceptual speed. These findings suggest that age differences in central executive functioning are primarily attributable to a general slowdown in the rate at which information is activated within the working memory system and that no specific deficits in the central executive occur as a consequence of aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A test of the frontal lobe functioning hypothesis of age deficits in production priming.

Older adults have been hypothesized to show reduced priming relative to younger adults on implicit memory tests that require production of a response because these tasks place high demands on attentional processes associated with frontal lobe function, which are often reduced with age (see D. A. Fleischman & J. D. E. Gabrieli, 1998). The current study directly tested this frontal lobe hypothesis of age effects in production priming. Younger adults and older adults who differed in their attentional abilities as measured by a battery of neuropsychological tests were given two production priming tasks, word stem completion and category production, followed by explicit free recall tests. Results showed that explicit memory performance was reduced by age and older adults' frontal functioning. Age and frontal functioning influenced category production priming but not word stem completion priming. Results failed to support the frontal account of age reductions in production priming. Instead, results implicate the influence of other processes often involved in production priming tasks, such as explicit memory strategies and response competition, as critical for understanding age effects in implicit memory performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aging, episodic memory feeling-of-knowing, and frontal functioning.

Groups of normal old and young adults made episodic memory feeling-of-knowing (FOK) judgments and took 2 types of episodic memory tests (cued recall and recognition). Neuropsychological tests of executive and memory functions thought to respectively involve the frontal and medial temporal structures were also administered. Age differences were observed on the episodic memory measures and on all neuropsychological tests. Compared with young adults, older adults performed at chance level on FOK accuracy judgments. Partial correlations indicated that a composite measure of frontal functioning and FOK accuracy were closely related. Hierarchical regression analyses showed that the composite frontal functioning score accounted for a large proportion of the age-related variance in FOK accuracy. This finding supports the idea that the age-related decline in episodic memory FOK accuracy is mainly the result of executive or frontal limitations associated with aging. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Plasticity of executive functioning in young and older adults: Immediate training gains, transfer, and long-term maintenance.

The authors investigated immediate training gains, transfer effects, and 18-month maintenance after 5 weeks of computer-based training in updating of information in working memory in young and older subjects. Trained young and older adults improved significantly more than controls on the criterion task (letter memory), and these gains were maintained 18 months later. Transfer effects were in general limited and restricted to the young participants, who showed transfer to an untrained task that required updating (3-back). The findings demonstrate substantial and durable plasticity of executive functioning across adulthood and old age, although there appear to be age-related constraints in the ability to generalize the acquired updating skill. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age-related practice effects across longitudinal neuropsychological assessments in older people with schizophrenia.

Objective: The relationship between aging and practice effects on longitudinal neuropsychological assessments was investigated in middle-aged and older people with schizophrenia and healthy controls. Method: Older people with schizophrenia (n = 107; M age = 56.1) and age-comparable nonpsychiatric controls (n = 107; M age = 57.7) were scheduled to receive annual assessments on a comprehensive battery of neuropsychological tests for an average of 2.5 years (range 11 months to 4 years). Mixed-model analyses were used to separately examine the effects of practice and age on test performance. Results: Number of prior assessments (practice) was associated with significant performance improvement across assessments, whereas older age was associated with significant decline in performance. The groups did not differ significantly in extent of age-related cognitive decline, but a three-way interaction among group, age, and practice was found, such that greater age-related decline in practice effects were found for older people with schizophrenia relative to nonpsychiatric participants. Conclusions: This study did not find any evidence of neurodegenerative age-related decline in neuropsychological abilities in middle-aged and older people with schizophrenia, but older age was associated with diminished ability to benefit from repeated exposure to cognitive tasks in people with schizophrenia. Cognitive impairment in schizophrenia may combine with cognitive decline associated with normal aging to reduce practice effects in older patients. These findings have important implications for the design of studies examining the longitudinal trajectory of cognitive functioning across the life span of people with schizophrenia, as well as clinical trials that attempt to demonstrate cognitive enhancement in these individuals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Can training in a real-time strategy video game attenuate cognitive decline in older adults?

Declines in various cognitive abilities, particularly executive control functions, are observed in older adults. An important goal of cognitive training is to slow or reverse these age-related declines. However, opinion is divided in the literature regarding whether cognitive training can engender transfer to a variety of cognitive skills in older adults. In the current study, the authors trained older adults in a real-time strategy video game for 23.5 hr in an effort to improve their executive functions. A battery of cognitive tasks, including tasks of executive control and visuospatial skills, were assessed before, during, and after video-game training. The trainees improved significantly in the measures of game performance. They also improved significantly more than the control participants in executive control functions, such as task switching, working memory, visual short-term memory, and reasoning. Individual differences in changes in game performance were correlated with improvements in task switching. The study has implications for the enhancement of executive control processes of older adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Working Memory Capacity, Indirect Semantic Priming, and Stroop Interference: Pattern of Interindividual Prefrontal Performance Differences in Healthy Volunteers.

Using neuropsychological models of prefrontal function, the authors investigated the pattern of interindividual prefrontal performance differences in healthy volunteers. Using a correlation and an extreme group approach, they compared verbal and visuospatial working memory capacity with performance on the Stroop interference task as a measure of executive control and on the direct and indirect semantic priming tasks as a measure of semantic access. Subjects with low visuospatial working memory capacity exhibited increased Stroop interference Subjects with low verbal memory capacity showed increased priming and Stroop interference only. The study shows that prefrontal functioning varies interindividually, forming patterns of performance differences. These findings suggest that working memory, executive control, and semantic retrieval are functionally related to some extent. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

How do health and biological age influence chronological age and sex differences in cognitive aging: Moderating, mediating, or both?

Much research on cognitive competence in normal older adults has documented age and sex differences. The authors used new cross-sectional data from the Victoria Longitudinal Study (VLS) (n = 386; age 61 to 95 years) to examine how health and biological age influence age and sex differences in cognitive aging. The authors found evidence for both moderating and mediating influences. Age differences were moderated by health status, such that the negative effects of age were most pronounced among participants of relatively better health. Sex differences were moderated by health and were more pronounced among participants reporting comparatively poorer health. Although health mediated a notable amount of age-related cognitive variation, BioAge mediated considerably more variance, even after statistical control for differences in health. A complex pattern emerged for the mediation of sex differences: Although BioAge accounted for sex-related variation in cognitive performance, health operated to suppress these differences. Overall, both health and BioAge predicted cognitive variation independently of chronological age. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Do young and older adults rely on different processes in source memory tasks? A neuropsychological study.

Source memory has consistently been associated with prefrontal function in both normal and clinical populations. Nevertheless, the exact contribution of this brain region to source memory remains uncertain, and evidence suggests that processes used by young and older adults may differ. The authors explored the extent to which scores on composite measures of neuropsychological tests of frontal and medial temporal function differentially predicted the performance of young and older adults on source memory tasks. Results indicated that a frontal composite measure, consistently associated with source memory performance in older adults, was unrelated to source memory in young adults, although it was sensitive to a demanding working memory task. The memory composite score, however, predicted performance in the young group. In addition, item and source memory were correlated in young but not older people. Findings are discussed in terms of age-related differences in working memory and executive functions, and differential binding processes necessary for item and source memory. The requirement to integrate item and source information at encoding appears to place greater demands on executive or working memory processes in older adults than in younger adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Use of IQ-Adjusted Norms to Predict Progressive Cognitive Decline in Highly Intelligent Older Individuals.

Identifying high-functioning older individuals in preclinical phases of Alzheimer's disease (AD) may require more sensitive methods than the standard approach. The authors explored the utility of adjusting for premorbid intelligence to predict progressive cognitive decline or Mild Cognitive Impairment (MCI) in 42 highly intelligent older individuals. When scores were adjusted for baseline IQ, 9 participants had executive impairments, 11 had memory impairments, and 22 scored in the normal range. None were impaired according to standard age norms. Three and a half years later, 9 participants with IQ-adjusted memory impairment declined in naming, visuospatial functioning, and memory; 6 convened to MCI. Three participants with normal memory declined. Implications for using IQ-adjusted norms to predict preclinical AD are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A twin study of cognitive function in chronic fatigue syndrome: The effects of sudden illness onset.

Variable reports of neuropsychological deficits in individuals with chronic fatigue syndrome (CFS) may, in part, be attributable to methodological limitations. In this study, these limitations were addressed by controlling for genetic and environmental influences and by assessing the effects of comorbid depression and mode of illness onset. Specifically, the researchers conducted a co-twin control study of 22 pairs of monozygotic twins, in which 1 twin met strict criteria for CFS and the co-twin was healthy. Twins underwent a structured psychiatric interview and comprehensive neuropsychological assessment evaluating 6 cognitive domains. Results indicated that twin groups had similar intellectual and visual memory functioning, but fatigued twins exhibited decreases in motor functions (p = .05), speed of information processing (p = .02), verbal memory (p = .02), and executive functioning (p = .01). Major depression did not affect neuropsychological functioning among fatigued twins, although twins with sudden illness onset demonstrated slowed information processing compared with those with gradual onset (p = .01). Sudden onset CFS was associated with reduced speed of information processing. If confirmed, these findings suggest the need to distinguish illness onset in future CFS studies and may have implications for treatment, cognitive rehabilitation, and disability determination. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age differences in explicit and implicit memory for pictures.

In the present study, the authors examined age effects in memory for nonverbal material. A picture fragment completion task was used to test explicit and implicit memory in a younger and an older group. Explicit memory was indexed by free recall of pictures, whereas implicit memory was indexed by perceptual learning (priming). Both free recall and perceptual learning performance were found to be impaired in the older group. A measure of executive functioning was found to be predictive of both explicit and implicit memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)