Consequences of Age-Related Cognitive Declines

Consequences of Age-Related Cognitive Declines
Timothy Salthouse; 2011
http://faculty.virginia.edu/cogage/publications2/Salthouse%20(in%20press)%20Consequences%20of%20age-related%20cognitive%20declines.pdf


Abstract

Adult age differences in a variety of cognitive abilities are well documented, and many of those abilities have been found to be related to success in the workplace and in everyday life. However, increased age is seldom associated with lower levels of real-world functioning, and the reasons for this lab-life discrepancy are not well understood. This article briefly reviews research concerned with relations of age to cognition, relations of cognition to successful functioning outside the laboratory, and relations of age to measures of work performance and achievement. The final section discusses several possible explanations for why there are often little or no consequences of age-related cognitive declines in everyday functioning.

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"The preceding review indicates that with only a few exceptions, there is little evidence of a negative relation of age (at least within the range of 20 to 75 years of age) and indices of overall level of functioning in society. Assuming that the age-cognition and cognition-functioning relations reviewed above are valid estimates of the true population relations, the positive cognition-functioning relation and negative age-cognition relation lead to expectations of negative relations between age and functioning that are rarely observed."

Openness to Experience and Activity Engagement Facilitate the Maintenance of Verbal Ability in Older Adults

Openness to Experience and Activity Engagement Facilitate the Maintenance of Verbal Ability in Older Adults
Michael J Hogan et al.; 2012
http://scottbarrykaufman.com/wp-content/uploads/2013/01/Hogan-et-al.-2012.pdf



Abstract

The current study used data from the Aberdeen Birth Cohort, 1936, to investigate the hypothesis that the positive effects of the personality trait Openness on cognitive ability are mediated by activity levels. Results of latent growth modeling analysis revealed that higher Openness predicted better reading ability, inductive reasoning, and memory performance across three testing occasions when participants were aged 64 – 68 years. Higher Openness predicted higher activity levels, and higher activity levels in turn predicted higher reading ability, but not higher performance on measures of inductive reasoning, memory, and speed of processing. Overall, Openness and activity engagement appear related to preserved higher cognitive ability in older adults, with Openness having a direct effect on marker tests of fluid ability and with the combined influence of Openness and activity being particularly important for marker tests of crystallized intelligence.

Are Old Adults Just Like Low Working Memory Young Adults? Filtering Efficiency and Age Differences in Visual Working Memory

Are Old Adults Just Like Low Working Memory Young Adults? Filtering Efficiency and Age Differences in Visual Working Memory
Kerstin Jost et al.; 2011
http://cercor.oxfordjournals.org/content/21/5/1147.full


Abstract

While it is well known that working memory functions decline with age, the functional reasons for this decline are not well understood. A factor that has proven critical for general individual differences in visual working memory capacity is the efficiency of filtering irrelevant information. Here, we examine to what degree this factor is also responsible for age differences in working memory. Young and old participants performed a change-detection task where some items in the encoding display were marked as irrelevant. The contralateral delay activity of the electroencephalogram was used to assess individual participants' filtering efficiency (see Vogel EK, McCollough AW, Machizawa MG. 2005. Neural measures reveal individual differences in controlling access to working memory. Nature. 438:500–503.). Older adults showed smaller filtering scores than young adults, but only early in the retention interval, suggesting that efficient filtering was delayed. In contrast, age-independent individual differences in filtering were reflected primarily later in the retention interval. Thus, age and individual differences in filtering are reflected in different ways showing that old adults are not simply like less efficiently performing young adults.

Contribution of Physical Fitness, Cerebrovascular Reserve and Cognitive Stimulation to Cognitive Function in Post-Menopausal Women

Contribution of Physical Fitness, Cerebrovascular Reserve and Cognitive Stimulation to Cognitive Function in Post-Menopausal Women

Gail A Eskes et al., 2010

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2967376/

Abstract

Studies of the effects of physical fitness on cognition suggest that exercise can improve cognitive abilities in healthy older adults, as well as delay the onset of age-related cognitive decline. The mechanisms for the positive benefit of exercise and how these effects interact with other variables known to influence cognitive function (e.g., involvement in cognitive activities) are less well understood. The current study examined the associations between the physical fitness, cerebrovascular blood flow regulation and involvement in cognitive activities with neuropsychological function in healthy post-menopausal women.

Methods: 

Forty-two healthy women between the ages of 55 and 90 were recruited. Physical fitness (VO2max), cerebrovascular reserve (cerebral blood flow during rest and response to an increase in end-tidal (i.e., arterial) PCO2), and cognitive activity (self-reported number and hours of involvement in cognitive activities) were assessed. The association of these variables with neuropsychological performance was examined through linear regression. 

Results:

Physical fitness, cerebrovascular reserve and total number of cognitive activities (but not total hours) were independent predictors of cognitive function, particularly measures of overall cognitive performance, attention and executive function. In addition, prediction of neuropsychological performance was better with multiple variables than each alone.

Conclusions:

Cognitive function in older adults is associated with multiple factors, including physical fitness, cerebrovascular health and cognitive stimulation. Interestingly, cognitive stimulation effects appear related more to the diversity of activities, rather than the duration of activity. Further examination of these relationships is ongoing in a prospective cohort study.

Body mass index across midlife and cognitive change in late life

Body mass index across midlife and cognitive change in late life
Dahl AK et al., 2012


Abstract
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Background: 

High midlife body mass index (BMI) has been linked to a greater risk of dementia in late life, but few have studied the effect of BMI across midlife on cognitive abilities and cognitive change in a dementia-free sample. 

Methods:

We investigated the association between BMI, measured twice across midlife (mean age 40 and 61 years, respectively), and cognitive change in four domains across two decades in the Swedish Adoption/Twin Study of Aging.

Results:

Latent growth curve models fitted to data from 657 non-demented participants showed that persons who were overweight/obese in early midlife had significantly lower cognitive performance across domains in late life and significantly steeper decline in perceptual speed, adjusting for cardio-metabolic factors. Both underweight and overweight/obesity in late midlife were associated with lower cognitive abilities in late life. However, the association between underweight and low cognitive abilities did not remain significant when weight decline between early and late midlife was controlled for.

Conclusion:

There is a negative effect on cognitive abilities later in life related to being overweight/obese across midlife. Moreover, weight decline across midlife rather than low weight in late midlife per se was associated with low cognitive abilities. Weight patterns across midlife may be prodromal markers of late life cognitive health.
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Being Overweight in Midlife Is Associated With Lower Cognitive Ability and Steeper Cognitive Decline in Late Life

Being Overweight in Midlife Is Associated With Lower Cognitive Ability and Steeper Cognitive Decline in Late Life
Anna Dahl et al., 2010
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2796876/


Abstract

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Background

Although an increasing body of evidence links being overweight in midlife with an increased risk for dementia in late life, no studies have examined the association between being overweight in midlife and cognitive ability in late life. Our aim was to examine the association between being overweight in midlife as measured by body mass index (BMI) and cognitive ability assessed over time.

Methods

Participants in the Swedish Adoption/Twin Study Aging were derived from a population-based sample. The participants completed baseline surveys in 1963 or 1973 (mean age 41.6 years, range 25–63 years). The surveys included questions about height, weight, diseases, and lifestyle factors. Beginning in 1986, the same individuals were assessed on neuropsychological tests every 3 years (except in 1995) until 2002. During the study period, 781 individuals who were 50 years and older (60% women) had at least one complete neuropsychological assessment. A composite score of general cognitive ability was derived from the cognitive test battery for each measurement occasion.

Results

Latent growth curve models adjusted for twinness showed that persons with higher midlife BMI scores had significantly lower general cognitive ability and significantly steeper longitudinal decline than their thinner counterparts. The association did not change substantially when persons who developed dementia during the study period were excluded from the analysis.

Conclusions

Higher midlife BMI scores precede lower general cognitive ability and steeper cognitive decline in both men and women. The association does not seem to be mediated by an increased risk for dementia.

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Individual Differences in Aging

Trajectories of brain aging in middle-aged and older adults: Regional and individual differences
Naftali Raz et al., 2011 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2879584/

Abstract

The human brain changes with age. However, the rate and the trajectories of change vary among the brain regions and among individuals, and the reasons for these differences are unclear. In a sample of healthy middle-aged and older adults, we examined mean volume change and individual differences in the rate of change in 12 regional brain volumes over approximately 30 months. In addition to the baseline assessment, there were two follow-ups, 15 months apart. We observed significant average shrinkage of the hippocampus, entorhinal cortex, orbital–frontal cortex, and cerebellum in each of the intervals. Shrinkage of the hippocampus accelerated with time, whereas shrinkage of the caudate nucleus, prefrontal subcortical white matter, and corpus callosum emerged only at the second follow-up. Throughout both assessment intervals, the mean volumes of the lateral prefrontal and primary visual cortices, putamen, and pons did not change. Significant individual differences in shrinkage rates were observed in the lateral prefrontal cortex, the cerebellum, and all the white matter regions throughout the study, whereas additional regions (medial–temporal structures, the insula, and the basal ganglia) showed significant individual variation in change during the second follow-up. No individual variability was noted in the change of orbital frontal and visual cortices. In two white matter regions, we were able to identify factors associated with individual differences in brain shrinkage. In corpus callosum, shrinkage rate was greater in persons with hypertension, and in the pons, women and carriers of the ApoEε4 allele exhibited declines not noted in the whole sample.

Cognitive and Sensory Declines in Old Age: Gauging the Evidence for a Common Cause

Cognitive and Sensory Declines in Old Age: Gauging the Evidence for a Common Cause
U Lindenberger et al., 2009

http://library.mpib-berlin.mpg.de/ft/ul/UL_Cognitive_2009.pdf


Abstract

Resource accounts of behavioral aging postulate that age-associated impairments within and across intellectual and sensory domains reflect, in part, a common set of senescent alterations in the neurochemistry and neuroanatomy of the aging brain. Hence, these accounts predict sizeable correlations of between-person differences in rates of decline, both within and across intellectual and sensory domains. The authors examined reliability-adjusted variances and covariances in longitudinal change for 8 cognitive measures and for close visual acuity, distant visual acuity, and hearing in 516 participants in the Berlin Aging Study (ages 70 to 103 years at 1st measurement). Up to 6 longitudinal measurements were distributed over up to 13 years. Individual differences in rates of cognitive decline were highly correlated, with a single factor accounting for 60% of the variance in cognitive change. This amount increased to 65% when controlling for age at first measurement, distance to death, and risk of dementia. Contrary to expectations, the correlations between cognitive and sensory declines were only moderate in size, underscoring the need to delineate both domain-general and function-specific mechanisms of behavioral senescence.