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  • Aging
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  • 1
    In: The Journals of Gerontology Series B: Psychological Sciences and Social Sciences, 2008, Vol. 63(3), pp.P121-P128
    Description: Effects of cognitive activities on walking variability are poorly understood. We parametrically manipulated working-memory load by using an n -back task in 32 younger adults and 32 older adults walking on a treadmill at self-selected speed. We found no dual-task costs for cognitive performance. Stride-to-stride variability was lower when participants performed an easy working-memory task than when they walked without cognitive tasks. Increasing working-memory load from 1-back to 4-back produced decreasing variability of stride time and stride length in younger but not in older adults. Extending the 2006 dual-process account proposed by Huxhold, Li, Schmiedek, and Lindenberger, we conclude that normal aging alters the trade-off between the effects of focus of attention and resource competition on walking variability.
    Keywords: Dual - Task Cost ; Resource Competition ; Walking Variability
    ISSN: 1079-5014
    E-ISSN: 1758-5368
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  • 2
    Language: English
    In: Gait & Posture, January 2015, Vol.41(1), pp.258-262
    Description: The dual-process account of sensorimotor-cognitive interactions postulates that easy cognitive tasks can lead to performance improvements in the motor domain (e.g., an increased stability while walking or balancing) across the lifespan. However, cross-domain resource competition can lead to performance decrements in motor tasks when the concurrent cognitive task is very difficult, and older adults have shown performance decrements in their motor functioning under such circumstances. Resource limitations are particularly pronounced not only in old adulthood, but also in childhood. The current study investigates the relationship of walking speed and cognitive load on walking regularity in 7- and 9-year olds and young adults, with 18 participants in each group. Participants were walking on a treadmill at their preferred speed, and with speeds that were 30% faster and 30% slower than preferred. Regularity of lower-body coordination was operationalized as the residual variance of principal component analyses performed on the data of a motion analysis system. All age groups showed a more regular gait with increasing walking speed. Young adults’ gait regularity was not influenced by cognitive load, whereas children showed a U-shaped relationship of cognitive load and walking regularity, with the highest regularity when performing an easy cognitive task. It can be concluded that children are also influenced by cross-domain resources competition in challenging cognitive-motor dual-task situations.
    Keywords: Dual-Task ; Walking ; Cognition ; Children ; Young Adults ; Medicine ; Anatomy & Physiology
    ISSN: 0966-6362
    E-ISSN: 1879-2219
    E-ISSN: 14321106
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  • 3
    Language: English
    In: Psychological Bulletin, 2010, Vol.136(4), pp.659-676
    Description: Does plasticity contribute to adult cognitive development, and if so, in what ways? The vague and overused concept of plasticity makes these controversial questions difficult to answer. In this article, we refine the notion of adult cognitive plasticity and sharpen its conceptual distinctiveness. According to our framework, adult cognitive plasticity is driven by a prolonged mismatch between functional organismic supplies and environmental demands and denotes the brain's capacity for anatomically implementing reactive changes in behavioral flexibility (i.e., the possible range of performance and function). We distinguish between 2 interconnected but distinct cognitive outcomes of adult cognitive plasticity: alterations in processing efficiency and alterations in representations. We demonstrate the usefulness of our framework in evaluating and interpreting (a) increments in frontal brain activations in the course of normal aging and (b) the effects of cognitive training in adulthood and old age. Finally, we outline new research questions and predictions generated by the present framework and recommend design features for future cognitive-training studies.
    Keywords: Adult Cognitive Development ; Aging ; Compensation ; Cognitive Intervention ; Transfer
    ISSN: 0033-2909
    E-ISSN: 1939-1455
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  • 4
    Language: English
    In: Psychology and Aging, 2014, Vol.29(3), pp.503-520
    Description: This study examined how children (9 years), adolescents (13 to 15 years), younger adults (21 to 26 years), and older adults (70 to 76 years) chart age gradients of cognitive and social functioning from childhood to old age. Participants ( N = 156) rated typical performance levels in different life phases for 10 aspects of cognitive and social functioning. Compared with older participants, children expected lower performance levels and higher temporal stability, particularly during adulthood and into old age, and showed lower interindividual consensus in their ratings. Individuals in all 4 age groups recognized that fluid cognitive abilities reach their developmental peak earlier in life and decline more steeply thereafter than crystallized cognitive abilities. Older adults and, to a lesser extent, children evaluated their own current functioning as being better than that of their typical age peers. Furthermore, older adults charted typical cognitive development in middle and earlier late adulthood more positively than the participants in the other 3 age groups, which possibly reflects a partial externalization of their own positive self-views and a self-enhancing bias. Comparisons with life span gradients of cognitive performance ( McArdle, Ferrer-Caja, Hamagami, & Woodcock, 2002 ) suggest that the ratings of adolescents and younger adults were in better agreement with empirically observed average performance trajectories than the ratings of children and older adults. We conclude that beliefs about normative cognitive and social aspects of life span development emerge in late middle childhood, solidify into culturally shared scripts by mid-adolescence, and remain subject to further change into old age.
    Keywords: Beliefs About Aging ; Cognitive Development ; Social Development ; Biexponential Latent Growth Curve Modeling ; Age Differences
    ISSN: 0882-7974
    E-ISSN: 1939-1498
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  • 5
    Language: English
    In: Gait & Posture, 2011, Vol.33(3), pp.401-405
    Description: We investigated dual-task performance of cognitive (semantic fluency) and sensorimotor tasks (walking) in 120 children and adults from four age groups (9-year olds, = 9.52 years; 11-year olds, = 11.51 years; young adults, = 25.34 years; older adults, = 64.28 years; = 30 per group). Distances walked during 90 s and numbers of category exemplars generated in the semantic fluency task showed an inverted U-shape function with age. In line with general resource models proportional dual-task costs in walking also showed a U-shaped relation as a function of age with pronounced decrements in the youngest and oldest groups. Only 9-year olds showed significant costs in the cognitive task. Individual differences in single-task performance accounted for more than half of the variance in dual-task performance. Reliable age-related residual variance implicated additional factors particularly in children's developing multi-tasking performances.
    Keywords: Dual-Task ; Lifespan ; Semantic Fluency ; Cognitive Resources ; Medicine ; Anatomy & Physiology
    ISSN: 0966-6362
    E-ISSN: 1879-2219
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  • 6
    Language: English
    In: Gerontology, April 2011, Vol.57(3), pp.239-246
    Description: Reaching late adulthood is accompanied by losses in physical and mental resources, but lifestyle choices seem to have a considerable influence on the aging trajectory. This review deals with the interplay between cognitive and motor functioning in old age, focusing on two different lines of research, namely (a) dual-task studies requiring participants to perform a cognitive and a motor task simultaneously, and (b) intervention studies investigating whether increases in physical fitness also lead to improvements in cognitive performance. Dual-task studies indicate that healthy older adults show greater performance reductions in both domains than young adults when performing a cognitive and a motor task simultaneously. In addition, older adults often tend to protect their motor functioning at the expense of the cognitive task when the situation involves a threat to balance. This can be considered an adaptive behavior since fall-related injuries can have severe consequences. Fitness intervention studies which increased the aerobic fitness of previously sedentary older adults have demonstrated impressive performance improvements in the cognitive domain, especially for tasks involving executive control processes. These findings are interesting in light of cognitive intervention studies, which often fail to find significant transfer effects to tasks that have not been trained directly. The authors argue that future research should compare the effects of cognitive and aerobic fitness interventions in older adults, and they present a study design in which cognition and fitness are trained sequentially as well as simultaneously. Finally, methodological issues involved in this type of research and potential applications to applied settings are discussed.
    Keywords: Bridging the Gap Between Clinical and Behavioural Gerontology Part I: Promoting Late-Life ; Cognition ; Motor Functioning ; Exercise ; Intervention ; Dual Tasks ; Medicine ; Social Welfare & Social Work ; Anatomy & Physiology
    ISSN: 0304-324X
    E-ISSN: 1423-0003
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  • 7
    Language: English
    In: NeuroImage, 01 May 2016, Vol.131, pp.155-161
    Description: This study investigates the effects of fitness changes on hippocampal microstructure and hippocampal volume. Fifty-two healthy participants aged 59–74 years with a sedentary lifestyle were randomly assigned to either of two levels of exercise intensity. Training lasted for six months. Physical fitness, hippocampal volumes, and hippocampal microstructure were measured before and after training. Hippocampal microstructure was assessed by mean diffusivity, which inversely reflects tissue density; hence, mean diffusivity is lower for more densely packed tissue. Mean changes in fitness did not differ reliably across intensity levels of training, so data were collapsed across groups. Multivariate modeling of pretest–posttest differences using structural equation modeling (SEM) revealed that individual differences in latent change were reliable for all three constructs. More positive changes in fitness were associated with more positive changes in tissue density (i.e., more negative changes in mean diffusivity), and more positive changes in tissue density were associated with more positive changes in volume. We conclude that fitness-related changes in hippocampal volume may be brought about by changes in tissue density. The relative contributions of angiogenesis, gliogenesis, and/or neurogenesis to changes in tissue density remain to be identified.
    Keywords: Aging ; Fitness ; Physical Exercise ; Hippocampal Volume ; Hippocampal Microstructure ; Latent Difference Modeling ; Medicine
    ISSN: 1053-8119
    E-ISSN: 1095-9572
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  • 8
    Language: English
    In: NeuroImage, 15 February 2012, Vol.59(4), pp.3389-3397
    Description: A widespread network involving cortical and subcortical brain structures forms the neural substrate of human spatial navigation. Most studies investigating plasticity of this network have focused on the hippocampus. Here, we investigate age differences in cortical thickness changes evoked by four months of spatial navigation training in 91 men aged 20–30 or 60–70 years. Cortical thickness was automatically measured before, immediately after, and four months after termination of training. Younger as well as older navigators evidenced large improvements in navigation performance that were partly maintained after termination of training. Importantly, training-related cortical thickening in left precuneus and paracentral lobule were observed in young navigators only. Thus, spatial navigation training appears to affect cortical brain structure of young adults, but there is reduced potential for experience-dependent cortical alterations in old age.
    Keywords: Cortical Thickness ; Plasticity ; Spatial Navigation ; Aging ; Medicine
    ISSN: 1053-8119
    E-ISSN: 1095-9572
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  • 9
    Language: English
    In: Psychology and Aging, 2009, Vol.24(1), pp.75-81
    Description: We investigated effects of concurrent cognitive task difficulty ( n -back) on the regularity of whole-body movements during treadmill walking in women and men from 3 age groups (20–30, 60–70, and 70–80 years old). Using principal component analysis of individual gait patterns, we separated main (regular) from residual (irregular) components of whole-body motion. Proportion of residual variance (RV) was used as an index of gait irregularity. The gait in all age groups became more regular (reduced RV) upon introduction of a simple cognitive task (1-back), relative to walking without a concurrent cognitive task. In contrast, parametrically increasing working memory load from 1-back to 4-back led to age-differential effects, with gait patterns becoming more regular in those 20–30 years old, becoming less regular in those 70–80 years old, and showing no significant effects in those 60–70 years old. Our results support the dual-process account of sensorimotor–cognitive interactions ( O. Huxhold, S.-C. Li, F. Schmiedek, and U. Lindenberger, 2006 ), with age-general effects of internal versus external attentional focus and age-specific effects of resource competition with increasing cognitive task difficulty.
    Keywords: Gait ; Principal Component Analysis ; Dual-Tasking ; Aging ; Working Memory
    ISSN: 0882-7974
    E-ISSN: 1939-1498
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  • 10
    Language: English
    In: Frontiers in Human Neuroscience, March 16, 2017
    Description: Neural specificity refers to the degree to which neural representations of different stimuli can be distinguished. Evidence suggests that neural specificity, operationally defined as stimulus-related differences in functional magnetic resonance imaging (fMRI) activation patterns, declines with advancing adult age, and that individual differences in neural specificity are associated with individual differences in fluid intelligence. A growing body of literature also suggests that regular physical activity may help preserve cognitive abilities in old age. Based on this literature, we hypothesized that exercise-induced improvements in fitness would be associated with greater neural specificity among older adults. A total of 52 adults aged 59–74 years were randomly assigned to one of two aerobic-fitness training regimens, which differed in intensity. Participants in both groups trained three times a week on stationary bicycles. In the low-intensity (LI) group, the resistance was kept constant at a low level (10 Watts). In the high-intensity (HI) group, the resistance depended on participants’ heart rate and therefore typically increased with increasing fitness. Before and after the 6-month training phase, participants took part in a functional MRI experiment in which they viewed pictures of faces and buildings. We used multivariate pattern analysis (MVPA) to estimate the distinctiveness of neural activation patterns in ventral visual cortex (VVC) evoked by face or building stimuli. Fitness was also assessed before and after training. In line with our hypothesis, training-induced changes in fitness were positively associated with changes in neural specificity. We conclude that physical activity may protect against age-related declines in neural specificity.
    Keywords: Old Age Cognition -- Physiological Aspects ; Exercise -- Psychological Aspects
    ISSN: 1662-5161
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