| 1. |
- Bäckman, Lars, et al.
(författare)
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The correlative triad among aging, dopamine, and cognition : current status and future prospects.
- 2006
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Ingår i: Neuroscience and Biobehavioral Review. - : Elsevier BV. - 0149-7634. ; 30:6, s. 791-807
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The brain neuronal systems defined by the neurotransmitter dopamine (DA) have since long a recognized role in the regulation of motor functions. More recently, converging evidence from patient studies, animal research, pharmacological intervention, and molecular genetics indicates that DA is critically implicated also in higher-order cognitive functioning. Many cognitive functions and multiple markers of striatal and extrastriatal DA systems decline across adulthood and aging. Research examining the correlative triad among adult age, DA, and cognition has found strong support for the view that age-related DA losses are associated with age-related cognitive deficits. Future research strategies for examining the DA-cognitive aging link include assessing (a) the generality/specificity of the effects; (b) the relationship between neuromodulation and functional brain activation; and (c) the release of DA during actual task performance.
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| 2. |
- de Frias, Cindy, et al.
(författare)
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Revisiting the dedifferebtion hypothesis with longitudinal multi-cohort data
- 2007
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Ingår i: Intelligence. ; 35, s. 381-392
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Tidskriftsartikel (refereegranskat)abstract
- The present longitudinal multi-cohort study examines whether interindividual variability in cognitive performance and change increases in old age, and whether associations among developments of different cognitive functions increase with adult age. Multivariate multiple-group latent growth modeling was applied to data from narrow cohorts separated by five years of age. Tests assessing episodic recall, semantic knowledge, semantic fluency, and visuospatial ability were administered to 1000 non-demented adults (initially aged 35–80 years), participating in the Betula Project at three occasions over a 10-year period. Greater interindividual differences in change were noted in older age groups. Age-related increases in correlations among performance scores were noted for different cognitive measures beginning in old age, but not earlier. Our study supports a dynamic view of dedifferentiation of cognitive aging.
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| 3. |
- Lövdén, Martin, et al.
(författare)
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Studying Individual Aging in an Interindividual Context : Typical Paths of Age-Related, Dementia-Related, and Mortality-Related Cognitive Development in Old Age
- 2005
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Ingår i: Psychology and Aging. - Washington : American Psychological Association (APA). - 0882-7974 .- 1939-1498. ; 20:2, s. 303-316
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Tidskriftsartikel (refereegranskat)abstract
- This study has 2 objectives: (a) to explore typical paths of cognitive development associated with aging, terminal decline, and dementia and (b) to promote and illustrate an individual-oriented approach to the study of cognitive aging based on longitudinal panel data from a population-based sample (N = 500; age range-sub(T1)= 60-80, where T refers to time) tested at 3 occasions 5 years apart. Results document interindividual differences in multivariate patterns of change. Although cognitive changes generally covary, the present study indicates that subgroups of individuals develop along different paths characterized by selective changes in subsets of cognitive functions. Typical progression of dementia followed a developmental cascade from low declarative memory, via low functioning across all observed cognitive measures, to dementia diagnosis, and finally, death.
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| 4. |
- Nagel, Irene E, et al.
(författare)
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Performance level modulates adult age differences in brain activation during spatial working memory.
- 2009
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 106:52, s. 22552-22557
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Tidskriftsartikel (refereegranskat)abstract
- Working memory (WM) shows pronounced age-related decline. Functional magnetic resonance imaging (fMRI) studies have revealed age differences in task-related brain activation. Evidence based primarily on episodic memory studies suggests that brain activation patterns can be modulated by task difficulty in both younger and older adults. In most fMRI aging studies on WM, however, performance level has not been considered, so that age differences in activation patterns are confounded with age differences in performance level. Here, we address this issue by comparing younger and older low and high performers in an event-related fMRI study. Thirty younger (20-30 years) and 30 older (60-70 years) healthy adults were tested with a spatial WM task with three load levels. A region-of-interest analysis revealed marked differences in the activation patterns between high and low performers in both age groups. Critically, among the older adults, a more "youth-like" load-dependent modulation of the blood oxygen level-dependent signal was associated with higher levels of spatial WM performance. These findings underscore the need of taking performance level into account when studying changes in functional brain activation patterns from early to late adulthood.
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| 5. |
- Noack, Hannes, et al.
(författare)
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Cognitive plasticity in adulthood and old age: Gauging the generality of cognitive intervention effects
- 2009
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Ingår i: Restorative Neurology and Neuroscience. - 1878-3627. ; 27:5, s. 435-453
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Forskningsöversikt (refereegranskat)abstract
- Interventions enabling aging individuals to fulfill their plastic potential promise to postpone, attenuate, or even reverse the adverse effects of senescent brain changes on cognitive abilities and everyday competence in old age. Based on an overview of the concept of plasticity in lifespan development, we selectively review evidence from cognitive intervention studies and conclude that most of them have failed to observe generalizable performance improvements, as documented by the small size and scope of positive transfer to untrained tasks. We further note that generally accepted criteria for defining transfer distance are lacking, rendering the relevant evidence difficult to interpret. Hence, we propose a taxonomy of transfer distance based on the structure of human intellectual abilities.
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| 6. |
- Schmiedek, Florian, et al.
(författare)
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Complex Span Versus Updating Tasks of Working Memory: The Gap Is Not That Deep
- 2009
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Ingår i: Journal of Experimental Psychology: Learning, Memory, and Cognition. - : American Psychological Association (APA). - 0278-7393 .- 1939-1285. ; 35:4, s. 1089-1096
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Tidskriftsartikel (refereegranskat)abstract
- How to best measure working memory capacity is an issue of ongoing debate. Besides established complex span tasks, which combine short-term memory demands with generally unrelated secondary tasks, there exists a set of paradigms characterized by continuous and simultaneous updating of several items in working memory, such as the n-back, memory updating, or alpha span tasks. With a latent variable analysis (N = 96) based on content-heterogeneous operationalizations of both task families, the authors found a latent correlation between a complex span factor and an updating factor that was not statistically different from unity (r = .96). Moreover, both factors predicted fluid intelligence (reasoning) equally well. The authors conclude that updating tasks measure working memory equally well as complex span tasks. Processes involved in building, maintaining, and updating arbitrary bindings may constitute the common working memory ability underlying performance on reasoning, complex span, and updating tasks.
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| 7. |
- Schmiedek, Florian, et al.
(författare)
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On the Relation of Mean Reaction Time and Intraindividual Reaction Time Variability
- 2009
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Ingår i: Psychology and Aging. - : American Psychological Association (APA). - 0882-7974 .- 1939-1498. ; 24:4, s. 841-857
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Tidskriftsartikel (refereegranskat)abstract
- Researchers often statistically control for means when examining individual or age-associated differences in variances, assuming that the relation between the 2 is linear and invariant within and across individuals and age groups. We tested this assumption in the domain of working memory by applying variance-heterogeneity multilevel models to reaction times in the n-back task. Data are from the COGITO study, which comprises 101 younger and 103 older adults assessed in over 100 daily sessions. We found that relations between means and variances vary reliably across age groups and individuals, thereby contradicting the invariant linearity assumption. We argue that statistical control approaches need to be replaced by theoretical models that simultaneously estimate central tendency and dispersion of latencies and accuracies and illustrate this claim by applying the diffusion model to the same data. Finally, we note that differences in reliability between estimates for means and variances need to be considered when comparing their unique contributions to developmental outcomes.
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| 8. |
- Verrel, Julius, et al.
(författare)
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Interacting Effects of Cognitive Load and Adult Age on the Regularity of Whole-Body Motion During Treadmill Walking
- 2009
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Ingår i: Psychology and Aging. - : American Psychological Association (APA). - 0882-7974 .- 1939-1498. ; 24:1, s. 75-81
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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