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- Jonasson, Lars, 1983-, et al.
(författare)
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Aerobic fitness influences working memory updating via the striatal dopaminergic system in older adults
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- There is much evidence that dopamine is vital for cognitive functioning in aging. Here we tested the hypothesis that aerobic exercise and fitness influences dopaminergic neurotransmission in the striatum as measured by positron emission tomography (PET) and the non-displacable binding potential (BPND ) of [11C]raclopride, and in turn performance on offline working-memory updating tasks. In a sample of 58 older sedentary adults undergoing a six-months exercise intervention, aerobic exercise compared to stretching, toning, and resistance training did not have a differential effect on BPND . At baseline, higher aerobic fitness levels (VO2peak ) were associated with higher BPND in the striatum. Following the intervention, for both forms of training, we found reduced BPND , indicating increased dopamine (DA), in a cluster in the anterior striatum in individuals with larger improvements in VO2peak . This reduction in BPND mediated a positive indirect effect of VO2peak on working-memory updating performance. Collectively these findings implicate DA as a neurocognitive mechanism explaining the positive effects of staying physically active at an old age for working memory.
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- Pudas, Sara, 1983-, et al.
(författare)
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Midlife memory ability accounts for brain activity differences in healthy aging
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Cross-sectional neuroimaging studies suggest that hippocampal and prefrontal cortex (PFC) functions underlie individual differences in memory ability in elderly individuals, but it is unclear how individual differences in cognitive ability in youth contribute to cognitive and neuroimaging measures in older age. Here, a sample from a longitudinal population-based study (N = 201, aged 55-80) was used to investigate the relative influence of midlife memory ability and age-related memory change on memory-related BOLD-signal variability in healthy elderly. Hierarchical regression analyses showed that midlife memory ability, assessed 15-20 years earlier, explained at least as much variance as memory change in clusters in the left inferior PFC and the bilateral hippocampus, during memory encoding. Memory change estimates, however, were found to be more sensitive in detecting bilateral frontal regions specifically diagnostic of age-related memory change. These finding highlight challenges in interpreting individual differences in neurocognitive measures as age-related changes in the absence of longitudinal data, and also demonstrates the improved sensitivity of longitudinal measures.
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- Berginström, Nils, et al.
(författare)
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White matter hyperintensities increases with traumatic brain injuryseverity : associations to neuropsychological performance and fatigue
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Objective: To examine the prevalence of white matter hyperintensities (WMHs) in patients with traumatic brain injury (TBI) as compared to healthy controls, and to investigate whether there is an association between WMH lesion burden and performance on neuropsychological tests in patients with TBI.Methods: A total of 59 patients with TBI and 27 age- and gender- matched healthy controls underwent thorough neuropsychological testing and magnetic resonance imaging. The quantification of WMH lesions was performed using the fully automated Lesion Segmentation Tool.Results: WMH lesions were more common in patients with TBI than in healthy controls (p = 0.032), and increased with higher TBI severity (p = 0.025). Linear regressions showed that WMH lesions in patients with TBI were not related to performance on any neuropsychological tests (p > 0.05 for all). However, a negative relationship between number of WMH lesions in patients with TBI and self-assessed fatigue was found (r = –0.33, p = 0.026).Conclusion: WMH lesions are more common in patients with TBI than in healthy controls, and WMH lesions burden increases with TBI severity. However, these lesions do not seem to explain the decreased cognitive functioning or the increased fatigue in patients with TBI.
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