1.
Grandy, Thomas H., et al.
(author)
Individual alpha peak frequency is related to latent factors of general cognitive abilities
2013
In: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 79, s. 10-18
Journal article (peer-reviewed) abstract
Some eighty years after the discovery of the human electroencephalogram (EEG) and its dominant rhythm, alpha (similar to 10 Hz), the neurophysiological functions and behavioral correlates of alpha oscillations are still under debate. Similarly, the biological mechanisms contributing to the general factor of intelligence, or g, have been under scrutiny for decades. Individual alpha frequency (IAF), a trait-like parameter of the EEG, has been found to correlate with individual differences in cognitive performance and cognitive abilities. Informed by large-scale theories of neural organization emphasizing the general functional significance of oscillatory activity, the present study replicates and extends these findings by testing the hypothesis that IAF is related to intelligence at the level of g, rather than at the level of specific cognitive abilities. Structural equation modeling allowed us to statistically control for measurement error when estimating the association between IAF and intellectual functioning. In line with our hypothesis, we found a statistically reliable and substantial correlation between IAF and g (r = .40). The magnitude of this correlation did not differ significantly between younger and older adults, and captured all of the covariation between IAF and the cognitive abilities of reasoning, memory, and perceptual speed. The observed association between IAF and g provides a parsimonious explanation for the commonly observed diffuse pattern of correlations between IAF and cognitive performance. We conclude that IAF is a marker of global architectural and functional properties of the human brain.
2.
Karalija, Nina, 1984-, et al.
(author)
Longitudinal Dopamine D2 Receptor Changes and Cerebrovascular Health in Aging
2022
In: Neurology. - 1526-632X .- 0028-3878. ; 99, s. e1278-e1289
Journal article (peer-reviewed) abstract
BACKGROUND AND OBJECTIVES: Cross-sectional studies suggest marked dopamine (DA) decline in aging, but longitudinal evidence is lacking. The aim of this study was to estimate within-person decline rates for DA D2-like receptors (DRD2) in aging and examine factors that may contribute to individual differences in DRD2 decline rates. METHODS: We investigated 5-year within-person changes in DRD2 availability in a sample of older adults. At both occasions, PET with 11C-raclopride and MRI were used to measure DRD2 availability in conjunction with structural and vascular brain integrity. RESULTS: Longitudinal analyses of the sample (baseline: n = 181, ages: 64-68 years, 100 men and 81 women; 5-year follow-up: n = 129, 69 men and 60 women) revealed aging-related striatal and extrastriatal DRD2 decline, along with marked individual differences in rates of change. Notably, the magnitude of striatal DRD2 decline was ∼50% of past cross-sectional estimates, suggesting that the DRD2 decline rate has been overestimated in past cross-sectional studies. Significant DRD2 reductions were also observed in select extrastriatal regions, including hippocampus, orbitofrontal cortex (OFC), and anterior cingulate cortex (ACC). Distinct profiles of correlated DRD2 changes were found across several associative regions (ACC, dorsal striatum, and hippocampus) and in the reward circuit (nucleus accumbens and OFC). DRD2 losses in associative regions were associated with white matter lesion progression, whereas DRD2 losses in limbic regions were related to reduced cortical perfusion. DISCUSSION: These findings provide the first longitudinal evidence for individual and region-specific differences of DRD2 decline in older age and support the hypothesis that cerebrovascular factors are linked to age-related dopaminergic decline.
3.
Köhncke, Ylva, et al.
(author)
Self-rated intensity of habitual physical activities is positively associated with dopamine D-2/3 receptor availability and cognition
2018
In: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 181, s. 605-616
Journal article (peer-reviewed) abstract
Between-person differences in cognitive performance in older age are associated with variations in physical activity. The neurotransmitter dopamine (DA) contributes to cognitive performance, and the DA system deteriorates with advancing age. Animal data and a patient study suggest that physical activity modulates DA receptor availability, but data from healthy humans are lacking. In a cross-sectional study with 178 adults aged 64-68 years, we investigated links among self-reported physical activity, D(2/3)DA receptor (D2/3DR) availability, and cognitive performance. D2/3DR availability was measured with [C-11]raclopride positron emission tomography at rest. We used structural equation modeling to obtain latent factors for processing speed, episodic memory, working memory, physical activity, and D2/3DR availability in caudate, putamen, and hippocampus. Physical activity intensity was positively associated with D2/3DR availability in caudate, but not putamen and hippocampus. Frequency of physical activity was not related to D2/3DR availability. Physical activity intensity was positively related to episodic memory and working memory. D2/3DR availability in caudate and hippocampus was positively related to episodic memory. Taken together, our results suggest that striatal DA availability might be a neurochemical correlate of episodic memory that is also associated with physical activity.
4.
Nilsson, Jonna, et al.
(author)
Associations of cardiorespiratory fitness and moderate-to-vigorous physical activity with latent cognitive abilities in older adults
2022
In: Psychology of Sport And Exercise. - : Elsevier. - 1469-0292 .- 1878-5476. ; 60, s. 102171-102171
Journal article (peer-reviewed) abstract
It has been demonstrated that physical activity has a small but positive effect on cognition in old age, which suggests that it may be possible to alter the trajectory of age-related cognitive decline. However, our understanding of which aspects of physical activity that are important for modifying cognition remains incomplete. Adopting an exploratory approach in a sample of 115 healthy older adults (65–75 years), the present cross-sectional study used structural equation modelling to investigate the dissociable associations of physical activity (moderate-to-vigorous activity, derived from 7-day accelerometry) and cardiorespiratory fitness (VO2 max, derived from maximal treadmill ergometer test) with multiple latent cognitive abilities (working memory, episodic memory, spatial and verbal reasoning). The results showed a significant positive association between fitness and working memory, when physical activity was statistically controlled for, and a positive association of similar point magnitude between physical activity and episodic memory, when fitness was statistically controlled for, although the latter association did not reach statistical significance. The results add to the foundation for a more careful investigation of the dissociable associations of moderate-to-vigorous physical activity and fitness with cognition in old age, and encourages future research to test the hypothesis that cardiorespiratory fitness benefits working memory via general cerebrovascular effects on grey matter volume, whilst moderate-to-vigorous physical activity benefits episodic memory via effects on neuroplastic processes.
5.
Nilsson, Jonna, et al.
(author)
No Significant Effect of Prefrontal tDCS on Working Memory Performance in Older Adults
2015
In: Frontiers in Aging Neuroscience. - : Frontiers Media SA. - 1663-4365 .- 1663-4365. ; 7
Journal article (peer-reviewed) abstract
Transcranial direct current stimulation (tDCS) has been put forward as a non pharmacological alternative for alleviating cognitive decline in old age. Although results have shown some promise, little is known about the optimal stimulation parameters for modulation in the cognitive domain. In this study, the effects of tDCS over the dorsolateral prefrontal cortex (dIPFC) on working memory performance were investigated in thirty older adults. An N-back task assessed working memory before, during and after anodal tDCS at a current strength of 1 mA and 2 mA, in addition to sham stimulation. The study used a single-blind, cross-over design. The results revealed no significant effect of tDCS on accuracy or response times during or after stimulation, for any of the current strengths. These results suggest that a single session of tDCS over the dIPFC is unlikely to improve working memory, as assessed by an N-back task, in old age.
6.
Nyberg, Lars, 1966-, et al.
(author)
Longitudinal stability in working memory and frontal activity in relation to general brain maintenance
2022
In: Scientific Reports. - : Springer Nature. - 2045-2322. ; 12:1
Journal article (peer-reviewed) abstract
Cognitive functions are well-preserved for some older individuals, but the underlying brain mechanisms remain disputed. Here, 5-year longitudinal 3-back in-scanner and offline data classified individuals in a healthy older sample (baseline age = 64–68 years) into having stable or declining working-memory (WM). Consistent with a vital role of the prefrontal cortex (PFC), WM stability or decline was related to maintained or reduced longitudinal PFC functional responses. Subsequent analyses of imaging markers of general brain maintenance revealed higher levels in the stable WM group on measures of neurotransmission and vascular health. Also, categorical and continuous analyses showed that rate of WM decline was related to global (ventricles) and local (hippocampus) measures of neuronal integrity. Thus, our findings support a role of the PFC as well as general brain maintenance in explaining heterogeneity in longitudinal WM trajectories in aging.
7.
Papenberg, Goran, et al.
(author)
Magnified effects of the COMT gene on white-matter microstructure in very old age
2015
In: Brain Structure and Function. - : Springer Science and Business Media LLC. - 1863-2653 .- 1863-2661. ; 220:5, s. 2927-2938
Journal article (peer-reviewed) abstract
Genetic factors may partly account for between-person differences in brain integrity in old age. Evidence from human and animal studies suggests that the dopaminergic system is implicated in the modulation of white-matter integrity. We investigated whether a genetic variation in the Catechol-O-Methyltransferase (COMT) Val158Met polymorphism, which influences dopamine availability in prefrontal cortex, contributes to interindividual differences in white-matter microstructure, as measured with diffusion-tensor imaging. In a sample of older adults from a population-based study (60-87 years; n = 238), we found that the COMT polymorphism affects white-matter microstructure, indexed by fractional anisotropy and mean diffusivity, of several white-matter tracts in the oldest age group (81-87 years), although there were no reliable associations between COMT and white-matter microstructure in the two younger age groups (60-66 and 72-78 years). These findings extend previous observations of magnified genetic effects on cognition in old age to white-matter integrity.
8.
Raz, Naftali, et al.
(author)
Differential brain shrinkage over 6 months shows limited association with cognitive practice
2013
In: Brain and Cognition. - : Elsevier BV. - 0278-2626 .- 1090-2147. ; 82:2, s. 171-180
Journal article (peer-reviewed) abstract
The brain shrinks with age, but the timing of this process and the extent of its malleability are unclear. We measured changes in regional brain volumes in younger (age 20-31) and older (age 65-80) adults twice over a 6 months period, and examined the association between changes in volume, history of hypertension, and cognitive training. Between two MRI scans, 49 participants underwent intensive practice in three cognitive domains for 100 consecutive days, whereas 23 control group members performed no laboratory cognitive tasks. Regional volumes of seven brain structures were measured manually and adjusted for intracranial volume. We observed significant mean shrinkage in the lateral prefrontal cortex, the hippocampus, the caudate nucleus, and the cerebellum, but no reliable mean change of the prefrontal white matter, orbital-frontal cortex, and the primary visual cortex. Individual differences in change were reliable in all regions. History of hypertension was associated with greater cerebellar shrinkage. The cerebellum was the only region in which significantly reduced shrinkage was apparent in the experimental group after completion of cognitive training. Thus, in healthy adults, differential brain shrinkage can be observed in a narrow time window, vascular risk may aggravate it, and intensive cognitive activity may have a limited effect on it.
9.
Wenger, Elisabeth, et al.
(author)
Expansion and Renormalization of Human Brain Structure During Skill Acquisition
2017
In: Trends in cognitive sciences. - : Elsevier BV. - 1364-6613 .- 1879-307X. ; 21:12, s. 930-939
Research review (peer-reviewed) abstract
Research on human brain changes during skill acquisition has revealed brain volume expansion in task-relevant areas. However, the large number of skills that humans acquire during ontogeny militates against plasticity as a perpetual process of volume growth. Building on animal models and available theories, we promote the expansion-renormalization model for plastic changes in humans. The model predicts an initial increase of gray matter structure, potentially reflecting growth of neural resources like neurons, synapses, and glial cells, which is followed by a selection process operating on this new tissue leading to a complete or partial return to baseline of the overall volume after selection has ended. The model sheds new light on available evidence and current debates and fosters the search for mechanistic explanations.
10.
Bellander, Martin, et al.
(author)
Behavioral correlates of changes in hippocampal gray matter structure during acquisition of foreign vocabulary
2016
In: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 131, s. 205-213
Journal article (peer-reviewed) abstract
Experience can affect human gray matter volume. The behavioral correlates of individual differences in such brain changes are not well understood. In a group of Swedish individuals studying Italian as a foreign language, we investigated associations among time spent studying, acquired vocabulary, baseline performance on memory tasks, and gray matter changes. As a way of studying episodic memory training, the language learning focused on acquiring foreign vocabulary and lasted for 10 weeks. T-1-weighted structural magnetic resonance imaging and cognitive testing were performed before and after the studies. Learning behavior was monitored via participants' use of a smartphone application dedicated to the study of vocabulary. A whole-brain analysis showed larger changes in gray matter structure of the right hippocampus in the experimental group (N = 33) compared to an active control group (N = 23). A first path analyses revealed that time spent studying rather than acquired knowledge significantly predicted change in gray matter structure. However, this association was not significant when adding performance on baseline memory measures into the model, instead only the participants' performance on a short-term memory task with highly similar distractors predicted the change. This measure may tap similar individual difference factors as those involved in gray matter plasticity of the hippocampus.
