Chandramallika Basak

Bio: Chandramallika Basak is an academic researcher from University of Texas at Dallas. The author has contributed to research in topics: Cognition & Working memory. The author has an hindex of 23, co-authored 43 publications receiving 6376 citations. Previous affiliations of Chandramallika Basak include Syracuse University & University of Illinois at Urbana–Champaign.

Exercise training increases size of hippocampus and improves memory

Abstract: The hippocampus shrinks in late adulthood, leading to impaired memory and increased risk for dementia. Hippocampal and medial temporal lobe volumes are larger in higher-fit adults, and physical activity training increases hippocampal perfusion, but the extent to which aerobic exercise training can modify hippocampal volume in late adulthood remains unknown. Here we show, in a randomized controlled trial with 120 older adults, that aerobic exercise training increases the size of the anterior hippocampus, leading to improvements in spatial memory. Exercise training increased hippocampal volume by 2%, effectively reversing age-related loss in volume by 1 to 2 y. We also demonstrate that increased hippocampal volume is associated with greater serum levels of BDNF, a mediator of neurogenesis in the dentate gyrus. Hippocampal volume declined in the control group, but higher preintervention fitness partially attenuated the decline, suggesting that fitness protects against volume loss. Caudate nucleus and thalamus volumes were unaffected by the intervention. These theoretically important findings indicate that aerobic exercise training is effective at reversing hippocampal volume loss in late adulthood, which is accompanied by improved memory function.

Can training in a real-time strategy video game attenuate cognitive decline in older adults?

Abstract: Declines in various cognitive abilities, particularly executive control functions, are observed in older adults. An important goal of cognitive training is to slow or reverse these age-related declines. However, opinion is divided in the literature regarding whether cognitive training can engender transfer to a variety of cognitive skills in older adults. In the current study, the authors trained older adults in a real-time strategy video game for 23.5 hr in an effort to improve their executive functions. A battery of cognitive tasks, including tasks of executive control and visuospatial skills, were assessed before, during, and after video-game training. The trainees improved significantly in the measures of game performance. They also improved significantly more than the control participants in executive control functions, such as task switching, working memory, visual short-term memory, and reasoning. Individual differences in changes in game performance were correlated with improvements in task switching. The study has implications for the enhancement of executive control processes of older adults.

Plasticity of Brain Networks in a Randomized Intervention Trial of Exercise Training in Older Adults

Abstract: Research has shown the human brain is organized into separable functional networks during rest and varied states of cognition, and that aging is associated with specific network dysfunctions. The present study used functional magnetic resonance imaging (fMRI) to examine low-frequency (.008<.08 Hz) coherence of cognitively relevant and sensory brain networks in older adults who participated in a one-year intervention trial, comparing the effects of aerobic and non-aerobic fitness training on brain function and cognition. Results showed that aerobic training improved the aging brain’s resting functional efficiency in higher-level cognitive networks. One year of walking increased functional connectivity between aspects of the frontal, posterior, and temporal cortices within the Default Mode Network and a Frontal Executive Network, two brain networks central to brain dysfunction in aging. Length of training was also an important factor. Effects in favor of the walking group were observed only after 12 months of training, compared to non-significant trends after six months. A non-aerobic stretching and toning group also showed increased functional connectivity in the DMN after six months and in a Frontal Parietal Network after 12 months, possibly reflecting experience-dependent plasticity. Finally, we found that changes in functional connectivity were behaviorally relevant. Increased functional connectivity was associated with greater improvement in executive function. Therefore the study provides the first evidence for exercise-induced functional plasticity in large-scale brain systems in the aging brain, using functional connectivity techniques, and offers new insight into the role of aerobic fitness in attenuating age-related brain dysfunction.

Are expert athletes 'expert' in the cognitive laboratory? A meta-analytic review of cognition and sport expertise

Abstract: SUMMARY Recent literature has demonstrated the usefulness of fitness and computer-based cognitive training as a means to enhance cognition and brain function. However, it is unclear whether the combination of fitness and cognitive training that results from years of extensive sport training also results in superior performance on tests of cognitive processes. In this study we examine, in a quantitative meta-analysis (k ¼20), the relationship between expertise in sports and laboratory-based measures of cognition. We found that athletes performed better on measures of processing speed and a category of varied attentionalparadigms, andathletesfrominterceptive sporttypesandmalesshowedthelargesteffects. Based on our results, more research should be done with higher-level cognitive tasks, such as tasks of executive function and more varied sub-domains of visual attention. Furthermore, future studies should incorporate more female athletes and use a diverse range of sport types and levelsof expertise.

Ageing and switching of the focus of attention in working memory: results from a modified N-back task.

Abstract: We conducted two experiments using a modified version of the N-Back task. For younger adults, there was an abrupt increase in reaction time of about 250 ms in passing from N = 1 to N > 1, indicating a cost associated with switching of the focus of attention within working memory. Response time costs remained constant over the range N = 2 to N = 5. Accuracy declined steadily over the full range of N (Experiment 1). Focus switch costs did not interact with either working memory updating (Experiment 1), or global task switching (Experiment 2). There were no age differences in RT costs once general slowing was taken into account, but there was a larger focus-switch-related accuracy cost in older adults than in younger adults. No age sensitivity was found for either updating or global task switching. The results suggest (a) that focus switching is a cognitive primitive, distinct from task switching and updating, and (b) that focus switching shows a specific age-related deficit in the accuracy domain.

Cognitive reserve in ageing and Alzheimer's disease

Abstract: The concept of cognitive reserve provides an explanation for differences between individuals in susceptibility to age-related brain changes or pathology related to Alzheimer's disease, whereby some people can tolerate more of these changes than others and maintain function. Epidemiological studies suggest that lifelong experiences, including educational and occupational attainment, and leisure activities in later life, can increase this reserve. For example, the risk of developing Alzheimer's disease is reduced in individuals with higher educational or occupational attainment. Reserve can conveniently be divided into two types: brain reserve, which refers to differences in the brain structure that may increase tolerance to pathology, and cognitive reserve, which refers to differences between individuals in how tasks are performed that might enable some people to be more resilient to brain changes than others. Greater understanding of the concept of cognitive reserve could lead to interventions to slow cognitive ageing or reduce the risk of dementia.

The projected effect of risk factor reduction on Alzheimer's disease prevalence

Abstract: At present, about 33·9 million people worldwide have Alzheimer's disease (AD), and prevalence is expected to triple over the next 40 years. The aim of this Review was to summarise the evidence regarding seven potentially modifiable risk factors for AD: diabetes, midlife hypertension, midlife obesity, smoking, depression, cognitive inactivity or low educational attainment, and physical inactivity. Additionally, we projected the effect of risk factor reduction on AD prevalence by calculating population attributable risks (the percent of cases attributable to a given factor) and the number of AD cases that might be prevented by risk factor reductions of 10% and 25% worldwide and in the USA. Together, up to half of AD cases worldwide (17·2 million) and in the USA (2·9 million) are potentially attributable to these factors. A 10-25% reduction in all seven risk factors could potentially prevent as many as 1·1-3·0 million AD cases worldwide and 184,000-492,000 cases in the USA.

Exercise as medicine – evidence for prescribing exercise as therapy in 26 different chronic diseases

Abstract: This review provides the reader with the up-to-date evidence-based basis for prescribing exercise as medicine in the treatment of 26 different diseases: psychiatric diseases (depression, anxiety, stress, schizophrenia); neurological diseases (dementia, Parkinson's disease, multiple sclerosis); metabolic diseases (obesity, hyperlipidemia, metabolic syndrome, polycystic ovarian syndrome, type 2 diabetes, type 1 diabetes); cardiovascular diseases (hypertension, coronary heart disease, heart failure, cerebral apoplexy, and claudication intermittent); pulmonary diseases (chronic obstructive pulmonary disease, asthma, cystic fibrosis); musculo-skeletal disorders (osteoarthritis, osteoporosis, back pain, rheumatoid arthritis); and cancer. The effect of exercise therapy on disease pathogenesis and symptoms are given and the possible mechanisms of action are discussed. We have interpreted the scientific literature and for each disease, we provide the reader with our best advice regarding the optimal type and dose for prescription of exercise.