Brain, cognition and physically active lifestyle in healthy ageing

Abstract

Normal ageing is accompanied by profound changes in brain structure and declines in the automatic processing of sensory stimuli, which in turn lead to altered cognitive performance. However, behaviour and lifestyle factors, such as physical activity, may help to maintain the brain’s structural connectivity and function, as well as cognitive functioning in old age. Study I examined the effects of age on the brain’s capability to detect changes in somatosensory stimuli by recording event-related potentials (ERPs) in response to electrical stimulation of different fingers in young and older adults. The results of Study I show that somatosensory mismatch response (sMMR) was attenuated in amplitude in older subjects as compared to young adults, indicating age-related decline in somatosensory change detection. Study II investigated whether age- related decline in the change detection mechanism in somatosensory and auditory modalities is associated with age-related alterations in cognitive performance, and whether physical fitness modulates this relationship. The results of Study II showed that the higher the sMMR amplitudes were the better executive functions older adults had. In addition, better aerobic fitness was linked to higher somatosensory ERP amplitudes and to better executive functions. Study III examined whether physical activity mediates the effect of age on the brain’s white matter integrity, and whether, in tracts sensitive to physical activity, this integrity mediates age-related decline in cognitive speed and fluid cognitive capabilities. The results of Study III show that overall daily physical activity mitigates age-related decline of white matter integrity. In addition, physical activity that benefits white matter integrity in the genu of the corpus callosum is associated with reduced ageing-related slowing of reaction times. Overall, these results indicate that age-related changes in the brain’s electrophysiological responses are linked to changes in cognitive performance, and that a physically active lifestyle protects against age-related structural disconnection and cognitive slowing, as good aerobic fitness helps to preserve physiological and executive functions in ageing.