Motor control and aging: links to age-related brain structural, functional, and biochemical effects

Abstract

Although connections between cognitive deficits and age-associated brain differences have been elucidated, relationships with motor performance are less well understood. Here, we broadly review age-related brain differences and motor deficits in older adults in addition to cognition-action theories. Age-related atrophy of the motor cortical regions and corpus callosum may precipitate or coincide with motor declines such as balance and gait deficits, coordination deficits, and movement slowing. Correspondingly, degeneration of neurotransmitter systems-primarily the dopaminergic system-may contribute to age-related gross and fine motor declines, as well as to higher cognitive deficits. In general, older adults exhibit involvement of more widespread brain regions for motor control than young adults, particularly the prefrontal cortex and basal ganglia networks. Unfortunately these same regions are the most vulnerable to age-related effects, resulting in an imbalance of "supply and demand". Existing exercise, pharmaceutical, and motor training interventions may ameliorate motor deficits in older adults.

Copyright 2009 Elsevier Ltd. All rights reserved.

Figures

Figure 1

“Supply and demand” framework applied to age-related changes in the neural control of movement. Older adults increasing rely on cognitive brain processes for motor control (“cognitive demand”) due to structural and functional declines in the motor cortical regions (MC), cerebellum, and basal ganglia pathways, coupled with reduced neurotransmitter availability. At the same time attentional capacity and other relevant cognitive resources (“cognitive supply”) are reduced due to differential degradation of the prefrontal cortex (PFC) and anterior corpus callosum (CC). Young Adults (YA); Older Adults (OA). Note: we use the term “cognitive” here in a general sense to represent attention, working memory, visuospatial processing, and other functions contributing to motor control.