Age-related changes in the neural control of standing balance

Abstract

Controlling body sway while standing is an active process involving lower as well as higher neural centers. This chapter examines how the central nervous system controls undisturbed standing balance and summarizes the current knowledge concerning the effects of task difficulty and old age on postural control of standing. There is an age-related reorganization of neural control of standing, with decreased efficacy of Ia afferents to activate spinal motor neurons, increased cortical activation and corticospinal excitability, and reduced intracortical inhibition. Age does not affect the motor control strategy of reducing intracortical inhibition with increasing postural challenge. However, the threshold for down-modulation decreases with aging. It thus seems that motor cortical involvement in the control of standing balance becomes more prominent with age and postural task difficulty. Future studies will determine if it is beneficial and necessary through interventions to reduce the cortical involvement in the control of standing balance in healthy old adults especially if this involvement should increase in old adults with a history of falls.