Motor system changes in the aging brain: what is normal and what is not.

Age-related changes in the nervous system may present with physical signs that are not unlike early manifestations of several clinical disorders. Gait disturbances (immobility), balance difficulties (instability), and certain motor control problems (i.e., tremor) are not necessarily signs of a disease state. The clinician needs to be reminded that most physiologic functions decline at a rate of 1% per year, beginning at age 30. Often compounding "natural" decline are the motor problems related to disuse. This is especially true for the inactive individual suffering from depression, cardiac or pulmonary insufficiency, painful joint and muscle conditions, substance abuse and, sometimes, simply social isolation.