BEHAVIORAL DISTURBANCE AND IMPAIRMENT OF EXECUTIVE FUNCTIONS AMONG THE ELDERLY

Among the elderly, measures of general cognitive ability are not consi stently related to the capacity for independent functioning. Some olde r patients perform well on global tests of cognition, yet demonstrate behavior that is disruptive to their lives and those of their families . The genesis of these behavior problems is poorly understood, and car egivers, both professional and non-professional, frequently attribute their behavior to wilful misconduct. We propose that there are suffici ent data concerning the so-called executive functions of the brain and their impairment in both normal aging and various types of dementia, to support the hypothesis that many behavioral disturbances among deme nted older adults are a function of different degrees of loss of the c apacity to engage in purposeful, goal-directed activity. The executive functions are complex, and include the capacities for planning, organ ization and active problem solving, and the ability to engage in purpo seful, goal-directed behavior. Impaired executive functioning is commo n in dementia, but also may be present in the context of an age-relate d decline in the speed and capacity of information processing and vary ing levels of general cognitive impairment. We review data in support of this model, and discuss a patient whose case illustrates deficits i n the independent regulation of behavior, an important executive funct ion mediated primarily by the prefrontal area. In the discussion we ad dress several hypotheses suggested by this perspective.