Frontal lobe cognitive functions in aging: methodologic considerations.

The empirical literature has been contradictory regarding whether frontal functions decline with age, perhaps due to important differences across studies in medical and psychiatric exclusion criteria. We review literature and present preliminary data suggesting that frontal lobe functions are particularly affected by several medical and psychiatric disorders common in old age. Investigations of frontal lobe functions in aging require careful screening of subject samples; otherwise, any impact of age on cognition is contaminated by the effects of coexistent physical and/or psychiatric illness.