Apathy and executive function in Alzheimer's disease.

Apathy is a common behavioral disturbance in patients with Alzheimer's disease (AD). Recent studies have linked the presence of apathy to alterations in frontal lobe functions, but few studies have explored the relationship using standard neuropsychological measures in patients with AD. We administered a comprehensive battery of neuropsychological tests and a behavior rating scale to 80 patients with AD. We explored the relationship of apathy to executive dysfunction. AD patients with apathy performed significantly worse on tests of executive function (WAIS-R Digit Symbol, Trail-Making, Stroop Color Interference Test) than AD patients without apathy. The presence of dysphoria did not modify these results and no significant relationships were found between tests of executive functions and dysphoria. Performance on executive measures as a group were effective in correctly classifying patients as apathetic or nonapathetic with 75% accuracy. Neuropsychological measures not dependent on executive functions were unrelated to apathy. Apathy is associated with executive dysfunction and not with other neuropsychological deficits. Apathy is distinct from dysphoria.