Apathy and executive dysfunction in mild cognitive impairment and Alzheimer disease.

OBJECTIVE: The authors assessed and contrasted frontally mediated behavior changes in patients diagnosed with Mild Cognitive Impairment (MCI) and Alzheimer disease (AD). Apathy, executive dysfunction, and disinhibition are common in AD, but these behaviors have not been studied in MCI. METHODS: Participants were patients diagnosed with AD (n=25) or MCI (n=20). Current behavior and behavior before the onset of cognitive impairment was rated by knowledgeable informants on the Frontal Systems Behavior Scale (FrSBe). RESULTS: Apathy and executive dysfunction exhibited the greatest increase in both MCI and AD, and both increased significantly over baseline scores. No significant differences in behavior change were found between the two groups. Behavior change was moderately correlated with a measure of dementia severity, indicating that greater disease severity was associated with more abnormal behavior. CONCLUSION: Changes in frontally-mediated behaviors are common in very early and mild stages of cognitive impairment, even before functional decline in daily living is evident. These behaviors deserve more study in MCI because they may have implications for prognosis, treatment adherence, family distress, and patient quality of life.