Apathy predicts more severe parkinsonism in Alzheimer's disease.

OBJECTIVES: Parkinsonian signs are frequent in Alzheimer disease (AD) and are associated with a faster cognitive decline, worse quality of life, and early nursing home admission. Cross-sectional studies in AD reported a significant association between parkinsonism and apathy. The aim of this study was to assess the chronological association between apathy and parkinsonism in AD.
DESIGN: Longitudinal study of a consecutive series of patients with AD.
SETTING: Dementia clinic from a tertiary clinical center. PARTICIPANTS: One hundred sixty-nine patients meeting diagnostic criteria for AD. INTERVENTION: A consecutive series of 169 patients with probable AD were assessed for the presence of parkinsonism, cognitive deficits, apathy, and depression with the Unified Parkinson's Disease Rating Scale and a comprehensive neuropsychiatry assessment. One hundred thirty-six (80%) of the patients had a follow-up assessment between 1 and 4 years after the baseline evaluation. MEASUREMENTS: Scores on apathy, parkinsonism, and depression scales at follow-up were the main outcome measures.
RESULTS: Patients with apathy at baseline or those who developed apathy during follow-up had a significant increase in parkinsonism at follow-up when compared with patients with no apathy at both assessments. The association between apathy and increasing parkinsonism was unrelated to age, gender, the severity of cognitive deficits, the presence of depression, or use of psychotropic medications. On the other hand, neither the presence of parkinsonism nor depression at baseline was significantly associated with more severe apathy at follow-up.
CONCLUSION: Apathy may be an early manifestation of a more aggressive AD phenotype characterized by loss of motivation, increasing parkinsonism, a faster cognitive and functional decline, and more severe depression.