Background Apathy is a common neuropsychiatric symptom in patients with Huntington's disease (HD).

Aims To examine the incidence, course and predictors of apathy in subjects with HD.

Methods At baseline 152 HD subjects were examined with the Apathy Scale (AS), in relation to socio-demographic, clinical, and neuropsychiatric characteristics. Two-year follow-up evaluation included 122 (80%) subjects. Incident and persistent apathy were examined using logistic regression analysis.

Results At follow-up, 13 (14%) of the 88 subjects free of apathy at baseline had developed apathy. Of the 34 subjects with apathy at baseline, 14 (41%) had recovered from apathy whereas 20 (59%) had persistent apathy. In subjects without apathy at baseline, univariate predictors of incident apathy were low Mini Mental State Examination score (MMSE; p=0.01) and Total Functional Capacity (TFC; p=0.02) scores at baseline. A low baseline MMSE score remained a predictor in multivariate analysis. In subjects with apathy at baseline, univariate baseline predictors of persistent versus remitted apathy after two years were older age (p=0.006), longer disease duration (p=0.02), and lower scores on TFC (p=0.02), Symbol Digit Modalities Test (SDMT; p=0.008) and Stroop Word Test (p=0.04). A low baseline SDMT was the only predictor of persistent apathy in multivariate analysis.

Conclusion Apathy in HD is most closely linked to global and executive cognitive performance, predicting incident and persistent apathy, respectively. Because apathy may be reversible it is important to examine HD patients for treatable causes of apathy.