Motor activity-based prediction of the presence of apathy in schizophrenia

OBJECTIVE: Apathy, a reduction in self-initiated goal-directed behavior, is a quality-of-life diminishing characteristic of schizophrenia, which often goes underrecognized and undertreated. Actigraphy-derived motor activity measures provide potential objective markers for assessing apathy, but the value for assessing clinically relevant levels of apathy has yet to be determined in patients with schizophrenia. METHODS: Patients with schizophrenia with (SZ+; n = 42) and without (SZ-; n = 40) severe apathy symptoms and a group of age and education matched non-affected individuals (NAC; n = 40) were included. Activity indices derived from actigraphy recordings on two weekend days were compared between the three groups. Logistic regression analyses were conducted to examine whether actigraphy indices could predict presence of 1) a diagnosis of schizophrenia and 2) severe apathy. RESULTS: Lower levels and lower variability of activity and step counts during weekend days and the most active ten-hour period were associated with the presence of a schizophrenia diagnosis, and presence of severe apathy within patients. These associations were independent of sociodemographic, lifestyle status and clinical confounders. Backwards regression revealed that mean steps during the most active ten-hour period exhibited the strongest predictor of apathy severity. CONCLUSION: Results suggest that amount and variability of physical activity as measured with an actigraphy device can help to identify individuals with schizophrenia with high levels of apathy. Especially, the number of steps taken during the most active hours could be used to screen patients with a presence of severe apathy, therefore informing further diagnostics and treatment.