Apathy in patients with Parkinson’s disease following deep brain stimulation of the subthalamic nucleus

Objective Apathy has been reported as a possible adverse effect of deep brain stimulation of the subthalamic nucleus (STN-DBS). We investigated the prevalence and severity of apathy in 22 patients with Parkinson's disease (PD) who underwent STN-DBS, as well as the effects of apathy on quality of life (QOL). Methods All patients were assessed with the Lille Apathy Rating Scale (LARS), the Apathy Scale (AS), and the Parkinson's Disease Questionnaire and were compared to a control group of 38 patients on pharmacotherapy alone. Results There were no significant differences in the prevalence or severity of apathy between patients who had undergone STN-DBS and those on pharmacotherapy alone. Significant correlations were observed between poorer QOL and degree of apathy, as measured by the LARS (p<0.001) and the AS (p=0.021). PD-related disability also correlated with both apathy ratings (p<0.001 and p=0.017, respectively). Conclusion Our findings suggest that STN-DBS is not necessarily associated with apathy in the PD population; however, more severe apathy appears to be associated with a higher level of disability due to PD and worse QOL, but no other clinico-demographic characteristics.