Editor’s Pick: Clinical Significance of Apathy in Parkinson’s Disease

Apathy, or lack of motivation, is increasingly recognised as a major factor affecting quality of life and prognosis in Parkinson’s disease (PD). Impacting every stage of the disease, including de novo cases, reports have suggested it can affect up to 70% of patients. Despite the pervasiveness of apathy in PD, challenges remain in its detection, clinical assessment, and treatment. Strong overlap with depression and anhedonia can complicate diagnosis, and although common features exist between all of these neuropsychiatric conditions, dissociations may be suggestive of different underlying brain mechanisms. Several lines of evidence have implicated frontostriatal reward and effort-related neural pathways in the genesis of apathy, but the precise processes remain to be fully elucidated. The mainstay of current approaches in the treatment of apathy rely on dopamine replacement, although there is growing evidence that support a potential role for other agents. This paper reviews the current understanding of this important non-motor complication of PD.