Apathy in Parkinson's Disease: A Diagnostic Conundrum Explored in a Cohort Characterization Study.

Objective: Apathy is a prevalent neuropsychiatric feature of Parkinson's disease (PD), marked by reduced goal-directed behavior. Apathy is distinct from depression and significantly affects daily functioning and quality of life. Despite this, the DSM-5 does not acknowledge apathy as its own diagnostic category. The authors sought to examine how individuals with PD who score high on a self-report apathy scale are diagnostically classified by psychiatrists within a clinical setting.

Methods: Fifty-five individuals with "pure apathy" were identified from a larger clinical convenience sample of 458 patients with PD. The pure-apathy group consisted of patients who scored above the clinical cutoff on a self-report measure of apathy but whose symptoms were below the cutoffs for depression and anxiety measures. These patients also received a standard clinical psychiatric evaluation using DSM-5 criteria. The authors examined the diagnoses provided by psychiatrists who were unaware of results of the mood scales.

Results: More than half (53%) of the pure-apathy group had received no psychiatric diagnosis. The remainder had received the following diagnoses: anxiety (27%), depression (5%), comorbid depression and anxiety (5%), and other psychiatric diagnoses (9%). The most common anxiety diagnoses were unspecified or other specified anxiety disorders and generalized anxiety disorder. The most common depression diagnoses were unspecified or other specified depressive disorders.

Conclusions: This study highlights a gap in diagnosing psychiatric conditions in PD, specifically for individuals with primarily apathetic presentations. More than 50% of PD patients in the pure-apathy group had received no psychiatric diagnosis, possibly resulting in unmet clinical needs.