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

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.

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.

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.

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.