Apathy without depression in PD patients

Apathy may be a core feature of Parkinson disease (PD) and can occur in the absence of depression, according to recent trial results.The trial was conducted to examine the hypothesis that apathy is a feature of PD due to the involvement of the mesial frontal cortex and can be dissociated from depression. The trial investigators say it has been proposed that apathy, defined as a primary loss of motivation, loss of interest, and loss of effortful behaviour, can manifest in neurologic disorders as both a symptom and a syndrome. However, it remains unclear as to whether apathy is merely a symptom of depression. Eighty patients with PD were assessed using apathy and depression measures including the Marin Apathy Evaluation Scale, Beck Depression Inventory, and Centers for Epidemiologic Studies-Depression Scale. A further 20 patients with dystonia were included as a clinical control group to determine whether apathy rates are uniquely higher in PD than in other movement disorders.The results showed that there was a significantly higher frequency of apathy in PD patients (51%) than in patients with dystonia (20%). Patients with PD also had significantly more severe apathy scores than patients with dystonia. Apathy in the absence of depression was frequent in PD patients (28.8%) but was not seen in any patient with dystonia (0%). The authors say, "This was the most dramatic and potentially important finding of the study. This finding suggests that apathy in PD, but not dystonia, manifests at a significant level independent of depression level." The authors postulate that PD may cause disruption to mesial frontal-anterior cigulate cortex connections, which seem to be involved in apathy. They explain that it is important to educate caregivers and spouses that apathy is a characteristic of the disorder and may be a direct result of disease pathology. "Thus, apathetic behavior is not under the PD patient's voluntary control and is not oppositional behavior or laziness, but a symptom of PD," they explain.Discussing the results in an accompanying editorial, Dr Richard from Rochester, NY, notes, "The recognition that apathy can be present without depression is important so that we do not inappropriately diagnose and treat a depressive disorder that is not present." Reference...