Neuropsychiatric symptoms in Serbian patients with Parkinson's disease.

Background: Parkinson's disease [PD] is associated with wide variety of neuropsychiatric symptoms, although it is primarily considered as a movement disorder.

Objective: To examine whether PD patients can be meaningfully classified into subgroups according to their neuropsychiatric symptoms, reported by their caregivers.

Methods: Three hundred and sixty PD patients [mean age=63.5, SD=10.3] from the academic clinical setting were assessed with the 12-subscale Neuropsychiatric Inventory Questionnaire [NPI]. A two-stage cluster analysis was used to identify the subgroups groups of patients with specific neuropsychiatric profile.

Results: Three hundred and twenty-one PD patients [89%] showed at least one psychiatric symptom. The most common symptoms were anxiety [73.1%], depression [64.7%], and apathy [51.7%], and nighttime disturbance [51.3%], whereas the least common were euphoria [0.3%], and delusions [1.7%]. The mean [SD] total NPI composite score was 16.9 [17.4]. Two hundred eight PD subjects [58%] of the total sample had at least one symptom with a score ≥4. Three clusters were identified: a] Cluster 1, with no or few NPI symptoms [n=200; 55.6%]; b] Cluster 2, with mild to moderate symptoms on depression, anxiety and apathy scales [n=140; 38.9%]; and c] Cluster 3 with high agitation, disinhibition and irritability scores [n=20 patients; 5.6%]. PD subjects with clinically significant neuropsychiatric symptoms were older with more severe motor and cognitive impairment.

Conclusions: This study emphasizes the high prevalence and importance of neuropsychiatric symptoms in PD patients; therefore clinicians should also focus on treating in parallel with motor symptoms.