Increased suicide risk and clinical correlates of suicide among patients with Parkinson's disease

•We explored 4362 Parkinson's disease patients enrolled in a clinical registry.•Standardized mortality ratio for suicide was 1.99, out of 29 suicide observed.•Retrospective case-control study was conducted to identify correlates of suicide.•Depression, delusion and higher L-dopa dosage were associated with suicide.•We suggest that suicide risk in PD is higher than that of the general population.

IntroductionParkinson's disease (PD) is a debilitating, neurodegenerative condition frequently complicated by psychiatric symptoms. Patients with PD may be at higher risk for suicide than the general population, but previous estimates are limited and conflicting. The aim of this study is to estimate the suicide rate based on the clinical case registry and to identify risk factors for suicide among patients diagnosed with PD.MethodsThe target sample consisted of 4362 patients diagnosed with PD who were evaluated at a general hospital in Seoul, South Korea, from 1996 to 2012. The standardized mortality ratio for suicide among PD patients was estimated. In order to identify the clinical correlates of suicide, case-control study was conducted based on retrospective chart review. The 29 suicide cases (age: 62.3 ± 13.7 years; females: 34.5%) were matched with 116 non-suicide controls (age: 63.5 ± 9.2 years; females 56.9%) by the year of initial PD evaluation.ResultsThe SMR for suicide in PD patients was 1.99 (95% CI 1.33-2.85). Mean duration from time of initial diagnosis to suicide among cases was 6.1 ± 3.5 years. Case-control analysis revealed that male, initial extremity of motor symptom onset, history of depressive disorder, delusion, any psychiatric disorder, and higher L-dopa dosage were significantly associated with suicide among PD patients. Other PD-related variables such as UPDRS motor score were not significantly associated with death by suicide.ConclusionSuicide risk in PD patients is approximately 2 times higher than that in the general population. Psychiatric disorders, and also L-dopa medication need further attention with respect to suicide.