Risk factors associated to the presentation of episodes of major depression in a population of outpatients with Parkinson's disease

Introduction. Depression is a frequently occurring problem in Parkinson's disease (PD). The purpose of this study is to describe the characteristics of episodes of major depression (EMD) in a population of outpatients with PD and the risk factors linked to their appearance. Patients and methods. We conducted an open study involving 85 patients with PD; their mean age was 65.8 +/- 12.3 years and the mean length of time since disease onset was 7.2 +/- 5 years. Data that was collected included information from the patient record, evaluation with the Motor Examination section of the Unified PD Rating Scale (UPDRS-III), the Parkinson Mini-Mental test, the Neuropsychiatric Inventory (NPI) and the short version of Beck's Depression Inventory (BDI). EMD were diagnosed clinically by means of a semi-structured interview that allowed us to examine the symptoms that are included in the DSM-IV criteria for diagnosis of EMD. Results. In 21 cases (24.7%) DSM-IV criteria for EMD were satisfied, with a BDI score (mean standard deviation) of 17.5 +/- 6.2. In 64 cases (75.3%) who did not fulfil the criteria for EMD, the BDI score was 6.4 +/- 4.7 (p < 0.001). The items on the UPDRS-III related to the dopaminergic response in patients with EMD were 24.9 +/- 11.9 and in patients without EMD the values were 21.2 +/- 10.9 (NS). Those not related to the dopaminergic response in patients with EMD were 9.9 +/- 5.3 and in those without EMD the values were 62 +/- 4.6 (p < 0.001). Conclusion. In our sample, the presence of motor symptoms that do not respond to levodopa in patients with PD is a risk factor for the appearance of EMD.