Aims Depression is the most common neuropsychiatric disturbance in Parkinson's disease. Evidence is accumulating that motor subtype may be a critical risk factor for the development of depression throughout the disease and that the gender prevalence seen for common depression may not hold for patients with Parkinson's disease. Here we set out to analyse a database containing information about motor subtype, gender and depression in a large pool of well-characterised patients with idiopathic Parkinson's disease.
Methods Standardised neurological and psychiatric tests were administered to 224 patients (154 male) suffering from idiopathic Parkinson at the Parkinson Centre Nijmegen (ParC) of the Radboud University Nijmegen Medical Centre (UMCN) in the Netherlands. ParC is an outpatient centre recognised as Centre of Excellence by the National Parkinson Foundation. The data were collected during a 3-day programme for diagnosis and the development of an individual multidisciplinary treatment programme. Data were statistically analysed using SPSS.
Results Of the 224 patients, 74 (33%) suffered from the tremor-dominant subtype, 129 (56%) had a bradykinetic/rigidity subtype and 24 (11%) patients were diagnosed as having a postural instability and gait disorder subtype. Overall and for each of the subtypes, there was a significant higher prevalence of males in the group (minimum t(255)=12.9; p=0.000). We therefore corrected subsequent analyses for this difference in prevalence. Duration of illness did not differ between groups. Our statistical analysis further indicated that the prevalence of depression did not differ between male and female in any of the groups both for minor and major depression.
Conclusions Our data contained a homogenous set of patients suffering from idiopathic Parkinsons disease in a mild to moderate stage. We could not replicate recent evidence of a predominance of depression in the postural instability and gait disorder subtype in this sample possibly due the stage of the disease. Our data, however, do suggest that contrary to the general population there is an equal prevalence of male and female patients suffering from minor or major depression. These results may suggest that there is a different pathophysiology underlying depression in Parkinson's diseases independent of subtype.