Subthreshold depression in patients with Parkinson's disease and dementia - clinical and demographic correlates

Background About 40% of the patients with Parkinson's disease (PD) have depressive symptoms, either major depression (MD) or subthreshold depression. Depression was found to be associated with age and age at onset of PD, female gender, more severe parkinsonism, in particular with left-sided and akinetic-ligid symptoms, more functional impairment and cognitive impairment. However, the findings are inconsistent and partly contradictory and most of the studies focused on major depression in PD without dementia. The aim of this study was to examine the relationship between subthreshold depression and other clinical features in 538 PD patients with dementia but without MD drawn from a randomized, placebo-controlled multicentre trial of rivastigmine in PD. Results One hundred and sixteen patients (21%) had subthreshold depression. Depression was associated with a younger age and age at onset and female gender, but not with severity of parkinsonism, cognition or activities of daily living or laterality of motor symptoms. However, in male patients, an association between depression and left-sided parkinsonism was found. Conclusion In contrast to previous findings in PD patients with major depression but without dementia, we found no relationship between subthreshold depression and other clinical symptoms in patients with PDD. Copyright (c) 2007 John Wiley & Sons, Ltd.