Dysphoria, dopaminergic medication and spatial memory in Parkinsons disease

Abstract

Depression is considered a potential risk factor for developing cognitive deficits and dementia during the progression of Parkinson's disease (PD). Depression and dysthymia are also among the most frequent neuropsychiatric comorbidities, especially in later stages of PD. Regardless of the depression diagnosis, clinical and subsyndromal depressive symptoms in PD patients are associated with decreased daily functioning. However, very little is known about subsyndromal depressive symptoms and their relations to cognitive function and dopamine medication in PD. Here we investigated depressive symptoms and spatial memory performance in 34 early PD patients compared to 36 matched healthy controls in a pharmacobehavioral cross-over study. Despite that none of the PD patients fulfilled clinical criteria for major depression or dysthymia, PD patients showed elevated scores of depressive symptoms compared to healthy controls. Depressive symptom load was further negatively correlated with spatial memory performance in PD patients when off dopaminergic medication. Furthermore, it could be shown that the factor dysphoria but not retardation or vegetative symptoms of the MADRS was associated with reduced spatial memory off dopaminergic medication. Present findings indicate that under dopaminergic withdrawal affective symptoms of depression i.e., dysphoria may be associated with spatial memory deficits in early PD patients. Future studies are needed to specify the underlying mechanisms and interactions of depressive symptoms and dopaminergic treatment in PD, especially in context of clinically relevant depression.