Parkinson and depression: review and outlook

Depression in Parkinson's Disorder (DPD) has been estimated to appear in up to 40% of people with PD and negatively impacts quality of life, motor and cognitive deficits and functional disability. Knowledge of the pathophysiology of DPD is unclear, DPD may be related to dysfunction in subcortical nuclei and the prefrontal cortex, striatal-thalamic-prefrontal and basotemporal limbic circuits, brainstem monoamine, and indolamine (i.e. dopamine, serotonin, and norepinephrine) systems. DPD is characterized by sadness, loss of interest, increased exhaustibility, feelings of helplessness, reduced drive, dysphoria, irritability, and pessimism about future. The diagnosis is complicated by overlap with PD symptoms, Detection of depression in PD should be made by psychometric depression scales. DPD is underrecognized and undertreated in clinical practice. Treatment mainly includes antidepressive medications and behavioral interventions as psychotherapy. Dopamine agonists showed some antidepressant effects, there are no sufficient numbers of RCTs. Important randomized clinical trials (RCTs) are summarized. SSRIs and SNRIs have a satisfying efficacy in DPD. TCAs are also good for improving depression. Side effects of different antidepressants (e.g. TCAs, SSRIs, SNRIs, bupropion, MAOIs) and potential interactions should be considered. In existing guidelines so far no statements, algorithms and recommendations are given for diagnosis and treatment of DPD. Methodologically adequate designed RCTs and comparative studies (NIS) which offer evidence-based results are urgently needed having the impact of DPD in mind.