[Depression and Parkinson's disease: neurobiologic foundations and therapeutic management]

The prevalence of depression in Parkinson's disease (PD) is estimated to be around 40% and generally takes the form of dysthymia. Although psychological factors probably contribute to depression, data point to a relation to structural and biochemical changes linked to PD. Thus, the onset of motor impairment is often preceded by a depressive episode, although there is no consistency between the seriousness of motor disability and depression. Furthermore, depression aggravates the memory and language impairments of PD and is thought to be a risk factor for developing dementia. Regional cerebral blood flow abnormalities in the medial frontal and cingulate cortices and low 5-HIIA concentrations in cerebro-spinal fluid suggest that degeneration of the mesocorticolimbic dopaminergic system as well as dorsal raphe changes may be implicated. Assessment of depression in PD is difficult, as none of the currently available scales were specifically designed for patients with this disease Furthermore, there is a lack of well-controlled studies showing that current antidepressants are effective in PD patients or are safe for use when the motor, cognitive and autonomic impairments of PD are present.