Depression in Parkinson's disease: biogenic amines in CSF of "de novo" patients

Etiology of depression in Parkinson's disease (PD) is associated with serotonergic dysfunction. Previous studies, supporting this hypothesis, were performed on patients treated with antiparkinsonian drugs. To eliminate the influence of parkinsonian drug therapy and to elucidate significance of different biochemical pathways in PD associated with depression we determined levels of biogenic amines in cerebrospinal fluid (CSF) of 26 untreated "de novo" Parkinsonian patients.

Patients were scored with the Hamilton depression scale (HD) and subdivided into groups with HD score > or = 18 and HD score < 18. Diagnosis of depression was made according to DSM III R. Both groups were matched for age and motor disability.

In both groups no significant differences appeared between CSF levels of dopamine, noradrenaline, 3,4-dihydroxyphenylacetic acid, homovanillic acid, 3-methoxy-4-hydroxyphenylglycol and 5-hydroxyindole acetic acid, determined by high-performance liquid chromatography.

In contrast to previous studies on treated Parkinsonian patients no sign of altered serotonin metabolism especially in context with severity of depression in early stages of PD was found. Due to our results, we suggest, that biochemical markers of depression in CSF of PD may be influenced by antiparkinsonian therapy and that depression in PD may respond to serotonin reuptake inhibitors mainly in later stages of PD.