Monoamines, BDNF, IL-6 and corticosterone in CSF in patients with Parkinson’s disease and major depression

The biochemical basis of major depression (MD) in Parkinson’s disease (PD) is largely unknown. To increase our understanding of MD in PD patients, the levels of monoamine metabolites (HVA, 5-HIAA and MHPG), BDNF, orexin-A, IL-6 and corticosterone were examined in cerebrospinal fluid. The analyses were performed in MD patients with (n = 11) and without (n = 12) PD at baseline and after 12 weeks’ of treatment with the antidepressant citalopram, and in patients with solely PD (n = 14) at baseline and after 12 weeks. The major findings were that PD patients with MD had significantly lower baseline levels of MHPG, corticosterone and IL-6 when compared to patients with solely MD. In response to citalopram treatment, patients with solely MD exhibited an expected decrease in 5-HIAA and MHPG levels which was not found in PD patients with MD. Moreover, the levels of BDNF and IL-6 were lower in PD patients with MD compared with patients with solely MD after treatment with citalopram. Thus, the biochemical basis and the response to citalopram differ between PD patients with MD and patients with solely MD.