Age-associated decrease in serum glial cell line-derived neurotrophic factor levels in patients with major depressive disorder.

BACKGROUND

Many studies have supported the role of neurotrophic hypothesis in the pathophysiology of mood disorders. This study examined serum levels of glial cell line-derived neurotrophic factor (GDNF), one of the neurotrophic factors, in patients with major depressive disorder (MDD) at different disease states.

METHODS

The serum GDNF levels were measured in 55 patients with MDD (29 severe patients and 26 remitted patients) and 35 healthy controls by ELISA method. Severity of depressive symptoms was assessed using the 17-item Hamilton Rating Scale of Depression (HAM-D) (HAM-D >/= 19 for severe MDD, HAM-D </= 7 for remitted MDD).

RESULTS

MDD patients were found to have significantly lower serum GDNF levels than healthy controls (p<0.001). This decrease was significant in older-aged (p=0.003) and middle-aged (p=0.026) groups, but not in the younger-aged group. We found no difference in GDNF level between severe and remitted MDD patients.

CONCLUSIONS

In spite of some limitations, our results indicate an age-associated reduction in serum GDNF levels in patients with MDD, further supporting the role of the neurotrophic factor as a disease marker and a new target for developing antidepressant treatment.