Changes in plasma and platelet BDNF levels induced by S-citalopram in major depression.

Background: Neuroplastic processes are thought to be involved in the pathophysiology of major depression. It has been reported that serum brain-derived neurotrophic factor (BDNF) is decreased in depressed patients.

Objectives: Compare BDNF levels in depressed patients and healthy controls in platelet poor plasma and in washed platelets. Observe the effects of 8- and 24-week treatment with S-citalopram on these levels.

Methods: We assessed the levels of BDNF in platelet poor plasma and in washed platelets from 18 major depression patients, and compared them with 14 healthy controls. Blood samples were obtained from patients before and during treatment (8 and 24 weeks) with a selective serotonin reuptake inhibitor, S-citalopram.

Results: A significant decrease in severity of depressive symptoms was observed from the first month of treatment with S-citalopram, and symptoms continued decreasing until the 6th month. Plasma BDNF levels in untreated patients appeared significantly increased (p<0.01) but reached values similar to those of controls at the 24th week. In contrast, levels of platelet BDNF appeared significantly decreased (p<0.05), but treatment also normalized levels so that values obtained were equivalent to those of controls.

Conclusions: Untreated depressed patients showed increased plasma BDNF levels and decreased platelet BDNF levels, as compared with control subjects, and tend to normalize during treatment with S-citalopram for 24 weeks, with BDNF reaching levels similar to those in healthy controls at the 24th week in both samples. We observed that improvement in depressive symptoms was accompanied by normalization of plasma and platelet BDNF levels.