Introduction: Stress, glucocorticoids and anti-depressant treatment have been found to modulate the expression of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF). Recent research suggests that serum BDNF concentration is reduced in depression and that successful antidepressant treatment leads to an increase in serum BDNF concentration.
Methods: We studied depressed patients receiving a standardized antidepressant treatment with either 150 mg amitriptyline (n=20) or 40 mg paroxetine (n=20) for 36 days in a prospective design. Changes in the concentrations of serum neurotrophins and salivary cortisol in response to antidepressant treatment were assessed.
Results: Independent of clinical efficacy there was a significant 'treatment' by 'medication' interaction effect on BDNF serum concentrations that indicated a decline of BDNF by 12% in paroxetine-treated patients while there was an increase by 13% in amitriptyline-treated patients. Neither antidepressant altered NGF concentrations. The changes in cortisol and neurotrophin concentrations were not related.
Discussion: Changes in BDNF serum concentrations as a result of antidepressant therapy depend on the antidepressant instead of being a general characteristic of response to antidepressant treatment.