Objective: In this study, it is aimed to compare the level of Brain-Derived Neurotrophic Factor (BDNF) of patients with migraine and fibromyalgia to that of depressive patients and healthy subjects in order to answer the question whether stress is related to pain syndromes. Methods: In the migraine group 27 patients and in the fibromyalgia group 19 patients without any previous antidepressant treatment and psychiatric diagnosis were included. In the depression group, 24 patients with at least eight weeks of antidepressant-free period were invited to the study. In the depression group no co-morbid diagnosis in the first axis was made. Twenty-six subjects without any previous psychiatric diagnosis and psychiatric treatment consisted the control group. For making diagnosis of depression and other first axis disorders Structured Clinical Interview for DSM-IV (SCID-1) was used in all study groups. For the assessment of the severity of depression Hamilton Depression Rating Scale (HAM-D) was applied. The diagnosis of migraine was made according to the criteria of International Headache Society. For the diagnosis of the fibromyalgia the criteria of American College of Rheumatology was used. The severity of pain was assessed with visual analogue scale (VAS) in the migraine and fibromyalgia groups. Serum BDNF was kept at -70 degrees C before testing, and assayed with an ELISA Kit (Promega; Madison, WI, USA), after dilution with the Block and Sample solution provided with the kit. The data were subjected to Kruskal Wallis Test in the comparison of serum BDNF levels. Results: The serum BDNF level of the depression group (21.2 +/- 11.3 ng/ml) was statistically lower (p < 0.0001) than the level of the migraine group (32.2 +/- 10.1 ng/ml), fibromyalgia group (30.7 +/- 8.9 ng/ml) and the control group (31.4 +/- 8.8 ng/ml). The level of BDNF was not significantly different in the migraine, fibromyalgia and control groups. There was no significant correlation between serum BDNF levels, and age and gender. In pain syndromes there was no signification correlation between serum BDNF levels, and mean scores of HAM-D and VAS (r= 0.085; p= 0.579 and r= 0.191; p= 0.204 respectively). Similarly there was no significant correlation between serum BDNF levels and HAM-D scores in the depression group (r=0.122; p= 0.579). Conclusions: Even though the pain syndromes were suggested to be associated with stress, in this present work, serum BDNF level as one of the markers of stress does not support this hypothesis. This might be related to the factor that in pain syndromes such as fibromyalgia or migraine, serum BDNF level may be affected by the alteration in peripheral platelet functions. Furthermore in a limited chronic stress serum BDNF levels tend to be not affected and this may play a significant role in our results
