Also the correlation between migraine and molecules of pain was investigated. Several observation suggested a relationship between low serum levels of vitamin D and higher incidence of chronic pain [37,38]. However, in a large cross-sectional study, Kjaergaard et al. have found that low level of serum vitamin D were associated with non-migraine type of headache [39]. Further studies should be conducted to clarify the potential association of vitamin D and migraine pain. Brain-derived neurotrophic factor (BDNF) is a neurotrophin associated with pain modulation and central sensitization [40]. Fisher et al. have demonstrated that in migraineurs, BDNF was significantly elevated during migraine attacks (31.24 ± 9.31 ng/ml) compared with headache-free periods (24.50 ± 9.17 ng/ml), tension-type headache (20.97 ± 2.49 ng/ml) and healthy controls (21.20 ± 5.64 ng/ml) [41]. This study, showing a correlation between migraine and BDNF, supports the hypothesis that BDNF has a role in the pathophysiology of migraine. The results are in agreement with a pilot study of Tanure et al. [42].