 There is sound evidence that quetiapine is effective in the treatment of manic and depressive episodes associated with Bipolar Disorder BD Yatham et al 2006. However, even with the development of effective new treatment options, not all patients respond to treatments available. Biological markers have been investigated as predictors of response to treatment and of remission of symptoms. This would explain in part the individuals differences in the response to treatment, taking into account the genetic variability plus environmental factors influencing specific biological markers. A potential biological marker of response to treatment in BD would be the levels of neurotrophins, as they are, in fact, altered during acute mood episodes Cunha et al 2006. Among neurotrophins, the Brain-Derived Neurotrophic Factor BDNF has been repeatedly and consistently reported to be associated with BD physiopathology Post 2007. Furthermore, medications that are known to be effective in BD, like lithium and divalproex, increase BDNF levels. Diverse sources of evidence provide support to the alteration of BDNF in mood disorders: 