Mapping vulnerability to bipolar disorders

Introduction Although early interventions in individuals with bipolar disorder may reduce the associated personal and economic burden, the neurobiologic markers of enhanced risk are unknown. Objectives The objective of this paper is to analyze the existence of neurobiological abnormalities in individuals with genetic risk for developing bipolar disorder (HR) Material and methods A literature search was performed in the available scientific literature on the subject study object, by searching MEDLINE. Results There were 37 studies included in this systematic review. The overall sample for the systematic review included 1258 controls and 996 HR individuals. No significant differences were detected between HR individuals and controls in the selected ROIs (regions of interest): striatum, amygdala, hippocampus, pituitary and frontal lobe. The HR group showed increased grey matter volume compared with patients with established bipolar disorder. The HR individuals showed increased neural response in the left superior frontal gyrus, medial frontal gyrus and left insula compared with controls. The overall results found no significant differences between individuals at high genetic risk and controls since the magnitude of the association as corresponds to an OR  Conclusion There is accumulating evidence for the existence of neurobiologic abnormalities in individuals at genetic risk for bipolar disorder at various scales of investigation. The etiopathogenesis of bipolar disorder will be better elucidated by future imaging studies investigating larger and more homogeneous samples and using longitudinal designs to dissect neurobiologic abnormalities that are underlying traits of the illness from those related to psychopathologic states, such as episodes of mood exacerbation or pharmacologic treatment.