Identification of suicide candidate genes in amygdala and its application to neuroimaging studies

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1. We studied the clinical and psychological characteristics associated with suicidality based on the history of lethal suicide attempt in 76 patients mainly with mood disorders. Hopelessness rather than depression, aggression in less than 40 years old patients and neuroticism were associated with suicidality. The perspectives on death were not associated with suicidality.2. We performed the profiling of mRNA expressions in amygdala of suicide brains. The 21 increased and the 9 decreased expressions of genes were identified. Among the genes with increased expressions, the polymorphisms of 14-3-3 ε gene were associated with suicide. Any polymorphisms in genes with the decreased expressions were not associated with suicide.3. Among the functional gene polymorphisms which affect a hypothalamic-pituitary-adrenal system (HPA system), we found the significant associations of OPRM1 Asn40Asp, ACE I/D and ADEA2A C-1291G polymorphism with suicide.4. For functional MRI, we made a neuropsychological task which activates emotion. A stronger activation in amygdala and posterior cingulate gyrus was shown in case of recognition in emotionally negative words, compared with emotionally neutral words. We made the tasks comprising the recall of past negative or positive episodes and the imagination of future negative or positive episodes. The activations were found in the medial frontal cortex, dorsolateral prefrontal cortex posterior cingulate gyrus.