The findings described above suggest that neuropsychological, neurophysiological and neuroimaging alterations may represent valuable endophenotypes in SB (Figure 1), but with the exception of impulsive aggression do not currently meet stringent endophenotype criteria including heritability, state independence and familiar aggregation both in affected and unaffected relatives. Altered cognitive and emotional processes, modulated by specific genetic polymorphisms, were found in patients, even in the euthymic phase. These alterations may decrease the ability of some individuals to respond with resilience to life stressors or facilitate acting on emerging suicidal ideas. A number of other potential endophenotypes for SB exist as well, including hypothalamic–pituitary–adrenal axis hyperfunction.10, 68
