Low testosterone levels may be associated with suicidal behavior in older men while high testosterone levels may be related to suicidal behavior in adolescents and young adults: a hypothesis.

Several lines of evidence suggest that there is an association between testosterone and suicidal behavior. A link between testosterone and the neurobiology of suicidal behavior may be related to: a) a direct effect of testosterone on suicidality via certain brain mechanisms; and/or b) a testosterone influence on aggression and, consequently, suicidality; and/or c) a testosterone effect on mood and, consequently, suicidality; and/or d) a testosterone effect on cognition and, consequently, suicidality. At least one study has demonstrated a relation between high levels of testosterone and suicide in young people. A significant number of studies suggest that high testosterone levels are associated with aggression in adolescents and adults. Multiple lines of evidence indicate that aggression is associated with suicidal behavior. The effect of high testosterone levels on suicidality in adolescents and young adults may be mediated by testosterone-related elevated aggression. It is also possible that, in young people, high testosterone levels are directly linked to suicidality via certain brain mechanisms. In older men, decreased testosterone levels are associated with depressive symptoms and reduced cognitive function, whereas higher blood levels of testosterone are associated with better mood and cognitive functioning. Depression and reduced cognition are associated with suicidal behavior and may mediate the effect of decreased testosterone levels on suicidality. Therefore, it is reasonable to propose that suicidal behavior in adolescents and young adults is associated with high testosterone levels, whereas suicidality in older men is associated with decreased testosterone secretion.