phrenic patients with and without suicidal behavior. In this design, diseased states remain constant while suicidal behavior varies. It should be emphasized that identified genes associated with suicide may or may not be causative, but may be vulnerability genes, or downstream modulating genes. Nevertheless, this technology will provide important candidate genes for future interaction with the pharmaceutical industry in the development of novel therapeutic compounds and could make important contributions to our understanding of the pathophysiology of suicide.
Dysregulation of one of the body’s primary stress response systems, the hypothalamic-pituitary-adrenal (HPA) axis, appears associated with suicidality across psychiatric diagnoses. Such HPA axis dysfunction often develops following adverse developmental experiences and traumatic or chronic stress; HPA axis dysregulation is also implicated in the development of some mental disorders. Although screening for abnormal HPA axis function seems promising for predicting eventual suicide, it does not consistently predict acute suicidal behavior.
The utility of assessing HPA axis function as a physiological screening tool for suicide risk should be explored. Longitudinal, prospective studies of the influence of HPA axis function on suicidality are needed. Medical and psychosocial treatments that attenuate HPA dysregulation should be further developed and tested for their efficacy in reducing suicide.
Neurobiological research on suicide has revealed significant changes in the serotonergic systems. Low levels of serotonin and/or its metabolite have been found in the brains and cerebrospinal fluid of serious suicide attempters and/or those who complete suicide; abnormalities in serotonin receptors have also been found in those who complete suicide. Studies suggest that impaired serotonin function specifically influences suicidality via increased impulsive aggression. Other neurotransmitter systems, especially noradrenergic function, also show alterations with suicidal behavior. Neurochemical changes appear to be specific to certain brain regions. Brain mapping techniques provide a valuable tool for determining biological markers for suicide.
Studies find evidence of genetic influences on suicidality via familial aggregation of suicide, high suicide rates among adoptees whose biological families have elevated rates, and high concordance of suicide among identical vs. fraternal twins. This line of research represents a still-developing area of suicidology; no studies of suicide in identical twins