The neurobiology of suicide risk: A review for the clinician

Suicidal behavior has neurobiological determinants independent of the psych iatric illnesses with which it is associated. We have found that some patie nts with major depression are vulnerable to acting on suicidal impulses. Th is vulnerability results from the interaction between triggers or precipita nts and the threshold for suicidal behavior. An important factor in setting an individual's threshold for acting on suicidal impulses is brain seroton ergic function. Serotonin function has been shown to be lower in suicide at tempters by studies measuring serotonin metabolites in cerebrospinal fluid and studies of prolactin response to fenfluramine. Postmortem studies of su icide victims also reveal decreased serotonin activity in the ventrolateral prefrontal cortex. New neuroimaging paradigms, such as positron emission t omography (PET), offer an opportunity to visualize serotonin function in vi vo in a more direct way than has previously been available. This technology may provide the possibility of timely therapeutic intervention in patients at high risk for suicide.