Aggressivity, suicide attempts, and depression: Relationship to cerebrospinal fluid monoamine metabolite levels

Background: We have proposed a stress-diathesis model for suicidal behavior ; in which major depression is a stressor and the diathesis is shared with aggression. Neurotransmitter correlates of the stress or diathesis have not been adequately evaluated by previous studies, because they did not simult aneously examine the relationship of multiple neurotransmitters to all thre e psychopathologies in the same population. In the present study we investi gated the relationship of monoamine metabolites to aggressivity, suicidal b ehavior, and depression in patients with mood disorders. Methods: Ninety-three drug free subjects with a major depressive episode un derwent lumbar puncture and psychiatric evaluation. Cerebrospinal fluid (CS F) levels of 5-hydroxyindolacetic acid (5-HIAA), homovanillic acid (HVA) an d methoxy-hydroxy-phenylglycol (MHPG) were assayed. The relationships betwe en monoamine metabolites and clinical variables were statistically evaluate d. Results: Higher lifetime aggressivity correlated significantly with lower C SF 5-HIAA. Lower CSF 5-HIAA and greater suicidal intent were found in high- lethality suicide attempters compared with low-lethality suicide attempters . Low-lethality attempters did not differ biologically from nonattempters. No correlation between CSF HVA arid any of the psychopathological variables was found. Only aggression showed a trend statistically in correlating pos itively with CSF MHPG levels. Conclusions: Lower CSF 5-HIAA concentration was independently associated wi th severity of lifetime aggressivity and a history of a higher lethality su icide attempt and may be part of the diathesis for these behaviors. The dop amine and norepinephrine systems do not appear to be as significantly invol ved in suicidal acts, aggression, or depression. The biological correlates of suicide intent warrant further study. (C) 2001 Society of Biological Psy chiatry.