Are cerebrospinal fluid or urinary monoamine metabolite measures stronger correlates of suicidal behavior in depression?

A series of depressed patients had monoamine metabolites measured in cerebrospinal fluid (CSF) and urine. We wished to see if CSF or urinary measures were more strongly associated with suicidal behavior in depression. Using a variety of graphical and analytic statistical approaches we found that the urinary measures of dopamine metabolism had the strongest association with suicide attempts in depression. These surprising results suggest that selected peripheral correlates of monoaminergic neurotransmission deserve further study in suicidal behavior.