Relation of serum cholesterol, lipid, serotonin and tryptophan levels to severity of depression and to suicide attempts

Objective: To determine if there is a relation to low serum cholesterol, li poprotein, serotonin or tryptophan levels in patients with depression who h ave recently attempted suicide. Design: Biochemical and behavioural study. Setting: Inpatient and outpatient treatment at the Institute Mexicano de Ps iquiatria. Participants: Thirty-three patients with a diagnosis of major de pressive episode. Eighteen of these patients had attempted suicide in the m onth before the start of the study; 15 patients had never attempted ed suic ide. Outcome measures: Serum levels of total cholesterol, high-density lipo protein (HDL), low-density lipoprotein (LDL), triglycerides, serotonin (5-H T) and tryptophan. Scores on Hamilton Depression Rating Scale, Carroll Depr ession Rating Scale, Beck Hopelessness Scale and Beck Suicide Attempt Sever ity Scale,. Results: There were no significant differences between patients who had attempted suicide and those who had not in terms of serum choleste rol, HDL, LDL and triglyceride levels. Serum levels of 5-HT and tryptophan were significantly lower in patients with depression who had a recent suici de attempt than in those patients who had never attempted suicide. A compar ison of patients not taking antidepressant medication found serum 5-HT leve ls to be more than 3 times lower in those patients with a recent suicide at tempt than in patients with no history of suicide attempt. Conclusions: The study found no difference in lipid profiles between patients who had attem pted suicide and those who had not. Low serum levels of 5-HT may increase t he risk of suicide attempt in patients who are depressed.