Depression, suicide, and aggression in alcoholics and their relationship to plasma amino acids

In an earlier study we found an association in alcoholic patients between depression and low ratios of tryptophan over amino acids sharing with it the same transport carrier into the brain. A decreased tryptophan ratio has been shown to be correlated with lower brain tryptophan and serotonin. Because it has been postulated that altered serotonin metabolism may be a highly significant contributing factor not only to depression but also to aggressive and suicidal behavior, we decided to assess the existence of possible associations between amino acid abnormalities and these behaviors in a population of alcoholics. We observed a significant association between histories of aggression and depression. In addition, depressed patients with a history of aggression were found to have the lowest tryptophan ratio values. These values differed significantly from those found in depressed patients with no aggression history and from those observed in patients with no history of aggression and depression. Two of the three suicide attempters in the study fell also in the group of patients with an aggression history. Our data suggest the existence of a subgroup of alcoholics with marked amino acid abnormalities at risk for manifestations of depression, suicide, and aggression.