Association between amino acid alterations and hallucinations in alcoholic patients.

Because available evidence suggests that alterations in the serotonergic as well as dopaminergic tones underlie hallucinatory activity, we decided to investigate whether serotonin and dopamine pathways are modified in alcoholics with a history of hallucinosis. Brain serotonin has been shown to depend on the plasma ratio of its precursor tryptophan over other amino acids competing with it for brain entry. Similarly, brain dopamine depends on the plasma ratio of its precursors phenylalanine and dopamine over their competitors. Amino acid abnormalities are common in alcoholics. For this reason, we assessed whether alcoholics who had experienced hallucinations have alterations in amino acids believed to be associated with neurotransmitter modifications. Patients with a history of hallucinations were found to have a tryptophan ratio significantly lower than that of patients without such a history, and a tyrosine + phenylalanine ratio significantly higher. These data suggest that amino acid abnormalities believed to result in decreased brain serotonin and in increased brain dopamine render certain individuals more vulnerable to hallucinatory experiences.