Anxiety states: relationship to atmospheric cations and serotonin.

Five cases are described that offer evidence for the existence of the "serotonin irritation syndrome," an anxiety state associated with high cation environments, elevated serum serotonin, and decreased urinary 5-hydroxyindoleacetic acid. The therapeutic response and reduction in serum serotonin after treatment with methysergide and/or removal from the high-cation environment support a serotonergic basis of the anxiety.