Effects on mood of acute phenylalanine/tyrosine depletion in healthy women

Catecholamines have been implicated in the etiology and pathophysiology of mood and anxiety disorders. In the present study, we investigated the effec ts of experimentally reducing catecholamine neurotransmission by means of a cute phenylalanine/tyrosine depletion (APTD). healthy female volunteers ing ested: (1) a nutritionally balanced amino acid (AA) mixture (n = 14); (2) a mixture deficient in the serotonin precursor, tryptophan (n = 15); or (3) one deficient in the catecholamine precursors, phenylalanine and tyrosine ( n = 12). Mood was measured at three times: at baseline and both immediately before and after an aversive psychological challenge (public speaking and mental arithmetic) conducted 5 hours after AA mixture ingestion. Acute tryp tophan depletion (ATD) lowered mood and energy and increased irritability s cores. These effects were statistically significant only after the psycholo gical challenge. The effect of APTD on mood was similar to that of ATD. APT D did not attenuate the anxiety caused by the psychological challenge. Thes e findings suggest that, in healthy women, reduced serotonin and/or catecho lamine neurotransmission increases vulnerability to lowered mood, especiall y following exposure to aversive psychological events. [Neuropsychopharmaco logy 22;52-63, 2000] (C) 1999 American College of Neuropsychopharmacology. Published by Elsevier Science Inc.