Antidopaminergic effects of dietary tyrosine depletion in healthy subjects and patients with manic illness.

Journal article

BACKGROUND: In rats, amino acid mixtures lacking tyrosine and its precursor phenylalanine decrease the release of dopamine produced by the psychostimulant drug amphetamine. Amphetamine has been proposed as a model for clinical mania. AIMS: To assess whether dietary tyrosine depletion attenuates the psychostimulant effects of methamphetamine in healthy volunteers and diminishes the severity of mania in acutely ill patients. METHOD: Sixteen healthy volunteers received a tyrosine-free amino acid mixture and a control mixture in a double-blind crossover design 4 h before methamphetamine (0.15 mg/kg). Twenty in-patients meeting DSM-IV criteria for mania were allocated blindly and randomly to receive either the tyrosine-free mixture or the control mixture. RESULTS: The tyrosine-free mixture lowered both subjective and objective measures of the psychostimulant effects of methamphetamine. Ratings of mania were lower in the patients who received the tyrosine-free mixture. CONCLUSIONS; Decreased tyrosine availability to the brain attenuates pathological increases in dopamine neurotransmission following methamphetamine administration and putatively in mania.

Authors: McTavish, S; McPherson, M; Harmer, C; Clark, L; Sharp, T

• Publication status: Published
• Journal: British journal of psychiatry : the journal of mental science
• Volume: 179
• Issue: OCT.
• Pages: 356-360
• Publication date: 2001-10-01
• DOI: 10.1192/bjp.179.4.356
• EISSN: 1472-1465
• ISSN: 0007-1250
• Language: English
• Keywords: Tyrosine; Male; Double-Blind Method; Humans; Cross-Over Studies; Dopamine; Brain; Middle Aged; Analysis of Variance; Bipolar Disorder; Central Nervous System Stimulants; Methamphetamine; Female; Adult; Psychiatric Status Rating Scales