Acute phenylalanine/tyrosine depletion: A new method to study the role of catecholamines in psychiatric disorders

The acute phenylalanine/tyrosine depletion (APTD) method was recently developed as a new tool to transiently decrease catecholamine transmission in humans. Initial studies indicate that the treatment is safe, well tolerated, and effective. Studies in primates suggest that both dopamine and norepinephrine synthesis are decreased, and it might be possible to separate these effects. Behavioral effects appear to develop rapidly, within 3 hours in some studies. Preliminary findings in healthy individuals suggest that APTD can lead to a mild mood-lowering effect associated with decreased interest in both natural and drug rewards. In bipolar patients, more pronounced effects may be elicited, and manic symptoms might be reduced. A variant of this technique is being developed that would be suitable for extended administration, and an initial study suggests that it could have clinical utility as a treatment augmentation strategy for hyper-dopaminergic disorders.