Alpha-methyl-p-tyrosine (AMPT) is a drug that temporarily reduces brain catecholamine activity by competitively inhibiting tyrosine hydroxylase. AMPT administration leads to a transient exacerbation of depressive symptoms in patients that have responded to catecholaminergic antidepressants. The mood changes induced by AMPT may be mediated by decreases in norepinephrine, while changes in selective attention and motivation may be mediated by dopamine. It prevents the conversion of tyrosine to L-DOPA, the precursor to dopamine.