Depression and MHPG Excretion

A study of 12 depressed inpatients shows a significant correlation of improvement with both double-blind administration of dextroamphetamine sulfate and tricyclic antidepressant drug treatment and thelow mean baseline excretion of 3-methoxy-4-hydroxyphenylglycol (MHPG). The mean MHPG excretion for six patients with a good response to dextroamphetamine was found to be significantly lower than the mean MHPG level for six nonresponders. Five of six responders showed a slight increase in MHPG excretion with dextroamphetamine while five of six nonresponders showed a modest decrease in MHPG excretion. A correlation coefficient between low mean baseline MHPG excretion and improvement in depression ratings reached .58 (P< .50) for the third week and .84 (P< .01) for the fourth week of tricyclic drug therapy. These findings are discussed in terms of the catecholamine depletion hypothesis of depression and the problem of the prediction of response to tricyclic antidepressant therapy.