[Blood MAO/DBH index and the results of the treatment of endogenous depression].

In the group of 115 endogenous depression patients 84 responded to tricyclic antidepressant medication and 31 remained drug-resistance. The changes of platelet MAO activity and serum DBH activity in the latter group were found. Among drug-resistant patients, 40% showed low MAO/DBH index (.6) and in 36% the index was within the medium range (.6-1.9). The low value of the index is predominantly connected with the increase of DBH and decrease of MAO activity, and it may become the potential predictive factor for the pharmacotherapy in endogenous depression. The results show the influence of the disturbances of catecholamines synthesis and degradation on the phenomenon of drug-resistance to tricyclic antidepressants.