[Joint evolution of erythrocyte membrane transport of tyrosine and tryptophan as a function of the clinical course of depression].

The clinical state and the erythrocyte membrane transports of tyrosine and tryptophan were studied longitudinally during one year (minimum period of 3 months) in 44 depressive patients, 21 men and 23 women of 30 to 77 years of age. According to the DSM III, 18 patients had bipolar disorders (8 with short cycles), 14 had recurrent major depressions and 12 dysthymic disorders. Abnormal values for the membrane transports are found in the majority of patients; the pattern of these abnormalities differs among the nosological groups but decreased ratio of the tyrosine to tryptophan is the predominant finding. The membrane transports normalize as the clinical status improves. In bipolar disorders, the changes observed at the time of switching into mania differ among short and long cyclers. Short cyclers who become manic generally present a short period of normal mood and show values of membrane transports higher than when depressed or euthymic and higher than those of normal controls. Long cyclers directly switch into mania, and when manic have the same ratio of tyrosine to tryptophan than when depressed. Based on these biochemical observations, long cyclers resemble patients with recurrent major depression and short cyclers resemble dysthymic disorder patients, a group for which it has been suggested that one fifth become bipolar within years of evolution.