Biological predictors of success of antidepressant drug therapy

The predictive value of patients' characteristics with regard to subsequent success of antidepressant therapy was investigated in a prospective study. Starting from the amine-deficiency hypotheses the sample was randomized and 30 patients were treated with maprotiline, 30 with clomipramine. Sociodemographic data, data about the immediate history of the illness and also most of the psychopathological symptoms before the start of treatment have no predictive capacity. Predictors of a subsequent response to clomipramine proved to be: positive reaction to sleep deprivation, decrease in MAO activity as a result of sleep deprivation, absence of signs of fatigue in the EEG after the first infusion, a serum concentration of at least 75 ng clomipramine/ml serum or 30 ng desmethyl-clomipramine/ml serum on the 7th day of treatment. A negative response to sleep deprivation, an increase in MAO activity as a result of sleep deprivation, the appearance of signs of fatigue (vigilance index) in the EEG after the first infusion as well as obvious autonomic symptoms before the start of treatment are indicative of a response to maprotiline. Diurnal variations of mood point rather to a general responsiveness to antidepressants without preference for a particular antidepressant. The results of this study provide theoretical reasons why unchangeable characteristics of patients, so-called 'static variables', can be of only slight predictive value. In contrast, changeable characteristics, so-called 'dynamic variables', such as reaction to sleep deprivation, EEG changes resulting from the first infusion, etc., could be of predictive value.