OPTIMUM RESPONSE PREDICTORS TO THE PHARMA COLOGICAL TREATMENT WITH ANTIDEPRESSANTS

The high prevalence of affective disorders in the community and its im pact on the functionality and quality of life, makes it important for us to know more about the clinical characteristics and biological vari ables that permit an optimum therapeutic response. Although antidepres sants have been available during the last 40 years, we still lack info rmation about the prediction of the therapeutic response. Recent disco veries concerning the biochemical characteristics of the placebo respo nders may lead to the definition of specific antidepressive effects an d, therefore, to the differentiation of response predictors. A suffici ent dosage and duration of drug administration are important factors i n the response prediction. Individual pharmacokinetic differences may be surpassed by the plasmatic measures in some antidepressants. Melanc holic features (''endogenecity'') are predictors of a good response to tricyclic antidepressants and electroconvulsive therapy. Independentl y of endogenecity, there is a curvilinear relationship between a sever e depression episode and the response to tricyclic antidepressants. On the contrary, the presence of a personality disorder or of certain ty pes of personality, such as histrionic traits or a high grade of neuro ticism, reflect a poor response to tricyclic antidepressants. An abrup t onset, an older age and a long duration of the depressive episode ar e predictors of a poor response. Depressions with psychotic symptoms o r with comorbility caused by substance abuse, or the lack of social su pport or a highly expressive emotional family environment are negative response predictors to tricyclic antidepressants. Depressed patients with atypical characteristics have a better response to monoamino oxid ase inhibitors (MAOls) and serotonine uptake-inhibiting drugs than tri cyclics. If the depressed patient has a first grade relative who respo nds favorably to an specific antidepressant, the possibilities of a go od response to the drug are higher. Recurrent depression increases the risk of chronicity. There fore, it is very important that patients wi th previous depressive episodes should continue their antidepressant t reatment for a prolonged and sufficient time. The existence of a subcl inical hypothyroidism is associated with a less favorable outcome. The reduction of the latency of rapid eye, movements sleep, after one or two days of tricyclic treatment, indicates a better long-term response .