Prediction of affective psychoses response to lithium prophylaxis. The role of socio-demographic, clinical, psychological and biological variables.

A set of socio-demographic, clinical, psychological and biological variables was examined in 100 patients diagnosed according to Perris as bipolar affective psychotics or unipolar depressive psychotics, maintained on prophylactic lithium for 2 years and divided into responders and non-responders to this treatment on the basis of strict criteria. The results confirmed the potential role of four indices as predictors of response to prophylaxis: a positive family history of bipolar affective illness and a high red blood cell/plasma lithium ratio (positive predictors) and the presence of the HLA-A3 antigen and a high score on the Neuroticism Scale of the Eysenck Personality Questionnaire (negative predictors). A stepwise discriminant analysis showed that neuroticism score, lithium ratio and HLA-A3 antigen, taken together, correctly classified 74.6% of responders and 68.3% of non-responders. It is hypothesized that these variables as a group may be of practical value in predicting response to lithium prophylaxis, and that pharmacogenetic and, perhaps, personality factors may be involved in treatment failures.