[Efficacy of low doses of atypical neuroleptics (benzamides) in defect states]

Recently many authors have hypothesized that the desinhibitory property of some neuroleptics at low doses might be related to the activation of the dopaminergic system and that, on the contrary, the overactivity of dopaminergic functions could underly the productive symptoms of some schizophrenic states. In order to test this bipolar hypothesis two independent controlled studies were set up using the same new benzamide compound (amisulpride) at different doses in the opposite forms of schizophrenia. According to the results of these studies there are evidences to sustain the assertion that amisulpride at low doses is efficient in negative symptoms of schizophrenia such as poverty of ideation, flattening of affect, inattention, asociality and that the same compound at high doses is also efficient in productive forms of schizophrenia. Whether this bipolar activity is due to the play of different kinds of receptors according to the dosage used, or is due to the dopaminergic blockade in different brain areas related to the dosage remains a problem to be solved.