New perspectives on biological treatment of schizophrenia.

Recent research seems to indicate that many schizophrenics suffer from a defective brain development, which is reflected by basic disturbances in cognitive, information-processing, volitional and emotional functions. Positive symptoms like hallucinations and delusions may be secondary to the more basic disturbances. Varying degrees of defective brain development places a ceiling on the functional improvement that can be obtained in this illness. However, whereas positive symptoms usually respond best to neuroleptics, even negative symptoms can be improved, for instance by clozapine. To obtain such improvement, it seems necessary, in addition to blocking dopamine D2 receptors, to influence other receptor systems, as for instance serotonergic 5HT-2 and possibly dopaminergic D1 and/or D4 receptors. Stimulation of glutamatergic NMDA receptors also seems to be a promising possibility.