Antipsychotic treatment of schizotypy and schizotypal personality disorder: a systematic review.

Schizotypal personality disorder (SPD) is characterised by thought disorders, experiences of illusions, obsessive ruminations, bizarre or eccentric behaviour, cognitive problems and deficits in social functioning - symptoms that SPD shares with schizophrenia. Efforts have been undertaken to investigate the relationship between these conditions regarding genetics, pathophysiology, and phenomenology. However, treatment of SPD with antipsychotics has received less scientific attention. Embase and PubMed databases were searched using all known generic names of antipsychotics as search terms in combination with the following diagnostic terms: latent schizophrenia, schizotypal disorder, latent type schizophrenia, or SPD. Studies were categorised according to evidence level on the basis of their methodology from A, being the best, to E, being the worst. Five hundred and nine studies were retrieved and scrutinised. Sixteen studies, from the period 1972 to 2012, on antipsychotic treatment of SPD were extracted. Four studies were categorised as evidence level A, two as level B, six as level C and three as level D, with one study level E. Only four randomised, double-blind, placebo-controlled trials, on subjects with well-defined diagnoses, exists. Only amisulpride, risperidone and thiothixene have been studied according to evidence level A. This result warrants further high quality studies of the effects of antipsychotic treatment of SPD.