Prodromes de la schizophrénie : consensus ou confusion ?

Abstract

Prospective studies of subjects at high genetic risk of psychosis (at least one first relative with schizophrenia) and retrospective studies of patients at the end of the first episode of delusion or hallucination have identified various subjective and objective symptoms which emerged months or years before the diagnostic of schizophrenia. The objective symptoms presently designed as prodromes are either transient or of infradiagnostic intensity. The objective signs have been used to define an ultrahigh risk (UHR) state, and have been operationalized by psychometric instruments, which also include criteria for genetic risk (schizotypal dimensions) and alteration of social functioning. The main instruments are the Comprehensive Assessment of At-risk Mental States (CAARMS) and the SIPS (Structured Interview for Prodromal Symptoms). The subjective symptoms, which consist exclusively in inner experiences, have been named basic symptoms, and are operationalized by the Bonn Scale for the Assessment of Basic Symptoms (BSABS) and the Schizophrenia Proneness Instrument (SPI-A, Adult version). Prospective studies of selected individuals with a psychiatric help demand have shown that signs of endogenicity (schizotypal traits), and severity (high symptomatic scores and poor functioning), are of major value to predict conversion. In contrast, the positive predictive value of isolated prodromal symptoms is rather poor (much less than the 80% required for clinical validation). This suggests that the population of subjects with prodromes is structured by two latent subgroups: those who express transient psychotic manifestations (which are quite frequent in the general population), and those with an active psychotic process, who are progressively evolving towards the categorical diagnostic of schizophrenia. However, results obtained by between groups comparison of mean psychometric variables are unable to distinguish between these two populations at baseline. Because of this, introduction of the risk of psychosis category in the DSM-V has been bitterly criticized. In accordance, therapeutic prevention assays using antipsychotics, antidepressants, or cognitive therapy have provided inconsistent results. Only the administration of ω-3 polyunsaturated fatty acids has produced a long term efficient effect.