Background: The accurate prediction of a transition to psychosis in high-risk and ultra-high-risk (UHR) populations is important because timely preventive interventions may succeed in delaying or even averting psychosis. However, current screening programmes have very low predictive power. Therefore, if prodromal signs are to be really useful they need to be objective and have strong predictive power. We hypothesise that in the prodromal phase movement disorders (MD) are probably better than screening programmes at predicting the development of psychotic disorders.
Aim: To determine, on the basis of published articles and personal experience, whether, in UHR populations, MD can predict a transition to psychosis more accurately that current screening programmes.
Method: We studied the literature using Medline.
Results: Our strategy was to search the literature for studies concerning 1. children with schizotypal personality disorder, 2. UHR adolescents and 3. siblings of patients with schizophrenia. Studies relating to the first two groups showed that the severity of MD was related to the severity of the prodromal signs both at baseline and at follow-up. Patients with more (and more severe) MD had a higher risk of transition to a psychotic disorder than patients without MD. Studies relating to the third group showed that the frequency of mechanically measured md was significantly higher in the siblings of patients with schizophrenia than in healthy controls.
Conclusion: MD are objective easy-to-measure prodromal signs which might be powerful predictors of a transition to psychosis in (U)HR populations.