Clinical and serotonergic predictors of non-affective acute remitting psychosis in patients with a first-episode psychosis

Objective: The study aimed to establish clinical predictors of non-affective acute remitting psychosis (NARP) and assess whether these patients showed a distinct serotonergic profile. Method: First-episode never treated psychotic patients diagnosed of paranoid schizophrenia (n = 35; 21 men and 14 women) or NARP ( n = 28; 15 men and 13 women) were included. Results: NARP patients showed significantly lower negative symptomatology, better premorbid adjustment, shorter duration of untreated psychosis, more depressive symptomatology and a lower number of 5-HT2A receptors than the paranoid schizophrenia patients. In the logistic regression, the four variables associated with the presence of NARP were: low number of 5-HT2A receptors; good premorbid adjustment; low score in the item 'hallucinatory behaviour' and reduced duration of untreated psychosis. Conclusion: Our findings support the view that NARP is a highly distinctive condition different from either affective psychosis or other non-affective psychosis such as schizophrenia, and highlight the need for its validation.