Time is the enemy: Negative symptoms are related to even slight differences in the duration of untreated psychosis

Negative symptoms (NS) represent a detrimental symptomatic domain in schizophrenia affecting social and occupational outcomes. We aimed to identify factors from the baseline visit (V1) — with a mean illness duration of 0.47 years (SD = 0.45) — that predict the magnitude of NS at the follow-up visit (V3), occurring 4.4 years later (mean +/− 0.45). Using longitudinal data from 77 first-episode schizophrenia spectrum patients, we analysed eight predictors of NS severity at V3: (1) the age at disease onset, (2) age at V1, (3) sex, (4) diagnosis, (5) NS severity at V1, (6) the dose of antipsychotic medication at V3, (7) hospitalisation days before V1 and; (8) the duration of untreated psychosis /DUP/). Secondly, using a multiple linear regression model, we studied the longitudinal relationship between such identified predictors and NS severity at V3 using a multiple linear regression model. DUP (Pearson's r = 0.37, p = 0.001) and NS severity at V1 (Pearson's r = 0.49, p