Stroop interference and facilitation effects in first-episode schizophrenic patients

In the Stroop test, interference occurs in naming the print color of a word when the word is itself the name of another color. Facilitation occurs whe n the word is the same as the print color. Previous studies on selective at tention in schizophrenia using the Stroop interference effects have yielded contradicting results. Constraints included limited sample size and the re cruitment of medicated chronic patients. We studied the Stroop interference and facilitation effects in a relatively large sample of first-episode sch izophrenic patients (n = 56), a substantial proportion of whom were medicat ion-naive (n = 30) at the time of initial testing. We have also carried out longitudinal follow-up assessments when patients reached a clinically stab le state, as well as 4 months after recovery from the episode. We found tha t the Stroop interference effect was not increased in first-episode schizop hrenic patients, whether medication-naive or not. This effect did not chang e over the follow-up period. In addition, we detected an increase in Stroop facilitation effect in medicated schizophrenic patients, but only in the i nitial assessment soon after they had received medication. After sustained treatment, the increase in facilitation was normalized. These observations supported previous findings of a normal Stroop interference effect amongst schizophrenic patients. The increased facilitation effect for patients in t heir early phase of treatment (but not later) may represent an acute effect of anti-psychotic medication. Its nature and significance require further investigation (C) 2001 Elsevier Science B.V. All rights reserved.