Functional magnetic resonance imaging correlates of memory encoding in relation to achieving remission in first-episode schizophrenia

Abstract

Background: Previous studies in schizophrenia have shown a strong relationship between memory deficits and a poor clinical outcome. However, no previous study has identified the functional neural correlates of memory encoding in relation to remission.

Aims: To determine whether functional magnetic resonance imaging (fMRI) activation patterns differed between individuals that later achieved remission v. those who did not.

Method: Forty-two participants with first-episode schizophrenia were divided into two groups after 1 year of treatment as per the 2005 remission in schizophrenia consensus definition. We then examined fMRI activation using three contrasts (associative v. item-oriented strategy, semantically unrelated v. related image pairs, and successful v. unsuccessful memory encoding) among 15 participants who had achieved remission (remitted group), 27 who had not (non-remitted group) and 31 healthy controls (control group).

Results: Participants in the non-remitted group displayed a positive activation in the posterior cingulate compared with those in the remitted group when encoding related images; no significant differences between the two groups were identified for the other contrasts. From the behavioural data, compared with the remitted and control groups, the non-remitted group demonstrated an inability to encode related images and displayed worse recognition memory overall.

Conclusions: This is the first study to identify differential neural activation between individuals with first-episode schizophrenia that later achieved remission v. those who did not. The behavioural and functional results together add to the growing evidence relating a poor clinical outcome in schizophrenia to memory-related deficits.