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

Abstract

BackgroundPrevious 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.AimsTo determine whether functional magnetic resonance imaging (fMRI) activation patterns differed between individuals that later achieved remission v. those who did not.MethodForty-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).ResultsParticipants 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.ConclusionsThis 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.