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

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Abstract:

<p><b>BACKGROUND: </b>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.</p><p><b>AIMS: </b>To determine whether functional magnetic resonance imaging (fMRI) activation patterns differed between individuals that later achieved remission v. those who did not.</p><p><b>METHOD: </b>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).</p><p><b>RESULTS: </b>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.</p><p><b>CONCLUSIONS: </b>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.</p>