Antipsychotics may counteract brain dysfunction
medwireNews: Susceptibility to psychosis is associated with impaired brain connectivity in regions involved with working memory, say researchers who found that antipsychotic treatment prevented this effect.
The patients in the study underwent functional magnetic resonance imaging while attempting a 2-back memory task (deciding if a letter corresponds to one presented two letters previously).
This task involves "numerous simultaneous cognitive processes, including a continuous encoding of incoming visual letters and rule updating," explain study author Stefan Borgwardt (University of Basel, Switzerland) and team in JAMA Psychiatry.
They report that psychosis status did not affect the modulatory effect of this task on interhemispheric connectivity, but did affect connectivity in the right hemisphere. Specifically, the influence of the working memory task on connectivity between the middle frontal gyrus and the superior parietal lobule progressively declined from 20 healthy controls (average age 26.5 years) to 17 patients at high risk for psychosis (age 25.2 years) and to 21 patients with first-episode psychosis (age 28.6 years).
The difference between the first-episode psychosis patients and controls was significant; that between at-risk patients and controls was marked, but not significant.
Nonetheless, the researchers suggest that abnormal working memory modulation of connectivity "may thus serve as a physiologic marker that predates the onset of psychosis."
The effect was altered by treatment status, however. Eight of the first-episode psychosis patients were taking antipsychotics at the time of the study, and the influence of the working memory task on connectivity in these patients was between that in controls and at-risk patients. By contrast, it was significantly impaired in untreated patients.
Moreover, the treatment effect was apparent in the working memory task itself, in which performance relative to the controls was slightly worse in at-risk patients and significantly worse in patients with first-episode psychosis, but only if they were untreated.
"The current study further demonstrates the potential of quantitative connectivity analysis for inferring the effects of antipsychotic treatment," say Borgwardt et al. "These findings may particularly benefit clinical efforts to predict the onset of psychosis from the extent of dysfunctional connectivity during [working memory]."
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Eleanor McDermid, Senior medwireNews Reporter