Brain imaging studies have identified robust changes in brain structure and function during the
development of psychosis, but the contribution of abnormal brain connectivity to the onset of
psychosis is unclear. Furthermore, antipsychotic treatment can modulate brain activity and
functional connectivity during cognitive tasks.
To investigate whether dysfunctional brain connectivity during working memory (WM) predates the
onset of psychosis and whether connectivity parameters are related to antipsychotic treatment.
Dynamic causal modeling study of functional magnetic resonance imaging data.
Participants were recruited from the specialized clinic for the early detection of psychosis at
the Department of Psychiatry, University of Basel, Basel, Switzerland.
Seventeen participants with an at-risk mental state (mean [SD] age, 25.24 [6.3] years), 21
individuals with first-episode psychosis (mean [SD] age, 28.57 [7.2] years), and 20 healthy controls
(mean [SD] age, 26.5  years).
Main Outcome and Measure
Functional magnetic resonance imaging data were recorded while participants performed an N-back
WM task. Functional interactions among brain regions involved in WM, in particular between frontal
and parietal brain regions, were characterized using dynamic causal modeling. Bayesian model
selection was performed to evaluate the likelihood of alternative WM network architectures across
groups, whereas bayesian model averaging was used to examine group differences in connection
We observed a progressive reduction in WM-induced modulation of connectivity from the middle
frontal gyrus to the superior parietal lobule in the right hemisphere in healthy controls, at-risk
mental state participants, and first-episode psychosis patients. Notably, the abnormal modulation of
connectivity in first-episode psychosis patients was normalized by treatment with
Conclusions and Relevance
Our findings suggest that the vulnerability to psychosis is associated with a progressive failure
of functional integration of brain regions involved in WM processes, including visual encoding and
rule updating, and that treatment with antipsychotics may have the potential to counteract this.