Presentation Association of IQ changes and progressive brain changes in patients with schizophrenia

Kubota, Manabu  ,  E. M. van Haren, Neeltje  ,  V. Haijma, Sander  ,  G. Schnack, Hugo  ,  Cahn, Wiepke  ,  E. Hulshoff Pol, Hilleke  ,  René, S. Kahn

Although schizophrenia is characterized by impairments in intelligence and the loss of brain volume, the relationship between changes in IQ and brain measures is not clear. In the current study, we aimed to investigate the association between IQ and brain measures in patients with schizophrenia across time. Participants were recruited at the University Medical Center Utrecht, the Netherlands, and included 84 patients with schizophrenia (mean illness duration, 4.35 years) and 116 age-matched healthy controls. MRI of the brain and IQ scores were obtained for them at baseline and the 3-year follow-up. This study was approved by the University Medical Center Utrecht Medical Ethics Committee for Research in Humans. Written informed consent was obtained from all participants. Cerebral gray matter volume (p = 0.006) and cortical volume (p = 0.03) and thickness (p = 0.02) decreased more in patients with schizophrenia across time compared with control participants. Patients showed additional loss in cortical volume and thickness of the right supramarginal, posterior superior temporal, left supramarginal, left postcentral, and occipital regions (p values were between <0.001 and 0.03 after clusterwise correction). Although IQ increased similarly in patients with schizophrenia and control participants, changes in IQ were negatively correlated with changes in lateral ventricular volume (p = 0.05) and positively correlated with changes in cortical volume (p = 0.007) and thickness (p = 0.004) only in patients with schizophrenia. Positive correlations between changes in IQ and cortical volume and thickness were found globally and in widespread regions across frontal, temporal, and parietal cortices (p values were between <0.001 and 0.03 after clusterwise correction). These findings were independent of symptom severity at follow-up, cannabis use, and the use of cumulative antipsychotic medications during the 3 years of follow-up. These results suggest that progressive brain tissue loss in schizophrenia is related to relative cognitive decline during the early course of illness.

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