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Progressive brain tissue loss linked to early cognitive decline among patients with schizophrenia

Results from a case-control longitudinal study indicate progressive brain tissue loss among patients with schizophrenia is associated with cognitive decline early in the illness.

“Because multiple cognitive domains are affected in schizophrenia and about half the variance across domains is explained by differences in general cognitive ability, cognitive functioning in schizophrenia is likely to be reflected by changes in IQ,” Manabu Kubota, MD, PhD, of the University Medical Center Utrecht in the Netherlands, and colleagues wrote in JAMA Psychiatry.

To determine if changes in brain volume could be explained by changes in IQ during the course of schizophrenia, researchers conducted MRI scans and IQ tests at baseline and 3 years later among 84 patients with schizophrenia and 116 control patients.

During the study period, cerebral gray matter volume (P = .006) and cortical volume (P = .03) and thickness (P = .02) decreased more in patients with schizophrenia than control patients.

Patients with schizophrenia exhibited additional significant decreases in cortical volume and thickness of the right supramarginal, posterior superior temporal, left supramarginal, left postcentral and occipital regions.

All study participants demonstrated similar increased in IQ, though these changes were negatively associated with changes in lateral ventricular volume (P = .05) and positively associated with changes in cortical volume (P = .007) and thickness (P = .004) only among patients with schizophrenia.

Positive correlations between changes in IQ and cortical volume and thickness were found across the study cohort and in regions across frontal, temporal and parietal cortices.

The study findings were independent of symptoms severity at follow-up, cannabis use at baseline and use of cumulative antipsychotics during the study period, according to researchers.

“We reported that loss of cortical volume and thinning were significantly related to a relative IQ decrease across a 3-year interval in relatively young patients with schizophrenia. The effect might be explained by a subgroup characterized by both cognitive deterioration and brain tissue loss, which could well be clinically and genetically distinct with implications for diagnosis, treatment and drug development,” Kubota and colleagues wrote. – by Amanda Oldt

Disclosure: The researchers report no relevant financial disclosures.