Longitudinal trajectories of cortical folding in schizophrenia spectrum disorders: a 13-year follow-up study

Background and HypothesisAltered cortical folding is a putative marker of neurodevelopmental disruption in schizophrenia spectrum disorders (SSD). Patients with SSD have been hypothesized to exhibit an accelerated decline in age-related cortical folding, quantified with the Local Gyrification Index (LGI). Here, we assessed longitudinal and cross-sectional LGI differences in patients with chronic SSD relative to healthy controls across 13 years. Study DesignThe sample comprised patients with SSD (mean baseline age=41.28 years) and healthy controls (mean baseline age=41.56 years) with MRI acquisitions at baseline (103 SSD; 99 controls) and follow-up after 5 (50 SSD; 57 controls) and 13 years (42 SSD; 60 controls). T1-weighted images were processed with the longitudinal pipeline in FreeSurfer. Spatio-temporal linear mixed-effects models were used to test for longitudinal and cross-sectional case-control differences in LGI, as well as the impact of symptom severity and antipsychotic medication dose among patients. Study ResultsAlthough cross-sectional LGI was lower in patients in extensive frontal, parietal, and occipital regions, we observed no significant differences in longitudinal trajectories between patients and controls after FDR correction. Medication dose was linked cross-sectionally to lower LGI of the anterior cingulate and orbitofrontal cortex, and the postcentral gyrus. ConclusionIn the longest longitudinal study on cortical folding in SSD to date, we found no accelerated progressive decline in cortical folding in patients. Thus, chronic SSD appears to be characterized by a state of stable hypogyria relative to healthy controls, supporting the interpretation of LGI as a marker of neurodevelopmental or early-life disturbances in SSD.