Sex, Age, Symptoms and Illness Duration and Their Relation with Gyrification Index in Schizophrenia

The Gyrification Index (GI) represents the degree of cortical folding and is of special interest in schizophrenia, since alterations in cortical folding indirectly reflect white matter development and axonal connectivity underneath. To the best of our knowledge, very few studies have investigated the effect of sex on GI in schizophrenia. Differences in the GI between patients with schizophrenia and healthy controls and the relation between sex, age symptoms and duration of illness with GI were investigated.

T1-images were acquired from schizophrenia patients (24 males [SZ-M] and 24 females [SZ-F]) and healthy volunteers (24 males [NC-M] and 24 females [NC-F]) matched for age, sex and handedness. GI analyses were performed using the fully automated CIVET pipeline.

Significantly lower GI was found in patients relative to controls bilaterally in frontal, temporal, and parietal cortex. Sex differences were found: negative correlation was found between the duration of illness and the right parietal GI and right occipital GI in SZ-M, while SZ-F was found in the left frontal and bilateral temporal GI. Patients, regardless of sex, showed positive correlations between negative symptoms and GI in the right occipital. NC-F had greater GI values than SZ-F and both male groups.

Since GI reflects, in part, alterations in cerebral development and connectivity, the decrease in GI observed in patients is in agreement with the neurodevelopmental model of disconnectivity in schizophrenia; in addition, we emphasize the importance of sex differences in schizophrenia.