A comparative study of paracingulate sulcus length and posterior cingulate cortex volumes in first-degree relatives of schizophrenia patients and healthy controls

Morphological differences identified through neuroimaging in individuals diagnosed with schizophrenia are also being investigated in their first-degree relatives to shed light on the hereditary etiology of the disorder and to identify potential structural endophenotype candidates. In studies conducted on this subject, structural abnormalities that deviate from normal morphology and are similar between patients and their relatives have been identified in certain brain regions. In light of findings from family studies in the field of psychosis, this study aims to compare, via magnetic resonance imaging (MRI), the paracingulate sulcus (PCS) length and posterior cingulate cortex (PCC) volume among first-degree relatives of schizophrenia patients who experience psychosis-like experiences (PLEs) and a healthy control group, also experiencing PLEs. The study included 35 first-degree relatives of schizophrenia patients who were either treated as outpatients or inpatients at Fırat University Hospital's psychiatry clinic, and 35 healthy controls without a family history of psychotic disorders. Participants' healthy mental status was determined using the Structured Clinical Interview for DSM-5 Disorders – Clinician Version (SCID-5-CV). Subsequently, the Sociodemographic and Clinical Data Form was administered Psychosis-like experiences were assessed using the positive subscale of the Community Assessment of Psychic Experiences (CAPE-42), while PCS lengths and PCC volumes were measured via MRI. Data were analyzed using the SPSS 22 statistical software package. In the case group including first-degree relatives of schizophrenia patients, the positive subscale scores of the CAPE-42 and the corresponding weighted positive symptom severity dimension scores were significantly higher than those of the control group. Although no significant differences were found between the groups in terms of PCS length or PCC volume, a significant negative correlation was observed in the case group between left PCS length and the number of positive psychotic experiences, positive subscale scores, and the weighted positive symptom severity dimension. In the control group, no correlation was found between PCS length and the corresponding scale values. There are only a few studies in the literature investigating PCS length and PCC volumes in relatives of individuals with schizophrenia. We believe that our study is the first in the literature to investigate the relationship between PCS length and psychosis-like experiences (PLEs) in relatives of individuals with schizophrenia and to report significant findings. Our results need to be supported by future studies involving larger sample sizes and including patient groups as well. Keywords: Schizophrenia, Magnetic Resonance Imaging, Psychosis-Like Experiences, Paracingulate Sulcus, Posterior Cingulate Cortex