Abstract
Background: Recent studies have demonstrated brain structural changes that predate or accompany the onset of frank psychosis, such as schizophrenia, among individuals with an at-risk mental state (ARMS). The planum temporale (PT) is a brain region involved in language processing. In schizophrenia patients, gray matter volume reduction and lack of normal asymmetry (left > right) of PT have repeatedly been reported. Some studies showed progressive gray matter reduction of PT in first-episode schizophrenia patients, and in ARMS subjects during their development of psychosis.Methods: MRI scans (1.5 T field strength) were obtained from 73 ARMS subjects and 74 gender- and age-matched healthy controls at three sites (University of Toyama, Toho University and Tohoku University). Participants with ARMS were clinically monitored for at least 2 years to confirm whether they subsequently developed frank psychosis. Cortical thickness, gray matter volume, and surface area of PT were estimated using FreeSurfer-initiated labeled cortical distance mapping (FSLCDM). PT measures were compared among healthy controls, ARMS subjects who later developed overt psychosis (ARMS-P), and those who did not (ARMS-NP). In each statistical model, age, sex, intracranial volume, and scanning sites were treated as nuisance covariates.Results: Of 73 ARMS subjects, 18 developed overt psychosis (12 schizophrenia and 6 other psychoses) within the follow-up period. There were no significant group differences of PT measures. In addition, significant asymmetries of PT volume and surface area (left > right) were found in all diagnostic groups. PT measures did not correlate with the neurocognitive performance of ARMS subjects.Discussion: Our results suggest that the previously-reported gray matter reduction and lack of normal anatomical asymmetry of PT in schizophrenia patients may not emerge during the prodromal stage of psychosis; taken together with previous longitudinal findings, such PT structural changes may occur just before or during the onset of psychosis.
Highlights
Structural anomaly of the superior temporal gyrus (STG) in individuals with schizophrenia has been shown in many studies [1]
Using Labeled cortical distance mapping (LCDM), we previously reported reduced thickness and less asymmetry in the volume of planum temporale (PT) among schizophrenia patients compared with controls [17]
Selfreported educational attainment was significantly higher in healthy controls (HC) than in the at-risk mental state (ARMS)-NP (p < 0.001) and ARMS-P (p < 0.001) groups
Summary
Structural anomaly of the superior temporal gyrus (STG) in individuals with schizophrenia has been shown in many studies [1]. PT is thought to be an asymmetric (left > right) structure in healthy subjects [4], the leftward laterality is reduced or reversed in schizophrenia [5, 6]. Some studies demonstrated progressive gray matter reduction of PT in first-episode schizophrenia patients [8, 9] (the mean intervals between scans were 1.5 and 2.7 years, respectively). Recent studies have demonstrated brain structural changes that predate or accompany the onset of frank psychosis, such as schizophrenia, among individuals with an at-risk mental state (ARMS). Gray matter volume reduction and lack of normal asymmetry (left > right) of PT have repeatedly been reported. Some studies showed progressive gray matter reduction of PT in first-episode schizophrenia patients, and in ARMS subjects during their development of psychosis
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