Reduced parahippocampal cortical thickness in subjects at ultra-high risk for psychosis

Abstract

BackgroundGrey matter volume and cortical thickness represent two complementary aspects of brain structure. Several studies have described reductions in grey matter volume in people at ultra-high risk (UHR) of psychosis; however, little is known about cortical thickness in this group. The aim of the present study was to investigate cortical thickness alterations in UHR subjects and compare individuals who subsequently did and did not develop psychosis.MethodWe examined magnetic resonance imaging data collected at four different scanning sites. The UHR subjects were followed up for at least 2 years. Subsequent to scanning, 50 UHR subjects developed psychosis and 117 did not. Cortical thickness was examined in regions previously identified as sites of neuroanatomical alterations in UHR subjects, using voxel-based cortical thickness.ResultsAt baseline UHR subjects, compared with controls, showed reduced cortical thickness in the right parahippocampal gyrus (p < 0.05, familywise error corrected). There were no significant differences in cortical thickness between the UHR subjects who later developed psychosis and those who did not.ConclusionsThese data suggest that UHR symptomatology is characterized by alterations in the thickness of the medial temporal cortex. We did not find evidence that the later progression to psychosis was linked to additional alterations in cortical thickness, although we cannot exclude the possibility that the study lacked sufficient power to detect such differences.

Lack of Evidence for Regional Brain Volume or Cortical Thickness Abnormalities in Youths at Clinical High Risk for Psychosis: Findings From the Longitudinal Youth at Risk Study: Table 1.

“…One study reported cortical thinning in several brain regions, including frontal, temporal, and limbic areas 17 while 3 studies did not report any cortical thinning significant at the whole-brain level in a larger sample of ARMS individuals when compared at baseline with healthy controls (HC). [18][19][20] Fewer studies have investigated alterations of white matter volume (WMV) in ARMS but their findings are consistent with what has been reported for GMV. They reported smaller WMV in fronto-temporo-limbic areas 5,6,21 as well as a global reduction of WM growth over time 22 in ARMS compared to HC.…”

“…Our results are consistent with the absence of cross-sectional difference between ARMS subject and HC at the whole-brain level reported by the 3 largest studies. 18,19,22 Additional comparison of hippocampal volumes between ARMS and HC showed no significant difference as well. Reduced hippocampal volume is a frequent finding from regionof-interest studies in ARMS samples [47][48][49][50][51] and has been shown to be statistically significant at the whole-brain level in 1 VBM study, 4 although some inconsistences have also been reported.…”

“…15,44 Only 3 whole-brain VBM studies reported negative findings but their ARMS sample was either unusually young (12-18 years old) 20,22 or small (n = 14). 26 Concerning CT, only one previous study 18 used the same preprocessing technique (Freesurfer), while 3 others 17,19,20 used a different algorithm: CLASP 45 or voxel-based CT. 46 Their findings were divergent, reporting either extended 17 or no CT differences at the whole-brain level [18][19][20] in ARMS subjects when compared with HC at baseline. Our results are consistent with the absence of cross-sectional difference between ARMS subject and HC at the whole-brain level reported by the 3 largest studies.…”

“…However, a recent well powered study has also reported the absence of structural abnormalities in ARMS-T when compared with ARMS-NT at the whole brain level. 19 The absence of relationship between clinical high-risk status (regardless of later transition or nontransition to psychosis) and brain structure might be attributed to unique characteristics of LYRIKS. Understanding the local pathways to care for the ARMS subjects is an important area of work, and efforts are currently underway.…”

Does neuroanatomy account for superior temporal dysfunction in early psychosis? A multimodal MRI investigation

“…[3][4][5] More recently, qualitatively similar changes have been reported in the earliest stages of the disorder -both in those at ultrahigh risk (UHR) for psychosis and in those who have experienced a first epi sode of the disorder (FEP). [6][7][8][9][10][11][12][13][14][15][16] Compared with more estab lished psychosis, 3,17 however, little is known about the associa tion between the functional and structural alterations observed in the UHR and FEP states. [18][19][20] In support of a similar relation ship existing to that seen in established psychosis, Rasser and colleagues 19 reported a correlated reduction between neuro function during performance of the Tower of London task and cortical thickness in the left frontoparietal regions of 10 pa tients with FEP versus 10 controls.…”