Life Event Stress and Reduced Cortical Thickness in Youth at Clinical High Risk for Psychosis and Healthy Control Subjects

Abstract

Background: A decline in cortical thickness during early life appears to be a normal neuromaturational process. Accelerated cortical thinning has been linked with conversion to psychosis among individuals at clinical high risk for psychosis (CHR-P). Previous research indicates that exposure to life event stress (LES) is associated with exaggerated cortical thinning in both healthy and clinical populations, and LES is also linked with conversion to psychosis in CHR-P. To date, there are no reports on the relationship of LES with cortical thickness in CHR-P. This study examines this relationship and whether LES is linked with cortical thinning to a greater degree in individuals at CHR-P who convert to psychosis compared with individuals at CHR-P who do not convert and healthy control subjects.

Methods: Controlling for age and gender (364 male, 262 female), this study examined associations between LES and baseline cortical thickness in 436 individuals at CHR-P (375 nonconverters and 61 converters) and 190 comparison subjects in the North American Prodrome Longitudinal Study.

Results: Findings indicate that prebaseline cumulative LES is associated with reduced baseline cortical thickness in several regions among the CHR-P and control groups. Evidence suggests that LES is a risk factor for thinner cortex to the same extent across diagnostic groups, while CHR-P status is linked with thinner cortex in select regions after accounting for LES.

Conclusions: This research provides additional evidence to support the role of LES in cortical thinning in both healthy youth and those at CHR-P. Potential underlying mechanisms of the findings and implications for future research are discussed.

Keywords: Clinical high risk; Cortical thickness; Environment; Life stress; Neuromaturation; Psychosis.

Figure 1.

A) Life event stress (LES) is inversely correlated with cortical thickness in bilateral superior and middle temporal cortex, as well as right OFC, IFG, and parahippocampal gyrus, as discussed in the text (β = − .15 – − .04, tfce fwep < 0.05). Map indicates the effects of LES on thickness after controlling for age, gender, and MRI scanner. B) Individuals in the CHR-P group exhibit lower cortical thickness, particularly in bilateral temporal, occipital, and parietal areas (β = − .17 – − .04, tfce fwep < 0.05). Map indicates the effect of diagnostic group (0 = HC, 1 = CHR-NC, 2 = CHR-C) on thickness after controlling for age, gender, LES, and MRI scanner. C) An interaction between diagnostic group and LES reached significance in left superior frontal cortex (β = 0.06 – 0.16, tfce fwep < 0.05), as discussed in the text. Map indicates the LES and diagnostic group interaction effect on cortical thickness after controlling for main effects of each, as well as age, gender, and MRI scanner. fwep = family wise error corrected p-value; tcfe = threshold free cluster enhancement; OFC = orbitofrontal cortex; IFG = inferior frontal gyrus.

Figure 2.

LES and diagnostic group are both associated with thinner cortex in several of the same cortical areas, including right lateral occipital and temporal cortex and the left lateral anterior temporal lobe. Conjunction map indicates vertices (shown in blue) which are sensitive to both LES (Figure 1a) and diagnostic group (Figure 1b), separately.