Reduced cortical thickness as an outcome of differential sensitivity to environmental risks in schizophrenia.
BACKGROUND
The etiology of schizophrenia is thought to involve differential-likely genetically mediated-sensitivity to environmental exposures. However, examination of differential sensitivity in models of psychopathologic constructs is subject to bias because psychopathology itself may distort exposure assessment. The use of neuroimaging phenotypes, conversely, may provide unbiased evidence for differential sensitivity to environmental exposures. This study examined the impact of two environmental exposures associated with both schizophrenia and magnetic resonance imaging (MRI) cerebral alterations in models of cerebral cortical thickness.


METHODS
T1-weighted MRI scans were acquired from 88 patients with schizophrenia, 98 healthy siblings at higher than average genetic risk for schizophrenia, and 87 control subjects. Freesurfer software was used to measure cortical thickness for 68 brain regions. Associations between 1) cortical thickness and 2) cannabis use and developmental trauma were examined.


RESULTS
A significant group × developmental trauma interaction (χ(2) = 9.65, p = .01), as well as a significant group × cannabis interaction (χ(2) = 6.04, p = .05) was apparent, indicating differential sensitivity of the patient group, which displayed stronger reductions of cortical thickness for both exposures. A similar pattern was found in the sibling-control comparison for cannabis. For developmental trauma, siblings did not differ from control subjects, displaying an increase in cortical thickness with higher levels of trauma.


CONCLUSIONS
The findings suggest that schizophrenia and its genetic liability are associated with differential cerebral cortical sensitivity to developmental environmental exposures such as cannabis. Gene-environment interactions may underlie some of the brain alterations observed in patients with schizophrenia and their relatives.
Department of Psychiatry and Psychology, School for Mental Health and Neuroscience, European Graduate School of Neuroscience, Maastricht University Medical Centre, (Vijv1) Maastricht, The Netherlands.
Petra
P
Habets
Machteld
M
Marcelis
Ed
E
Gronenschild
Marjan
M
Drukker
Jim
J
van Os
D000328:Adult; D017668:Age of Onset; D000428:Alcohol Drinking / Q000473:pathology; D002540:Cerebral Cortex / Q000473:pathology*; D002648:Child; D002649:Child Abuse / Q000523:psychology; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004781:Environmental Exposure / Q000706:statistics & numerical data*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008385:Marijuana Smoking / Q000473:pathology; D012307:Risk Factors; D012559:Schizophrenia / Q000453:epidemiology* / Q000473:pathology*; D012565:Schizophrenic Psychology