Progressive temporal lobe grey matter loss in adolescents with schizotypal traits and mild intellectual impairment

Abstract 

Adolescents with mild intellectual impairment are known to have an increased risk of schizophrenia compared to the general population. However, little is known regarding the association between potential risk markers for later schizophrenia within this population. We therefore set out to examine the association between schizotypal traits and progressive grey matter loss in adolescents with mild intellectual impairment. Ninety-eight adolescents receiving educational assistance were divided into two groups based on their degree of schizotypal features, measured using the Structured Interview for Schizotypy (SIS). Each participant received two structural magnetic resonance imaging scans approximately 16 months apart. Changes over time in the voxel-wise presentation of tissue were evaluated using tensor based morphometry. Those with marked schizotypal features exhibited significantly greater grey matter losses in the left medial temporal lobe than those without. Three focal locations were identified, two within the left amygdala and one in the left parahippocampal gyrus. Thus, adolescents with cognitive impairment and schizotypal features show changes in brain structure over time, changes that are consistent with those identified in other high risk populations. Medial temporal grey matter loss may therefore represent a common neuroanatomical substrate of risk for schizophrenia, common to familial, prodromal and cognitive high risk groups.

Keywords: Mild mental retardation, High risk for psychosis, Tensor based morphometry, Longitudinal MRI