Smaller Gray Matter Volumes in Frontal and Parietal Cortices of Solvent Abusers Correlate with Cognitive Deficits

BACKGROUND AND PURPOSE: Abuse of toluene-containing organic solvents by inhalation is a prevalent practice among adolescents. Long-term abuse of toluene causes cognitive deficits. The mechanism of cognitive deficits induced by long-term toluene abuse has not yet been defined. In the current study, we assessed the effects of chronic toluene abuse on cortical gray matter volume and the association between cognitive impairment and cortical gray matter volume distribution in chronic toluene abusers.

MATERIALS AND METHODS: Fifteen toluene abusers and 20 healthy control subjects matched in sex, age, education level, and handedness were investigated by structural MR imaging. The cognitive states of the subjects were assessed by using the third edition of the Wechsler Intelligence Scale for Children (WISC-III). The voxel-based comparison and correlation analyses of MR images were performed by using SPM5 software.

RESULTS: The voxel-based morphometric analysis revealed that toluene abusers had significantly lower gray matter volumes in the bilateral frontotemporal and right parietal cortices. In addition, the lower gray matter volumes in the frontal and parietal regions correlated with the duration of toluene abuse. There was a positive correlation between the WISC performance scale scores and gray matter volumes in the frontal and parietal cortices of the abusers.

CONCLUSIONS: The results of the current study demonstrate that chronic toluene abusers have smaller gray matter volumes than nonabusers in various regions of the brain. Moreover, the cognitive deficits are associated with the lower gray matter volumes in the frontal and parietal cortices of chronic toluene abusers.