Our findings, which benefited from greater image resolution and methodological control than previous studies conducted in adolescents with schizophrenia, provide strong evidence for lower white matter integrity in the left ILF, particularly for patients with a history of visual hallucinations.

Background There is growing evidence that adolescence is a key period for neuronal maturation. Despite the high prevalence of marijuana use among adolescents and young adults in the United States and internationally, very little is known about its impact on the developing brain. Based on neuroimaging literature on normal brain developmental during adolescence, we hypothesized that individuals with heavy cannabis use (HCU) would have brain structure abnormalities in similar brain regions that undergo development during late adolescence, particularly the fronto-temporal connection. Method Fourteen young adult males in residential treatment for cannabis dependence and 14 age-matched healthy male control subjects were recruited. Patients had a history of HCU throughout adolescence; 5 had concurrent alcohol abuse. Subjects underwent structural and diffusion tensor magnetic resonance imaging. White matter integrity was compared between subject groups using voxelwise and fiber tractography analysis. Results Voxelwise and tractography analyses revealed that adolescents with HCU had reduced fractional anisotropy, increased radial diffusivity, and increased trace in the homologous areas known to be involved in ongoing development during late adolescence, particularly in the fronto-temporal connection via arcuate fasciculus. Conclusions Our results support the hypothesis that heavy cannabis use during adolescence may affect the trajectory of normal brain maturation. Due to concurrent alcohol consumption in five HCU subjects, conclusions from this study should be considered preliminary, as the DTI findings reported here may be reflective of the combination of alcohol and marijuana use. Further research in larger samples, longitudinal in nature, and controlling for alcohol consumption is needed to better understand the pathophysiology of the effect of cannabis on the developing brain.

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The aim of the current study was to determine whether components of executive functioning and two diverging aspects of religiosity (scriptural literalism and quest) are significant predictors of postconventional moral reasoning. An additional goal of the study was to determine whether components of executive functioning moderate the relationship between religiosity and postconventional moral reasoning. Postconventional moral reasoning was assessed using the Defining Issues Test, Version 2 (DIT2), which is primarily based on Lawrence Kohlberg's model. Results indicated that components of executive functioning, along with quest, were significant predictors of postconventional moral reasoning and were significantly correlated with each other. In addition, analyses demonstrated that the relationship between quest and postconventional moral reasoning was moderated by performance on the Comprehension subtest of the Wechsler Adult Intelligence Scale, 3rd ed. (WAIS-III), a measure assessing social awareness and general reasoning.