Diffusion tensor imaging reveals micro-structural alterations in brain white matter of adult chronic active marijuana users

Abstract

Since CB1 receptors are expressed within adult brain white matter (Molina-Holgado, Vela et al. 2002) and influence brain white matter development (Armstrong, Schleicher et al. 1995; Berrendero, Garcia-Gil et al. 1998), we hypothesized that longterm, daily MJ use in adults would result in lower FA and AD and higher Trace and RD in regions that continue to myelinate into adulthood such as the superior longitudinal fasciculus (Sowell, Thompson et al. 1999; Ashtari, Cervellione et al. 2007), temporal white matter (Ashtari, Cervellione et al. 2007), and frontal white matter (Ashtari, Cervellione et al. 2007). Conversely, we did not expect to see alterations in the corpus callosum or internal capsule as these structures complete myelination within the first year of life (Brubaker, Schmithorst et al. 2009). Additionally, we hypothesized that there would be a correlation between microstructural changes and age of MJ initiation.