Another question of interest is whether cannabis use is associated with differential effects on brain structure according to the age of consumption onset; more specifically, does the use of cannabis during adolescence lead to the same changes in brain structure as initial exposure later in life? Adolescence is an important period in brain development when proper structural maturation of fiber tracts occurs (necessary for the development of cognitive, motor, and sensory functions) (Paus et al, 1999). Environmental factors, such as drug use, can alter the maturational arrangements that normally occur in the adolescent brain (Hurd et al, 2013), increasing the incidence of psychiatric illness and substance abuse (Paus et al, 2008). The study by Zalesky et al (2012) shows a linear correlation between measures of white matter (WM) integrity and the age of onset of regular cannabis use, thus suggesting a toxic effect of long-term cannabis use to WM development.
