Decrease in hippocampal volume in regular cannabis smokers has been correlated with lifetime consumption (Ashtari et al, 2011; Yücel et al, 2008) and psychotic symptoms (Yücel et al, 2008). In Cousijn et al (2012), volume reduction in the amygdala and the hippocampus does not differ significantly between regular cannabis users and controls but still correlates with the amount of cannabis used and the severity of cannabis dependence, respectively.
