We included eight case-control studies comparing resting rCBF in adult chronic cannabis users and non cannabis using healthy controls (Table 2). The imaging methods used were as follows: H215O-PET [157], 133Xe-SPECT [158], 18F-FDG-PET [159], [11C]- raclopride-PET [159]–[162] and [18F]FMPEP-d2 [163]. Functional differences between groups were found in all studies, except for the four [11C]-raclopride-PET studies [159]–[162]. Abstinence periods ranged from 12 hours to 542 days (for details see Table 2). Block et al. (2000) [157] described reduced bilateral rCBF in the posterior cerebellum and ventral prefrontal cortex but also increased rCBF in the anterior cingulate cortex in cannabis users. Lundqvist et al. (2001) [158] found a trend of lower global CBF in cannabis users, as well as reduced rCBF in the right prefrontal and superior frontal cortex. Sevy et al. (2008) [159] reported lower glucose metabolism in the right orbitofrontal cortex, putamen bilaterally and precuneus in chronic cannabis users. However, there were no significant differences between the groups in striatal D2/D3 receptor availability and no correlation between striatal [11C]-raclopride-PET binding potential and glucose metabolism [159]. Consistent with these results, three
