CNR1 and Cognitive impairment: We hypothesized that the differences in cognitive deficits were related to the affinity of CB1 and CB2 receptors, as CB2 receptors are less centrally expressed and a single administration of CB2 would have a weaker effect on cognitive function or even on cognitive deficits due to CB1 activation, whereas CB2R activation was reportedly ineffective for hippocampal-dependent spatial cognitive dysfunction in the Morris water maze test (p > 0.05) [19].