CNR1 and Alzheimer disease: The major natural exogenous cannabinoids are delta-9-THC (THC) and cannabidiol (CBD), mainly found in the plant Cannabis sativa. The THC is agonist of CB1, and has psychotropic effects, in AD patients, THC has been evaluated to treat neuropsychiatric symptoms in a randomized trial, 24 subjects were administered THC (1.5 mg/three times day) for three weeks.