Acute exposure to cannabinoids clearly produces cognitive impairments that are transient. Heavy and prolonged cannabis exposure may be associated with deficits in memory, sustained attention, and executive functioning [75, 135, 182, 203, 204]. But whether these impairments persist and for how long is unclear. Some studies suggest full recovery after 28 days [181] or 3 months of abstinence [69], but others show some recovery only after an average of 2 years’ abstinence [82, 203]. Others have found persistent cognitive impairments and other indices of alterations in brain function even after 4 weeks of abstinence [22, 23, 60, 175, 196, 202]. Early cannabis use may be associated with greater vulnerability to persistent cognitive deficits [59, 180]. Finally, very early exposure (prenatal) to cannabinoids has been associated with long-lasting cognitive, motor and social deficits [68, 74].
