In This Issue

Adolescent rhesus monkeys administered Δ⁹-tetrahydrocannabinol (THC) 5 days a week for 6 months showed less practice-related improvement than unexposed monkeys on a test measuring working memory of spatial relationships. The exposed and unexposed monkeys did not differ in memory of colored objects, Verrico et al. (CME, p. 416) report. The discrepancy between spatial and object memory effects may stem from different developmental trajectories of underlying brain circuits. In an editorial, Corcoran (p. 381) observes that IQ loss in human marijuana users appears to have a “window of recovery,” i.e., IQ develops normally in regular users who become abstinent in adolescence, but not those who do so as adults.