There is much controversy concerning the use and abuse of illicit drugs such as marijuana. One of the main controversial issues surrounding this drug is whether or not its use hinders cognition. Authors Robert Block, L D Chait, Robert Mathias and Peter Fried, Barbara Watkinson, Deborah James, and Robert Gray have all conducted slightly differing studies on the cognitive effects of marijuana. Block, the author of, "The Effect of Chronic Marijuana Use on Human Cognition," …showed first 75 words of 2119 total…

…showed last 75 words of 2119 total…and cognitive functions. These studies also raise several other questions for future study. One of the most prevalent questions is what the effects of marijuana use on cognitive functions are after a prolonged period of abstinence from use of the drug. Another question raised is why did marijuana cause impaired cognitive function? Was it due to the residue of the drug left in the system, withdrawal from the drug, or some type of neurotoxic effect?