Though marijuana is illegal, it is the most widely used illicit drug in most developed societies today; over fifty percent of people will use it at some point in their lifetime (Hubbard, Franco, Onaivi 1999). Its peak usage occurred in the 1960's, but is still at a high today. To many peoples dislike, cannabis actually has legitimate medical purposes. Many anti-drug messages provide people with exaggerated claims concerning the undesirable affects of the drug. Moreover, its recent legalization in ten states, for medicinal purposes, has emphasized the need to understand and know the long-term effects on the central nervous system.
Pope and Yurgelun-Todd(1996) conducted a blind comparison among college students of regular marijuana users versus infrequent users. Their goal was to determine whether frequent marijuana use can be associated with residual neuropsychological effects. Their findings suggested that although marijuana use may produce some effect in memory functions, that the more significant effects are in the attention-executive system. While the recall memory functions stay reasonably unaltered. Also reported by them is a show of impairments in mental flexibility, abstraction and in some aspects of learning, in frequent users more then less frequent users.
Most of the cognitive damage is not big when compared to normal cognitive variability in normal individuals. These impairments would not cause a heavy smoker to "stand out from the crowd." This does not mean that they don't have some sort of significance; theoretically speaking, they could still have detrimental effects on a students academic performance.
Even though alcohol is legal and marijuana is illegal, Wayne Hall and Nadia Solowij(1998) have found that long-term heavy use of marijuana does not cause the harsh impairment of memory, attention, and cognitive function that can be found in chronic abuse of alcohol.
