The use of marijuana, or cannabis, is widespread in the United States. At least 40 percent of Americans have tried it. Marijuana use among adolescents and teens is high, with 20 percent of all 12th graders describing themselves as current users, according to the National Institute on Drug Abuse, or NIDA. The prevalence of marijuana use coincides with a corresponding prevalence of the medical and societal problems that its use causes.
Respiratory Disturbances
Marijuana contains 20 to 50 percent more of the carcinogenic hydrocarbons than are found in tobacco, and yet a convincing link between marijuana use and lung cancer has not been found, according to researcher Robert Melamede of the University of Colorado Biology Department.
Marijuana does, however, result in a number of respiratory problems, such as coughing, increased phlegm and vulnerability to lung infections. Long-term marijuana use can lead to bronchitis and emphysema, according to NIDA.
Intellectual Dysfunction
Active users of marijuana who smoke at least 5 joints a week experience a 4-point decrease in intelligence quotient, or I.Q., according to Carlton University's Department of Psychology. Long-term cannabis users have impaired short-term memory and learning skills, and heavy marijuana users show significantly lower test scores in mathematical and verbal examinations, according to NIDA. Marijuana's influence on short-term memory compromises the ability to learn new skills, prompting the likelihood of heavy users to fall behind in terms of career advancement and intellectual pursuits.
Cognitive Disturbances
Marijuana may exacerbate any predisposition to schizophrenia, according to the U.S.National Library of Medicine. Marijuana users are more prone to experience hallucinations and delusions, with the risk of psychosis increasing in proportion to the length of time that the individual has been using marijuana.
The causal relationship between marijuana and schizophrenia requires further study. Those who are already vulnerable to psychosis may be using the marijuana to self-medicate. The subsequent marijuana use may then accelerate the conversion to full blown psychosis.
Impaired Physical Performance
The use of marijuana increases the likelihood of work-related or motor vehicle accidents. The National Highway Traffic Association has found that moderate doses of marijuana decrease reaction time and the ability to accurately detect changes in velocity.
THC, the drug present in marijuana, disrupts the body's ability to balance, coordinate movement and respond to external stimuli, conditions that could lead to workplace accidents, especially in conjunction with the use of power tools or heavy machinery.
