We are in the midst of a major national debate on the legalization of marijuana. The outcome of this debate is likely to have profound implications for our society. To make an informed choice on this issue, we need accurate information about these implications.

There has never been a greater need for unbiased scientific data on the physical and psychological effects of marijuana use. Unfortunately, there has been more heat than light shed on this issue in the mainstream media.

Perhaps with this in mind, the National Institute on Drug Abuse has just issued a major research report on the effects of marijuana. The report may be surprising to most people who regard marijuana as a benign or harmless drug.

According to NIDA, marijuana is a drug that can and does cause addiction. THC, the active ingredient in marijuana, activates the brain’s reward system in the same way as other drugs of abuse — by triggering the release of dopamine.

Dopamine, a chemical found in the brain, is associated with a sense of euphoria. Like other drugs of abuse, chronic administration of marijuana depletes dopamine supplies and causes other brain changes, which creates a craving for the drug. After a certain period of time, cessation of use results in a defined marijuana withdrawal syndrome as demonstrated in both animal and human studies. These factors combined with other functional impairments define drug dependence or addiction. According to NIDA, more than 2 million people met the criteria for marijuana dependence in 1999 alone.

Marijuana also causes major problems with learning, memory, concentration and judgment. Individuals who smoke marijuana have an impaired ability to learn for at least 24 hours. Long-term users have been shown to be impaired for up to four weeks after cessation of use. In animal studies, rats treated with THC showed nerve cell loss resulting in memory loss. The nerve cell loss was “equivalent to that of unexposed animals twice their age,” according to the report.

Marijuana also contains more carcinogenic material than cigarettes and has been statistically linked to cancer. It also impairs the immune system’s ability to fight off diseases and infections. It increases the risk of a heart attack fourfold for the first hour after smoking it.

Students who smoke marijuana get lower grades and are less likely to graduate from high school than their nonsmoking peers. Workers who smoke marijuana experience a variety of problems, absences, tardiness, accidents, etc., when compared with workers who do not smoke marijuana.

The fact that marijuana is a dangerous, addictive drug is not in and of itself a definitive reason for it to be illegal. Alcohol is certainly a dangerous, addictive drug that is legal. It is, however, a reason to have a careful, reasoned debate before we make decisions about legalization.

Some hard questions need to be asked. How does this affect productivity in society? How will the health of individuals be affected? Perhaps, most importantly, what impact will legalization have on our children?

As someone who has worked for more than 20 years with teenagers who smoke marijuana, I am aware that it becomes difficult to tell kids not to smoke marijuana when society is actively moving toward legalization. These questions deserve more debate and discussion before we move forward with a decision that can have powerful negative implications and may be almost impossible to undo.

Robert Margolis is a licensed clinical psychologist in Roswell.