From the National Post.

Summary:

Smoking a few joints with friends growing up may be the furthest thing from harmless for developing young brains, a new U.S. study suggests.

Teenagers who regularly use cannabis during their adolescent years may cause permanent brain abnormalities by using the drug, and increase their risk of developing serious mental disorders such as schizophrenia, a study published this month in the journal Neuropsychopharmacology, a division of the journal Nature, hints at.

The problems occurred in younger mice but not in older mice:

The study, conducted by researchers at the University of Maryland School of Medicine, examined the cortical oscillations in mice. Cortical oscillations (patterns of activity of neurons in the brain believed to underlie various functions) are very abnormal in schizophrenia and in other psychiatric disorders. Scientists exposed young mice to very low doses of the active ingredient in marijuana for 20 days, and then allowed them to return to their siblings and develop normally.

“In the adult mice exposed to marijuana ingredients in adolescence, we found that cortical oscillations were grossly altered, and they exhibited impaired cognitive abilities,” says the study’s lead author, Sylvina Mullins Raver, a PhD candidate in neuroscience and neurobiology at the University of Maryland, in a press release with the study. “We also found impaired cognitive behavioral performance in those mice. The striking finding is that, even though the mice were exposed to very low drug doses, and only for a brief period during adolescence, their brain abnormalities persisted into adulthood.”

When researchers repeated the experiment solely on adult mice, cortical oscillations and ability to perform cognitive behavioral tasks remained normal.

[…]“Previous research has shown that children who started using marijuana before the age of 16 are at greater risk of permanent cognitive deficits, and have a significantly higher incidence of psychiatric disorders such as schizophrenia. There likely is a genetic susceptibility, and then you add marijuana during adolescence and it becomes the trigger,” says the study’s senior author Asaf Keller, PhD, Professor of Anatomy and Neurobiology at the University of Maryland.

Now I know that young people have trouble making decisions, and that they have the attitude that no matter what they do, nothing bad will happen to them. But I still think that when you teach a young person, it’s important to appeal to evidence like this and say to them “this isn’t just me telling you what to do, this me me telling you what is true”. Obviously how you impart this information to them is going to affect whether they believe it and apply it to themselves.

In case you need more data, here is some more from previous posts.

Fox News reports:

Excerpt:

Recent research from Duke University in Durham, N.C., found teenagers who smoked marijuana habitually during their adolescence showed a decrease in their general intellectual ability as they progressed into adulthood.

But now, there is an even more chilling possible side effect of cannabis use – an increased risk of stroke.

According to a new study from the University of Auckland in New Zealand, marijuana may double the risk of ischemic stroke and transient ischemic attack (TIA) in young adults – even those who had no risk factors that often contribute to an attack.

[…]Conducting the first case-controlled study of its kind, Barber and his colleagues studied 160 ischemic stroke/TIA patients between the ages of 18 to 55 (an average age of 45), who had their urine samples screened when they entered the hospital.  As a comparison, the researchers examined urine samples of 160 control subjects who had been admitted to the hospital for other medical reasons.

Of the 160 stroke patients, 16 percent tested positive for marijuana use within the past couple of days, compared to only 8.1 percent of the control patients.  According to Barber, the stroke patients were very well matched to the controls, with no differences in age, mechanisms for stroke or other vascular risk factors.

Here’s a study from last year that found that smoking marijuana can permanently damage intelligence.

From the UK Telegraph.

Excerpt:

Teenagers who regularly smoke cannabis are putting themselves at risk of permanently damaging their intelligence, according to a landmark study.

Researchers found persistent users of the drug, who started smoking it at school, had lower IQ scores as adults.

They were also significantly more likely to have attention and memory problems in later life, than their peers who abstained.

Furthermore, those who started as teenagers and used it heavily, but quit as adults, did not regain their full mental powers, found academics at King’s College London and Duke University in the US.

They looked at data from over 1,000 people from Dunedin in New Zealand, who have been followed through their lives since being born in 1972 or 1973.

[…]Professor Terrie Moffitt, of KCL’s Institute of Psychiatry, who contributed to the study, published in the journal Proceedings of the National Academy of Sciences, said “persistent users” who started as teenagers suffered a drop of eight IQ points at the age of 38, compared to when they were 13.

In addition to looking at studies, it’s important to look at countries that have legalized marijuana, so that we can see the results.

Other countries have tried permissive drug policies have been tried and they have failed.

Excerpt:

The Family Research Council explains how permissive drug policies don’t actually work.

Excerpt:

History provides evidence that legalization of drugs in foreign nations has not been successful. For example, opium was legalized in China earlier this century. That decision resulted in 90 million addicts and it took a half-century to repair the damage.[59]

Egypt allowed unrestricted trade of cocaine and heroin in the 1920s. An epidemic of addiction resulted. Even in Iran and Thailand, countries where drugs are readily available, the prevalence of addiction continues to soar.[60]

Modern-day Netherlands is often cited as a country which has successfully legalized drugs. Marijuana is sold over the counter and police seldom arrest cocaine and heroin users. But official tolerance has led to significant increases in addiction. Amsterdam’s officials blame the significant rise in crime on the liberal drug policy. The city’s 7,000 addicts are blamed for 80 percent of all property crime and Amsterdam’s rate of burglary is now twice that of Newark, New Jersey.[61] Drug problems have forced the city to increase the size of the police force and the city fathers are now rethinking the drug policy.[62]

Dr. K. F. Gunning, president of the Dutch National Committee on Drug Prevention, cites some revealing statistics about drug abuse and crime. Cannabis use among students increased 250 percent from 1984 to 1992. During the same period, shootings rose 40 percent, car thefts increased 62 percent, and hold-ups rose 69 percent.[63]

Sweden legalized doctor prescriptions of amphetamines in 1965. During the first year of legalization, the number of intravenous”speed” addicts rose 88.5 percent. A study of men arrested during the legalization period showed a high correlation between intravenous use and a variety of crimes.[64]

Dr. Nils Bejorot, director of the Swedish Carnegie Institute and professor of social medicine at the Karolinska Institute in Stockholm, believes the solution to the growing drug problem is consistent social and legal harassment of both users and dealers.[65]

Great Britain experimented with controlled distribution of heroin between 1959 and 1968. According to the British Medical Journal, the number of heroin addicts doubled every sixteen months and the increase in addicts was accompanied by an increase in criminal activity as well.[66] And British authorities found that heroin addicts have a very good chance of dying prematurely. On the crime front, Scotland Yard had to increase its narcotics squad 100 percent to combat the crime caused by the “legal” addicts.[67]

The Swiss opened a “legalized drug” area in Zurich seven years ago and local addicts were given drugs, clean needles, and emergency medical care. Unfortunately, the liberal policy backfired and the number of addicts surged to 3,500; violence surged, too. “Needle Park,” as it came to be known, was a place of open warfare among rival gangs, and even police faced gunfire. Their cars were attacked and overturned. In February 1995, officials ended the experiment, conceding that it had evolved into a grotesque spectacle.[68]

Now are the people who push for legalizing marijuana aware of these facts? Do they think about society will be like if more human beings who have spouses, children and jobs are more able to get their hands on drugs? Will they complain when their spouse loses their job, or they lose their job, and their children suffer? Will they blame themselves, or will they keep on smoking and blame others for their own decisions? We all have to think about the people around us before we do stupid, selfish things.