Marijuana can cause mental disorders, loss of intelligence: 20-year study – New York Daily News

Scott Harms/Thinkstock/Getty Images/iStockphoto Lighting up makes you twice as likely to crash your car and lose brain functioning, the study says.

Smoking marijuana can lead to mental disorders, car crashes, unhealthy babies and more problems, according to a major 20-year study.

Professor Wayne Hall, a drugs advisor to the World Health Organization and professor of addiction policy at King’s College London, said that heavy, daily use can also lead to dependence and serve as a gateway to other harder drugs.

Among the more startling findings in his study, published in the journal Addiction, are that people who drive after smoking marijuana are twice as likely to be in a car accident, and teens who smoke regularly are twice as likely to have impaired brain function and mental disorders as adults.

“The perception that cannabis is a safe drug is a mistaken reaction to a past history of exaggeration of its health risks,” Hall told Live Science.

Other findings of the study: Babies born to mothers who had smoked marijuana may have lower birth weights and smoking marijuana may increase the risk for chronic bronchitis.

Teens and young adults are just as likely to smoke marijuana as they are cigarettes, the study also said.

Because overdosing on cannabis is rare, many view it as safer. But the long-term effects should not be discounted, Hall said. For example, smoking marijuana may not immediately cause a heart attack, but people can die of heart problems that may have been brought on by repeated use.

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