Researchers in Montreal, after an extensive study of cannabis on laboratory rats, have revealed that regular use of marijuana affects teenagers' brains much worse than estimated before. As per the findings of the study, regular use can cause depression and anxiety in teens and can also lead to permanent and irreversible effect on the brain.

For the sake of study, 18 adult rats were exposed to cannabis, and those given the drug, it was noted, had decreased levels of serotonin, the mood affecting hormone.

As per Dr. Gabriella Gobbi, a psychiatric researcher from the Research Institute of the McGill University Health Centre, the rats also displayed higher norepinephrine levels which can increase vulnerability to long terms stress.

"These permanent changes in the brain are also linked to certain mental illnesses, like schizophrenia. And we showed that even if we stopped the cannabis use at the end of adolescence, the changes were still detectable in adulthood", said Dr. Gobbi.

The study, which was funded by a grant from The Canadian Psychiatric Research Foundation, has been detailed in the journal Neurobiology of Disease.