The impact of smoking marijuana is often minimized. Although it is a natural drug, it is not harmless. In fact, a new study suggests that chronic marijuana use can lead to a drop in IQ among teenagers.
According to a study conducted in New Zealand, young people who started smoking marijuana before age 18 and were diagnosed as being addicted to cannabis by age 38 experienced a significant IQ drop in early adulthood. The greater the marijuana use, the greater the IQ drop was (up to 8 IQ points). The effect was maintained even when controlling for factors such as psychiatric illnesses (e.g. schizophrenia) and the use of other drugs. Stopping or reducing marijuana use did not fully restore the lost mental capacities. On the other hand, participants who started using the drug after the age of 18, even with heavy use, did not show any significant cognitive decline. The researchers believe that cannabis impacts brain development in adolescents, but that this does not occur in individuals above the age of 18 because their brain is already fully developed.
Another study published recently suggests that the risk of testicular cancer is doubled in marijuana users, compared with non-users. The study involved 163 men who were diagnosed with testicular cancer between 1986 and 1991in the United States, and it included a detailed report on their drug use.
While cannabis is a natural drug, more and more studies seem to be showing that regular use can have harmful effects on the user’s health. In addition to the effects on IQ and the possible link with testicular cancer, previous studies have also shown that marijuana reduces concentration and motivation. Users can become anxious, suspicious and even paranoid. Lastly, regular use is also thought to increase the risk of developing psychiatric diseases such as schizophrenia.