Up to now cannabis has been considered an "inoffensive" dope as compared to stronger and highly health-damaging others such as amphetamines, heroin, cocaine etc. It was thought not to cause any addiction and proved to have a very beneficial effect on relieving pain in multiple sclerosis severe condition and also to help controlling muscle spasm.

However, the side effects are numerous, starting with loss of concentration that affects one's ability to drive, work etc. Besides that, there may be many other unpredictable negative effects of cannabis upon our health, as the plant contains more than 400 active ingredients.

Nevertheless, a study published in the Neuropsychopharmacology journal has carried on tests on mice that lead to the conclusion that cannabis consumers may become heroin addicted later on. The research was conducted on mice that have been administrated cannabis for a certain period of time and then they were taught how to procure themselves heroin if they needed to. The number of mice that took cannabis and then felt the need for opium was unexpectedly high.

This study on mice showed that for teenagers and youngsters that consume cannabis on a regular basis, heroin might be the next step. The research team that conducted the study explains that this road from cannabis to opium addiction is not that hard to be understood and is just a matter of time. It seems that with time, cannabis' effects upon the body - the euphoric states - wear off and call for a stronger drug to replace the old, soft cannabis. This is how teenagers become addicted to heroin and opium.

Drug addiction is known to be caused most of the time by the environmental, social and emotional factors, but the research team at the Karolinska Institute in Sweden wanted to track down the physiological connection between marijuana and opium. The explanation was simple: marijuana alters the brain chemistry, which will need stronger drugs later on and will lead to heroin addiction.

"Adolescents in particular should never take cannabis - it's far too risky because the brain areas essential for behavior and cognitive functioning are still developing and are very sensitive to drug exposure," Dr. Jasmin Hurd, leader of the experiment, stated.