People who have used marijuana may be more susceptible to the addictive properties of nicotine, researchers from the National Institute on Drug Abuse reported in the journal Neuropsychopharmacology.
More specifically, it is the consumption of the main psychoactive ingredient in marijuana – tetrahydrocannabinol (TCH) – that is linked to stronger nicotine addiction among laboratory rats.
THC has been of great interest to scientists, doctors and patients with chronic pain. Tests have demonstrated that THC has mild/moderate analgesic (painkilling) effects and can be effective for the treatment of pain. THC alters transmitter release in the spinal cord, resulting in less pain. The compound is known to stimulate appetite. It also induces a relaxed state, as well as having effects on a human’s sense of hearing, sight and smell. In some individuals THC can cause fatigue, while in others it can make them aggressive. Some limited studies have even shown that THC may help people with nausea.
This is the first study to show that THC may enhance nicotine’s addictive properties.
The authors suggest that people who have used marijuana might potentially become more addicted to nicotine and subsequently be at greater risk of developing tobacco-related illnesses, including several cancers and heart disease.
Even though tobacco smoking has dropped considerably in the USA over the last 40 years, it remains the number 1 cause of preventable death in the country.
Many have viewed tobacco as a gateway to other drugs. The researchers explained that the evidence, in fact, also points the other way round – the consumption of other drugs may play a role in nicotine dependence.
Steven Goldberg, from the National Institute on Drug Abuse, Baltimore, MD, and team set out to determine whether laboratory rats exposed to THC might self-administer nicotine.
They worked with two groups of rats for three days:
- The THC group – the rats were administered injections of THC twice a day
- The placebo group – the rats were administered injections of an inactive placebo twice a day
One week later, the animals were trained to work for intravenous nicotine injections.
The rats in the THC group self-administered nicotine much more rapidly and frequently than those in the placebo group.
The authors also found that the rats in the THC group were willing to work much harder to get their nicotine, compared to those in the placebo group. This suggests that nicotine was of much greater value after exposure to THC.
There are many established factors that can contribute to a progression from marijuana usage to tobacco dependence. This study, however, suggests that the THC has lasting effects which can make marijuana users more vulnerable to tobacco’s addictive effects.
In most industrialized nations, the consumption of tobacco products has been steadily falling, while the opposite has been the case with marijuana. A report issued by the NIDA (National Institute on Drug Abuse) titled Monitoring the Future, informed that cigarette and alcohol consumption among 14-18 year old Americans has fallen, while marijuana usage has increased. Some people may wonder why marijuana usage did not drive up tobacco smoking if THC strengthens the addictive properties of nicotine.
Several studies have examined the effects of marijuana and tobacco, either separately or combined. Researchers from the University of British Columbia reported in CMAJ (Canadian Medical Association Journal) (April 2009 issue) that the risk of COPD (chronic obstructive pulmonary disease) is much greater when people smoke both tobacco and marijuana. They found no increased risk of COPD among individuals who smoked just marijuana (and not tobacco).
Written by Christian Nordqvist