Marijuana is the most widely used illegal drug, and the legalization trend contributes to its further spreading. While it is perceived by many as something harmless, numerous studies found that cannabis can have a wide range of negative effects on health. The system it affects most is the nervous system, and, consequently, it is the mind that suffers.
Many cannabis users are in their teens. This age is an important stage of brain development, and the effect THC has on the nervous system leads to disruption of these processes. A new research revolving around long-term effects of cannabis use highlights how it can have an even more serious impact on health if combined with stress.
A team of researchers at Pompeu Fabra University and their colleagues from other Spanish research institutes carried out a study focused on how exposure to stress and cannabis use in adolescence affect the nervous system and mind in the long run.
They reported that the combination of these two factors in adolescence may increase the risk of anxiety disorders when the affected person grows up. These disorders stem from a pathological, persisting fear, which leads to anxiety in its different manifestations.
The scientists treated adolescent mice with Δ9-tetrahydrocannabinol, which is often abbreviated as THC. It is this chemical that is behind the notorious getting-high effect following cannabis use. Besides, they exposed the rodents to stress. After that, they evaluated how these two conditions affected the brain’s ability to properly carry out extinction of fear.
Extinction of fear is a psychological process that is normally initiated to substitute negative associations with a particular thing, person or situation with neutral ones. For instance, a person who was once bitten by a dog is likely to fear the animal after the accident. Through such experiences, associations develop, and negative ones lead to fear. It can diminish over time as encountering the same thing again may result in neutral or positive reactions, and the fear is supposed to go away. This process is called fear extinction. However, if it is disrupted, the brain cannot rid itself of the fears rooted in negative associations, which leads to a wide range of psychiatric disorders, including various anxiety forms, panic attacks, etc.
When the mice grew up, the scientists evaluated their fear extinction and found that it was impaired. However, the impairment was observed only in those mice that were exposed to both THC and stress, and in the groups that were exposed to either of them the effect was not observed. Another finding was that fear extinction impairment was associated with decreased neuronal activity in several regions of the brain, including the infralimbic prefrontal cortex and the basolateral amygdala, which play a major role in fear regulation.
These findings support previously reported evidence that cannabis can affect the nervous system and prevent the brain from maturing properly. Most people experience stress on a regular basis, and it is virtually impossible to avoid it in adolescence, i.e. the age when quite a lot of people start consuming cannabis in some form.
The study highlights the need to raise awareness about the dangers of cannabis. Marijuana has recently been praised as a good option for treatment of various diseases, but it is best to use only the part of cannabis that has proven health benefits (CBD) and avoid THC, because, as numerous studies have showed, it can undermine crucial processes in the body.