While many people worry that THC will have a serious long term effect on their brain, in fact recent studies have shown that this is far from being the case among most users. Studies which have been carried out as recently as 2015 have demonstrated that users do not develop brain abnormalities from using marijuana, with MRI scans of brains of users and non-users showing no statistical differences. Although there is some evidence to show that weed users have lower scores in IQ tests shortly after exposure, after a couple of months, their brain function returns back to normal once more, proving that concerns about the long term negative effects on the brain are unfounded in most cases.
Positive Effects of THC on the Brain
Marijuana and its THC content has been shown to have an anti-inflammatory effect on the brain while acting as a neuroprotective and antioxidant and promoting the growth of new brain cells. All of this evidence points towards cannabis and THC actually improving brain health, rather than impairing it, in some individuals. For example, Parkinson’s Disease sufferers can benefit from THCs action in saving dopamine producing neurons in the brain to help with the control of body movements.
THC and Older Brains
There have been recent studies carried out with mice which have suggested that using marijuana can prevent memory less in old age and restore lost cognitive function in ageing adults. While younger mice performed more poorly on memory and learning tests after 28 days of receiving THC, old mice improved their performance dramatically. This was found to have been caused by molecular changes in the hippocampus which restored the brain to a younger appearance and function. This research has now paved the way for studies to be carried out in the near future on human subjects which are suffering from age related mild cognitive impairments.
Short Term Effects Of THC On The Brain
Although it has been shown that THC has negligible effects on the brain in the long term for most users, it does have a short term effect. A temporarily lowered IQ, and impaired cognitive function has been associated with marijuana use, with detrimental effects on learning, memory, decision making and attention. This is one of the reasons why operating machinery or driving after using weed should be avoided.
The Effect Of THC On Adolescents And Young People
It appears, however, that the lack of long term damage from marijuana use is only applicable to those who begin using weed as an adult. For those who start using cannabis in their youth, the long term effects are more pronounced. Adolescents who start cannabis use at an early age are more likely to do poorly in school and to have a lower IQ than those who either do not use weed at all or who started using at a later age.
This is thought to be because young people are especially susceptible to incurring lasting damage from the use of cannabis because the brain is developing until the age of 20 at least, and in many cases until the mid-20s. It is during this period of development that the human brain is believed to be especially sensitive to being damaged from exposure to drugs, and as the frontal cortex – the part of the brain which is responsible for decision making, judgement and planning – is one of the last areas of the brain to be fully developed, it stands to reason that it is these facets which are likely to be impaired in the long term by cannabis use during youth.
Teenagers also have an immature endocannabinoid system which is vital to emotional control, stress responses, cognition and neurodevelopment. If young people are exposed to marijuana on a regular basis, the cellular activity in this system can be reduced and this is another reason why young people are more sensitive to long term problems due to weed use.
Studies carried out into the structure of young adult and teen brains have shown that those who were heavy cannabis users and those who used the most potent strains had functional and structural changes which were linked to cognitive differences, and this was especially the case for those who had become regular users before the age of 16.
THC and Its Effect on Developing Babies
Pregnant women may want to avoid using marijuana while pregnant as at the present time, there is conflicting evidence about whether or not it can cause developmental problems for the fetus’ brain. While some studies have hinted at cannabis use during pregnancy being more likely to cause anencephaly (which, even with a doubled risk is still an extremely rare condition), however most health care professionals seem to support the idea that cannabis use does not directly cause any kind of birth defect. However, when it comes to possibility of long term effects on the brain, the evidence is even more mixed, with some studies having revealed that children whose mothers used weed when they were pregnant perform more poorly on behavioral and cognitive tests than the rest of their peer group, and that memory continued to be impaired 4 years after birth, although there appears to be no lasting effect on intelligence. Even by the age of 10, children born to weed using mothers showed a small increased risk of inattention, impulsivity and hyperactivity and tests on 14 year olds showed that their scores on reading, math and spelling tests were also lower than average. This is believed to be because brains that are still developing are affected by THC as it alters the cell connections inside the brain, leaving lasting chances to memory and cognitive function.
All of this evidence shows that, although pregnant women and adolescents should avoid THC, adults and the elderly are unlikely to experience any long term negative effects on their brain and, in fact, in some cases, may actually experience improvements in their brain function.