If you lived in the United States in the 80s and 90s, you may remember the classic anti-drug advertisement “This is your brain on drugs.” In the short television ad, we see an egg and are told, “this your brain.” Then the egg is cracked into a frying pan and the “brain” get fried as the narrator declares: “This is your brain on drugs. Any questions?”
Well, we’ve got a lot of questions. But instead of oversimplifications in frying pans, let’s look to the research for answers.
How cannabis interacts with your brain
Cannabis interacts with your brain via the endocannabinoid system. The ECS is primarily responsible for maintaining balance — or homeostasis — in many of our bodily functions, such as sleep, hunger, pain, inflammation, mood, and memory.
The ECS contains receptors throughout the body, including the brain. They can be activated by endocannabinoids — natural chemicals produced by our bodies — but also cannabinoids from the cannabis plant.
Once absorbed into our bloodstream, these chemicals in cannabis, like THC and CBD, are deposited throughout the body where they can cause some impressive effects.
What does THC do?
THC is particularly relevant because it activates CB1, a receptor found in many regions in the brain like those responsible for memory (the hippocampus) and emotion (amygdala). When THC reaches those receptors, it starts a chain reaction that suppresses certain neurotransmitters and amino acids.
These same process can also influence neurotransmitters that affect your mood, sleep, and pain, like GABA, dopamine, and serotonin. This is what causes many of the effects cannabis can have, including pain relief, relaxation, and the euphoria we usually describe as a “high.”
CBD, another prevalent cannabinoid in cannabis, works a little differently. CBD can block part of THC’s effect, altering how it impacts the brain and lessening its disorienting psychotropic effects.
How cannabis feels
When THC or CBD trigger their reactions in the brain, they can lead to a wide variety of effects. You might have notice slight changes in coordination, feel euphoric, anxious, relaxed, disoriented, confused, or “high.” Your memory can be impaired, and pain or nausea may be relieved or heightened.
While there is some evidence that mild cognitive impairment can result for chronic users, the data is fairly inconclusive — some studies show no difference at all between cannabis users and non-users. Other studies have found mild deficits for long-term cannabis users. Notably, these cognitive impairments are far less intense than what we see with alcohol.
There is also evidence that suggests some medical cannabis users — such as those with ADHD or Tourette’s may do better cognitively using cannabis than abstaining from it. Furthermore, if it helps conditions such as chronic pain, depression, anxiety or other chronic diseases that impact cognition, it may have a beneficial impact.
Cannabis may impact different people differently, depending on what part of the brain is activated by the drug. One study found that those who had the front-most portion of the nucleus accumbens stimulated by cannabis were more likely to have rewarding experiences with cannabis, while those whose posterior area is activated may experience more adverse and unpleasant effects.
Those who say “cannabis just isn’t for me” may be on the right track, since it may be a matter of genetics.
Does cannabis damage the brain?
While cannabis doesn’t actively kill brain cells like alcohol does, there has been some worry about its effects on the brain. For one thing, some studies show changes like grey matter reduction to certain parts of the brain. Still, these changes weren’t tied to functional differences between cannabis users and non-users.
There has also been some evidence suggesting that adolescent cannabis use before age 16 is tied to lowered IQ later in life. Other studies using twins, where one twin uses cannabis and one doesn’t, found that these drops in IQ aren’t necessarily correlated with cannabis use — but might be related to other factors that lead to both lowered IQ and higher rates of cannabis use.
Still, THC can be addictive for approximately 10% of users because of how it stimulates reward centers in the brain. Its use has also been tied to an increased risk of developing certain mental conditions like schizophrenia — for those who are already genetically predisposed.
On the other hand, there is also evidence of cannabis’ positive effects on the brain. One study found that long-term cannabis use leads to increased connectivity between certain parts of the brain, which may help compensate for other cognitive deficits it causes. Other studies show cannabis use can decrease Aβ peptides in the brain, a factor that contributes to Alzheimer’s disease.
So does using cannabis use help or hurt the brain? It certainly won’t fry it like an egg in a hot pan, but the impacts can often depend on who is using it, how they’re using, and the type of cannabis they’re taking.