India's #1 Addiction & Recovery Online Resource

Generic filters
Exact matches only
Search in title
Search in content
Browse Centers Recovery Resources

How does weed affect your brain

April 14, 2023
Reviewed by: Rajnandini Rathod

“You might feel really hungry, or you might feel like passing out. But mostly, it will be the best feeling ever,” said a Quora user when asked, “How does it feel after smoking weed?” Many people report feeling happy or relaxed, but weed can also cause some negative effects like anxiety and paranoia. 

Please note that Marijuana is illegal in many countries, including India. In this blog, we discuss how marijuana affects your body and brain. 

Disclaimer: This blog aims to provide an objective and informative overview of how marijuana affects the brain and its potential positive and negative effects on mental health. We do not endorse the use of drugs or any other illegal substances. 

Weed is a term used for the leaves, stems, flowers and seeds of the plant Cannabinoids Sativa. This plant contains a chemical called tetrahydrocannabinol (THC), which is responsible for most of the plant’s psychoactive properties. Marijuana has been used for thousands of years for medicinal and recreational purposes. It has gained a lot more popularity in recent years. 

Despite that, the use of weed is a highly controversial topic. A few countries have legalised its use, but in many, it is still illegal to use it medicinally or recreationally. This is because research has not fully understood the effects of marijuana on the body and brain. Research on marijuana use is difficult since most users also consume other substances.

Why do people like smoking weed?

Most people smoke weed for its psychoactive properties. It gives people a feeling a euphoria, relaxation and creativity. People who are generally looking for an easy escape from stress or anxiety might be attracted to the use of weed for these reasons. Sometimes weed can also lead to some less-desired experiences. Some people report feeling extremely anxious and having panic attacks after using weed. 

For others, it is a social activity to bond with their peers. Weed is also like an expression to rebel against societal norms. Some people might be using it to cope with some underlying mental health issues. This kind of self-medication can have negative consequences and worsen their physical and mental health. 

How does weed interact with your body?

When one smokes weed, the THC interacts with the body’s endocannabinoid system (ECS). Researchers studying THC first found this cell-signalling system in the early 1990s. This system in our body regulates systems like sleep, mood, appetite, and memory. It produces natural cannabinoids, which help in keeping these systems running smoothly. 

The THC in marijuana binds with the Cannabinoid receptors. This causes various effects, both desirable and undesirable. This may stimulate your appetite or reduce pain in your body. While in other cases, it may lead to anxiety. There is still some debate among scientists about how this exactly works. 

Another main effect of THC on the brain is the activation of the reward system. THC reduces the production of GABA, which inhibits the release of dopamine. This results in the production of more dopamine in the brain, which leads to positive feelings. 

As we know, the ECS is responsible for many functions, including emotions, decision-making, memory and learning. Marijuana can have an effect on all of these systems. This kind of deep interaction with the brain increases the risk of addiction and other mental health issues.

How does weed affect your brain?

Marijuana has a complex effect on the brain affecting many different areas and neurotransmitter systems. It affects different brain parts responsible for attention, emotions, coordination, learning, memory and reaction time. Some of these effects might be short-term, and others might be long-term.

Among children and adolescents, marijuana can affect brain development. Although more research needs to be done to understand how it affects the brain, studies show that marijuana use by mothers during pregnancy can lead to mental and behavioural problems in their children. This is also seen in animal studies, and these changes are seen to be permanent. 

The long-term effects of weed depend on several factors. Firstly the amount of THC in the weed marks the concentration or strength. How often the person consumes weed, in what quantity, and what is the starting age of first use? Another important factor is what other substances are used along with it. For example, people might sometimes combine tobacco and weed or also consume alcohol. 

Many longitudinal studies have shown that marijuana use can affect the user’s cognitive abilities. A study showed that individuals with higher levels of cannabis use showed poorer performance on a verbal memory test. This memory impairment occurs because of the effect of THC on the hippocampus. The hippocampal volume is seen to be reduced among long-term users. Consumption of marijuana can fasten neuron loss in the hippocampal region, which occurs as people age.

Weed also has an effect on the amygdala in the brain. Amygdala processes fearful and threatening stimuli and activates a fight-or-flight response. An fMRI study showed adolescents using cannabis short movies displaying angry or neutral faces. The results show that people with a history of using cannabis showed greater reactivity to the angry faces. This means that the use of weed in adolescence is linked with hypersensitivity to signals of threat, and they may be at risk for depression or bipolar disorder in adulthood. 

Potential risks of using marijuana

For people who use cannabis regularly, there might be many risks. Although people seldom experience these negative effects, some of these might be long-term changes in the brain. Firstly, THC can affect many cognitive functions like memory, attention and decision-making. 

Although weed is not as addictive as some other substances, it can still be habit-forming for people who use it regularly. Some people have also reported experiencing withdrawal symptoms like sleep disturbances, nausea, headaches or reduced appetite.

Long-term use of weed can have an effect on your respiratory health. Smoking of any kind is detrimental to your health. Using weed in high doses can be a sign of some underlying mental health issues that one might be trying to cope with. In cases like these, it is very risky as marijuana use can make the symptoms worse.

In conclusion, weed has both positive and negative effects on the body and the brain. While a lot of research has been done to understand how weed works in the body, much research is still required to understand its long-term effects. If you or someone you know is using cannabis and need any guidance with regard to your mental health, you can browse our directory of treatment centres here.


Auer, R., Vittinghoff, E., Yaffe, K., Künzi, A., Kertesz, S. G., Levine, D. A., … & Pletcher, M. J. (2016). Association between lifetime marijuana use and cognitive function in middle age: the Coronary Artery Risk Development in Young Adults (CARDIA) study. JAMA internal medicine, 176(3), 352-361. 

Brain Health | Health Effects | Marijuana | CDC. (n.d.).

Grewen, K. M., Salzwedel, A. P., & Gao, W. (2015). Functional Connectivity Disruption in Neonates with Prenatal Marijuana Exposure. Frontiers in Human Neuroscience, 9. 

Lu, H., & Mackie, K. (2016). An Introduction to the Endogenous Cannabinoid System. Biological Psychiatry, 79(7), 516–525. 

Spechler, P. A., Orr, C., Chaarani, B., Kan, K., Mackey, S., Morton, A. B., Snowe, M. P., Hudson, K., Althoff, R. R., Higgins, S. T., Cattrell, A., Flor, H., Nees, F., Banaschewski, T., Bokde, A. L., Whelan, R., Büchel, C., Bromberg, U., Conrod, P. J., . . . Garavan, H. (2015). Cannabis use in early adolescence: Evidence of amygdala hypersensitivity to signals of threat. Developmental Cognitive Neuroscience, 16, 63–70.
The Reward Circuit: How the Brain Responds to Marijuana | National Institute on Drug Abuse. (2016, March 10). National Institute on Drug Abuse.