Scientists reveal how smoking weed leads to brain 'shrinkage' and what parts are most at risk

Smoking weed and tobacco has a significant impact on your brain, new research has found.

With 420 fast approaching, some smokers may be planning to celebrate by lighting up a joint, even if the risks of smoking have been well documented.

There is research that the devil’s lettuce is not all that beneficial. Whether it's giving you sleep problems, respiratory irritation, or like the Cleveland Clinic states, lower life achievements.

Aging naturally reduces brain volume, and smoking accelerates this loss, raising the risk of cognitive decline.

And now, new research has found that both marijuana and tobacco physically affect the brain, leading to shrinkage.

A study in the journal Addiction analyzed multiple studies on cannabis use, tobacco use, and co-use in relation to brain volume. The researchers found that both cannabis and tobacco use were associated with reduced amygdala volume.

Smoking impacts the brain according to the study (Getty Stock)

Although small, the amygdala plays a key role in processing emotions, fear, survival instincts, memory, and learning. A smaller amygdala can impair emotional regulation, increase anxiety, cause emotional detachment, and reduce fear recognition, potentially leading to risky behavior.

Tobacco use was also linked to reduced volumes in the pallidum and insula. The pallidum, located deep in the brain, is essential for controlled voluntary movement and for processing emotions such as motivation, risk, and reward.”

Shrinkage of the pallidum is often linked to neurodegenerative diseases like Huntington’s and Alzheimer’s, leading to motor and cognitive symptoms.

The insula monitors internal states such as hunger and pain, while supporting feelings, cognition, and self-awareness.

Weed and tobacco were found to cause shrinkage (Getty Stock)

The study also found that regular cigarette smoking reduced total gray matter, which handles sensory processing, muscle control, and decision-making. Smoking more cigarettes each day was strongly associated with smaller hippocampal volumes, the part of the brain that is crucial for learning, memory, spatial awareness, language, and recalling facts or experiences. Its shrinkage is a key marker of dementia and cognitive decline. Many of these regions work together, for example, the amygdala and hippocampus connect emotions and memories to shape emotional responses.

Cannabis is the plant species that includes both THC, the compound that produces a ‘high,’ and CBD, a non-intoxicating compound with antioxidative and anti-inflammatory effects.

Separately, another study listed the startling changes that happen to the body after just taking one puff of a cigarette.

If you need support and advice about quitting smoking, go to the American Lung Association's 'Freedom from Smoking' website where you can access resources and speak to professionals.