Add another downside of lighting up to the list.
The risks of smoking are well-documented, from the fact that a single cigarette shortens your life to weed not actually helping anxiety or depression.
And while each substance has different neurological effects, new research has found that both marijuana and tobacco physically affect the brain, resulting in shrinkage.
It’s long been known that aging is linked to a gradual reduction in brain volume, which is a key sign of degenerative conditions — and smoking speeds up the process.
A study published in the journal Addiction reviewed multiple studies looking at associations between cannabis use, tobacco use, co-use and brain volume.
The researchers discovered that both cannabis and tobacco use were linked to smaller volumes in the amygdala.
While a relatively small part of the brain, the amygdala has significant responsibilities, acting as the emotional processing center that manages fear and survival instincts, as well as memory and learning.
A reduced amygdala can result in less ability to regulate emotions, severe anxiety, emotional detachment and the inability to recognize fear, leading to risky behavior.
Meanwhile, smoking tobacco was also connected to smaller volumes in the pallidum and insula.
The pallidum is located deep within the brain and is necessary for smooth, controlled voluntary movement as well as processing emotions like motivation, risk and reward.
Shrinkage of the pallidum is often linked back to neurodegenerative diseases like Huntington’s or Alzheimer’s disease, causing motor and cognitive symptoms.
Considered the hidden “fifth lobe” of the brain, the insula is a primary hub for monitoring internal bodily states like hunger or pain, generating feelings, cognitive processing and self-awareness.
The study also found that regularly smoking cigarettes reduced total gray matter volume, the brain tissue that’s responsible for processing sensory information, muscle control and decision-making.
There was also strong evidence that smoking more cigarettes per day might significantly decrease hippocampal volumes.
The hippocampus is responsible for learning, short- and long-term memory, spatial awareness, remembering which words to say and recollection of facts or experiences. A reduction in volume is also a key marker for dementia and cognitive impairment.
Many of these various parts work together for full cognitive function, such as the amygdala and hippocampus, which connect emotions and memories for emotional responses.
Tobacco contains thousands of harmful carcinogens, so the researchers believe the harmful effects on the brain could be traced back to oxidative stress and inflammation from these ingredients.
CBD in cannabis, though, has been recognized for it’s antioxidative and anti-inflammatory effects, which may explain why it didn’t have as much of an effect on the brain.
