- Smoking tobacco and cannabis accelerates brain shrinkage beyond natural aging effects
- Cannabis use is linked to smaller amygdala, affecting emotions and survival instincts
- Tobacco use causes volume loss in the insula, pallidum, and total grey matter regions
While the brain naturally shrinks with age, a study published in Addiction suggests that smoking tobacco and cannabis significantly speeds up this decline. Researchers found that cannabis use correlates with a smaller amygdala, while tobacco use is tied to volume loss across multiple areas, including the insula, pallidum, and total grey matter.
Although the amygdala is a relatively small part of the brain, it has significant responsibilities of managing our emotions and survival instincts. A reduced size of the amygdala can disrupt a person's ability to stay emotionally balanced, leading to severe anxiety or a sense of detachment. In some cases, it even prevents someone from recognising danger, which can cause them to take unnecessary and risky actions.
Smoking tobacco was also connected to smaller volumes in the pallidum and insula. Located deep within the brain, the pallidum is necessary for smooth, controlled voluntary movement, as well as processing emotions. Its shrinkage is connected to neurodegenerative diseases such as Huntington's or Alzheimer's, causing motor and cognitive symptoms.
Meanwhile, a reduction in the insula can alter bodily sensations such as hunger or pain, generating feelings, cognitive processing and self-awareness.
The study also highlighted that brain volume changes could be attributed to the harms of combustion. "Combustion can cause high concentrations of reactive oxygen species (ROS), which cause oxidative stress and inflammation (with an increase of proinflammatory cytokines), leading to neuronal cell death," the researchers said.
Based on the evidence gathered, the researchers highlighted that smoking more cigarettes per day might significantly decrease hippocampal volumes.
The study authors urged that public health campaigns should involve messaging around the potential harms of tobacco and cannabis use.
"Healthcare professionals could discuss the impact of tobacco and cannabis on the brain when talking to their patients about their use, as well as physical outcomes such as lung cancer. Interventions could also consider the implications of the co-use of cannabis and tobacco and whether supplementing cannabis with tobacco is a technique for harm reduction, or if this increases harm."
