Smoking is linked to brain shrinkage, which is irreversible even after quitting smoking
summary: The researchers found that smoking causes brain shrinkage and premature aging, a condition that cannot be reversed even after quitting smoking.
The study analyzed data from more than 32,000 individuals in the UK Biobank, and revealed a direct link between smoking, genetic predisposition, and reduced brain size. This finding confirms that smoking is a modifiable risk factor for dementia, and highlights its irreversible harmful effect on brain health.
The research provides vital insights into the long-term neurological consequences of smoking and the importance of quitting.
Key facts:
- Smoking causes the brain to shrink, leading to premature brain aging, and this damage cannot be repaired even after quitting smoking.
- The study analyzed data from the UK Biobank, which included more than 32,000 participants, to determine the relationship between smoking, genetics and brain size.
- The research reinforces the critical importance of quitting smoking to prevent further brain damage and reduce the risk of dementia.
source: University of Washington
Smoking causes the brain to shrink in size, according to a study conducted by researchers at Washington University School of Medicine in St. Louis.
The good news is that quitting smoking prevents further loss of brain tissue, but stopping smoking still does not return the brain to its original size. The researchers said that since people’s brains naturally lose volume as they age, smoking effectively causes the brain to age prematurely.
Results published in Biological psychiatry: open global sciencehelp explain why smokers are at greater risk for age-related cognitive decline and Alzheimer’s disease.
“Until recently, scientists ignored the effects of smoking on the brain, in part because we focused on all the terrible effects smoking has on the lungs and heart,” said lead researcher Laura J. Beirut, MD, Alumni Foundation. Professor of Psychiatry.
“But when we started looking at the brain more closely, it became clear that smoking is very bad for your brain, too.”
Scientists have long known that smoking and small brain size are linked, but they have never been sure who is the culprit. There is a third factor to take into consideration: genetics. Both brain size and smoking behavior are genetic. Nearly half of a person’s risk of smoking can be attributed to their genes.
To untangle the relationship between genes, brains and behaviour, Bierut and first author Yunhu Zhang, a graduate student, analyzed data from the UK Biobank, a publicly available biomedical database containing genetic, health and behavioral information on half a million people, most of whom are of American origin. European.
A subset of more than 40,000 participants in the UK Biobank underwent brain imaging, which can be used to determine brain size. In total, the team analyzed de-identified data on brain size, smoking history and genetic risks of smoking in 32,094 people.
Each pair of factors has been shown to be related to each other: smoking history and brain size; Genetic risks of smoking and smoking history; Genetic risks of smoking and brain size. Furthermore, the association between smoking and brain size is dose-dependent: the more packs a person smokes daily, the smaller their brain volume.
When the three factors were taken into account together, the association between genetic risk for smoking and brain size disappeared, while the association between each of these factors and smoking behaviors remained.
Using a statistical approach known as mediation analysis, the researchers identified the sequence of events: genetic predisposition leads to smoking, which leads to reduced brain volume.
“It sounds bad, and it is bad,” Perot said. “Reduced brain volume corresponds with increased aging. This is important as our population ages, because aging and smoking are risk factors for dementia.”
Unfortunately, the downturn appears to be irreversible. By analyzing data on people who quit smoking years ago, researchers found that their brains remained permanently smaller than the brains of people who had never smoked.
“You can’t undo damage that’s already been done, but you can avoid causing more damage,” Zhang said. “Smoking is a modifiable risk factor. One thing you can change to stop your brain aging and putting yourself at increased risk for dementia is to quit smoking.
About this neuroscience research news
author: Diane Duke Williams
source: WUSTL
communication: Diane Duke Williams – WUSTL
picture: Image credited to Neuroscience News
Original search: Open access.
“Investigating the relationship between smoking behavior and global brain volume” by Laura J. Bierut et al. Biological psychiatry
a summary
Examining the relationship between smoking behavior and global brain size
background
Previous studies have shown that brain volume is negatively associated with cigarette smoking, but there is ongoing debate about whether smoking causes decreased brain volume or whether decreased brain volume is a risk factor for smoking. We address this debate through multiple methods that assess directionality: Bradford-Hill criteria, which are commonly used to understand causality in epidemiological studies, and mediation analysis.
Methods
In 32,094 participants of European descent from the UK Biobank dataset, we examined the association between daily smoking history and brain volume, as well as the association of smoking genetic risk score with brain volume.
results
A history of daily smoking was strongly associated with a decrease in brain volume, and a history of heavy smoking was associated with a greater decrease in brain volume. The strongest association was between total gray matter volume and daily smoking history (effect size = −2964 mm).3, s = 2.04 x 10-16), and there was a dose-response relationship with increasing number of pack-years smoked associated with a greater reduction in brain volume. The polygenic risk score for smoking initiation was significantly associated with daily smoking history (effect size = 0.05, s = 4.20 x 10-84), but were only modestly associated with total gray matter volume (effect size = −424 mm3, s = .01). Mediation analysis indicated that daily smoking history mediated the relationship between smoking initiation risk score and total gray matter volume.
Conclusions
A history of daily smoking is strongly associated with decreased overall brain volume.
