2024-01-17 11:18:29
PrintShare
Cigarette consumption is one of the biggest risk factors for health. © imago/imagebroker
A research team from the USA is investigating the connection between tobacco consumption and an increased risk of dementia.
St. Louis – Long-term smoking causes the brain to shrink – with the gray matter being particularly affected. This is the conclusion reached by researchers at the Washington University School of Medicine in St. Louis (US state of Missouri) in a paper published in the journal Biological Psychiatry Global open Science published study. Their work is based on an analysis of data from the UK Biobank, which surveyed around half a million people in Great Britain between 2006 and 2010 and also took blood samples; the latter for the purpose of genetic studies. In 2012/2013, 32,094 participants of European descent also had magnetic resonance imaging of the head, which also measured the volume of the brain.
The US team led by psychiatry professor Laura Bierut correlated this data from the UK biobank with the test subjects’ information about their smoking behavior. It found that men and women who smoked daily had brains that were on average 3,360.95 cubic millimeters smaller. The “gray cells” made up the lion’s share at 2964.18 cubic millimeters. There is a “strong connection” here, write the scientists.
But white matter is also lost, although to a much lesser extent. Gray matter is an essential component of the central nervous system; it consists predominantly of the cell bodies of nerve cells. The white matter contains nerve cell extensions through which nerve impulses are transmitted.
Smoking makes the brain smaller – millions of nerve cells are lost
The average adult brain volume is 1,230 cubic centimeters (1,230,000 cubic millimeters). Losses in the per mille range don’t sound like much at first – but when you realize how many millions of nerve cells are irretrievably lost as a result of the shrinkage process, the picture looks different. The study also showed that the decline increases with each pack-year (a pack-year is when someone smokes 20 cigarettes a day over a period of one year).
For the researchers, the loss of gray and white matter “provides a possible explanation for why 14 percent of Alzheimer’s cases worldwide could be due to cigarette smoking.” Smoking is considered a risk factor for dementia and, according to the study authors, accelerates the development of the disease. Lower volume of the hippocampus, “an important brain region affected by Alzheimer’s,” is also “negatively associated with a history of daily smoking.”
Smoking and its effects
Another study shows why smoking doesn’t always lead to lung cancer. “There is not enough awareness of the harmfulness of smoking,” say two Frankfurt doctors in an interview.
The Institute for Quality and Efficiency in Health Care evaluates anti-smoking drugs.
What role does genetics play in brain shrinkage?
Another focus of the study is the question of what role genetics plays in brain shrinkage. The background: Previous studies had already found that people with certain gene variants start smoking more often, so their addiction is partly “biologically determined”, as the current study says. Accordingly, the heritability of starting smoking is 44 percent.
Theoretically, it could also be the case that these “smoker genes” affect the brain independently of smoking, or that a smaller brain volume is itself a risk factor for smoking. However, the current work does not confirm this possible connection. The genetic disposition that makes people more susceptible to cigarette addiction does not appear to have a relevant influence on brain volume. This means that it is not the genes that are responsible for the shrinking process, but rather the substances inhaled when smoking.
Long-time smokers who want to quit may find it comforting to know that giving up cigarettes etc. can stop the brain from shrinking. However, it cannot be undone: Once the substance has been lost in the brain, it will never come back. (Pamela Dörhöfer)
#Regular #smoking #reduces #size #brain #nerve #cells #lost