By PM reporter Karen Barlow
Posted Tue Sep 4, 2007 7:00am AEST
The researchers followed almost 7,000 people for an average of seven years
It will wreck your lungs, it will hurt your heart, it may even give you gangrene, but now it seems smoking may also damage your brain.
Theories that smoking might actually help you think have been thrown to the wind after Dutch researchers found that smokers were more likely to develop dementia than people who have quit or never smoked.
The research, published in the journal Neurology, has found that in the long-term there appears to be a more permanent effect on the brain.
The Erasmus Medical Centre in Rotterdam has found that smokers over the age of 55 are 50 per cent more likely than similar non-smokers to develop dementia.
The researchers had followed almost 7,000 people for an average of seven years.
Professor Ian Hickie, from the Brain and Mind Research Institute at the University of Sydney, says the Dutch research adds to an Australian National University (ANU) study released this year which also showed smokers have a significantly increased risk of dementia.
"Smoking is not only a major threat to your heart and other major blood vessels and organs, but increasingly as we age, it is a major threat to the health of your brain," he said.
"Now that's only emerged in recent years. It does challenge some of the existing ideas about dementia, and certainly challenges any idea that smoking in some way is good for your cognition or for your brain health - it's clearly bad."
Much of the information that smoking may have a positive effect on the brain was driven by the tobacco industry.
Professor Simon Chapman, from the School of Public Health at the University of Sydney, says that is known from looking at the tobacco industry's internal documents.
"[The documents], which were made public at the end of the 1990s through court action in the United States, there were quite a deal of interest within the tobacco industry to say, 'look, let's try and promote research into this area', when an inkling of it came along in some of the earlier studies," Professor Chapman said.
"There was a bit of funding of Alzheimer's prevention style studies by the tobacco industry and if that did get up ahead of steam, it may well have been because of the propaganda machine of the tobacco industry rather than the science."
He says the tobacco industry had a very strong interest in the research, but quietly sat in the background.
"If they [tobacco industry] could find anything, a feared disease like Alzheimer's especially, that smoking might have protected against, then of course they were going to publicise that as much as they could," he said.
Professor Hickie says those studies were flawed anyway.
"The only suggestion of any benefit is really in people who already smoke, but when they stop smoking they're so distressed they can't think," he said.
"But really for the rest of us, the reality is that smoking represents one of the major risk factors to the blood supply to the brain - both the large vessels and the small vessels - and if you want to increase your chances of dementing, keep smoking."
As the population ages and smokes less there are fewer cases of early death through heart attack and stroke.
Professor Hickie says that makes preserving your brain more important.
"As we age it continues to be relevant throughout your whole life to never take up smoking, or if you are a smoker to quit as soon as possible," he said.