Quitting smoking can cut the risk of dementia by up to a third, according to new research.
A study of more than 46,000 older men found long-term smokers were 32 per cent more likely to develop vascular dementia than those who had given up.
Interestingly, the figure was slightly higher than the 29 per cent increase in risk compared to people who had never smoked.
This is the second most form of the neurological condition and is caused by reduced blood flow to the brain. It affects 150,000 people in the UK alone.
Tobacco smoke damages arteries. Depriving neurons of the oxygen and nutrients in blood can cause them to die and lead to vascular dementia.
Smokers were also 18 per cent more prone to Alzheimer’s disease – the most common type that affects over half a million Brits.
Overall long-term quitters and never smokers had 14 and 19 per cent lower risks for dementia, respectively.
The study, published in the joutnal Annals of Clinical and Translational Neurology, was based on men aged 60 or older from a health screening programme in South Korea between 2002 to 2013.
Senior author Dr Sang Min Park, of Seoul National University, said: “Smoking cessation was clearly linked with a reduced dementia risk in the long term, indicating smokers should be encouraged to quit in order to benefit from this decreased risk.”
He said smokers should be encouraged to quit in order to reduce the risk of developing dementia – especially in the elderly population who are already at risk.
Doctors have long known smoking increases the risk of heart disease, stroke and lung cancer. The relationship with dementia has been less clear.
But a growing body of scientific research conducted over the last decade suggests a strong connection.
Dr Park said smoking is one of the most important causes of preventable death in the world.
He said: “However, relatively less is known on the risk of smoking on neuro-degenerative disease.”
Interestingly, early studies funded by the tobacco company have suggested a possible
beneficial role of smoking in cognitive function due to the effects of nicotine, he said.
Furthermore, several early case–control studies funded by the tobacco industry have
reported a preventive effect of smoking on Alzheimer’s.
Dr Park said: “However, since then, a number of cohort studies have shown smoking was associated with increased risk of dementia.
The World Health Organisation estimates smoking may be responsible for up to 14 percent of all cases of Alzheimer’s.
But there’s also evidence to suggest kicking the habit can minimise the risk – even back to around that of never smokers. The latest findings back this up.
Dr Park added: “In conclusion, smokers should be encouraged to quit in order to reduce the risk of developing dementia.
“Smoking should be understood as a risk factor for dementia, especially in the elderly population as our study showed, and proper education regarding the benefit of
smoking cessation should be done.
“Future studies with a longer follow-up duration investigating the effect of smoking cessation on Alzheimer’s disease are needed.”
A 2015 analysis that pooled results from 37 earlier studies found current smokers were 30 percent more likely to develop some form of dementia than people who never smoked.
Inhaling tobacco smoke triggers a phenomenon known as oxidative stress which harms the DNA in cells throughout the body – including the brain.
Oxidative stress appears to promote the formation of amyloid plaques – rogue proteins closely associated with Alzheimer’s.
Smoking also boosts levels of the amino acid homocysteine and inflammation – both of which have been linked to dementia.
