The risk of dementia in people who quit smoking in middle age is the same as people who have never smoked Dementia

People who stop smoking in midlife can reduce their cognitive decline so significantly that within 10 years their chances of developing dementia are the same as those of people who have never smoked, a recent study has found.

Kicking the habit halves the rate of decline in verbal fluency and slows memory loss by 20%, according to a study of 9,436 people in England, the United States and 10 other European countries.

These findings add to a growing body of evidence that quitting smoking can slow the rate of mental decline that aging brings, and thus help prevent the onset of dementia.

Dr Michaela Blomberg, from University College London, and lead researcher, said: “Our study suggests that quitting smoking may help people maintain better cognitive health in the long term even when we are in our 50s or older when we stop smoking.”

She added: “We already know that quitting smoking, even later in life, is often followed by improvements in physical health and well-being. It appears that for our cognitive health as well, it is never too late to quit.”

Blomberg and her colleagues from University College London reached their conclusions by comparing the cognitive performance of adults aged at least 40 in 12 countries who had quit smoking with those who continued to smoke. While their performance was the same at first, the quitters gained significant advantages over smokers when their cognitive abilities were assessed over the next six years.

“Individuals who smoked completely were more positive [cognitive] “Trajectories following smoking cessation compared to those who continued smoking,” they wrote in The Lancet Healthy Longevity. “The rate of cognitive decline was slower for smokers who quit compared with continued smokers in the period after smoking cessation.”

“The findings suggest the importance of smoking cessation, even later in life, for long-term cognitive health.”

The researchers added that although the findings do not prove cause and effect, they could provide a “compelling motivation” for older smokers – who are less likely than younger age groups to try to quit smoking – to do so.

Smoking is one of 14 risk factors for dementia compiled by a panel of experts The scalpel Medical journal identified last year. They added that there is growing evidence that treating these problems, which include depression, heavy drinking, hearing loss and high cholesterol, reduces the risk of developing dementia in the first place.

Dr Richard Oakley, associate director of research and innovation at the Alzheimer’s Society, said: ‘The findings reinforce existing evidence that changing to a healthier lifestyle can have a measurable impact on brain health.’ “We know that quitting smoking, staying physically active, eating a healthy, balanced diet and drinking less alcohol can help reduce the risk of dementia.”

The paper explains that smoking is thought to contribute to neurodegeneration by harming cardiovascular health, by affecting the blood vessels that supply oxygen to the brain, and also by causing chronic inflammation and directly damaging brain cells through oxidative stress.

However, Dr Julia Dudley, head of research at Alzheimer’s Research UK, warned: “Greater cognitive decline in smokers does not mean these people will develop dementia.” Differences between the two groups in their socioeconomic background or alcohol intake may have influenced the results, she said.

“We’ve known for some time that smoking increases the risk of dementia and cognitive decline, but this important evidence shows that the damage can be slowed by quitting,” said Caroline Cerny, executive vice president of Action for Smoking and Health (ASH).

“It demonstrates why it is important to stop smoking at any age, but especially in midlife before many symptoms of cognitive decline appear, and highlights the need for sustained investment in smoking cessation services.”

Last month, 35% of smokers in England tried to quit and 29% succeeded, double the rate seen when records began in 2007.