Research has shown that people who quit smoking in midlife can reduce their cognitive decline so dramatically that within 10 years their chances of developing dementia are the same as those who have never smoked.
According to a study of 9,436 people, quitting this habit cut the rate of decline in verbal fluency in half and slowed memory loss by 20%. EnglandUSA and 10 other European countries.
The findings add to growing evidence that quitting smoking can slow the rate of mental decline caused by aging and thus help prevent the onset of dementia.
“Our study shows that quitting smoking can help people maintain better cognitive health over the long term, even if we are aged 50 or over when we quit,” said Dr Michaela Blumberg of University College London, lead researcher.
“We already know that quitting smoking, even later in life, is often accompanied by improvements in physical health and well-being. It appears that it is never too late to quit smoking for our cognitive health, too,” she added.
Bloomberg and her UCL colleagues reached their findings by comparing the cognitive performance of adults aged 40 and over in 12 countries who had quit smoking with those who continued to smoke. Although their results were similar initially, quitters gained significant advantages over smokers when their cognitive abilities were assessed over the next six years.
“Those who quit smoking had more favorable [cognitive] “The rate of cognitive decline was slower in smokers who quit than in smokers who continued to smoke during the post-cessation period.
“The results highlight the importance of quitting smoking even later in life for long-term cognitive health.”
While the findings do not prove cause and effect, they may provide “compelling motivation” for older smokers, who are less likely than younger age groups to try to quit, the authors add.
Smoking is one of 14 risk factors for dementia identified by a panel of experts. Lancet medical journal identified last year. There is growing evidence that tackling problems such as depression, excessive drinking, hearing loss and high cholesterol reduces the risk of developing dementia in the first place, they added.
“The results reinforce existing evidence that adopting a healthier lifestyle can have a measurable impact on your brain health,” said Dr Richard Oakley, deputy director of research and innovation at the Alzheimer's Society. “We know that stopping smoking, staying physically active, eating a healthy, balanced diet and drinking less alcohol can help reduce your risk of developing dementia.”
The paper explains that smoking is believed to contribute to neurodegeneration by harming cardiovascular health by affecting the blood vessels that supply the brain with oxygen, as well as causing chronic inflammation and directly damaging brain cells through oxidative stress.
However, Dr Julia Dudley, director of research at Alzheimer's Research UK, cautioned that “the greater cognitive decline seen in smokers does not mean these people will go on to develop dementia.” Differences between the two groups in their socioeconomic status or alcohol consumption could have affected the results, she said.
Caroline Cerny, Deputy CEO, Action on Smoking and Health (ASH) said: “We have long known that smoking increases the risk of dementia and cognitive decline, but these important findings show that harm can be reduced by quitting.
“This illustrates why it is so important to quit smoking at any age, but especially in middle age, before many symptoms of cognitive decline occur, and highlights the need for sustained investment in smoking cessation services.”
Last month, 35% of smokers in England tried to quit and 29% succeeded, almost double the rate when records began in 2007.