Quitting smoking preserves memory: evidence from an international study

This discovery adds an important argument in favour of kicking the bad habit - even when it comes to people over the age of 50.

The results are published in The Lancet Healthy Longevity journal.

What the study showed

The study involved data from 9,436 people aged 40 and over (average age 58) from 12 countries, including England, the US and a number of European countries. Scientists compared the dynamics of cognitive test results in those who quit smoking and those who continued.

Key indicators - memory and verbal fluency (the ability to select words) - deteriorated significantly slower in those who gave up cigarettes.

• The rate of decline in verbal fluency in ex-smokers was half that of continuing smokers.

• Memory deteriorated 20 per cent slower.

• Translated into years, this meant that with each year of aging, those who quit smoking lost 3-4 months less memory and six months less verbal skills than those who continued to smoke.

Why it matters

"Our results show that it's never too late to quit smoking - even after the age of 50, it can benefit not only the body but also the brain," said lead study author Dr Michaela Blumberg from the UCL Institute of Epidemiology and Public Health.

She also emphasised that older smokers are less likely to make attempts to quit nicotine, even though they are the ones who suffer the most from the effects of smoking. A new argument in favour of quitting cigarettes is the possible protection against cognitive decline and the resulting reduced risk of dementia.

How smoking affects the brain

Smoking impairs cognitive health through several mechanisms:

• Disrupts blood flow and damages the blood vessels that supply oxygen to the brain;

• Causes chronic inflammation;

• Increases oxidative stress levels, damaging brain cells.

Is there evidence of a link to dementia?

Although this study did not directly examine the risk of dementia, one of its authors, Professor Andrew Steptoe, said:

"Slower cognitive decline is directly associated with a lower risk of dementia. Our findings confirm that smoking cessation may be part of a strategy to prevent it."

The study is observational, which means it cannot definitively prove causality. However, before and after smoking cessation, the participants' scores were similar in both groups, reinforcing the validity of the finding.