It’s Never Too Late: Quitting Smoking May Slow Memory Decline

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Many people know that quitting smoking can lower the risk of heart disease, cancer and lung problems — but new research shows it may also help protect your brain health as you age.

A recent international study published in The Lancet Healthy Longevity examined whether quitting smoking in mid- to late life could slow the decline in memory and thinking skills (known as cognitive function) over time.

“Evidence that quitting may support cognitive health could offer new compelling motivation for this group to try and quit smoking,” said lead investigator Mikaela Bloomberg, Ph.D., research fellow in social epidemiology and social statistics at University College London (UCL).

Alzheimer’s disease and related dementias are now the eighth leading cause of death worldwide, affecting nearly 57 million people. Because these conditions develop gradually over decades, finding ways to prevent or delay them by addressing lifestyle and environmental risk factors is crucial. One key risk factor is cigarette smoking, which may accelerate cognitive decline.

Smoking can damage the brain through oxidative stress and inflammation and also raises the risk of cardiovascular disease — both of which contribute to faster cognitive decline and a higher likelihood of developing dementia.

Investigators analyzed data from three large national studies conducted in 12 countries, following adults aged 40 to 89 for up to 18 years (from 2002 to 2020). They focused on nearly 9,500 people who smoked at the start of the studies. Half of them eventually quit smoking, and the other half continued to smoke. The two groups were matched by age, gender, education, income, and baseline memory and fluency scores — so any differences seen over time would likely be related to smoking behavior.

In the six years before quitting, both groups showed similar rates of decline in memory and verbal fluency (the ability to think and speak quickly). However, in the six years after quitting, those who gave up smoking began to experience a slower rate of decline compared with those who continued smoking. Specifically, people who quit had small but measurable improvements in how quickly their memory and word-finding skills declined. These benefits were consistent regardless of whether participants quit smoking in their 40s, 50s, 60s or even later.

The results suggest that stopping smoking — even later in life — can lead to better brain health over the long term. While short-term “brain boosts” after quitting have been noted before, this study is among the first to show that these improvements can last for many years.

“We already know that quitting smoking, even later in life, is often followed by improvements in physical health and well-being. It seems that, for our cognitive health too, it is never too late to quit,” said Bloomberg. “This finding is especially important because middle-aged and older smokers are less likely to try to quit than younger groups, yet they disproportionately experience the harms of smoking.”

Investigators noted several limitations, including possible unmeasured confounding, reliance on self-reported data and differences between cohorts. Results may not be generalizable across patient populations because participants were generally healthier older smokers who survived long enough to be studied. Missing data limited analyses by race, smoking history, alcohol use and country differences, though the findings appeared consistent across ages.

“Slower cognitive decline is linked to lower dementia risk,” said Andrew Steptoe, DSc, Ph.D., professor of psychology and epidemiology and head of the Research Department of Behavioural Science and Health at UCL. “These findings add to evidence suggesting that quitting smoking might be a [preventive] strategy for the disease. However, further research will be needed that specifically examines dementia to confirm this.”

For older adults who might feel it’s “too late” to quit, this research offers powerful motivation: Giving up cigarettes can help preserve your memory and thinking abilities as you age.