Quitting smoking is good for you, no matter when in life it happens.
Mikaela Bloomberg, senior research fellow in social epidemiology and social statistics at the department of epidemiology and public health at the institute of epidemiology and health care at University College London, explores why.
Mikaela Bloomberg is a Senior Research Fellow in Social Epidemiology and Social Statistics at University College London’s Department of Epidemiology and Public Health. She is part of the English Longitudinal Study of Ageing research team, where her work examines how social and behavioural pathways contribute to inequalities in health and wellbeing in later life. Her research integrates lifecourse perspectives with longitudinal population data to understand how socioeconomic circumstances and behavioural patterns shape cognitive ageing, dementia risk, and other ageing-related outcomes.
The harmful effects of smoking are well known. Smoking damages heart and lung health and is also linked to poorer cognitive outcomes: people who smoke tend to show faster decline in cognitive abilities such as memory and thinking skills and are more likely to develop dementia.
However, research suggests that some of smoking’s health harms are reversible—not only for heart and lung health, but also for the brain. For example, people who quit smoking earlier in life have dementia risks and later-life cognitive abilities similar to those who never smoked.
What has been less clear is whether quitting later on can still make a difference once cognitive decline has already begun. Age-related cognitive decline typically accelerates from around age 65, so by that stage, many assume their cognitive trajectory is already set. We wanted to know whether quitting could still slow that decline.
To find out, we analysed data from over 9000 adults aged 40 and older across 12 countries, tracking their performance on cognitive tests over 18 years. We matched people who quit smoking with continuing smokers based on their age, sex, education level, and cognitive abilities before quitting. We examined cognitive trajectories in the years before and after quitting and compared these with the matched control group.
Before quitting, both groups declined at a similar rate. But in the years after, those who quit experienced 20%-50% slower cognitive decline than those who continued to smoke. This was true whether they quit in midlife or later.
These findings matter because many long-term smokers believe there’s no point in quitting after decades of smoking. Our results suggest that when it comes to maintaining cognitive health, it is never too late to quit.
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