Quitting smoking, even in middle age or later, can slow age-related cognitive decline, according to new research from University College London (UCL). The study, which analyzed data from nearly 10,000 adults across 12 countries, found that individuals who stopped smoking in midlife experienced a slower reduction in memory and verbal fluency compared with those who continued smoking.
Quantifying the Impact on Memory and Verbal Fluency
The researchers observed that the rate of decline in verbal fluency roughly halved among those who quit smoking, while memory decline slowed by approximately 20 percent within six years of cessation. Published in The Lancet Healthy Longevity, the study suggests that quitting smoking may lower the risk of developing dementia.
Understanding the Mechanisms of Brain Ageing
Smoking accelerates brain ageing by damaging blood vessels responsible for delivering oxygen and nutrients to the brain. Additionally, tobacco use triggers chronic inflammation and oxidative stress, processes that contribute to cognitive deterioration. Collectively, these effects increase the pace of age-related decline in cognitive functions.
Study Design and Methods
To assess the cognitive effects of smoking cessation, the UCL team analyzed 18 years of data (2002–2020) from three nationally representative cohort studies, including participants from England, the United States, and 10 European countries. The study included 9,436 adults aged 40 to 89, half of whom quit smoking during the study period. Memory and verbal fluency were tracked over time, comparing quitters with demographically and socioeconomically matched individuals who continued smoking.
Comparing Cognitive Decline Before and After Quitting
In the six years prior to cessation, the cognitive decline rates of both groups were nearly identical. However, after quitting, participants experienced slower decline in both memory and verbal fluency. Specifically, memory decline slowed by 20 percent, while verbal fluency decline decreased by 50 percent compared with ongoing smokers. Although the differences were modest, they were statistically significant and suggest a meaningful cognitive benefit from quitting.
Practical Implications for Memory and Verbal Skills
In tangible terms, individuals who quit smoking experienced three to four months less memory decline and approximately six months less fluency decline per year compared with those who continued smoking. These findings demonstrate that cessation has measurable benefits for maintaining cognitive function with age.
Benefits Across Age Groups
The cognitive advantages of quitting smoking were observed across all age groups studied, whether cessation occurred in midlife or later. Dr. Mikaela Bloomberg of the UCL Institute of Epidemiology and Health Care emphasized, “Our study suggests that quitting smoking may help people maintain better cognitive health over the long term, even when we are in our 50s or older. It is never too late to quit.”
Encouraging Middle-Aged and Older Smokers to Quit
The findings are particularly significant because middle-aged and older adults are less likely to attempt quitting compared with younger smokers, despite experiencing greater health risks. Dr. Bloomberg added, “Evidence that quitting may support cognitive health could offer compelling motivation for this group. As policymakers address the challenges of an ageing population, investing in tobacco control remains crucial.”
Implications for Dementia Prevention
Since slower cognitive decline is associated with reduced dementia risk, the researchers suggest that these results reinforce the notion that quitting smoking can help prevent the disease. However, they caution that further research is necessary to establish a definitive causal relationship between smoking cessation and long-term dementia risk.
Conclusion
Overall, the study highlights the cognitive and long-term brain health benefits of quitting smoking at any age. Beyond improvements in physical health and well-being, cessation in midlife offers a promising strategy to slow cognitive decline, preserve memory, and support verbal skills, potentially lowering the risk of dementia.
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