Smoking Identified as Major Contributor to Cognitive Decline in Older Adults: Study

Smoking may be among the most important lifestyle factors affecting how quickly cognitive skills decline as we age, suggested a new study led by UCL researchers.

The study was published in the journal Nature Communications.

Smoking has severe impacts on health, affecting nearly every organ in the body. It is a major cause of cardiovascular diseases, including heart attacks and strokes, and significantly increases the risk of various cancers, particularly lung cancer. Smoking also damages the respiratory system, leading to chronic obstructive pulmonary disease (COPD) and other breathing issues. Additionally, it accelerates cognitive decline, contributing to memory loss and dementia in older adults. The harmful chemicals in cigarettes weaken the immune system, reduce overall life expectancy, and negatively impact quality of life.

In the study, researchers analysed data from 32,000 adults aged 50 and over who participated in surveys over a 10-year period. The study aimed to explore how different combinations of health-related behaviours—smoking, physical activity, alcohol consumption, and social contact—affect cognitive decline in healthy older adults.

Cognitive function was measured using memory and verbal fluency tests. Participants were categorised into different lifestyle groups based on their behaviours: whether they smoked, engaged in moderate and vigorous physical activity at least once a week, and their alcohol consumption levels.

The findings revealed that cognitive decline was significantly faster among those who smoked compared to non-smokers. Specifically, smoking lifestyles experienced cognitive scores that declined up to 85% more over 10 years than those of non-smoking lifestyles.

“Our study is observational so cannot definitively establish cause and effect, but it suggests smoking might be a particularly important factor influencing the rate of cognitive ageing. Previous evidence suggests individuals who engage in more healthy behaviours have slower cognitive decline; however, it was unclear whether all behaviours contributed equally to cognitive decline, or if there were specific behaviours driving these results. Our findings suggest that among the healthy behaviours we examined, not smoking may be among the most important in terms of maintaining cognitive function,” said the authors.

Reference: Bloomberg, M., Muniz-Terrera, G., Brocklebank, L. et al. Healthy lifestyle and cognitive decline in middle-aged and older adults residing in 14 European countries. Nat Commun 15, 5003 (2024). https://doi.org/10.1038/s41467-024-49262-5