Study Reveals Smoking’s Strong Link to Cognitive Decline [(Credit: Laurent T/Shutterstock)]
LONDON — Smoking might be the most significant factor influencing whether older adults develop dementia, according to a new study spanning 14 European countries. Research from University College London highlights that not smoking could be the key to maintaining cognitive function as we age.
The study, published in Nature Communications, tracked over 32,000 adults aged 50 to 104 for up to 15 years. Unlike previous research that grouped various healthy behaviors, this study focused on isolating the effects of smoking, alcohol consumption, physical activity, and social contact on cognitive decline.
H2: Methodology: Unraveling the Cognitive Puzzle
Researchers used data from two major aging studies: the English Longitudinal Study of Ageing (ELSA) and the Survey of Health, Ageing and Retirement in Europe (SHARE). These studies provided a wealth of information on health, lifestyle, and cognitive function.
The researchers examined four key lifestyle factors:
- Smoking (current smoker or non-smoker)
- Alcohol consumption (no-to-moderate or heavy)
- Physical activity (weekly moderate-plus-vigorous activity or less)
- Social contact (weekly or less than weekly)
By combining these factors, they created 16 distinct lifestyle profiles. For example, one profile could be a non-smoker who drinks moderately, exercises weekly, and has frequent social contact, while another might be a smoker who drinks heavily, doesn’t exercise regularly, and has limited social interaction.
To measure cognitive function, researchers used two tests: a memory test where participants recalled a list of words and a verbal fluency test where participants named as many animals as possible in one minute. These tests were repeated over several years to track changes in cognitive function for each lifestyle profile. The researchers excluded anyone showing signs of cognitive impairment at the start of the study or diagnosed with dementia during the follow-up period to ensure they captured the effects of lifestyle rather than early signs of dementia.
H2: Key Results: Smoking Takes Center Stage
The results were striking. Regardless of other lifestyle factors, non-smokers consistently showed slower rates of cognitive decline compared to smokers. This finding suggests that quitting smoking—or never starting—could be the most crucial step in preserving brain function as we age.
For instance:
- Smokers with heavy alcohol consumption, infrequent exercise, and limited social contact showed the fastest rate of cognitive decline.
- Even smokers who followed all other healthy behaviors still showed faster cognitive decline than non-smokers.
- Among non-smokers, differences in other lifestyle factors had much smaller effects on cognitive decline.
Over a 10-year period, smokers’ memory scores declined up to 0.17 standard deviations more than non-smokers, and their verbal fluency scores declined up to 0.16 standard deviations more. While these numbers might seem small, they could translate to noticeable differences in daily cognitive function over time.
Interestingly, the effects of other lifestyle factors were less pronounced. Moderate alcohol consumption was associated with slightly slower cognitive decline compared to heavy drinking, but the difference was much smaller than that seen with smoking. Regular physical activity and social contact showed little to no independent effect on cognitive decline in this study.
H2: Discussion & Takeaways
These findings have significant implications for individuals and public health efforts. The researchers suggest that quitting smoking—or never starting—may be the most crucial step to maintain cognitive function as we age. This is particularly relevant given the lengthy preclinical period of conditions like Alzheimer’s disease, where brain changes can occur decades before symptoms appear.
However, the researchers caution against completely disregarding other healthy behaviors. While this study didn’t find strong independent effects of physical activity and social contact on cognitive decline, these factors are known to have numerous other health benefits. Additionally, for those who smoke and find it difficult to quit, adopting other healthy habits may help to some extent in mitigating cognitive decline.
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