What is the relationship between smoking and cognitive decline?

A new study, conducted by researchers from University College London, has found that smoking may be among the most important lifestyle factors that influence how quickly our cognitive skills decline as we age.

The study analyzed data from 32,000 adults, aged 50 or older, from 14 European countries who answered surveys over a 10-year period.

The researchers studied how rates of cognitive decline differed between cognitively healthy older adults and those with different sets of health-related behaviors, including smoking, physical activity, alcohol consumption, and social interaction.

Cognitive function was assessed based on participants' performance on tests of memory and verbal fluency.

The research team found that cognitive decline was faster in smokers, and smoking was associated with an 85% lower cognitive scores over 10 years.

The study explained that these results excluded smokers who had a healthy lifestyle in all other areas, meaning they exercised and socialized regularly. 

“Our study is observational, so cause and effect cannot be conclusively determined, but it suggests that smoking may be a particularly important factor in influencing the rate of cognitive aging,” said lead author Dr. Michaela Blumberg. “Previous evidence suggests that individuals who engage in more healthy behaviors have slower cognitive decline. However, it has been unclear whether all behaviors contributed equally to cognitive decline, or whether specific behaviors drive these outcomes.”

“For people who are unable to quit smoking, our findings suggest that engaging in other healthy behaviors, such as regular exercise, may help offset the harmful cognitive effects associated with smoking,” she added.

The study was published in the journal Nature Communications.