That cigarette may be doing more damage than meets the eye. If you've been smoking for an extended period of time, you're likely familiar with at least some -- if not all -- of the bodily symptoms associated with smoking, including but certainly not limited to: Cravings, coughing, shortness of breath and changes to teeth, hair and skin. Coronary heart disease and/or lung cancer might not be far behind.
But a new study published in the journal Age & Ageing concludes that smoking can damage your mind, too. A consistent association was observed between smoking and low global cognitive functioning, including memory.
The bottom line: Smoking and long-term high blood pressure appear to increase the risk of cognitive decline.
How researchers did it
Researchers at Kings College London set out to explore the association between cardiovascular and stroke risk and cognitive decline in adults over the age of 50. Working with a nationally representative sample of nearly 9,000 participants, they analyzed data on smoking, blood pressure, cholesterol levels, and body mass index (BMI).
At four- and eight-year follow-up appointments, participants' cognitive performance was measured. To test for memory, researchers taught the participants 10 unrelated words, then tested both their immediate and delayed recall capabilities. Subjects were also asked to name as many animals as they could in one minute, a test designed to measure verbal fluency. Lastly, the subjects were asked to cross through specified letters in a series (letter cancellation), to measure attention, mental speed and visual scanning.
What they found
The study concludes that smoking has the most consistent impact on hastening ageing in the brain. Those with high BMI, blood pressure, or stroke risk scores performed less well on cognitive tasks, but those results varied more widely across the three objective tests.
"Cognitive decline becomes more common with aging and for an increasing number of people, interferes with daily functioning and well-being," said Dr. Alex Dregan, lecturer in Translational Epidemiology and Public Health at Kings College London. "Some older people can become forgetful, have trouble remembering common words, or have problems organizing daily tasks more than others."
To be clear, the researchers did not draw any conclusions as to whether a decline in brain function could lead to conditions such as dementia.
Asked for a comment, William Thies, chief medical and scientific officer for the Alzheimer's Association, responded by acknowledging the growing body of research over more than a decade - including this new study - that point toward several factors that may impact our risk of Alzheimer's disease and cognitive decline, the strongest being heart health risk factors.
"These (factors) include physical inactivity, smoking, and poor control of blood pressure, blood lipids, and blood sugar levels," Thies said. "Currently, the strongest data for lifestyle-based Alzheimer's risk reduction is for physical activity."
Dregan agrees. "We have identified a number of risk factors which could be associated with accelerated cognitive decline, all of which could be modifiable," he said. "This offers valuable knowledge for future prevention and treatment interventions."
"We recognize and agree that smoking has serious health consequences and causes serious diseases," said David Sylvia, a spokesman for Altria, the parent company of Philip Morris USA. "That's why we think it's... important the FDA has oversight of the industry to conduct further research about the harm caused by tobacco use and ways to reduce that harm."
"For those people who are concerned about the health effects of smoking," Sylvia said, "the best thing to do is to quit."