The more individuals smoke, the worse they perform on cognitive tests, regardless of other health conditions known to affect cognition, according to preliminary research results of adults aged 60 years and older to be presented at the American Stroke Association’s International Stroke Conference 2022 February 8 to 11, 2022.
Although smoking, high blood pressure (HBP), and type 2 diabetes (T2D) are all known to adversely affect brain health, a new study examined detailed national data of adults aged 60 years and older to evaluate whether smoking in combination with other medical conditions, such as HBP and T2D, had an amplified impact on cognitive abilities. Investigators reviewed data collected by the United States National Health and Nutrition Examination Survey, a large, ongoing health database managed by the CDC since the early 1960s, for the study.
The collection of surveys compiles interviews and physical examinations that assess the health and nutritional status of a representative sample of adults and children in the United States each year.
During the study, investigators examined health data for 3244 individuals collected between 2011 and 2014. HBP was present in 77% of individuals, determined by elevated blood pressure readings, medication use, and self-reported hypertension. T2D was present among 24% of individuals, determined by medication use, self-reported information, or levels of hemoglobin A1c reflecting the average blood sugar levels during the previous 3 months.
Smoking status was self-reported by 23% of individuals and an objective measure of exposure to cigarette smoke was determined by a biomarker called cotinine, which is a byproduct of nicotine that remains in the blood much longer than nicotine.
Individuals took 4 tests used to measure cognitive function. The tests reflected aspects of cognition, such as attention, fluency, processing speed, word recall, and working memory.
The findings showed that higher cotinine levels were associated with significantly worse scores on the Digit Symbol Substitution Test (DSST), which reflects multiple aspects of cognition, such as attention, processing speed, and working memory.
Additionally, high cotinine levels were not associated with significant differences in scores on tests that measured language fluency or memory.
Finally, the association between higher cotinine levels and lower scores on the DSST was comparable among individuals with HBP or T2D.
“We were surprised to find that smoking does not act synergistically with high blood pressure or T2D to impact cognitive performance,” Neal Parikh, MD, MS, an assistant professor of neurology and neuroscience in the clinical and translational neuroscience unit at the Feil Family Brain and Mind Research Institute, said in a statement.
“To us, these results suggest that smoking has a strong enough influence on brain health independent of other health conditions. This means that smoking is bad for brain health even in people who don’t have other health conditions typically linked with poor brain health,” Parikh said.
Investigators noted that the study is limited by using data collected from individuals living in the community, so the results may not be able to be generalized to individuals who live in other settings, such as assisted-living settings, long-term-care facilities, or nursing homes.