Higher blood cotinine level is associated with worse cognitive functioning in non-smoking older adults

Zhenmei Fu; Guiye Qi; Zhe Qu; Xuechun Lin; Li Xu; Biyu Shen; Fanghong Dong; Song Ge

doi:10.3389/fnins.2022.1080066

Higher blood cotinine level is associated with worse cognitive functioning in non-smoking older adults

Front Neurosci. 2022 Nov 24:16:1080066. doi: 10.3389/fnins.2022.1080066. eCollection 2022.

Authors

Zhenmei Fu¹, Guiye Qi², Zhe Qu³, Xuechun Lin⁴, Li Xu⁵, Biyu Shen⁶, Fanghong Dong⁷, Song Ge⁸

Affiliations

¹ Department of Radiology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China.
² Department of Medical Engineering, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China.
³ School of Nursing, Xuzhou Medical University, Xuzhou, Jiangsu, China.
⁴ Department of Nutrition and Food Hygiene, Hubei Key Laboratory of Food Nutrition and Safety, Ministry of Education Key Laboratory of Environment and Health, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
⁵ Department of Pulmonary and Critical Care Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, China.
⁶ Department of Nursing, Shanghai Children's Medical Center Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai, China.
⁷ School of Nursing, Hebei University, Baoding, China.
⁸ Department of Natural Sciences, University of Houston-Downtown, Houston, TX, United States.

Abstract

Introduction: Secondhand smoke (SHS) is common in older adults; however, its cognitive effect is unclear. We aimed to examine the association between serum cotinine level and cognitive functioning among non-smoking older adults.

Materials and methods: A total of 2,703 older adults aged 60 and above from the National Health and Nutrition Examination (NHANES) Survey 2011-2014 were included. Serum cotinine level was analyzed in the laboratory. A level ≤10 ng/ml and a response of "no" to the question "Do you currently smoke?" were used to select non-smokers. Cognitive functioning was measured using the Consortium to Establish a Registry for Alzheimer's disease Word Learning subtest (CERAD-WL) immediate and delayed recall tests, the Animal Fluency test (AFT), and the Digit Symbol Substitution test (DSST). Multivariable linear regression models were constructed to examine the association between serum cotinine level quartile and test-specific and global cognition z scores adjusting for age, race/ethnicity, education, depressive symptoms, body mass index, alcohol use, smoking history, prevalent coronary heart disease (CHD), stroke, and systolic blood pressure.

Results: About half of the participants (mean age 70.5 years) were female (53.6%), non-Hispanic White (48.3%), and completed some college and above (50.2%). Multivariate linear regressions with a reference group being those in the 1st quantile (lowest) showed that participants in the 4th quartile (highest) of serum cotinine level had lower immediate recall [β = -0.16, 95% confidence interval (CI) = -0.29, -0.03], AFT (β = -0.19, 95% CI = -0.33, -0.05), DSST (β = -0.27, 95% CI = -0.39, -0.15), and global cognition (β = -0.26, 95% CI = -0.39, -0.14) z scores. Participants in the 3rd quartile had lower immediate recall (β = -0.16, 95% CI = -0.30, -0.02) and global cognition (β = -0.16, 95% CI = -0.29, -0.02) z scores. Participants in the 2nd quartile had lower delayed recall z scores (β = -0.16, 95% CI = -0.29, -0.02).

Conclusion: Higher serum cotinine level was associated with worse cognitive functioning in non-smoking older adults. Prevention and reduction of SHS in older adults may help protect their cognitive functioning.

Keywords: NHANES; cognitive function; cotinine; older adults; secondhand smoke; tobacco.