Passive smoking as a risk factor for dementia and cognitive impairment: systematic review of observational studies

Abstract

Background:Smoking is a well-established risk factor for dementia, but the effects of passive smoking are unclear. We aimed to examine links between passive smoking and dementia or cognitive impairment.Methods:We searched seven medical research databases: MEDLINE, Web of Science (Core Collection), Cochrane, EMBASE, PsycINFO, Scopus, and CINAHL Plus. Studies were included if they examined measures of passive smoking and either cognitive impairment or dementia.Results:Of 1,425 records found, nine papers of varying methodologies were included after screening against inclusion criteria. Eight papers reported weak associations between passive smoking and either cognitive impairment or dementia. One paper only found this association alongside carotid artery stenosis. The papers’ quality was variable, with only two deemed high quality.Conclusion:There is limited weak observational evidence linking passive smoking with an increased risk of cognitive impairment or dementia. However, the studies were methodologically diverse and of inconsistent quality, preventing firm conclusions.

Passive Smoking Exposure in Living Environments Reduces Cognitive Function: A Prospective Cohort Study in Older Adults

“…Exposure to passive smoking can increase the risk of developing or dying from diseases such as cancer (particularly lung and breast cancer) and cardiovascular diseases (e.g., stroke, angina, and hypertension), as well as cognitive impairment [3][4][5]. Positive correlations between tobacco exposure and cognitive impairment, dementia, and other neurodegenerative diseases have also been reported [6,7]. However, some studies have suggested a protective role of nicotine against cognitive impairment [8,9].…”

Exploration of the Global Burden of Dementia Attributable to PM2.5: What Do We Know Based on Current Evidence?

“…We compared our final search results with seven previous systematic review papers (five focused on AAP [Killin et al., 2016; Paul et al., 2019; Peters et al., 2019; Power et al., 2016; Tsai et al., 2019]; one focused on SHS [Stirland et al., 2018]; one on AS [Anstey et al., 2007]), while including the most recent studies until October 2020. All studies that were selected in previous review papers were identified in our search, but some were subsequently excluded based on our inclusion criteria (“Criteria of inclusion” in supplementary information; Table ).…”

Modifiable Risk Factors and Prevention of Dementia

“…9,56 Meta-analyses have confirmed the association between smoking and all-cause dementia for current smokers (RR 1.3 95%CI 1.18-1.45), 56 with greater risk for elderly smokers. Passive smoking also increases risk of dementia, though the association is weak 57,58 and it impairs prospective memory and executive function. 59 The risk of dementia increases 3-fold among passive smokers with carotid artery stenosis.…”