Smoking and cognitive functioning at older ages: Evidence from the Health and Retirement Study

A Review of Common Independent Variables Used in Tobacco Smoking Related Studies

“…However, researchers conducted studies using different independent variables for different areas. Most studies used a binary variable to indicate the smoking or smoking cessation [4][5][6][7][8][9][10][11][12][13][14][15][16]. Some researchers further classified the variable into three groups including never smokers, ex-smokers and current smokers [17][18][19][20][21][22][23].…”

“…Amaral et al improved the method of early diagnosis of smoking-induced respiratory changes using machine learning algorithms[4].Feldman and Anderson revealed the relationship between the cigarette smoking and mechanisms of susceptibility to infections of the respiratory tract and other organ systems[5]. Ayyagari and Kessler studied the association between smoking and cognitive functioning at older ages according to the evidence from the health and retirement study[6]. Brody et al studied the effect of cigarette smoking on a marker for neuroinflammation with a [11C] DAA1106 positron emission tomography study[7].Current Smokers Versus Never smokers/Non-SmokersSome researches separated the study population into current smokers and never smokers/non-smokers.Yoshida et al discussed the effects of tiotropium on lung function among current smokers and never smokers with bronchial asthma [8].…”