Table 5.
Summary of case-control and longitudinal studies on smoking and TL.
| Author, Reference | Year | Type of Study | Participants | TL Measurements | Tissue for TL Analysis | Exposure Assessment Methods | Results |
|---|---|---|---|---|---|---|---|
| Zhang et al. [121] | 2016 | Longitudinal | 5624 participants from HRS, 16 y follow up | PCR | Saliva | Tobacco smoking reported by questionnaire | Shorter TL observed in smokers. The number of cigarettes was also inversely associated with TL in women, but not in men. Sex-specific prospective changes on smokers and TL were detected |
| Bendix et al. [122] | 2014 | Longitudinal | 1356 individuals (30–70 y). 10-y follow-up | PCR | Blood | Tobacco smoking reported by questionnaire | Tobacco influences the change in TL after follow-up, with smokers having a greater risk of telomere shortening |
| Chen et al. [123] | 2011 | Longitudinal | Follow-up of 271 participants at 3 times | SB | Blood | Tobacco smoking reported by survey | Smoking at baseline was associated with shorter TL and accelerated shortening |
| Marcon et al. [124] | 2017 | Twin study (case-control) | 22 homozygous twins (one smoker and the other non-smoker) | SB and methylation arrays | Blood | Tobacco smoking reported by questionnaire, and urine cotinine | Statistically significant higher values of TL in smokers compared to non-smoking twins |
| Müezzinler et al. [125] | 2015 | Longitudinal | 3600 elderly adults. Follow-up on 1000 participants | PCR | Blood | Tobacco smoking reported by questionnaire | Smoking was inversely associated with TL at baseline. On average, current smokers had 73 bp shorter telomeres, but this relationship could not be shown longitudinally |
| Strandberg et al. [126] | 2011 | Longitudinal | 622 participants from Finland (30–45 y). Follow-up at 30–40 years | SB | Blood | Tobacco smoking reported by questionnaire | Age-adjusted TL was significantly longer among lifelong non-smokers compared to past or present smokers |
| Walters et al. [127] | 2014 | Case-Control | Healthy smokers (n = 29) vs. non-smokers (n = 29) | SB | Epithelial cells or whole blood | Tobacco smoking reported by questionnaire, and urine cotinine | No differences were observed between TL and being a smoker or not |
TL: telomere length; y: years; bp: base pairs; PCR: polymerase chain reaction; SB: Southern blot analysis of terminal restriction fragment lengths (TRF); HRS: Health and Retirement Study; CHS: Cardiovascular Health Study.