Meta-analysis of the Connection Between Alzheimer Disease and Telomeres

Background: Alzheimer disease (AD) is the most common neurodegenerative disease of the central nervous system. The stability of the telomere-telomerase system is closely related to AD. A previous meta-analysis indicated that AD patients had shorter telomere length (TL) than control subjects. However, there are no consistent telomerase activity findings in AD patients, and the published telomerase studies were not meta-analyzed yet. Methods: We searched all the related studies that probed into TL and/or telomerase activity in AD patients based on PubMed and Embase database from the establishment to September 2020. The Chinese National Knowledge Infrastructure, Wanfang and China Science and Technology Journal Database were also utilized. The quality of the included studies was evaluated by using Newcastle-Ottawa Scale. All the statistical analyses of this meta-analysis were performed using Stata version 15.0. Results: Analyzing 30 TL data from 2248 AD patients and 4865 controls, AD patients had a significantly shorter TL than the controls, with a standardized mean difference of −0.70 (confidence interval: −0.95 to −0.46; P <0.05). The meta-analysis included 3 primary studies and did not find a significant difference in the telomerase activity between 233 AD patients and 132 controls, but AD patients had a trend of increased telomerase activity compared with controls (standardized mean difference: 0.47; confidence interval: −0.29 to 1.23; P >0.05). Conclusion: Our results showed that compared with the control group, the AD group had a shorter TL and may have higher telomerase activity.