Decreased Levels of Insulin-Like Growth Factor-1 Are Associated with Alzheimer’s Disease: A Meta-Analysis

Article type: Research Article

Authors: Xu, Ling-Zhi^{a; b; c; d; e; 1} | Li, Fang-Yu^{a; b; c; d; e; 1} | Li, Bing-Qiu^{a; b; c; d; e; 1} | Cao, Shu-Man^{a; b; c; d; e} | Li, Yan^{a; b; c; d; e} | Xu, Jin^f | Jia, Jian-Ping^{a; b; c; d; e; *}

Affiliations: [a] Innovation Center for Neurological Disorders and Department of Neurology, Xuanwu Hospital, Capital Medical University, National Clinical Research Center for Geriatric Diseases, Beijing, P.R. China | [b] Beijing Key Laboratory of Geriatric Cognitive Disorders, Beijing, P.R. China | [c] Clinical Center for Neurodegenerative Disease and Memory Impairment, Capital Medical University, Beijing, P.R. China | [d] Center of Alzheimer’s Disease, Beijing Institute of Brain Disorders, Collaborative Innovation Center for Brain Disorders, Capital Medical University, Beijing, P.R. China | [e] Key Laboratory of Neurodegenerative Diseases, Ministry of Education, Beijing P.R. China | [f] Department of Library, Xuanwu Hospital, Capital Medical University, Beijing, P.R. China

Correspondence: [*] Correspondence to: Jianping Jia, MD, PhD, Professor of Neurology, Innovation Center for Neurological Disorders and Department of Neurology, Xuanwu Hospital, Capital Medical University, National Clinical Research Center for Geriatric Diseases, Changchun Street 45, Xicheng District, Beijing 100053, China. Tel.: +86 10 83199449; E-mail: jjp@ccmu.edu.cn.

Note: [1] These authors contributed equally to this work.

Abstract: Background:Alterations in levels of peripheral insulin-like growth factor-1 (IGF-1) in Alzheimer’s disease (AD) have been reported in several studies, and results are inconsistent. Objective:We conducted a meta-analysis to investigate the relationship between peripheral and cerebrospinal fluid IGF-1 levels and AD or mild cognitive impairment (MCI). Methods:A systematic search in PubMed, Medline, Web of Science, Embase, and Cochrane Library was conducted and 18 studies were included. Results:Results of random-effects meta-analysis showed that there was no significant difference between AD patients and healthy control (17 studies; standard mean difference [SMD], –0.01; 95%CI, –0.35 to 0.32) and between MCI patients and healthy control (6 studies; SMD, –0.20; 95%CI, –0.52 to 0.13) in peripheral IGF-1 levels. Meta-regression analyses identified age difference might explain the heterogeneity (p = 0.017). However, peripheral IGF-1 levels were significantly decreased in AD subjects (9 studies; SMD, –0.44; 95%CI, –0.81 to –0.07) and MCI subjects exhibited a decreasing trend (4 studies; SMD, –0.31; 95%CI, –0.72 to 0.11) in studies with sample size≥80. Cerebrospinal fluid IGF-1 levels also significantly decreased in AD subjects (3 studies; SMD, –2.40; 95%CI, –4.36 to –0.43). Conclusion:These findings suggest that decreased peripheral and cerebrospinal fluid IGF-1 levels might be a potential marker for the cognitive decline and progression of AD.

Keywords: Alzheimer’s disease, cognitive impairment, insulin-like growth factor-1, meta-analysis.

DOI: 10.3233/JAD-210516

Journal: Journal of Alzheimer's Disease, vol. 82, no. 3, pp. 1357-1367, 2021