Meta-Analysis of Serum Insulin-Like Growth Factor 1 in Alzheimer’s Disease

• Published in: PloS one Vol. 11; no. 5; p. e0155733
• Main Authors: Ostrowski, Philip P., Barszczyk, Andrew, Forstenpointner, Julia, Zheng, Wenhua, Feng, Zhong-Ping
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 26.05.2016; Public Library of Science (PLoS)
• Subjects: Alzheimer Disease - blood; Alzheimer Disease - pathology; Alzheimer's disease; Animal cognition; Biology and Life Sciences; Biomarkers - blood; Blood-brain barrier; Brain research; Case-Control Studies; Clinical trials; Cognitive ability; Data processing; Dementia; Development and progression; Diabetes; Disease control; Growth hormones; Health aspects; Humans; Insulin; Insulin-like growth factor I; Insulin-Like Growth Factor I - analysis; Insulin-like growth factors; Medical ethics; Medical research; Medicine and Health Sciences; Meta-analysis; Neurogenesis; Pathology; Phosphorylation; Physical Sciences; Physiological aspects; Physiology; Proteins; Research and Analysis Methods; Rodents; Serum levels; Statistical analysis; Studies; Transgenic animals; Toronto Ontario Canada; Canada; Macao
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0155733

Insulin-like growth factor 1 (IGF-1) serum levels have been reported to be altered in Alzheimer's disease patients, and it was suggested that the changes in IGF-1 serum level may play a role in disease pathology and progression. However, this notion remained controversial due to conflicting findings. We conducted a meta-analysis to determine the relationship between IGF-1 serum levels and Alzheimer's disease. We searched the databases PUBMED, Ovid SP, and Cochrane library for relevant studies. The primary data analyzed was serum IGF-1 from Alzheimer's disease subjects and controls. Pooled weighted mean difference using a random effects model was used to determine the relationship between serum levels and disease state. Nine studies were included in the meta-analysis compromising a total of 1639 subjects. The pooled weighted mean difference was -2.27ng/ml (95% CI: [-22.221, 17.66]) with a P value of 0.82. Thus our finding did not show clear relationship between low IGF-1 and Alzheimer's disease subjects. We did not find evidence of publication bias by analyzing a funnel plot as well as Egger's and Begg's tests. While eight out of the nine studies included in this meta-analysis detected a statistically significant increase or decrease in serum levels of IGF-1 in Alzheimer's disease subjects, the analysis as a whole did not show a significant trend in either direction. Thus, IGF-1 level is likely a critical personalized factor. A large database of clinical trials is required for better understanding the relationship between IGF-1 levels and Alzheimer's disease.