The relation between insulin-like growth factor I levels and cognition in healthy elderly: A meta-analysis

• Published in: Growth hormone & IGF research Vol. 15; no. 6; pp. 416 - 422
• Main Authors: Arwert, L.I., Deijen, J.B., Drent, M.L.
• Format: Journal Article
• Language: English
• Published: Scotland Elsevier Ltd 01.12.2005
• Subjects: Aged; Aged, 80 and over; Aging; Attention; Cognition; Cognition Disorders; Correlation; Elderly; Female; Growth Hormone; Humans; IGF-I; Insulin-Like Growth Factor Binding Protein 3 - blood; Insulin-Like Growth Factor Binding Proteins - metabolism; Insulin-Like Growth Factor I - biosynthesis; Male; Memory; Memory Disorders; Mental Status Schedule; Middle Aged; Neuropsychological Tests; Surveys and Questionnaires; IGF-I; Correlation; Cognition; Elderly; Memory
• ISSN: 1096-6374; 1532-2238
• DOI: 10.1016/j.ghir.2005.09.001

Insulin-like growth factor I (IGF-I) levels and cognitive functioning decrease with aging. Several studies report positive correlations between IGF-I levels and cognitive functioning in healthy elderly. However, because of controversial data no definitive conclusions can be drawn concerning the relation between IGF-I and cognition. Therefore, we carried out a meta-analysis on studies that report on the relation between IGF-I and cognition in healthy elderly. We searched the electronic databases for articles about IGF-I and cognition. Studies from 1985 to January 2005 are included. Two reviewers independently extracted data on study design and cognitive outcomes. Thirteen studies on IGF-I and cognition in elderly, with a total number of 1981 subjects, met the inclusion criteria. On the data from these studies meta-analyses were carried out by means of the program Comprehensive Meta-analysis using a random effects model. Pooled effects show that IGF-I levels in healthy elderly have a positive correlation with cognitive functioning, which appeared to be mainly measured with the mini mental state examination (MMSE). The effect size is 0.6, which indicates the presence of a large positive relationship between IGF and cognition in healthy elderly. These meta-analyses showed an overall relationship between IGF-I levels and cognitive functioning in healthy elderly. Further studies should be performed to clarify the role of IGF-I substitution in preserving cognitive functions with aging.