Affiliations: [a] AP-HP, Hôpital Broca, Service de Gériatrie, Paris, France | [b] Université Paris Descartes, Sorbonne Paris Cité, Paris, France | [c] INSERM, UMR-S894, Centre de psychiatrie et neurosciences, Paris, France | [d] INSERM, IFR65, Paris, France | [e] INSERM/UPMC, Paris VI, UMRS 938, Centre de Recherche St-Antoine, Paris, France
Correspondence:
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Correspondence to: Jean-Sébastien Vidal and Emmanuelle Duron, Hôpital Broca, Service de Gériatrie, 54-56 rue Pascal, 75013 Paris, France. Tel.: +33 1 44 08 30 30; Fax: +33 1 44 08 35 10; E-mails: jean-sebastien.vidal@aphp.fr (Jean-Sébastien Vidal) and emmanuelle.duron@aphp.fr (Emmanuelle Duron).
Abstract: Background: The relationship between the insulin-like growth factor-I (IGF-I) system and Alzheimer’s disease (AD) is mostly based on transversal studies. It remains, however, to demonstrate whether IGF-I is associated with cognitive decline over time in AD. Objective:The objective of the study was to analyze the course of cognitive decline of AD subjects over a 24-month period in relation to serum IGF-I and insulin-like growth factor binding protein-3 (IGFBP-3) measured at baseline. Methods: Data are from the SIGAL follow-up study. IGF-I and IGFBP-3 were measured in AD subjects who performed a Mini-Mental State Examination (MMSE) every 6 months for 2 years. MMSE course was analyzed using a mixed model with random intercept and slope function. Results: Among the 200 AD participants, 146 (mean age = 81.1 (standard deviation (SD) = 5.9) years, 62.6% of women) had at least one follow-up visit. Mean IGF-I at baseline was 147.8 (74.2) ng/mL. Hundred forty-six participants (62.6%) had at least one follow-up visit. Mean MMSE was 21.7 (4.7)/30 and dropped on average by 2.28 points per year. MMSE decline was steeper among participants with lower IGF-I. For each decrease of 1 SD of IGF-I, subjects lost an additional 0.63 points per year in MMSE, e.g., participants with IGF-I level of 74 ng/mL lost 2.91 MMSE points per year whereas participants with IGF-I of 222 ng/mL lost 1.65 MMSE points per year. There was no association between IGFBP-3 and cognitive decline. Conclusion:Lower baseline serum IGF-I was associated with faster cognitive decline in AD over a 2-year period.
