The Associations Between Serum Insulin-like Growth Factor-I, Brain White Matter Volumes, and Cognition in Mild Cognitive Impairment and Alzheimer’s Disease
Affiliations: [a] Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| [b] Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| [c] Department of Immunology and Transfusion Medicine, Sahlgrenska University Hospital, Gothenburg, Sweden
| [d] Department of Acute Medicine and Geriatrics, Sahlgrenska University Hospital, Gothenburg, Sweden
| [e] Department of Internal Medicine, Skaraborg Central Hospital, Skövde, Sweden
Correspondence:
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Correspondence to: Alexandra Horvath, Department of Internal Medicine, Gröna Stråket 8, Sahlgrenska University Hospital, SE-413 45 Gothenburg, Sweden. Tel.: +46317411712; Fax: +4631821524; E-mail: alexandra.horvath@gu.se.
Abstract: Background:Insulin-like growth factor-I (IGF-I) regulates myelin, but little is known whether IGF-I associates with white matter functions in subjective and objective mild cognitive impairment (SCI/MCI) or Alzheimer’s disease (AD). Objective:To explore whether serum IGF-I is associated with magnetic resonance imaging – estimated brain white matter volumes or cognitive functions. Methods:In a prospective study of SCI/MCI (n = 106) and AD (n = 59), we evaluated the volumes of the total white matter, corpus callosum (CC), and white matter hyperintensities (WMHs) as well as Mini-Mental State Examination (MMSE), Trail Making Test A and B (TMT-A/B), and Stroop tests I–III at baseline, and after 2 years. Results:IGF-I was comparable in SCI/MCI and AD (113 versus 118 ng/mL, p = 0.44). In SCI/MCI patients, the correlations between higher baseline IGF-I and greater baseline and 2-year volumes of the total white matter and total CC lost statistical significance after adjustment for intracranial volume and other covariates. However, after adjustment for covariates, higher baseline IGF-I correlated with better baseline scores of MMSE and Stroop test II in SCI/MCI and with better baseline results of TMT-B and Stroop test I in AD. IGF-I did not correlate with WMH volumes or changes in any of the variables. Conclusions:Both in SCI/MCI and AD, higher IGF-I was associated with better attention/executive functions at baseline after adjustment for covariates. Furthermore, the baseline associations between IGF-I and neuropsychological test results in AD may argue against significant IGF-I resistance in the AD brain.
Keywords: Alzheimer’s disease, attention, corpus callosum, executive function, insulin-like growth factor-I, magnetic resonance imaging, mild cognitive impairment, speed, subjective mild cognitive impairment, white matter hyperintensities
