Patients with Alzheimer's Disease Have Increased Levels of Insulin-like Growth Factor-I in Serum but not in Cerebrospinal Fluid

• Background: Insulin-like growth factor-I (IGF-I) is important for amyloid-β (Aβ) metabolism, and also interacts with the brain vasculature. In previous IGF-I studies, it has not been evaluated whether Alzheimer's disease (AD) patients had vascular comorbidities. Objective and Methods: A cross-sectional study of 40 consecutive non-diabetic AD patients and 36 healthy controls. We measured IGF-I in serum and cerebrospinal fluid (CSF) and also serum insulin. Mixed forms of AD and vascular dementia were excluded. Results: After adjustment for covariates including age, serum IGF-I level was higher in the AD group than in the controls, whereas CSF IGF-I and serum insulin were unchanged. Binary logistic regression confirmed that high serum IGF-I was associated with increased prevalence of AD [adjusted Odds Ratio (OR):=:1.83, 95% confidence interval (CI): 1.005-3.32 per standard deviation (SD) increase in serum IGF-I]. This association was more robust after exclusion of patients receiving treatment with acetylcholinesterase inhibitors or N-methyl D-aspartate (NMDA) receptor antagonists (OR:=:2.23, 95 % CI: 1.10-4.48). In the total study population (n:=:76) as well in the AD group (n:=:40), serum IGF-I correlated negatively with CSF Aβ1-42, and CSF IGF-I correlated positively with CSF/serum albumin ratio, CSF total tau, and CSF phosphorylated tau. Conclusion: In AD patients without major brain vascular comorbidities, serum but not CSF levels of IGF-I were increased after correction for covariates. This association was strengthened by exclusion of patients receiving medical treatment. Overall, the results support the notion of IGF-I resistance in mild AD dementia. © 2020 - IOS Press and the authors. All rights reserved.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Neurovetenskaper (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Neurosciences (hsv//eng)

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Psykiatri (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Psychiatry (hsv//eng)

Keyword

Alzheimer's disease

cerebral vascular pathology

cerebrospinal fluid

CSF AD biomarkers

IGF-I

serum

amyloid beta protein[1-42]

cholinesterase inhibitor

insulin

n methyl dextro aspartic acid receptor blocking agent

serum albumin

somatomedin C

tau protein

aged

Alzheimer disease

Article

clinical article

controlled study

cross-sectional study

female

human

insulin blood level

male

Mini Mental State Examination

neuropsychological test

priority journal

protein blood level

protein cerebrospinal fluid level

protein phosphorylation

Publication and Content Type

ref (subject category)

art (subject category)