title: Serum insulin-like growth factor-I and amyloid beta protein in Alzheimer's disease: relationship with cognitive function.
abstract: OBJECTIVE
  Previous studies have suggested that insulin-like growth factor-I (IGF-I) deficiency may lead to cognitive deficits in neurodegenerative diseases such as Alzheimer's disease. The present study aimed to investigate the possible relationship between cognitive function and concentration of IGF-I or amyloid beta protein (Aβ) in serum in Alzheimer's patients.
  
  
  METHODS
  A total of 81 Japanese patients were enrolled in this study. Concentrations of IGF-I, Aβ42, and Aβ40 in serum were measured. Two neuropsychological tests, Mini-Mental State Examination and Hasegawa's Dementia Scale-Revised (HDS-R), were also performed. Linear correlations among the age, serum IGF-I, serum Aβ42 or Aβ40, Aβ42/Aβ40 ratio, Mini-Mental State Examination or HDS-R total score, and the scores for six HDS-R subscales were analyzed by regression analysis.
  
  
  RESULTS
  IGF-I showed a significant negative correlation with age (β = -0.357, P = 0.002) and a positive correlation with Aβ42/Aβ40 ratio (β = 0.318, P = 0.007). Serum IGF-I and both the Mini-Mental State Examination and the HDS-R total score also correlated (β = 0.505, β = 0.524, P < 0.01). Among the HDS-R subscales, 'Recall' (ρ = 0.379, P < 0.01), 'Verbal fluency' (ρ = 0.360, P < 0.01), and 'Attention and calculation' (ρ = 0.389, P < 0.01) showed significant positive correlations with serum IGF-I.
  
  
  CONCLUSIONS
  The results, specifically that lower serum IGF-I was associated with cognitive impairment, suggest that metabolism of IGF-I may be involved in the pathogenesis of cognitive deficits in Alzheimer's disease.
authors.affiliation: Department of Psychiatry and Behavioral Science, Graduate School of Medicine, Juntendo University, Tokyo, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Kimoto
authors.affiliation: Department of Psychiatry and Behavioral Science, Graduate School of Medicine, Juntendo University, Tokyo, Japan.|Juntendo Tokyo Koto Geriatric Medical Center, Juntendo University School of Medicine, Tokyo, Japan.
authors.forename: Koji
authors.initials: K
authors.lastname: Kasanuki
authors.affiliation: Department of Psychiatry and Behavioral Science, Graduate School of Medicine, Juntendo University, Tokyo, Japan.|Juntendo Tokyo Koto Geriatric Medical Center, Juntendo University School of Medicine, Tokyo, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Kumagai
authors.affiliation: Department of Psychiatry and Behavioral Science, Graduate School of Medicine, Juntendo University, Tokyo, Japan.
authors.forename: Nobuto
authors.initials: N
authors.lastname: Shibata
authors.affiliation: Department of Psychiatry and Behavioral Science, Graduate School of Medicine, Juntendo University, Tokyo, Japan.|Juntendo Tokyo Koto Geriatric Medical Center, Juntendo University School of Medicine, Tokyo, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Ichimiya
authors.affiliation: Department of Psychiatry and Behavioral Science, Graduate School of Medicine, Juntendo University, Tokyo, Japan.
authors.forename: Heii
authors.initials: H
authors.lastname: Arai
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000097:blood* / Q000175:diagnosis; D054458:Amplified Fragment Length Polymorphism Analysis; D016229:Amyloid beta-Peptides / Q000378:metabolism*; D044466:Asian People; D003071:Cognition / Q000502:physiology*; D003072:Cognition Disorders / Q000097:blood*; D060825:Cognitive Dysfunction / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000032:analysis* / Q000378:metabolism; D007564:Japan; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D016133:Polymerase Chain Reaction; D012044:Regression Analysis
chemical_list: D016229:Amyloid beta-Peptides; D007334:Insulin-Like Growth Factor I
keywords: Alzheimer's disease; Aβ40; Aβ42; IGF-I; cognitive function; dementia