YKL-40: a novel prognostic fluid biomarker for preclinical Alzheimer's disease

Biol Psychiatry. 2010 Nov 15;68(10):903-12. doi: 10.1016/j.biopsych.2010.08.025.


Background: Disease-modifying therapies for Alzheimer's disease (AD) would be most effective during the preclinical stage (pathology present, cognition intact) before significant neuronal loss occurs. Therefore, biomarkers that detect AD pathology in its early stages and predict dementia onset and progression will be invaluable for patient care and efficient clinical trial design.

Methods: AD-associated changes in cerebrospinal fluid (CSF) were measured using two-dimensional difference gel electrophoresis and liquid chromatography tandem mass spectrometry. Subsequently, CSF YKL-40 was measured by enzyme-linked immunosorbent assay in the discovery cohort (n = 47), validation cohort (n = 292) with paired plasma samples (n = 237), frontotemporal lobar degeneration (n=9) [corrected], and progressive supranuclear palsy (PSP; n = 6). Immunohistochemistry was performed to identify source(s) of YKL-40 in human AD brain.

Results: Discovery and validation cohorts, showed higher mean CSF YKL-40 in very mild and mild AD-type dementia (Clinical Dementia Rating [CDR] 0.5 and 1) versus control subjects (CDR 0) and PSP subjects. Importantly, CSF YKL-40/Aβ42 ratio predicted risk of developing cognitive impairment (CDR 0 to CDR > 0 conversion), as well as the best CSF biomarkers identified to date, tau/Aβ42 and p-tau 181/Aβ42. Mean plasma YKL-40 was higher in CDR 0.5 and 1 versus CDR 0, and correlated with CSF levels. YKL-40 immunoreactivity labeled astrocytes near a subset of amyloid plaques, implicating YKL-40 in the neuroinflammatory response to Aβ deposition.

Conclusions: These data demonstrate that YKL-40, a putative indicator of neuroinflammation, is elevated in AD and, together with Aβ42, has potential prognostic utility as a biomarker for preclinical AD.

Publication types

  • Evaluation Study
  • Multicenter Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adipokines
  • Aged
  • Aged, 80 and over
  • Alzheimer Disease / blood
  • Alzheimer Disease / cerebrospinal fluid*
  • Alzheimer Disease / diagnosis*
  • Amyloid beta-Peptides / cerebrospinal fluid
  • Astrocytes / metabolism
  • Biomarkers / blood
  • Biomarkers / cerebrospinal fluid*
  • Brain / metabolism
  • Chitinase-3-Like Protein 1
  • Disease Progression
  • Early Diagnosis
  • Female
  • Frontotemporal Lobar Degeneration / cerebrospinal fluid
  • Glycoproteins / blood
  • Glycoproteins / cerebrospinal fluid*
  • Glycoproteins / metabolism
  • Humans
  • Lectins / blood
  • Lectins / cerebrospinal fluid*
  • Lectins / metabolism
  • Male
  • Middle Aged
  • Prognosis
  • Proteomics / methods
  • Supranuclear Palsy, Progressive / cerebrospinal fluid
  • tau Proteins / cerebrospinal fluid


  • Adipokines
  • Amyloid beta-Peptides
  • Biomarkers
  • CHI3L1 protein, human
  • Chitinase-3-Like Protein 1
  • Glycoproteins
  • Lectins
  • tau Proteins