Cerebrospinal Fluid Levels of Amyloid Beta 1-43 Mirror 1-42 in Relation to Imaging Biomarkers of Alzheimer's Disease

Ina S Almdahl; Camilla Lauridsen; Per Selnes; Lisa F Kalheim; Christopher Coello; Beata Gajdzik; Ina Møller; Marianne Wettergreen; Ramune Grambaite; Atle Bjørnerud; Geir Bråthen; Sigrid B Sando; Linda R White; Tormod Fladby

doi:10.3389/fnagi.2017.00009

Cerebrospinal Fluid Levels of Amyloid Beta 1-43 Mirror 1-42 in Relation to Imaging Biomarkers of Alzheimer's Disease

Front Aging Neurosci. 2017 Feb 7:9:9. doi: 10.3389/fnagi.2017.00009. eCollection 2017.

Authors

Affiliations

¹ Division of Medicine and Laboratory Sciences, Institute of Clinical Medicine, Faculty of Medicine, University of OsloOslo, Norway; Department of Neurology, Akershus University HospitalLørenskog, Norway.
² Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and Technology Trondheim, Norway.
³ Preclinical PET/CT, Institute of Basic Medical Sciences, University of Oslo Oslo, Norway.
⁴ Aleris Oslo, Norway.
⁵ Department of Neurology and Clinical Neurophysiology, University Hospital of Trondheim Trondheim, Norway.
⁶ Department of Neurology, Akershus University HospitalLørenskog, Norway; Department of Clinical Molecular Biology (EpiGen), Institute of Clinical Medicine, University of Oslo - Akershus University HospitalLørenskog, Norway.
⁷ Department of Neurology, Akershus University Hospital Lørenskog, Norway.
⁸ The Intervention Centre, Oslo University Hospital Oslo, Norway.
⁹ Department of Neuroscience, Faculty of Medicine, Norwegian University of Science and TechnologyTrondheim, Norway; Department of Neurology and Clinical Neurophysiology, University Hospital of TrondheimTrondheim, Norway.

Abstract

Introduction: Amyloid beta 1-43 (Aβ43), with its additional C-terminal threonine residue, is hypothesized to play a role in early Alzheimer's disease pathology possibly different from that of amyloid beta 1-42 (Aβ42). Cerebrospinal fluid (CSF) Aβ43 has been suggested as a potential novel biomarker for predicting conversion from mild cognitive impairment (MCI) to dementia in Alzheimer's disease. However, the relationship between CSF Aβ43 and established imaging biomarkers of Alzheimer's disease has never been assessed. Materials and Methods: In this observational study, CSF Aβ43 was measured with ELISA in 89 subjects; 34 with subjective cognitive decline (SCD), 51 with MCI, and four with resolution of previous cognitive complaints. All subjects underwent structural MRI; 40 subjects on a 3T and 50 on a 1.5T scanner. Forty subjects, including 24 with SCD and 12 with MCI, underwent ¹⁸F-Flutemetamol PET. Seventy-eight subjects were assessed with ¹⁸F-fluorodeoxyglucose PET (21 SCD/7 MCI and 11 SCD/39 MCI on two different scanners). Ten subjects with SCD and 39 with MCI also underwent diffusion tensor imaging. Results: Cerebrospinal fluid Aβ43 was both alone and together with p-tau a significant predictor of the distinction between SCD and MCI. There was a marked difference in CSF Aβ43 between subjects with ¹⁸F-Flutemetamol PET scans visually interpreted as negative (37 pg/ml, n = 27) and positive (15 pg/ml, n = 9), p < 0.001. Both CSF Aβ43 and Aβ42 were negatively correlated with standardized uptake value ratios for all analyzed regions; CSF Aβ43 average rho -0.73, Aβ42 -0.74. Both CSF Aβ peptides correlated significantly with hippocampal volume, inferior parietal and frontal cortical thickness and axial diffusivity in the corticospinal tract. There was a trend toward CSF Aβ42 being better correlated with cortical glucose metabolism. None of the studied correlations between CSF Aβ43/42 and imaging biomarkers were significantly different for the two Aβ peptides when controlling for multiple testing. Conclusion: Cerebrospinal fluid Aβ43 appears to be strongly correlated with cerebral amyloid deposits in the same way as Aβ42, even in non-demented patients with only subjective cognitive complaints. Regarding imaging biomarkers, there is no evidence from the present study that CSF Aβ43 performs better than the classical CSF biomarker Aβ42 for distinguishing SCD and MCI.

Keywords: Alzheimer’s disease; amyloid beta 1-43; cerebrospinal fluid; magnetic resonance imaging; mild cognitive impairment; positron emission tomography.