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Plasma amyloid‐β 42/40 as a predictor of cognitive decline among community‐dwelling older adults: MAPT study
Author(s) -
Giudici Kelly V,
Barreto Philipe de Souto,
Li Yan,
Bateman Randall J,
Vellas Bruno
Publication year - 2020
Publication title -
alzheimer's and dementia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.713
H-Index - 118
eISSN - 1552-5279
pISSN - 1552-5260
DOI - 10.1002/alz.047556
Subject(s) - cognitive decline , confounding , dementia , medicine , clinical dementia rating , observational study , cognition , alzheimer's disease , effects of sleep deprivation on cognitive performance , body mass index , psychology , gerontology , disease , psychiatry
Background Plasma measures of amyloid‐β (Aβ) peptides recently emerged as a potential equivalent to brain positron‐emission tomography (PET) imaging and cerebrospinal fluid (CSF) measurements in determining Aβ status. Low plasma Aβ 42/40 has been associated with Alzheimer’s disease. However, further studies are needed to validate its use for predicting cognitive impairment. This study aimed to investigate the associations between plasma Aβ 42/40 and cognitive decline over time among community‐dwelling older adults. Method Observational study using data of 483 subjects ≥70 years (mean age 76.9 years, SD = 4.5; 59.2% women), volunteers from the Multidomain Alzheimer Preventive Trial (MAPT), who were followed for 5 years. Plasma Aβ 42 and Aβ 40 were measured at 12 months for 92.8% of participants and at 24 months for the rest. Participants were classified as low Aβ 42/40 (≤0.107) or normal Aβ 42/40 . Cognitive function was assessed at 12, 24, 36, 48 and 60 months of follow‐up, by a composite cognitive score (based on four tests); Mini Mental State Examination (MMSE); Clinical Dementia Rating (CDR) sum of boxes; Alzheimer's Disease Cooperative Study ‐ Activities of Daily Living (ADCS‐ADL). Linear mixed models were performed. Potential confounders included age, sex, education, body mass index, ApoE ε4 genotype and MAPT groups. Result From the total, 33.3% (n = 161) were classified as low plasma Aβ 42/40 . After adjusting for potential confounders, low plasma Aβ 42/40 was associated with higher decline in composite cognitive score, decline in MMSE score and with higher increase in CDR sum of boxes after 4 years, compared to the normal Aβ 42/40 group. Those with low Aβ 42/40 had approximately 2‐fold acceleration in outcomes evolution. Sensitivity analysis considering the 25 th percentile of Aβ 42/40 (≤0.103) as an alternative cutoff provided similar findings. Conclusion Low plasma Aβ 42/40 was associated with higher impairment in cognitive function (measured by multiple outcomes) over time among community‐dwelling older adults. Findings points towards the use of this inexpensive measure to quickly identify people at risk of Alzheimer’s disease and other neurodegenerative diseases, over more complex and expensive measures such as PET or CSF. Further studies with long follow‐ups are needed to confirm its utility in clinical practice and public health.