Age-Dependent Relationship Between Plasma A beta 40 and A beta 42 and Total Tau Levels in cognitively Normal Subjects

• Both amyloid plaques and neurofibrillary tangles are pathological hallmarks in the brains of patients with Alzheimer's disease (AD). However, the constituents of these hallmarks, amyloid beta (A beta) 40, A beta 42, and total Tau (t-Tau), have been detected in the blood of cognitively normal subjects by using an immunomagnetic reduction (IMR) assay. Whether these levels are age-dependent is not known, and their interrelation remains undefined. We determined the levels of these biomarkers in cognitively normal subjects of different age groups. A total of 391 cognitively normal subjects aged 23-91 were enrolled from hospitals in Asia, Europe, and North America. Healthy cognition was evaluated by NIA-AA guidelines to exclude subjects with mild cognitive impairment (MCI) and AD and by cognitive assessment using the Mini Mental State Examination and Clinical Dementia Rating (CDR). We examined the effect of age on plasma levels of A beta 40, A beta 42, and t-Tau and the relationship between these biomarkers during aging. Additionally, we explored age-related reference intervals for each biomarker. Plasma t-Tau and A beta 42 levels had modest but significant correlations with chronological age (r = 0.127, p = 0.0120 for t-Tau; r = -0.126, p = 0.0128 for A beta 42), ranging from ages 23 to 91. Significant positive correlations were detected between A beta 42 and t-Tau in the groups aged 50 years and older, with Rho values ranging from 0.249 to 0.474. Significant negative correlations were detected between A beta 40 and t-Tau from age 40 to 91 (r ranged from -0.293 to -0.582) and between A beta 40 and A beta 42 in the age groups of 30-39 (r = -0.562, p = 0.0235), 50-59 (r = -0.261, p = 0.0142), 60-69 (r = -0.303, p = 0.0004), and 80-91 (r = 0.459, p = 0.0083). We also provided age-related reference intervals for each biomarker. In this multicenter study, age had weak but significant effects on the levels of A beta 42 and t-Tau in plasma. However, the age group defined by decade revealed the emergence of a relationship between A beta 40, A beta 42, and t-Tau in the 6th and 7th decades. Validation of our findings in a large-scale and longitudinal study is warranted.

Ämnesord

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

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

MEDICIN OCH HÄLSOVETENSKAP  -- Annan medicin och hälsovetenskap -- Gerontologi, medicinsk/hälsovetenskaplig inriktning (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Other Medical and Health Sciences -- Gerontology, specialising in Medical and Health Sciences (hsv//eng)

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

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

Nyckelord

Alzheimer

plasma

amyloid

tau

immunomagnetic reduction

cognitively normal subjects

alzheimers association workgroups

amyloid-beta-peptide

a-beta

diagnostic guidelines

national institute

disease incidence

biomarkers

impairment

dementia

recommendations

Geriatrics & Gerontology

Neurosciences & Neurology

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