In an article recently published in JAMA, Stephen Salloway, MD, MS, Christopher Rowe, MD, and Jeffrey M. Burns, MD, MS discuss, “Are Blood Tests for Alzheimer Disease Ready for Prime Time?”
The authors discuss two studies. The first, “Blood Biomarkers to Detect Alzheimer Disease in Primary Care and Secondary Care,” by Palmqvist et al asked, “Can a blood test based on the ratio of plasma phosphorylated tau 217 (p-tau217) relative to non–p-tau217 (expressed as percentage of p-tau217) combined with the amyloid-β 42 and amyloid-β 40 plasma ratio (the amyloid probability score 2 [APS2]) accurately identify Alzheimer disease in primary care and secondary care when prospectively applying predefined biomarker cutoff values?”
They found that, “There were 1213 patients undergoing cognitive evaluation in primary or secondary care. The APS2 had high diagnostic accuracy (range, 88%-92%) for detecting Alzheimer disease pathology in both primary and secondary care. Dementia specialists identified clinical Alzheimer disease with a diagnostic accuracy of 73% vs 91% using the APS2 and primary care physicians had a diagnostic accuracy of 61% vs 91% using the APS2.”
Salloway et al said, “The study by Palmqvist et al shows that blood tests for Alzheimer disease pathology are at hand that compliment clinical assessment, and substantially improve diagnostic accuracy in both primary care and secondary care settings in persons with cognitive impairment due to Alzheimer disease. This important diagnostic advance will improve community access to accurate and early diagnosis of Alzheimer disease at a time when the arrival of amyloid monoclonal antibody treatment makes early diagnosis imperative.”
The second study, "Changes in Alzheimer Disease Blood Biomarkers and Associations With Incident All-Cause Dementia,” by Lu et al, asked, “What is the association of plasma biomarker (amyloid-β 42 to amyloid-β 40 [Aβ42:Aβ40] ratio, phosphorylated tau at threonine [p-tau181], neurofilament light [NfL], glial fibrillary acid protein [GFAP]) changes from midlife to late life with all-cause dementia?”
They found that, “In this retrospective analysis of prospectively collected plasma biomarkers from 1525 adults from the Atherosclerosis Risk in Communities study, only Alzheimer disease (AD)–specific (Aβ42:Aβ40, p-Tau181) biomarkers in midlife demonstrated significant long-term associations with late-life dementia. In late life, each of the biomarkers and their change from midlife were significantly associated with incident all-cause dementia.”
Salloway et al said, “The study by Lu et al demonstrates change in blood biomarkers for Alzheimer disease found in late midlife is a risk factor for late-life dementia. The potentially modifiable risk factors of hypertension and diabetes are associated with this biomarker change. This analysis poses the question of whether optimal management will reduce future dementia risk. The results suggest that there are important signals at the population level, but these signals do not yet support the use of these biomarkers for individual risk prediction in midlife.”
Read "Are Blood Tests for Alzheimer Disease Ready for Prime Time?" here
Read "Blood Biomarkers to Detect Alzheimer Disease in Primary Care and Secondary Care" here
