AD biomarkers at AAIC 2019

Progress in the search for blood-based biomarkers for Alzheimer disease (AD) and other dementias was highlighted in several presentations at the Alzheimer’s Association International Conference (AAIC) 2019 (14–18 July 2019, Los Angeles, CA, USA).

Using plasma levels of amyloid precursor protein (APP) and amyloid-β (Aβ) peptides, Akinori Nakamura and colleagues developed a composite biomarker comprising the APP_669–711:Aβ_1–42 and Aβ_1–40:Aβ_1–42 ratios. This biomarker was tested against imaging findings in 131 patients with mild cognitive impairment, AD or non-AD dementia and 70 cognitively healthy controls. The biomarker values were found to correlate with imaging measures of brain Aβ deposition, atrophy and glucose hypometabolism. “We found that the plasma biomarker can detect earlier stages of amyloid deposition, even before dementia symptoms are apparent,” concluded Nakamura.

In another study reported at AAIC 2019, Filippo Baldacci and co-workers measured levels of α-synuclein, Aβ and tau in red blood cells from healthy controls and patients with early-stage AD. The researchers showed that levels of α-synuclein — both alone and in combination with Aβ or tau — were reduced in the cells from patients with AD. “Red blood cells may represent workable and relevant models of neurodegeneration since they are likely to be involved in the accumulation and clearance of the misfolded proteins,” commented Baldacci.

In a third study, Adbul Hye and colleagues measured plasma levels of neurofilament light chain (NfL) — a marker of axonal damage — in a range of dementias. The investigators detected significantly elevated levels of plasma NfL in several neurodegenerative conditions, including AD, frontotemporal dementia, dementia with Lewy bodies, corticobasal syndrome, amyotrophic lateral sclerosis and Down syndrome with dementia. “Though, as previously seen in other studies, NfL is not specific for any condition, with validation it could be valuable as a relatively inexpensive and fast test for accumulating neurodegeneration in the brain,” concluded Hye.