Plasma β-amyloid in mild behavioural impairment – neuropsychiatric symptoms on the Alzheimer’s continuum

Introduction Simple markers are required to recognize older adults at higher risk for neurodegenerative disease. Mild behavioural impairment (MBI) and plasma β-amyloid (Aβ) have been independently implicated in the development of incident cognitive decline and dementia. Here we studied the associations between MBI and plasma Aβ 42 /Aβ 40 . Methods Participants with normal cognition (n = 86) or mild cognitive impairment (n = 53) were selected from the Alzheimer’s Disease Neuroimaging Initiative. MBI scores were derived from Neuropsychiatric Inventory items. Plasma Aβ 42 /Aβ 40 ratios were assayed using mass spectrometry. Linear regressions were fitted to assess the association between MBI total score as well as MBI domain scores with plasma Aβ 42 /Aβ 40 . Results Lower plasma Aβ 42 /Aβ 40 was associated with higher MBI total score ( p = 0.04) and greater affective dysregulation ( p = 0.04), but not with impaired drive/motivation ( p = 0.095) or impulse dyscontrol ( p = 0.29) MBI domains. Conclusion In persons with normal cognition or mild cognitive impairment, MBI was associated with low plasma Aβ 42 /Aβ 40 . Incorporating MBI into case detection can help capture preclinical and prodromal Alzheimer’s disease.