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 Aβ42/Aβ40.
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 Aβ42/Aβ40 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 Aβ42/Aβ40.
Results: Lower plasma Aβ42/Aβ40 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 Aβ42/Aβ40. Incorporating MBI into case detection may help capture preclinical and prodromal Alzheimer's disease.
Keywords: Alzheimer’s disease; beta-amyloid; mild behavioural impairment; neuropsychiatric symptoms.