Plasma ß-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 ß-amyloid (Aß) have been independently implicated in the development of incident cognitive decline and dementia. Here we studied the associations between MBI and plasma Aß42/Aß40. 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 Aß42/Aß40 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 Aß42/Aß40. RESULTS: Lower plasma Aß42/Aß40 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 Aß42/Aß40. Incorporating MBI into case detection may help capture preclinical and prodromal Alzheimer's disease.

White matter hyperintensities and mild behavioral impairment: Findings from the MEMENTO cohort study.

Background: White matter hyperintensities (WMH) contribute to cognitive decline and increase risk for dementia. Mild behavioral impairment (MBI) is a neurobehavioral syndrome characterized by the emergence and persistence of neuropsychiatric symptoms (NPS) in later life as an at-risk state for incident cognitive decline and dementia. Both WMH and MBI are common in patients with mild cognitive impairment (MCI), but few studies have established the link between these two risk markers in this population. Methods: Participants were memory clinic patients with MCI from the French MEMENTO study. WMH volume was quantified using brain magnetic resonance imaging. Participants were categorized into MBI+ and MBI- status based on NPS persistence, and the association between MBI status and domains with WMH volume was assessed with linear regression. Results: A total of 768 participants [mean age 72.8 (SD=8.00); 57% female] were included. MBI (i.e., persistent NPS) was present in 229 participants (29.8%). MBI+ status was significantly associated with lower MMSE score and male sex. Compared to MBI-, MBI+ status was associated with 9.4% higher WMH volume [p = 0.01 (95% CI 2.0% to 16.7%)]. In this model, MMSE score was not associated with WMH volume. None of the MBI domains individually predicted greater WMH volume, although emotional dysregulation, impulse dyscontrol, and apathy trended towards significance. Conclusions: In a memory clinic sample of older adults with MCI, MBI was associated with higher WMH volume. Global MBI status outperformed MMSE and individual MBI domains, supporting the utility of MBI, a multi-NPS-domain composite assessment, for predicting WMH volume.