The following is a summary of “Association Between β-Amyloid Accumulation and Incident Dementia in Individuals 80 Years or Older Without Dementia,” published in the December 2023 issue of Neurology by Lopez et al.

Despite dementia’s peak after 80, studies on β-amyloid (Aβ) and Alzheimer’s disease (AD) pathology’s impact on its onset in this age group are scarce, leaving a crucial gap in understanding its progression.

They analyzed 94 participants (mean age 85.9 + 2.8 years) with up to 5 Pittsburgh compound-B (PiB)-PET measurements and clinical evaluations spanning 2009 to 2020. All 94 participants underwent 2 PiB-PET scans, with 76 having 3 scans, 18 having 4 scans, and 10 having 5 scans. Aβ deposition rates were compared to 120 non-demented individuals under 80 (69.3 ± 5.4 years) from the Australian Imaging, Biomarker, and Lifestyle (AIBL) study with 3 or more annual PiB-PET assessments.

The results showed that, by 2020, 49% of participants developed dementia and 63% were deceased. A gradual increase in Aβ deposition occurred in all participants, regardless of baseline Aβ status. In a Cox model adjusting for age, sex, education level, APOE-4 allele, baseline Mini-Mental State Examination, and mortality, short-term change in Aβ deposition was not significantly associated with incident dementia (HR 2.19 (0.41–11.73)). However, predictors of incident dementia included baseline Aβ burden, cortical thickness, and white matter lesion volume. Aβ accumulation was faster (P=0.01) in the older cohort (5.6%/year) compared to AIBL (4.1%/year). Additionally, baseline Aβ deposition predicted short-term change (mean time 1.88 years).

They concluded that forgetting age was a barrier to active Aβ buildup in cognitively normal 80-year-olds linked to dementia, opening doors for early intervention with anti-Aβ therapies.

Source: neurology.org/doi/10.1212/WNL.0000000000207920