Amyloid-β PET Classification on Cognitive Aging Stages Using the Centiloid Scale

Area of Science:

• Neuroimaging and diagnostics
• Cognitive aging research
• Alzheimer's disease biomarkers

Background:

• Amyloid-β (Aβ) PET imaging is crucial for Alzheimer's disease (AD) diagnosis.
• The Centiloid (CL) method standardizes Aβ quantification across PET imaging centers.
• Understanding Aβ burden in different cognitive aging trajectories, including SuperAgers (SA), is essential.

Purpose of the Study:

• To evaluate the Centiloid (CL) method for amyloid-β PET quantification in distinct cognitive aging stages.
• To investigate classification mismatches in amyloid-β positivity using different CL cut-points.
• To compare Aβ burden across SuperAgers (SA), age-matched controls (AC), middle-aged controls (MC), and Alzheimer's disease (AD) groups.

Main Methods:

• Applied the CL equation to quantify Aβ burden in SA, AC, MC, and AD groups.
• Utilized three established cut-points (10, 19, and 30 CL) to define Aβ positivity.
• Correlated CL values with visual reads, RAVLT delayed recall (DR), and Mini-Mental State Examination (MMSE) scores.

Main Results:

• AD group showed significantly higher Aβ burden than MC, but not AC.
• No significant difference in Aβ burden was found between AC and MC groups.
• CL values moderately correlated with Aβ visual read, RAVLT DR, and MMSE.
• Using different cut-points resulted in classification mismatches for 7.5% of individuals; 40-60% of AC were classified as positive.

Conclusions:

• SuperAgers exhibit similar Aβ loads to controls despite cognitive performance differences.
• Three SA individuals were classified as Aβ positive, highlighting the clinicobiological duality in Alzheimer's.
• The choice of CL cut-point impacts Aβ positivity classification, necessitating caution for values between 10-30 CL.