Clinical and MRI features associated with amyloid positivity in secondary screening for anti-amyloid-β therapy

In Japan, confirmatory biomarker testing for Alzheimer's disease (AD) is insurance-covered only when evaluating eligibility for anti-amyloid-β therapies. This study aimed to identify clinical and magnetic resonance imaging (MRI) features associated with amyloid positivity in a real-world setting.

We reviewed patients attending our secondary screening clinic between 2023 and 2024. After clinical discussions, interested patients underwent 3T MRI and either amyloid positron emission tomography (PET) or cerebrospinal fluid biomarker testing.

Of the 200 patients, 147 proceeded to evaluation and 138 had biomarker results. The amyloid-positive group (n = 107) was younger and had lower Mini-Mental State Examination (MMSE) scores, despite similar symptom duration; younger age largely reflected early-onset cases. MRI indices overlapped between the groups, except for a higher medial-temporal-whole-brain atrophy ratio.

Younger age and lower MMSE scores were associated with amyloid positivity. Caution regarding referral bias for early-onset AD in real-world settings is warranted.