Many people with less common forms of Alzheimer's disease may not qualify for newer anti-amyloid treatments designed to slow the disease, according to a study published August 5, 2026, in Neurology®, the medical journal of the American Academy of Neurology.

Researchers found that the majority of people with atypical Alzheimer's disease, or forms that affect thinking, language or vision rather than memory first, would not meet eligibility criteria for treatment for Alzheimer's disease called anti-amyloid therapies. These therapies are given early in the disease, often at the first sign of memory problems.

Atypical Alzheimer's disease is often underrecognized and underrepresented in clinical trials. Our findings suggest that treatment criteria may unintentionally exclude many of these patients, even when they are in the early stages of disease."

Dror Shir, MD, study author of the Mayo Clinic in Jacksonville, Florida and member of the American Academy of Neurology

For the study, researchers looked at 184 people with atypical Alzheimer's disease confirmed by medical tests. Their first symptoms were not mainly memory problems.

Participants had one of the following types of atypical Alzheimer's disease: posterior cortical atrophy, which affects vision and spacial awareness; logopenic variant primary progressive aphasia, which affects communication and language; dysexecutive Alzheimer's disease, which affects planning and problem-solving; or corticobasal syndrome, which affects movement and thinking.

Researchers evaluated whether participants would qualify for the anti-amyloid therapies lecanemab and donanemab based on criteria used in major clinical trials and recommendations created for these drugs.

Researchers found that between 70% and 85% of participants with atypical Alzheimer's disease would not meet eligibility requirements.

The most common reason for exclusion was poor performance on cognitive screening tests, accounting for 50–67% of exclusions. Shir noted that people with atypical Alzheimer's disease may have lower scores on tests of visual-spatial abilities or executive functioning even though they are still functioning relatively well with daily activities.

Even though most people in the study were still in the early stages of the disease and could do many daily activities, many did not qualify for the treatments because they scored poorly on thinking tests.

The study found most patients did not meet eligibility criteria due to poor scores on the Mini-Mental State Examination, a 11-question screening test. Other reasons for exclusion included brain imaging findings, excluding 22% to 27% of participants, and disease severity, with 19% to 23% having moderate or severe dementia.

"These results suggest a mismatch between how we measure disease severity and how atypical Alzheimer's disease presents," Shir said. "Current tools might overestimate the functional stage of the disease."

A limitation of the study was that it was retrospective and based on existing clinical data, meaning researchers estimated eligibility rather than evaluating patients directly.

The study was supported by the National Institutes of Health and the Alzheimer's Association.