Why Atypical Alzheimer’s Patients Are Denied New Drugs

People who lose language, vision, or the ability to plan—rather than memory—are quietly slipping through the cracks of Alzheimer’s care. New data suggest that a large majority of those with atypical forms of the disease would not meet current eligibility rules for early anti-amyloid therapies, even when they still manage most daily tasks.

Researchers reviewed 184 cases of atypical Alzheimer’s confirmed by medical testing. These patients did not start with classic memory problems. Instead, their earliest signs included trouble with spatial perception and vision (posterior cortical atrophy), progressive language breakdown (logopenic primary progressive aphasia), impaired planning and problem solving (dysexecutive Alzheimer’s), or movement and cognitive difficulties (corticobasal syndrome).

Then the team applied the entry criteria used in major trials for lecanemab and donanemab. The result was startling: depending on the rule set, between 70% and 85% of the group would have been excluded from treatment. That’s not a small mismatch. It’s systemic.

So what disqualifies them? Cognitive screening tests drive most exclusions. Short instruments such as the Mini-Mental State Examination flagged many patients as too impaired, even though clinicians noted preserved everyday functioning. In plain terms, test scores often underestimated how well people were actually coping at home.

Imaging thresholds also cut people out. Brain scans led to 22%–27% of exclusions, while another 19%–23% were ruled out because their dementia was categorized as moderate to severe under current definitions. The researchers argue these measures can misread atypical presentations, where deficits cluster in non-memory domains and standard scales miss the nuance.

"Atypical Alzheimer’s is underrecognized and rarely represented in trials," said Dror Shir of the Mayo Clinic in Jacksonville. His point is practical: tools designed around the common memory-first picture don’t translate well for other clinical faces of the same disease.

The study is retrospective, meaning investigators reanalyzed previously collected clinical records to estimate eligibility rather than enrolling people prospectively for treatment. That limits some conclusions, but the pattern is clear enough to raise alarms for clinicians and policy makers: trial and treatment criteria risk leaving many patients without access to therapies that target amyloid pathology.

For patients and families, the takeaway is frustratingly simple. Diagnostic labels and short screening batteries can determine access to therapy as much as biology does. For researchers and regulators, the message is a challenge: adapt eligibility frameworks so they reflect the full spectrum of Alzheimer’s, not just the most familiar form.

As anti-amyloid drugs gain traction, asking who benefits—and who is excluded—matters more than ever. Will our clinics and trials evolve to match the disease’s diversity? That question will shape who gets treatment in the next decade.