Altered Mental Status in the Alzheimer's Patient

Altered mental status in a patient with Alzheimer disease demands a narrower, history-driven ED approach because routine testing can worsen agitation and iatrogenic harm. Anti-amyloid therapy adds a high-stakes wrinkle: amyloid-related imaging abnormalities can mimic stroke, and MRI is the definitive test.

AMS in Alzheimer Patients

• History-first evaluation: A good collateral history is the highest-yield way to narrow the differential in Alzheimer patients with AMS and avoid traumatic low-value testing like repeated blood draws or Foley placement.
• Agitation from routine care: Standard ED workups can escalate distress in dementia; patients with Alzheimer disease and AMS are more likely to undergo CT and urinalysis and twice as likely to receive antipsychotics.
• Collateral team approach: Nurses, case managers, social workers, and trainees can materially improve care by helping reach family or facility staff when the patient cannot provide a meaningful history, a workflow we lay out in the episode.
• Common ED presentations: Alzheimer disease is a frequent ED population problem, with roughly 23% of diagnosed patients visiting the ED each year; accidents and behavioral disturbance are prominent presenting complaints.

Anti-amyloid Therapy and ARIA

• Universal ATT screening: Screen every Alzheimer patient for anti-amyloid therapy use because ARIA can present as headache, confusion, focal deficits, seizures, or gait change and can easily resemble acute stroke.
• MRI as definitive imaging: CT is useful to look for major intracranial hemorrhage, but MRI is the preferred study for suspected amyloid-related imaging abnormality and should be treated as an emergent indication.
• Meaningful ARIA incidence: ARIA is common rather than rare: lecanemab carries about 12.6% edema and 17% hemorrhage rates, while donanemab reports even higher imaging abnormality rates.
• Thrombolysis red flag: Anti-amyloid therapy is a contraindication to alteplase or tenecteplase because severe hemorrhagic complications have been reported when ARIA is mistaken for ischemic stroke. That distinction is worth hearing in the chapter.
• Severe ARIA treatment: The sickest ARIA presentations can resemble PRES, and high-dose IV methylprednisolone is the headline first-line treatment, with admission and early neurology or neurosurgery input often warranted.
• Anticoagulation caution: Patients on anti-amyloid therapy appear to carry higher risk from cerebral bleeding, especially with baseline microbleeds or blood thinners, so routine anticoagulation decisions deserve extra caution.

References:

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