Trial
Clarity AD
Research Observatory
Evidence Update
Current evidence
CLARITY AD compared lecanemab 10 mg/kg intravenously every two weeks with placebo in 1,795 adults aged 50–90 with amyloid-confirmed early Alzheimer disease over 18 months. CLARITY AD showed less average cognitive-functional decline with lecanemab over 18 months, not recovery, with material ARIA and infusion-reaction risks.
What changed
Clarity AD's randomized 18-month comparison must remain separate from uncontrolled extension follow-up and aggregate-curve reanalysis.
What did not change
Both groups worsened; an 18-month randomized comparison does not demonstrate causal long-term extension benefit.
Why it matters
Prevents either optimistic durability or causal acceleration claims from outrunning the comparator.
Main limitation
Both groups worsened; trial result is not prevention in healthy adults, reversal of aging or an individual treatment recommendation. Population-average results do not determine an individual patient’s benefit-risk balance.
Next proof
Controlled longer-term evidence for durable cognitive-functional benefit and harms; uncontrolled extensions cannot establish causal durability.
Summary
CLARITY AD compared lecanemab 10 mg/kg intravenously every two weeks with placebo in 1,795 adults aged 50–90 with amyloid-confirmed early Alzheimer disease over 18 months. CLARITY AD showed less average cognitive-functional decline with lecanemab over 18 months, not recovery, with material ARIA and infusion-reaction risks.
Intelligence Take
Prevents either optimistic durability or causal acceleration claims from outrunning the comparator.
Limitations
Both groups worsened; trial result is not prevention in healthy adults, reversal of aging or an individual treatment recommendation. Population-average results do not determine an individual patient’s benefit-risk balance.