The dark side of monoclonal antibodies against Abeta

An article in the 7 April ’23 [ Science vol. 380 pp. 19 ’23 ] notes that a monoclonal antibody treatment against the aBeta peptide for Alzheimer’s disease (lecanemab) is associated with brain shrinkage.  Even worse, 21% of the 898 receiving lecanemab had ARIA (Amyloid Related Imaging Abnormalities) which is brain swelling and bleeding.  Although most of these people were asymptomatic, it isn’t something you’d want going on in your brain.  However ‘some’ with ARIA became severely ill and there were two deaths.

Now Alzheimer’s disease is associated with brain shrinkage as neurons die, but at 18 months those receiving lecanemab had 28% greater brain loss than those receiving placebo.  That isn’t as bad as it sounds, because the absolute loss of brain tissue was 5 milliLiters more in the lecanemab group, and most brains (even the shrunken ones have a volume of over 1,000 milliLiters)