Subtyping is what made precision medicine in cancer a reality. And for successful drug discovery in all its stages, finding subtypes in Alzheimer’s disease is all but imperative. Prior to the approval of the modestly effective Lequembi (lecanemab, Biogen Inc./Eisai Co. Ltd.) Kisunla (donanemab, Eli Lilly and Co.), and the since-withdrawn Aduhelm (aducanumab, Biogen Inc./Eisai Co. Ltd.), more than a dozen failed phase III clinical trials were all that amyloid-targeting drugs had to show for themselves for decades of effort.