News came last week that after the controversial early-June approval of Aduhelm, the first new treatment for Alzheimer’s disease in almost 20 years, the FDA (at manufacturer Biogen’s request) had narrowed its recommendation of who should receive it. The revised prescribing information now states that Aduhelm should be used in subset of patients with Alzheimer’s—those with mild dementia or mild cognitive impairment—rather than any patient with Alzheimer’s regardless of the level of severity. The clinical trials that led to its approval included only patients with mild disease and the confirmed presence of amyloid.

The FDA’s move to limit Aduhelm’s use to a specific type of patient underscores the importance of matching the right patient with the right treatment. And that means clinicians must have access to reliable tests to help them identify the patients most likely to benefit from a particular treatment. Individualized patient care depends on it.