When cholesterol lowering drugs were being investigated, there was no question that they lowered cholesterol levels in the blood.  But the cholesterol level is a mere number, and does not address the crucial question of whether patients actually benefit from these drugs.* This is the clinically relevant question, a concept that sometimes seems to get lost in the approval process of new drugs.

Enter Aducanumad (brand name Aduhelm).  The U.S. Food and Drug Administration (FDA) recently granted approval of this drug for patients with mild symptoms of Alzheimer Disease, based in no small part on its unquestioned ability to attack the amyloid plaques found in the brains of Alzheimer’s patients.  These collections of protein have been the subject of research for years in the neurological research community, and the idea that removing them to treat Alzheimer’s has been the subject of extensive investigation.

Well, does Aducanumad, in addition to obliterating the plaques, actually help patients?  Do the clinically relevant measures of cognitive decline improve, or at least progress more slowly?

Two large, well designed studies addressed this question.  One showed a miniscule advantage in the scores of Alzheimer’s patients on neurocognitive testing; the other found no difference between the patients who got the drug (the intervention group) and those who got placebo (the control group).  Neurologists have mostly concluded that we still do not know if Aducanumad is effective in treating Alzheimer Disease.

We do know it is expensive ($56,000 a year!), and we know that it is associated with brain swelling (reversible) and sometimes minor cerebral bleeding.  We also know that FDA approval was highly controversial.  The decision to approve went against the FDA’s advisory committee’s recommendation and occasioned the resignation of three scientists on the committee who protested the action.  

The clinically relevant question of whether Aducanumad is effective in treating Alzheimer Disease remains unanswered.  The question of whether Biogen, the manufacturer, has benefited financially is not in question.

*For patients with established cardiovascular disease, the evidence that statins (the most commonly prescribed pharmaceutical to lower cholesterol) reduce morbidity and mortality is solid.  This is secondary prevention.  The question whether primary prevention (giving a drug to people who have not had any clinical symptoms of heart disease) is complex and subject to some degree of controversy.

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