Medicare will only cover a drug for Alzheimer’s disease for patients in clinical trials, President Joe Biden’s administration announced on April 7. The drug, Aduhelm, is made by Biogen. The government said in January that it planned to limit coverage of the drug, which costs $28,000 a year, to trial enrollees. But the announcement was preliminary. The Centers for Medicare & Medicaid Services (CMS) launched a public comment period and ended up reviewing over 10,000 comments and hundreds of documents to determine whether to keep the plan in place or change it. The agency chose to stay the course, although the final determination does change which trials are eligible. Under the preliminary rule, only trials approved by CMS or sponsored by the National Institutes of Health would be considered. Under the final rule, any trial approved by the institutes or the Food and Drug Administration is covered. The final rule …