Minocycline at 2 Different Dosages vs Placebo for Patients With Mild Alzheimer Disease: A Randomized Clinical Trial

Importance There are no disease-modifying treatments for Alzheimer disease (AD), the most common cause of dementia. Minocycline is anti-inflammatory, protects against the toxic effects of β-amyloid in vitro and in animal models of AD, and is a credible repurposed treatment candidate. Objective To determine whether 24 months of minocycline treatment can modify cognitive and functional decline in patients with mild AD. Design, Setting, and Participants Participants were recruited into a double-blind randomized clinical trial from May 23, 2014, to April 14, 2016, with 24 months of treatment and follow-up. This multicenter study in England and Scotland involved 32 National Health Service memory clinics within secondary specialist services for people with dementia. From 886 screened patients, 554 patients with a diagnosis of mild AD (Standardised Mini-Mental State Examination [sMMSE] score ≥24) were randomized. Interventions Participants were randomly allocated 1:1:1 in a semifactorial design to receive minocycline (400 mg/d or 200 mg/d) or placebo for 24 months. Main Outcomes and Measures Primary outcome measures were decrease in sMMSE score and Bristol Activities of Daily Living Scale (BADLS), analyzed by intention-to-treat repeated-measures regression. Results Of 544 eligible participants (241 women and 303 men), the mean (SD) age was 74.3 (8.2) years, and the mean (SD) sMMSE score was 26.4 (1.9). Fewer participants completed 400-mg minocycline hydrochloride treatment (28.8% [53 of 184]) than 200-mg minocycline treatment (61.9% [112 of 181]) or placebo (63.7% [114 of 179];P  Conclusions and Relevance Minocycline did not delay the progress of cognitive or functional impairment in people with mild AD during a 2-year period. This study also found that 400 mg of minocycline is poorly tolerated in this population. Trial Registration isrctn.org Identifier:ISRCTN16105064