Cohen began studying multiple sclerosis (MS) in the 1980s when it was still considered an untreatable disease. Today, 15 disease-modifying treatments are approved for MS, and Cohen said he has 鈥渂een involved in some way or another鈥� with the development of each of them.

Cohen has worked with ACTRIMS since its founding in 1995. The group is made up of clinicians and researchers across North America who focus on sharing knowledge in hopes of improving MS treatment options and providing training to early-career physicians and scientists. It has counterparts in other areas of the world, including the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS).

During his residency, which began in 1981, Cohen was drawn to neuroscience and immunology, both fields than in their infancies and both notoriously complex. 鈥淢S is a field where those two topics intersect,鈥� he told Multiple Sclerosis 麻豆传媒 Today.

He came to the Mellen Center in 1994, just one year after the first disease-modifying treatment, Betaseron (interferon beta 1b, marketed by Bayer HealthCare), was approved for MS. He treats a large population of MS patients there and was named director of its Experimental Therapeutics Program in 2014. He designs and runs clinical trials for MS and related diseases, while training other specialists in the skills necessary to run MS trials.