In 2011, sitting at a restaurant with friends, Jennifer Brea was about to sign the check for her meal when she discovered she no longer knew how to write her name.

“I couldn’t tell my hands how to move,” she said. “I couldn’t draw the side of a circle.”

The moment was a turning point for Brea, who over the next few weeks rapidly deteriorated until, she said, “I became too weak to even sit up in a wheelchair.” A Ph.D. student in Harvard’s government department at the time, “I would be in lecture, and I would understand each individual word the professor was saying, but I could not for the life of me form meaning from the sentences.” Sometimes, she said, “I would lose the ability to think or speak in any language.”

For almost two years, Brea went through 15 different doctors and a host of different diagnoses, none of which seemed to fit her symptoms: She was told she was suffering from final-exam stress, she said, or an inner-ear infection, or depression, or conversion disorder. “One of my neurologists told me that all my symptoms were being caused by some distant trauma that I might not be able to recall,” she said.

From her own online research, Brea suspected chronic-fatigue syndrome, an incurable condition described by the Centers for Disease Control and Prevention as “unexplained, severe fatigue lasting at least six months that is not improved by bed rest.” While scientists have been unable to definitively pinpoint a cause, many believe that a viral infection can be a trigger; Brea traces her symptoms back to a 10-day period in 2011 when she battled a 104-degree fever. Eventually, she flew from Boston to Miami, where a chronic-fatigue specialist confirmed her suspicions.