Jennifer Brea was a PhD candidate at Harvard University when her mind started to fail her. At age 28, she was already an accomplished academic, a graduate of Princeton who’d moved to Massachusetts to delve into the world of political economy and statistics.

But in the midst of her studies, she got sick. At first, she didn’t think anything of the illness — it just seemed like a particularly bad case of the flu, one that came with a 104-degree fever. And yet long after the fever broke, she still felt like her brain was misfiring. She’d write one sentence of an email and then pass out for four hours. When she’d try to work on a paper, all the words would come out in the wrong order. She felt like she’d lost her grasp of the English language, substituting the word “hope” for something arbitrary, like “rake.”

She went to a number of doctors, but none was able to get to the bottom of her mysterious condition. One told her she had conversion disorder, a psychiatric illness that stems from a hidden trauma and was commonly referred to as “hysteria” in the late 19th century.

But Brea knew something more was going on. So the next time she fell to the ground in her home, unable to speak or move her head, she took out her iPhone and filmed herself. At her next doctor’s appointment, when the medical professional suggested she might have an inner ear infection or severe dehydration, she showed him the footage.

“The expression on his face was like, ‘Oh, my God,’ ” recalled Brea, now 35. “Suddenly, he went from ‘Drink more water’ to ‘Let’s go get a spinal tap.’ It gave me a sense that my story could only be told visually.”

In 2012 — a year and a half after that high fever — Brea finally got a diagnosis: myalgic encephalomyelitis, or chronic fatigue syndrome. Though the neuroimmune condition affects more than 1 million Americans, it is largely misunderstood by both the public and the medical community.