Lee Holloway was a brilliant coder, co-founder, and master architect of Cloudflare. He was “the resident genius, the guy who could focus for hours, code pouring from his fingertips while death metal blasted in his headphones.” But over time he became withdrawn, sleeping for days at a time, unable to engage with his family or friends. And his affect, when he did speak, was strangely flat. As Sandra Upson reports in this exceptional piece at Wired, no one knew a degenerative disease — frontotemporal dementia — lurked inside his brain, slowly killing off cells in his frontal and temporal lobes, irrevocably altering his personality in startling ways.

He was the master architect whose vision had guided what began as a literal sketch on a napkin into a tech giant with some 1,200 employees and 83,000 paying customers. He laid the groundwork for a system that now handles more than 10 percent of all internet requests and blocks billions of cyberthreats per day. Much of the architecture he dreamed up is still in place.

He was becoming erratic in other ways too. Some of his colleagues were surprised when Lee separated from his first wife and soon after paired up with a coworker. They figured his enormous success and wealth must have gone to his head. “All of us were just thinking he made a bunch of money, married his new girl,” Prince says. “He kind of reassessed his life and had just become a jerk.”

The people close to Lee felt tossed aside. They thought he’d chosen to shed his old life. In fact, it was anything but a choice. Over the next few years, Lee’s personality would warp and twist even more, until he became almost unrecognizable to the people who knew him best. Rooting out the cause took years of detective work—and forced his family to confront the trickiest questions of selfhood.

Few disorders ravage their victims’ selfhood with the intensity of the behavioral variant of FTD. It takes all the things that define a person—hobbies and interests, the desire to connect with others, everyday habits—and shreds them. Over time, the disease transforms its victims into someone unrecognizable, a person with all the same memories but an alarming new set of behaviors. Then it hollows them out and shaves away their mobility, language, and recollections.

Because it is relatively unknown and can resemble Alzheimer’s or a psychiatric disorder, FTD is often hard to diagnose. As in Lee’s case, the early stages can be misinterpreted as signs of nothing more serious than a midlife crisis. Patients can spend years shuttling to marriage counselors, human resources departments, therapists, and psychologists. By the time patients learn the name of their disorder, they are often unable to grasp the gravity of their situation.

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