Fidji Simo announced her departure from OpenAI’s senior leadership the way many people learn hard news about their own bodies, gradually and then all at once.

In a message on Thursday, she said a three-month medical leave had not gone as hoped, that recovery would be longer and more complicated than expected, and that she would step down as the company’s chief of applications.

Simo joined OpenAI a little over a year ago as CEO of Applications, running product and business and effectively serving as the company’s number two. She had been on leave since April, and the leave has now become an exit. She will remain at the company as a part-time adviser rather than a day-to-day executive.

The reason is medical. Simo said she had experienced a severe exacerbation of postural orthostatic tachycardia syndrome, a chronic neuroimmune condition she was diagnosed with in 2019 that affects heart rate, blood flow and energy.

The 💜 of EU techThe latest rumblings from the EU tech scene, a story from our wise ol' founder Boris, and some questionable AI art. It's free, every week, in your inbox. Sign up now!The condition is manageable for many people, but flares can be debilitating, and hers has been serious enough to make a demanding operating role untenable for now.