Shortly after 1am one night in April 2019, a CIA officer on a work trip to London was jolted awake in his hotel room by the most intense head pain he had ever experienced. His body was soaked with sweat and he felt like his eyes were spinning in their sockets. He manoeuvred his way out of bed, hoping to make it to the bathroom to vomit, but found his sense of balance had deserted him. Eventually, he fell back into a fitful, shallow sleep.
The next day, arriving at the work meeting he had travelled for, the officer found he could not remember the names of colleagues in the room, people he knew well. As the meeting got under way, he could barely follow the discussion. Initially, he chalked it up to a terrible – if rather odd – case of food poisoning. But over subsequent weeks, worrying symptoms persisted: brain fog, loss of balance and increasingly harsh tinnitus.
