David Stuart MacLean has written an amazing book, The Answer to the Riddle Is Me: A Memoir of Amnesia, about exactly that. In 2002, he was a graduate student in writing, living in India. One day, he found himself on a train platform with no idea who he was. He ended up in a mental hospital with horrible hallucinations. Eventually the symptoms of amnesia, psychosis, and depression he experienced were found to be the result of the malarial medication, Lariam, which was prescribed for malaria at the time. And those side effects continued to plague MacLean for a very long time. He had to reconstruct himself.
The Answer to the Riddle is Me is a brilliantly written memoir and more. MacLean has done a lot of research on malaria and Lariam and it's fascinating. Who knew that one out of fourteen human beings have genetic mutations that can be linked to malaria? Or that high doses of Lariam have been given to prisoners at Guantanamo prison, not because they had malaria, but for "pharmaceutical waterboarding."
David Stuart MacLean's memoir is a beautiful, disturbing, enlightening gem of a book. And if you'd like to read more books about memory, try these.