Four years ago, Sonja Mally was a busy tattoo artist with a photographic memory and penchant for long hikes.

Now, the 38-year-old Toronto woman considers it a good day if she can do a small drawing, muster the energy to walk around the block or “perform very basic tasks.”

“It’s a hard thing to have to explain to people why maybe one day you might be doing fine and the next day you can’t find the words to complete a sentence,” Mally said.