Over time, Ms. Purvis, the speech-language pathologist, incrementally ramped up the exercises: arrange numbers in descending order, repeat a sentence in reverse. She increased noise and distraction to approximate Ms. Lewis’s busy work environment. She kept the door open, turned on television news and eventually held sessions in the bustling physical therapy gym.

Amid the hum of treadmills, exercise bikes and other patients’ conversations, Ms. Lewis worked earnestly to arrange playing cards by suit in ascending order and flip numbers spelled with a “T,” like “two.” Simultaneously, Ms. Purvis recited words and Ms. Lewis tried to raise her hand whenever one started with “B.”

“You missed 12, which is a lot more than you normally miss,” Ms. Purvis said.

“Ay,” Ms. Lewis sighed, fingers fidgeting.

Two days later, asked to start at 1 and repeatedly add 9 and subtract 4 until reaching 130, Ms. Lewis was halting and slow.

“Oh my God,” she exclaimed after finishing. “That one was harder.”

But later, she accurately remembered four statements recited early in the session, including, “Rubber bands last longer when refrigerated.”

“It’s been challenging,” she told Ms. Purvis. “I don’t feel super-disheartened, though.”

Since for some patients physical or cognitive exertion exacerbates symptoms, Dr. Roth said the AbilityLab urges patients to “push themselves as much as they can, but not beyond.”