When Diane Thornton first realized she was having trouble keeping track of appointments, she would write herself reminder notes. When she got lost on her way to the office, she'd call her secretary and ask for directions. On days she had trouble speaking or remembering words, she would avoid answering her phone.
But when in her psychotherapist practice she could not remember her patients' names, could not recognize the notes she had written in their files, could not understand the mounting paperwork it took to handle their claims, and could not trust herself not to say inappropriate things -- she knew there would be no quick fix, no easy cover up.
She would have to quit, and face the fact that at age 52 she had dementia.
Though she admits she has "no reference for time" and difficulty "remembering when things happened," she remembers one date in particular.
"August 15, 2006. That date really sticks on the brain. That's when I left my job. That's the day I lost my identity," Thornton said.
Thornton, now 55, is one of the 200,000 Americans under age 65 estimated to be living with early onset dementia or Alzheimer's disease. Dementia, and its often attendant cause Alzheimer's, is marked by memory loss and declines in language and cognitive function. While it typically affects people in the final years of life, early onset dementia sometimes strikes people in their prime.
For a retiree with adult children, dementia is a frightening prospect. But for a middle-aged person with a mortgage and children who never anticipated early retirement, figuring out how to balance their diagnosis with their job adds another layer of anxiety to an already dire situation.
"I would forget the patient I was seeing. I'd look at my notes and at the patient's chart and I wouldn't recognize my own handwriting. After the HIPAA [privacy] laws changed there was all this new paperwork and I just could not keep track," Thornton told ABC News from her home in Memphis.
After months of seeing doctors, one of whom suggested she was just a "stressed-out soccer mom," Thornton received her diagnosis from a physician who "couldn't have looked more unhappy that I didn't have a brain tumor."
Much of what causes dementia and how to best treat it remains unknown, including how best to handle a diagnosis in the workplace.
"Unfortunately, it is a situation where people don't know what to do," said Shelley Bluethmann, director of Early Stage Initiatives for the Alzheimer's Association.
"It is a gray area. The disease affects individuals in different ways. Someone might seem fine and not look sick, but be struggling terribly," she said.
"A patient cannot know whether a supervisor will understand or if there will be misunderstandings amid the other employees," Bluethmann said, adding that it was best for patients to be upfront about their diagnosis with their employer.
"In the workplace setting it is important to have open communication with the supervisor especially," she said.
Unanswered questions abound about whether early-onset patients are covered by laws to protect disabled workers from discrimination and if younger workers laid low by dementia are entitled to disability insurance through Social Security.
Generally, employers are encouraged to find work a disabled person can do to remain employed, but the law is not explicit about when and if someone with early onset dementia can be fired outright.