After watching clips from the movie 'Still Alice' about a woman diagnosed with early onset Alzheimer's disease, I verified that the disease is genetically passed down. A child born to a parent with EOAD has a 50% chance of inheriting the genes that cause it, and if they do, it's almost 100% certain the child will develop EOAD. EOAD is a rare form of the disease, with symptoms beginning before age 65 and as early as age 30.
In the movie, Alice has three adult children. Two are tested: one positive and one negative. The third child chose not to get tested. She didn't want to know (at least at that point in her life). (Side note: one of the writers and directors of the movie, Richard Glatzer, was diagnosed with ALS before beginning the project of adapting the book to screenplay. He died three weeks after Julianne Moore won an Oscar for her performance as Alice.)
Would you function better knowing what was ahead of you (whether death by illness or injury) and how much time you had left, or would knowing destroy your peace of mind and keep you from enjoying life? If you did learn of your fate years in advance, would you tell anyone?
Part of me would want to know so I could plan ahead and make informed choices (and wear Depends on *the day* to make cleanup easier). However, it's possible the knowledge could put me into a tailspin of fear, causing me to shut down, unless I learned I would die at a healthy old age while sleeping. And then there's the issue that comes with seeing into the future: will you screw up the good stuff in your life while making choices in reaction to knowing your fate?