Mac Frischknecht is believed to have Creutzfeldt-Jakob disease, and his family fears he may have only a few weeks left to live

Rare Brain Disorder Leaves Father of Five With Just Weeks to Live: He's 'Lost Himself,' Son Says

A 56-year-old teacher admired by his community is battling a rare and degenerative brain disorder that is quickly wiping his memory.

Mac Frischknecht has taught math in Utah’s Jordan School District for more than three decades, where he is known for carrying a positive attitude and an infectious smile. He often worked extra hours to tutor his students—even ones who weren’t in his classes—and his willingness to provide his time and energy has doubtlessly created lasting memories for many. These memories are especially important today, as the father of five currently has no recollection of who he is and the impact he has made.

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“He’s probably the most selfless person you’ll ever meet. My whole life, he has been the main person we can always count on,” Frischknecht’s son, Tyson, tells PEOPLE. “He has always been someone I can go to for advice, and he’s been that way for a lot of his students.”

Since just before Christmas, Frischknecht has been hospitalized with a rare and degenerative brain disease that will eventually claim his life.

Image zoom Tyson and Mac Frischknecht Tyson Frischknecht

Tyson says his father’s symptoms first appeared in September when Frischknecht experienced dizziness and a slight tingling in his face. Though he went to doctors for answers, physicians told Frischknecht—who often spent long nights tutoring students or attending meetings at his local church—that he was likely just stressed from his busy schedule and needed rest.

But even with some time off, Frischknecht’s symptoms worsened.

“We didn’t see a huge change until right around the holidays. He was really having a hard time reasoning with anything,” Tyson says. “My mom would ask him to do the bills, and he would just sit there. It’s so unlike him to not be on his game. He’s the kind of guy who likes to have a list and check things off.”

Image zoom Mac Frischknecht with his wife, Tania Tyson Frischknecht

Doctors believe Frischknecht is battling Creutzfeldt-Jakob disease, a rare and fatal brain disorder that affects about one in a million people every year worldwide, according to the National Institute of Neurological Disorders and Stroke. Of that, just about 300 Americans are diagnosed per year with the condition.

The institute says CJD usually appears later in life, and when it does, its effects come on rapidly.

The first signs of the disorder include memory loss, behavioral changes, insomnia and muscular coordination problems. The only way to confirm CJD is through a brain biopsy, and Tyson says the family is currently waiting on test results to solidify the diagnosis — though he says doctors are confident it is CJD. As of now, there is no treatment to control or cure the disease, and it is always fatal within a year of diagnosis.

Tyson says his father’s intense symptoms indicate he may be gone in a matter of weeks.

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“His cognition is going, and he’s really lost himself with this,” says Tyson, who moved back home from Murray, Utah, to help his family through this time. “His cognition is deteriorating, and sometimes aggression comes out, and it’s just not who he is.”

Yet, at times, Tyson says his father experiences flashes of clarity that display his concern for the family.

“There are bits and pieces of him that will show, and there have been a few times where he’ll pull me in really close and tell me to take care of my mom and sister,” he says. “There have been times where he’ll say he wants to get out of the hospital and see his bank account—and that’s him expressing that he wants to get out because he knows how expensive it is per day in a hospital.”

Image zoom Caleb and Mac Frischknecht GoFundMe

With bills mounting, Tyson created a GoFundMe account to aid the family with hospital expenses. He also hopes to use the donations to ensure his mother, a secretary at a local elementary school, won’t be left with mountains of debt.

As the disease progresses, Tyson says he hopes people will remember his father’s optimistic nature—and his blood type.