Trump was 'visibly upset at his father’s descent into dementia' in the '90s: Mary Trump

While Republicans have relentlessly hammered President Joe Biden for being too old, their own presumptive 78-year-old presidential nominee has a history of dementia in his family.

Mary Trump, the niece of former President Donald Trump, tells the Washington Post that Trump grew "visibly upset at his father’s descent into dementia" in the 1990s when his father, Fred Trump, initially failed to recognize him at a family gathering.

A former Trump Organization executive who spoke with the Post on the condition of anonymity confirmed that watching his own father's struggle with dementia affected the former president.

"Donald is no doubt fearful of Alzheimer’s,” the executive said. “He’s not going to talk about and not going to admit to it. But it’s relevant because every day he is hitting Biden with whether or not he is capable mentally of doing the job.”

ALSO READ: A neuroscientist reveals how Trump and Biden's cognitive impairments are different

Just because Trump was upset at seeing his father slide into dementia, however, doesn't mean that he didn't allegedly try to benefit from it.

As the Post notes, "Trump’s father’s condition also drove a wedge into his family, which fell into years of lawsuits that alleged in part that Donald Trump sought to take advantage of his father’s dementia to wrest control of the family estate — litigation that introduced reams of medical records detailing Fred Trump Sr.’s condition."

In response to the Post's questions about Trump's family history of dementia, Trump campaign adviser Jason Miller argued that Trump put all of these questions to rest when he took a cognitive test in which he had to correctly identify a camel.

“President Trump has aced this test twice and is willing to take a third test if Joe Biden sits in the same room and takes it at the same time,” he said. “In fact, President Trump believes all Presidents should take the test.”