Mary L. Trump, a psychologist and the niece of President Donald Trump, said on Tuesday that her uncle's "cognitive decline" is tipping into the Alzheimer's disease she says runs in their family — and warned that as he deteriorates, he is going to take the country "down with him."

Her remarks, laid out in a post on her Substack, were reported by Alternet. Mary Trump, who has been an outspoken critic of her uncle for years, previously wrote about the family in the 2020 bestseller Too Much and Never Enough.

"People need to be alerted to just how detached from reality most of what he has to say now is," she asserted, "because he's getting increasingly dangerous as our country gets increasingly weaker, basically across the board."

In her estimation, "Donald has never been fit to be president of the United States temperamentally, psychologically, emotionally and in terms of his unfathomable incompetence and lack of credentials. He is the least qualified person by a trillion light-years to have failed upwards to this office. I think it goes without saying that he's unfit. But when you are somebody who is in obvious cognitive decline… Alzheimer's runs in my family. My grandfather had Alzheimer's. I know what it looks like, and I think we all recognize what cognitive decline looks like."

Her characterization amounts to a personal assessment; a formal Alzheimer's diagnosis requires clinical evaluation by medical professionals.

She also described what she characterized as a prolonged deterioration in the president's physical condition. "His physical health has been deteriorating for a long time," Mary Trump said. "We don't know specifically why, because the White House continues to lie about that. But he's also an 80-year-old who's much older than he would otherwise be because he's so deeply unhealthy. He doesn't sleep except during the meetings. He has a terrible diet. He drinks a lot of Diet Cokes. He doesn't exercise. So you have that going on. Plus, of course, he has very longstanding, untreated, undiagnosed psychiatric disorders that worsen over time. So it's like this perfect storm of deterioration and, in some cases, decompensation."

Her comments add to the recurring public scrutiny of the president's health, a subject on which she directly disputes the White House's public account.

In her view, her uncle has "some sense that he is losing it," a realization she argued is making him "more desperate" and impulsive.

Mary Trump pointed to what she described as an apparent fear of psychiatric hospitals as evidence that the president recognizes his decline on some level. She cited an "incoherent and garbled" story he recently told in which he claimed to have grown up "in the shadow" of Creedmoor Hospital in New York — an account she disputed, noting that the facility is "nowhere near" where her uncle lived. "He's going off about how forbidding its building is and the bars on the windows," she said, "and it's maybe two towns east."

In her assessment, "He's revealing to us in his increasingly nonsensical, incoherent, delusional ramblings what concerns him, what unconsciously he's fearing. And clearly, getting thrown into Creedmoor is at the top of the list."

"That, and also his fear of irrelevance," she added, "which is why he's naming everything after himself, his need for increasing amounts of attention, is why we have MMA cage matches on his birthday and whatever that car race was in D.C."

She closed with a stark warning: "If he thinks he's going down, he's more than happy to take all of us down with him."