Mary Trump, niece of US president Donald Trump, has claimed her uncle is exhibiting signs of dementia - the same condition his father Fred Trump was diagnosed with in the early 90s. Speaking live on ABC show Planet America, Mary claimed that she sees "a lot" of her late grandfather in Donald now.

She said: "My grandfather was about Donald's age, maybe a little younger... maybe my grandfather was in his mid-70s when he started to exhibit signs of dementia. You know, short term memory loss, impulse control issues, etcetera. It then worsened pretty suddenly in his early- to mid-80s.

"This was a man who, at his height, was a very intelligent person. He was very sharp. And suddenly he often looked as if he weren't oriented to time and space."

Mary continued to allege: "And it's alarming how often I see my grandfather in Donald these days. He also often doesn't seem to know where he is or why he's there or with whom.

"Of course, Donald has never had particularly good impulse control, but especially since the beginning of this year, we see that he is almost incapable of reining in his temper or keeping himself from saying what, in any instant, is exactly the wrong thing for him to say or post on social media. For example, threatening genocide."

Donald's father Fred "did not know his birth date or age" in his later years, and failed to recognise people he had known for decades, including his wife Mary L Trump and his son Donald.

He reportedly had to be reminded why he was at Donald's 1993 nuptials to Marla Maples - where he was the best man.

Fred Trump died in 1999 at the age of 93 - eight years after his initial dementia diagnosis.

Donald, however, has not been diagnosed with dementia or cognitive decline - and insists he passes regular cognitive tests with flying colours.