There is no question that President Joe Biden turned in a terrible performance during Thursday night's debate, and it isn't just Democratic strategists, pundits, and donors who are now expressing concerns about him.

Physicians in the U.S. and abroad, admittedly without having personally examined him, have nonetheless suggested that there may be some serious underlying health condition that explains Biden's dismal debate performance, the Washington Examiner reported.

One suggested dementia while another pointed to Parkinson's Disease with a third suggesting that it was simply normal cognitive decline for an elderly individual.

Medical expert suggests Biden suffers from dementia

Carole Lieberman, a forensic psychologist and medical expert witness of 20 years, told the Examiner of the president's obvious issues with speaking clearly and his memory during the debate, "Being like Biden is not a normal part of aging."

"If I had to take a guess, I would say that it is vascular dementia because he has long had cardiovascular problems," she continued. "He had a brain bleed years ago from an aneurysm. He had atrial fibrillation."

Lieberman ruled out Alzheimer's Disease as the probable cause of Biden's problems, but noted that it didn't really matter what, exactly, the root cause of his issues are, just so long as it is receiving the attention it warrants.

"The one good thing about this disaster last night was that it’s more obvious to more people," Lieberman, who has been noting Biden's progressive decline since the 2020 election, added. "Since then, it has definitely encroached. Now you don’t have to be a psychiatrist to figure this out. Last night should have made it really obvious for everybody."

British doctors suggest Parkinson's or other "cognitive impairment"

The Daily Mail reported that British psychiatry professor Robert Howard said, "Doctors can't diagnose someone without examining them, but based on the footage of the debate I've watched, the freezing and rambling make me concerned that Biden struggles to maintain attention."

"He's fine 98 percent of the time, but there are occasions when he appears to have lost his train of thoughts and others where he can't stop himself from rambling," he continued. "These fluctuations and dips in attention are a key symptom of Parkinson's."

Howard dismissed dementia as the likely culprit given that it presents symptoms all of the time and not intermittently like Parkinson's, and used an analogy of flickering lights in a house with electrical problems to explain.

"The difference is, with dementia it's like the lights in the house are blown: there's nothing you can do bring them back on," he said. "But with something like Parkinson's, the power dips, and the bulbs flicker and go a bit dim from time to time."

The Daily Mail also spoke with British physician Mike Smith, who said of Biden, "It is beyond doubt he has cognitive impairment. He struggles to find the right word, he sometimes finishes a sentence with something that makes no sense for example his sentence on Medicare … he appears to have to concentrate very hard to keep on topic. Also his shuffling indicates there's some locomotive issues there as well."

Normal cognitive decline consistent with age

Also weighing in with a non-diagnosis from afar was Israeli Dr. Itai Gal, who wrote in an op-ed for The Jerusalem Post that President Biden "does not meet the criteria for dementia and is experiencing cognitive decline consistent with his age -- 81 and a half years old."

He suggested that Biden undergo the same sort of basic cognitive test that former President Donald Trump took previously and passed.