Psychologist John Gartner wrote an op-ed for USA Today in which he breaks down the signs that Donald Trump is undergoing significant cognitive decline and must be tested for dementia.

In his essay, Gartner says that he’s been alarmed for several months about Trump’s mental condition, and he said that his concerns have only grown while following the continued decay of the president’s speech patterns.

“In Alzheimer’s, as language skills deteriorate, we see two types of tell-tale speech disorders, or paraphasias,” he writes.

“Semantic paraphasia involves choosing the incorrect words . . . Phonemic paraphasia, which is linked to the moderate to severe stages of Alzheimer’s, is described as ‘the substitution of a word with a nonword that preserves at least half of the segments and/or number of syllables of the intended word.’”

As examples of these disorders, Gartner recalls the president demanding to know the “oranges” of the Mueller probe, as well as references to “midtowm” and “midturn” elections.

While these slip-ups could be excused as harmless gaffes, Gartner says they’re only one sign that Trump’s mental faculties are failing.

On Twitter, Clause Taylor, a former staffer of President Bill Clinton, posted some videos to show Trump’s decline, and they are worrisome.

Take a look:

If this were your grandpa you’d take away the car keys. New video. pic.twitter.com/z68X1UqBLo

— Claude Taylor (@TrueFactsStated) April 14, 2019

The Wanderer pic.twitter.com/tsvDItn1E0

— Claude Taylor (@TrueFactsStated) April 15, 2019

Twitter was shocked:

I cringe so hard watching this, it’s impossible to get thru to the end because it’s too embarrassing…

— @brandeisstudent (@brandeisstudent) April 16, 2019

As I’ve said all along, its like grandpa is naked, teetering around the front lawn with a gun, screaming at the rain – someone would drape grandpa in a trench coat and lure him to the nursing home with promises of candy (or $$, for tRUmp)

— Katbuns (@katbuns) April 15, 2019

He can’t even pronounce the name of our country.

Neurological consult STAT

— Sue (@Pinkomomma) April 13, 2019

I’m with various dementia patients almost daily, for hours. Yes, it only gets worse. Yes, he seems like them. Yes, it’s seriously scary to think about any of them with his kinds of power.

— Betty (@parkerspolitics) April 14, 2019

Remember when it was news how W. Bush said the word “nuclear”?

— Noob Noob (@vindicatorn00b) April 14, 2019