Donald Trump’s latest comment about his cognitive health quickly backfired on Saturday, June 15, when his memory seemingly lapsed while he was touting his mind’s abilities.

During an event in Detroit, Trump was boasting about the results of a cognitive test he took early in his presidency, adding that President Joe Biden should also take one.

In the process, however, Trump — who turned 78 on Friday — mixed up the name of the physician who administered his cognitive test.

The presumptive GOP nominee joked on Saturday that he didn’t think Biden, 81, knew what the word “inflation” means. He suggested Biden should be assessed, like how he was during his time in office.

“I took a cognitive test, and I aced it. Doc Ronny — Doc Ronny Johnson,” Trump said. 

“Does everyone know Ronny Johnson, congressman from Texas?” he continued. “He was the White House doctor.”

Trump meant to say Dr. Ronny Jackson, who was the White House physician from 2013 until 2018 during the Trump and Obama administrations. He also served as the chief medical adviser to Trump in 2019.

Dr. Jackson is now a controversial Member of the U.S. House of Representatives, representing Texas’s 13th District. 

After flubbing Jackson’s name, Trump added: “He said I was the healthiest president, he feels, in history, so I liked him very much indeed immediately.”

Trump also claims that the doctor said that if he didn’t eat junk food, he would live to be 200 years old. 

Six years ago, Trump took the Montreal Cognitive Assessment (MoCA), and doctors said that he had no cognitive or mental issues at the time. MoCA is meant to identify early signs of memory loss or dementia.

According to Dr. Ziad Nasreddine, the inventor of the test, Trump’s perfect 30 out of 30 score is considered “normal performance.”

“It should be easy for someone who has no cognitive impairment. It’s not a sort of intelligence test,” he said in 2020 as per CTV News.

Two years later, Trump recalled the test’s difficulties during a Fox News appearance. “The first questions are very easy, the last questions are much more difficult,” he said at the time.

Meanwhile, in 2020 when Biden was asked if he had taken a cognitive test, he responded: “Why the hell would I take a test?”

“I am very willing to let the American public judge my physical as well as my mental fitness.”