When President Trump and Joe Biden faced off for the first — and so far, only — presidential debate late last month, Trump attacked his Democratic rival with a false claim about Hunter Biden.

"Hunter got thrown out of the military," Trump said of the former vice president's son. "He was thrown out, dishonorably discharged, for cocaine use."

That's factually wrong. Hunter Biden, 50, received an administrative discharge, not a dishonorable discharge, from the U.S. Navy Reserve in 2014 after he tested positive for cocaine.

He has spoken openly about his struggles with addiction, telling The New Yorker magazine last year that it's like a "darkness."

"My son, like a lot of people, like a lot of people you know at home, had a drug problem," said Joe Biden during the Sept. 29 debate with Trump.

"He's overtaken it, he's fixed it, he's worked on it, and I'm proud of him."

After the debate, however, Trump's son Donald Jr. doubled down on the attack. He called Hunter Biden a "crackhead" during an appearance on Glenn Beck's right-wing talk show.

Hunter Biden has been a fixture of Republican and conservative media attacks for years, focused mostly on his controversial business dealings in Ukraine.

But Biden's struggle with substance use disorder also surfaces regularly in right-leaning outlets and in attacks by Trump's political allies.

Rep. Matt Gaetz, R-Fla., raised the issue last year during a congressional hearing before the president's impeachment, recounting how Hunter Biden tried to buy crack cocaine while "wandering through homeless encampments."

It was an apparent reference to Hunter Biden's account of a relapse he experienced in 2016, described in The New Yorker article.

Relapses are a common experience for people in treatment for substance use disorder.

These attacks have raised alarm and sparked criticism from those who say the president and his allies are using a disease experienced by 20 million Americans as a political weapon.

"To hear the president of the United States say this is a legitimate political smear shows that he thinks this is a way to attack," said Eric Michael Garcia, a journalist who entered recovery last year for alcohol and sex addiction.

After the debate, Garcia wrote about the attacks on Hunter Biden in The Washington Post, arguing that "mocking people for their addiction will make them less willing to get help."

In an interview with NPR, Garcia said it was hard for him to admit needing help because he feared the kind of shame and public attacks now hitting the Bidens.

"I worried my personal shortcomings would be used against other people, people who I love," he said. "I think that's something that a lot of people with addiction fear."

Experts say stigma can be a life-or-death issue for Americans who have addiction problems. According to the National Institutes of Health, 75% of those people never get help, often because of shame and stigma.

"Words change the way we perceive those with this disease," said Gary Mendell who heads a national addiction recovery program called Shatterproof.

He told NPR that the kind of shame reinforced by political attacks on Hunter Biden will leave more people reluctant to get help.

Mendell lost his son, Brian, to addiction in 2011 when the 25-year-old died by suicide after wrestling with shame. "He wrote about it in a note to me. He talked about not being looked at as normal," Mendell said.

Drug overdoses killed more than 70,000 people last year. According to federal researchers, treatment could have prevented many of those deaths.

Addiction is now understood by scientists and health care providers as a treatable illness. But Mendell said that's only possible if people like his son feel safe getting the care needed to help them manage a "chronic illness, no different than someone with diabetes."

There's no data — no polls or surveys — to indicate whether this issue will matter to voters. But according to the Centers for Disease Control and Prevention, the addiction epidemic is hitting families especially hard in some of the battleground states, including Ohio and Pennsylvania, that could decide the presidential election in November.

Meanwhile, anyone needing help for substance use disorder can go findtreatment.gov.

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