The Associated Press Stylebook, one of the most widely used guides to language for news organizations, is recommending that journalists be mindful of the language they use to describe people like Jessica, who is a homeless Philadelphia woman with a heroin addiction. People concerned about addiction treatment are cheering a development that might, at first, seem inconsequential: a change in a word-usage guide. The Associated Press Stylebook , a word-choice and grammar bible for journalists, recommended May 31 that journalists use “addiction” instead of “substance abuse,” and “person with addiction” instead of “addict” or “abuser,” among other changes expected to influence writers, editors, and students around the globe. Those applauding the Associated Press’s shift see much more at stake than the nuances of proper diction. The words chosen to describe addiction, according to advocates, affect how the people who suffer from it see themselves, and how others see them. For too long, they say , the language around addiction implied moral failing rather than illness, a stigma that discourages treatment. The issue has special resonance in Massachusetts, where nearly 2,000 people died of overdoses in 2016. Many news organizations follow the rules in the AP Stylebook. But some, including The Boston Globe, have their own stylebooks to guide diction, grammar, and spelling. The Globe’s stylebook does not include a policy on the use of “addiction,” “addict,” or “substance abuse.” The phrase “substance abuse” fell out of favor among professionals after the diagnostic manual of psychiatric disorders , updated in 2013, changed the definition to “substance use disorder.” But many journalists continued to use “substance abuse” because its meaning is widely understood and also contained in the titles of many government organizations. Michael Botticelli, director of National Drug Control Policy at the White House under former president Barack Obama, called the AP Stylebook changes “a great step forward.” “We’ve seen through research and practice, quite honestly, that language plays a huge role in shaping how individuals think about themselves and in shaping public policy,” said Botticelli, who is now executive director of the Grayken Center for Addiction Medicine at Boston Medical Center. A study published in 2010 found that when a hypothetical patient was described as a “substance abuser,” health care providers were much more likely to find the patient culpable and recommend punishment. If told the patient had “substance use disorder,” they were more likely to recommend therapy. “Addict” defines a person by his illness. “Substance abuse,” with its echo of “child abuse,” suggests that a person is misbehaving rather than ill, advocates said. Changing the addiction lexicon had been one of Botticelli’s goals when in the White House. Shortly before leaving office in January, he produced a memorandum specifying how federal agencies should discuss addiction in their communications. Botticelli doesn’t know whether his recommendations were adopted, but his memo proved influential when the AP tackled the issue. Jeff McMillan, AP’s enterprise editor for the Eastern United States and a new member of AP’s style team, said Botticelli’s memo was one of the first documents the team read. The AP decided to add a section on addiction because, he said, “We realized that this was a hole in our guidance, especially considering the level of news coverage being given to addiction in recent years.” Previously the stylebook had entries about individual drugs but did not address addiction. The AP did not accept every recommendation from the academics it consulted, because they sometimes favored words that have little meaning for the public. “There’s a balance you have to strike between being accurate and being jargony,” McMillan said. For example, “substance use disorder” is an official diagnosis, but a phrase that many readers won’t understand. AP recommends “addiction” instead and suggests “substance use disorder” only when quoting others. The stylebook defines addiction as “a disease that affects a person’s brain and behavior.” It urges writers to avoid “abuse” and “problem” in favor of “use” with a modifier such as “risky,” “unhealthy,” “excessive,” or “heavy.” It also rejects “alcoholic,” “addict,” “user,” and “abuser” except in quotations or in the names of organizations, such as Alcoholics Anonymous. Dr. John F. Kelly, founder and director of the Recovery Research Institute at Massachusetts General Hospital and Harvard Medical School, said he was “delighted” with the AP’s guide. Kelly, author of the study on language, has been advocating for what he calls a new “addiction-ary” for more than a decade. Asked for critiques, he had a few quibbles. Kelly regrets that the AP allows “alcoholism,” which implies that addiction to alcohol is different from addiction to other drugs. He wishes the stylebook had offered a more nuanced discussion of the distinction between addiction and dependence. The guide also doesn’t address such common locutions as using “clean” to mean “sober” — implying that those who are still using drugs are dirty rather than ill. The AP’s McMillan said nothing is set in stone. “This addiction entry is bound to evolve over time,” he said. “We’re constantly making updates.” Felice J. Freyer can be reached at email@example.com . Follow her on Twitter @felicejfreyer.