More than 4 in 10 Americans personally know someone who has died of an overdose, and an estimated 13% of the population have had their lives disrupted as a result, according to a new study in the American Journal of Public Health.

Why it matters: With more than 100,000 people dying from overdoses a year, America's drug crisis has undeniably altered millions of lives. But the study suggests that the epidemic's reach into American life has, if anything, been underestimated.

The big picture: As the drug epidemic has evolved and become deadlier, it has grown from a public health issue to a divisive political topic — both because of its emotional resonance with voters and because of the controversial nature of potential solutions, like expanded access to methadone treatment.

• Big cities are grappling with how to reduce the number and impact of overdose deaths, and some of the bluest parts of the country are rethinking their harm reduction and compassion-first approaches.
• As fatalities and policy fights make headlines, however, there's been far less discussion about those left behind in the aftermath of fatal overdoses.

By the numbers: More than 125 million Americans know at least one person who has fatally overdosed, the RAND-led study projects.

• More than 40 million adults have had their lives disrupted by overdose loss, and an estimated 12.5 million people are still feeling a "significant or devastating effect."
• Exposure to overdose death was more common among women than men, married people than unmarried people, U.S.-born respondents than immigrants and those who live in urban areas rather than rural ones.
• Researchers based findings on a nationally representative survey of 2,072 adults.

Between the lines: Most who reported knowing someone who died of an overdose said they actually knew multiple people who died from drugs.

• Although there's limited research specifically on the impact of overdose losses, traumatic bereavement in general is known to have an adverse impact on physical health, mental health and substance use. Future research should look at overdose death "contagion," the authors note.
• Research on suicide loss may be instructive, the paper notes, and suicide "postvention" for those left behind is an important part of suicide prevention.