Sherri Reynolds' son Qual has been drug free for 16 months, thanks in large part to treatment he got through Medicaid under the Affordable Care Act.

Reynolds knows firsthand what can happen when people can't get coverage: Her 20-year-old stepson, Jarvis, suffered from mental illness and killed himself in 2010 after he couldn't get medical treatment. He bounced in and out of foster care and the juvenile justice system.

“I really hope they don’t dismantle Obamacare and I don’t understand why they would dismantle something which is credited for saving so many lives," says Sherri Reynolds.

As Congress works to repeal the Affordable Care Act with the support of President-elect Donald Trump, people with addiction and mental health disorders, their families and treatment providers wonder how patients would maintain their sobriety — and psyches — without insurance coverage.

The people helped the most by the ACA are the ones most likely to suffer from poor mental health and addiction. Nearly 30% of those who got coverage through Medicaid expansion have a mental disorder, such as anxiety or schizophrenia, or an addiction to substances, such as opioids or alcohol, according to the federal Substance Abuse and Mental Health Services Administration. That compares to the more than 20% of the overall population — 68 million people — who experienced a diagnosable mental health or substance abuse disorder in the past year, the American Psychiatric Association says.

In New Hampshire, which has the highest synthetic opioid death rate in the country, Democratic Sen. Jeanne Shaheen is reminding Trump about some of his campaign promises in her state.

"He pledged to take on this crisis, not immediately make matters much worse," Shaheen said in an email Friday. "Repealing the Affordable Care Act without a replacement is highly reckless and will come at a high cost for people struggling with substance use disorders.”

Almost any route taken on Capitol Hill leads to an unraveling of addiction and mental health.coverage for these people. Even the partial ACA repeal Congress is considering would eliminate the tax credits that reduce the premiums for about 85% of those who buy insurance on the federal and state exchanges. Most of those who get tax credits pay less than $100 a month for insurance and have very low out-of-pocket costs that make it possible for them to afford coverage.

The partial repeal would also scrap the expansion of Medicaid that gave millions of the lowest-income people in 31 states insurance. Instead, states would most likely get block grants that would require them to make cuts in what's covered, how much is spent and how many people can get coverage. States might instead get a set amount per person, which would also lead to cuts as the overall goal is cutting spending.

If the same legislation passed by Congress but vetoed by President Obama a year ago was enacted, people would still be able to keep their children on their insurance until age 26 and insurers wouldn't be able to discriminate against people who have preexisting health conditions, such as depression or cancer. It also retains the "essential health benefits," including mental health and addiction coverage, now required for all plans sold on the federal and state exchanges.

Without the ability to pay for insurance, however, some say that otherwise hopeful sign would carry little significance.

"Some families will do what they have to do to help their loved ones," says Amanda Fleckinger, a former heroin addict in Edgewood, Ky., who lost her brother and boyfriend to overdoses in the last 18 months. "If there’s no coverage,  I think we would definitely see an increase in deaths."

A 2008 law that required insurers to cover mental health and addiction at the same level they do other diseases is "useless" if there's no insurance coverage for low income patients that has to reach parity, says Linda Rosenberg, CEO of the National Council on Behavioral Health. She describes the current debate on Capitol Hill over the ACA's future as "the most critical time" in her 40-year career as a social worker.

Medication-assisted treatment for addiction "has really come into its own," she says. "There's been tremendous progress."

Former Rep. Patrick Kennedy, D-R.I., who wrote the mental health and addiction parity law, says it wasn't his law but the ACA that "made the greatest difference."

"It was the best mental health and addiction bill ever," he said. "It takes our mandates and makes them real for more people."

A lot of the mental health programs developed by the Montefiore Health System in the Bronx are contingent upon patients getting early treatment in primary care, says psychiatrist Henry Chung, chief medical officer of Montefiore’s care management organization.

Critical new mental health provisions in the recently enacted 21st Century Cures Act that improve access to treatment need "to be combined with strong, affordable insurance," says Chung. "You can’t have one without the other or some of that progress will be taken away," he says.

Among areas that would be hard hit:

• New Hampshire. Repealing the ACA would cause nearly 120,000 people to lose coverage in New Hampshire, where federal data shows a nearly 200% increase in overdose deaths in the last five years. Treatment is already insufficient in the state. Stripping away health insurance coverage from thousands of residents through ACA repeal would make treatment that much more inaccessible and unaffordable, Shaheen says. According to her office, more than 48,000 Medicaid claims were submitted for substance use disorder in 2015. The ACA also reduced the strain on hospitals and treatment providers in the state by allowing more patients to get  treatment without going to the emergency room, Shaheen says. The senator has visited more than 30 treatment centers in New Hampshire over the last year, which she says convinced her that repealing the ACA is "literally a matter of life and death.”

• Ohio. At the Cincinnati Center for Addiction Treatment, CEO Sandra Kuehn said she saw a huge uptick in the number of men seeking help after Medicaid was expanded to all adults under 138% of the federal poverty limit. Before states could expand Medicaid under the ACA with a large federal match, Medicaid eligibility varied widely and typically only covered women who were pregnant or had young children (along with the disabled and many seniors with very limited resources). About 30% of Kuehn's patients are covered for treatment because of the expansion, she said. Overdose deaths climbed from 2,531 in 2014 to 3,050 in 2015, a more than 20% jump. That included a sharp increase in overdose deaths related to the powerful synthetic opioid fentanyl, from 503 in 2014 to 1,155 in 2015, according to the Ohio Department of Health.

• Kentucky. Overdose deaths here totaled 1,248 in 2015, up about 17% from 2014, according to the Kentucky Office of Drug Control Policy.  Fentanyl — which is much stronger than heroin — was involved in 420 fatal overdoses in 2015 in Kentucky, up nearly 250% from the previous year. The drug caused 34% of all overdose deaths in the state, frequently in combination with heroin or other drugs, the report states. Fleckinger isn't surprised. At just 25, she is amazed at how in the time since she was in high school, it has gone from where young people were drinking "and having fun" to wanting to get "totally wasted" and often overdosing. She knows several people who have overdosed and many others who have died — including one in the last week.

• Chicago. The Cook County jail here is often referred to as the largest mental health facility in the country. Up to 30% of the 9,000 or more inmates in the jail have a diagnosed mental illness, according to jail data. "The ACA has been a game changer for those who are in and out of Cook County Jail," says Mark Ishaug, CEO of Thresholds, a community-based mental health and addiction services provider in Chicago. He says poor people of color, especially single men, were finally able to keep health coverage once they left the jail.  It costs less than $20,000 a year for Threshold's highest level of community-based mental healthcare with a housing voucher, compared to nearly $70,000 a year to keep the patients in jail. About a third of Threshold's 15,000 clients became eligible for coverage through the ACA.

Amanda Fleckinger’s parents paid thousands of dollars for her heroin treatment program before the Affordable Care Act took effect in 2013. By the time her brother Brian was struggling with heroin addiction in 2015, Kentucky had expanded Medicaid coverage and he could get treatment. So could her boyfriend.