Suicide among middle-aged Mainers has soared since 1999, fueling an overall increase in the suicide rate for people of all ages in Maine and mirroring a national trend.

The increasing rate among the 45-64 age group is largely responsible for a rise in the incidence of suicide among all ages since that year, according to figures released last week by the U.S. Centers for Disease Control and Prevention.

The number of Mainers who killed themselves in the 45-64 age group increased from 47 in 1999 to 102 in 2013 before declining to 86 in 2014, the latest year for which statistics are available, according to the CDC. The trend line was consistently higher in the 2010s when compared with the early to mid-2000s.

The figures translate into a suicide rate for middle-aged Mainers of 21.1 per 100,000 people in 2014. That’s a 37 percent increase from 1999, when the rate per 100,000 was 15.4. Across the United States, the rate for the same age group increased 48 percent, from 13.2 to 19.5, with 16,294 suicides in the 45-64 age group.

It’s not clear what might be driving the trend. Traditional risk factors for suicide include loss of employment, isolation and being a victim of sexual assault. One possible contributing factor is the surge in opioid addiction – including prescription opioids and heroin, experts say.

While research on the topic is still embryonic, a study conducted for the U.S. Department of Veterans Affairs and released in January points to opioid abuse as a risk factor for suicide. VA patients who were on higher doses of opioids to control pain – 100 milligrams or higher – were twice as likely to commit suicide as patients on lower doses, according to the study, although the study’s authors caution that there are many factors that contribute to suicide.

Dr. Mary Dowd, a physician who counsels clients for addiction treatment programs at the Milestone Foundation and Catholic Charities Maine, said many of her patients addicted to opioids have told her they have had suicidal thoughts.

“When I ask patients what it’s like being addicted to opioids, they tell me that it’s like being dead. They tell me they feel like they can be ‘courageous’ and overdose and die or they can be the ‘walking dead,’ ” Dowd said.

Overall, the number of suicides in Maine increased from 175 in 1999 to 220 in 2014, while in the United States, the toll from suicide escalated from 29,199 to 42,773 during the same period.

The change was largely driven by increases among middle-aged adults, as the rates for other age groups either did not change or rose only slightly between 1999 and 2014.

The role of opioid painkillers in suicide rates is not clear, but the drugs flooded the market in the early 2000s, displacing over-the-counter medications such as aspirin or Tylenol as a common treatment for chronic pain. By 2014, 350,000 Mainers were prescribed 80 million opioids a year, according to the Maine Department of Health and Human Services.

Peter Wohl, the owner of Behavioral Health Services in Portland, said middle-aged people, like the veterans in the VA study, are more likely to be prescribed opioid painkillers to control pain – to recover from injuries suffered during war or when the body becomes more vulnerable to injury or disease as people age.

Wohl said suicide is a major risk for those addicted to opioids, and even for those trying to get clean.

“Because it’s secondary to the opioid epidemic, suicide is easy to miss in the public discussion,” he said. Wohl said patients he has known have killed themselves, and he sees warning signs that suicide is a serious risk, particularly for middle-aged people, who often have a harder time believing they can turn their lives around.

“They kind of assess where their lives are, and many times they’ve lost their family, lost their kids, don’t have a job. There are social consequences,” Wohl said. “They see what’s happened to their life, and they become depressed, which can lead to suicide.”

Elizabeth Marquis, whose daughter Kelly Deyo of Westbrook died of a drug overdose in April 2015 at age 39, said she still can’t believe her daughter committed suicide. Deyo, a recovering heroin addict, was taking numerous medications for mental illness when she died, and the Falmouth psychiatrist who prescribed her the medications, Dr. Reinaldo De Los Heros, was placed on six months of probation in connection with how he practiced medicine in Deyo’s case. Deyo was also found with morphine, an opioid, in her system when she died.

Deyo left a suicide note, but Marquis said she didn’t notice that her daughter was depressed.

“I never in a million years would have thought she would commit suicide,” Marquis said. “I always thought that she would die by overdosing on heroin.”

Of Maine’s 220 suicides in 2014, 31 were by overdosing on drugs, according to the CDC.

Maine experienced 272 drug overdose deaths in 2015 and 208 in 2014, according to the Maine Attorney General’s Office, with the vast majority caused by heroin, fentanyl or prescription opioids.

Marcella Sorg, a research associate professor at the University of Maine’s anthropology department, which compiled the statistics for the Attorney General’s Office, said that for budgetary reasons, Maine does not conduct toxicology reports for suicides that are not drug overdoses. So it’s unknown, for instance, whether people who committed suicide with a firearm had opioids in their system when they died, Sorg said.

Sorg said undoubtedly more of the drug overdoses are also suicides, but Maine does not categorize them as suicides unless a note was left or there was some other compelling evidence pointing to suicide.

“We don’t know whether it was a suicide in many cases. It’s a gray area,” Sorg said.

Heather Carter, senior trainer for the Maine chapter of the National Alliance on Mental Illness, said it all seems to add up that the opioid crisis is contributing to suicide. But she said more research needs to be done.

“This coincides with what we’ve observed – what opioid addiction does to your life – but the research is behind. It’s a goal of ours to dig deeply into this subject,” she said.