• A new study found that people with ADHD likely have a shorter life expectancy.
• Men died about seven years earlier and women died nine years sooner than their peers.
• ADHD is linked to more impulsive or disorganized behavior, leading to worse health outcomes.

A new study of more than 9 million British adults found that people with ADHD died earlier than their peers without the disorder.

On average, men with ADHD died about seven years earlier while women died nine years sooner than their cohorts without ADHD, according to the research.

Published by the British Journal of Psychiatry, the study looked at data on 30,000 people diagnosed with ADHD, and compared it to data from around 300,000 people without — all around the same age and general health status.

While the study didn't explore the causes of death, the researchers say ADHD symptoms like impulsivity, hyperactivity, and forgetfulness can lead to "modifiable risk factors."

ADHD is a neurological disorder that can be linked to other health issues, like substance abuse, or other disorders, like autism.

"To me, the best analog is diabetes," Dr. Russell Barkley, the lead author of a 2019 study on ADHD and shorter estimated life expectancy, told the New York Times. "This is a disorder that you've got to manage, like high blood pressure, like cholesterol and diabetes. You've got to treat this for life."

The study is observational, which means it does not definitively show a causal relationship between ADHD and early death. It also leaves unanswered questions about what could be driving a connection.

Previous studies found a link between ADHD and risky behaviors like substance abuse. In a press release, Philip Asherson, a professor of molecular psychiatry at King's College London, said that adults with ADHD are more likely to engage in unhealthy habits like smoking or binge eating.

Over time, this can lead to health risks. "We know that ADHD is associated with higher rates of smoking, obesity, cardiovascular disease, and cancer among other health problems," he said.

The British study noted that many people are undiagnosed in the UK.

Given that less than 1% of the study's participants were diagnosed with ADHD, it's "also striking in showing how few people with ADHD get a diagnosis," Oliver Howes, a professor of molecular psychiatry at King's College London, who was not involved in the research, said in a statement to reporters.

The study researchers said that "unmet support and treatment needs" could be one of the causes of earlier death in people with ADHD.

Getting a diagnosis can help a person with ADHD find ways to manage their symptoms, be it from medication or adjustments in how they work or stay organized.