People with autism die much younger, on average, than the general population.

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People on autism spectrum die 18 years younger than average

People with autism spectrum disorder (ASD) die on average 18 years before the general population, according to a report released today by Autistica, a philanthropic group based in the United Kingdom. People with both ASD and an intellectual disability die even younger, on average 30 years earlier than those without the conditions.

Fatal accidents—often by drowning, when a child or adult with ASD wanders away from caregivers—are one of the classic causes of premature death in people who have both ASD and an intellectual disability, says Sven Bölte, a clinical psychologist at the Karolinksa Institute in Stockholm, whose research is cited in the Autistica report. Epilepsy, along with several other neurological disorders, is another common cause of death among people with both ASD and learning difficulties, suggesting that early disruption of neurodevelopment is to blame.

These “classic” causes of premature death in autism, however, do not fully account for a decades-long life span gap between autistic and nonautistic people, or the difference in mortality between autistic people with and without an intellectual disability, Bölte says. To explore these gaps, in 2015 Bölte’s group published a large epidemiological study of more than 27,000 Swedish people with ASD, 6500 of whom had an intellectual disability. They found that risk of premature death was about 2.5 times higher for the entire group, a gap largely due to increased prevalence of common health problems such as diabetes and respiratory disease. Patients may be being diagnosed too late because they do not know how to express health concerns to their doctors, Bölte says, making it “extremely important” for general practitioners to thoroughly explore autistic patients’ symptoms and histories.

Also troubling was the finding that autistic adults without a learning disability were nine times more likely than controls to die by suicide, with women at particular risk of taking their own life. That could be a reflection of the isolation and depression many high-functioning people with an ASD experience, Bölte says.

“We cannot accept a situation where many autistic people will never see their 40th birthday,” Autistica President John Spiers said in a press release. The charity called for immediate study and action by the United Kingdom's National Health Service, and announced that it will raise £10 million to fund its own research.