Autism identified in adolescence or adulthood may not be the same as autism diagnosed in early childhood, according to a major international study that suggests the condition is more diverse than previously thought.
For years, autism was viewed as a disorder that revealed itself in young children. But as definitions have broadened, more teenagers and adults have received the label, raising a question that researchers have long debated: are these simply late-recognized cases, or something distinct?
The new study, published Wednesday in Nature, leans toward the latter.
By analyzing genetic data from thousands of people in Denmark and the United States, scientists found that those diagnosed later in life had genetic patterns that diverged from individuals diagnosed before age 10.
“People diagnosed with autism later in life are genetically more similar to those with attention deficit hyperactivity disorder (ADHD),” said Thomas Bourgeron of France’s Pasteur Institute, one of the study’s authors.
The research also linked later diagnoses to a greater likelihood of depression and other mental health conditions.
The results challenge the idea that autism represents a single disorder with varying intensity. Instead, they reinforce the view that the spectrum may actually cover several biologically distinct conditions.
“People with autism are very different from one another,” Bourgeron said, arguing for treatment and support tailored to individual needs.
Uta Frith, emeritus professor of cognitive development at University College London, who was not involved in the study, said the findings underscored how misleading it is to talk about autism as one phenomenon.
“If there is talk about an ‘autism epidemic,’ a ’cause of autism’ or a ‘treatment for autism,’ the immediate question must be: which kind of autism?” she said.
