Can You Develop Autism Later In Life?

Autism, also called autism spectrum disorder (ASD), is characterized by difficulty with social skills and restricted or repetitive behaviors or interests, according to the Centers for Disease Control and Prevention (CDC). Approximately one in 44 children in the United States are diagnosed with an autism spectrum disorder, but can adults be diagnosed with autism?

Autism spectrum disorders are often diagnosed in childhood when a young child is significantly delayed on milestones, including not pointing at objects or babbling by 12 months of age, not saying single words by 16 months or phrases consisting of two words by two years old, and not responding to their name (via Verywell Health). Another common indicator is when children fail to make appropriate eye contact when socializing with others, or have abnormal responses to sensory input involving smell, touch, taste, and hearing. Many ASD diagnoses are made reliably by the age of three.

In 2020, the CDC released its first report on adults with autism, with an estimated 2.1% of people over the age of 18 living with an autism spectrum disorder. However, autism doesn't develop after early childhood. If a person suddenly begins displaying symptoms of autism as an adult, then they may have developed another mental health condition such as an anxiety disorder, points out Verywell Health. Although autism doesn't develop after early childhood, it is possible for older people to be diagnosed with autism.

The CDC has presented findings that the number of adults living with ASD is consistent with the number of children diagnosed with ASD, so it's believed that the children first diagnosed with autism as children have now aged into adulthood. However, many people are first diagnosed with autism in adulthood, which is likely due to a delayed diagnosis being given (via Verywell Health).

Many children with high functioning autism may be overlooked and not diagnosed during their youth. According to Cleveland Clinic, there are adults who seek out ASD diagnoses they didn't receive in childhood because in adulthood they've discovered that they have symptoms of autism such as communication difficulties, over- or under-stimulation to sensory experiences, and self-stimulating behaviors (stimming).

Women and girls are less likely to receive an accurate diagnosis in comparison with their male counterparts, reports Scientific American. Since autism can present differently in females, symptoms are often not recognized as being a form of ASD. Girls with autism don't present repetitive behaviors as often as boys with autism do, and they tend to have different interests, so their symptoms often aren't as obvious to their caregivers or medical providers. Girls are more likely to receive late diagnoses of ASD, as well as more likely to be misdiagnosed with conditions that include obsessive-compulsive disorder (OCD) or attention deficit hyperactivity disorder (ADHD).

Older children, teenagers, and adults who present with symptoms of autism but weren't diagnosed in early childhood may be experiencing symptoms that seem regressive, says Verywell Health. Studies have found that regression does in fact occur, but the reason for regression of symptoms is unknown. The U.K. National Autistic Society reports that regression occurs when a person with ASD, whether officially diagnosed or not, loses skills or functions. It's important to note that the term autism regression is typically used to describe the loss of developmental skills in young children, while many adults with ASD prefer the terms autism burnout or autism fatigue.

Because sensory experiences can be more intense, and social situations and communication more difficult for people with ASD, they can experience autism burnout when they become overwhelmed. Adults with ASD experience this burnout through distinct behaviors such as physically shutting down, increased meltdowns, experiencing heightened sensory sensitivity, physical pain, headaches, and even the loss of speech. These symptoms may lead a previously undiagnosed person to seek an ASD diagnosis after early childhood.

People who seek out an ASD diagnosis after early childhood may be noticing their symptoms for the first time because of burnout. Alternatively, they may simply become self-aware that they demonstrate signs of autism (per Cleveland Clinic). Diagnosing autism in teenagers and adults can be more difficult than diagnosing ASD in children, but with self-advocacy and testing, a diagnosis can be achieved.