Asperger's syndrome was officially recognized in 1994, when it was added to the fourth edition of the Diagnostic and Statistical Manual of Mental Disorders(DSM), the diagnostic guide recognized by the American Psychiatric Association. Although sometimes referred to as a high-functioning form of autism, the guide specified Asperger's was a distinct disorder [source: Hamilton]. Those with Asperger's have a hard time interacting with others and often are intensely interested in a particular topic, say trains, talking about them nonstop. While autism is also a developmental disorder, its symptoms are more pronounced. Autistic people tend to have more difficulty interacting with others -- sometimes they simply can't -- and often exhibit repetitive behaviors, such as flapping their arms or rocking.
In 2013, the DSM's fifth edition was published. Asperger's and autism were merged into the guide's new "autism spectrum disorder" category. The change was one of the most controversial in the new DSM-5 [source: Parry]. While many people with Asperger's don't see themselves as autistic at all -- most can function independently in society -- the broader category was seen by health care professionals as more reliable. Previously, when trying to diagnose a patient with one of these disorders, clinicians mainly relied on the patient's language skills. Reasonably good skills could mean Asperger's; less-developed ones might mean autism [source: Hamilton]. But that's a subjective call, and someone's language skills can change over time. With one category, the hope is to focus on how to best help the patient, not the specific label.