When was Autism Spectrum Disorder first recognized as a distinct condition?

Autism Spectrum Disorder (ASD) was first recognized as a distinct condition in the mid-1900s, particularly in the 1940s. Pioneering work by researchers like Leo Kanner in 1943 helped to define autism as a specific developmental disorder, distinguishing it from other conditions. Kanner's studies focused on children who displayed a unique set of social and communication challenges, leading to the acknowledgment of autism as a separate clinical entity in the psychiatric community.

In addition to Kanner, Hans Asperger also contributed to the understanding of autism through his work in the same period, describing a form of autism that exhibited different characteristics but remained part of the same spectrum. This foundational period set the stage for subsequent research and developments in the understanding and diagnosis of autism.

In contrast, the other time frames, such as the late 1800s, early 2000s, and 1990s do not accurately reflect the timeline for the formal recognition of ASD. The late 1800s was too early for the concepts of autism as we understand them today, while substantial developments in the understanding of the disorder primarily unfolded in the mid-20th century. The early 2000s and 1990s represent more