Which developmental condition is characterized by differences in thinking, language, behavior, and social skills, with signs evident before age 3 and possible diagnosis as early as 18 months?

• A. Autism
• B. ADHD
• C. Asperger's Syndrome
• D. Rett Syndrome

Answer: (A)

Autism spectrum disorder best fits this description. It involves differences in thinking, language, behavior, and social skills that typically appear in the first few years of life, with signs that can be noticeable before age 3 and sometimes as early as 18 months. Early indicators often include challenges with social communication (such as not responding to name, limited eye contact, difficulties sharing enjoyment or understanding others’ perspectives), language delays or unusual language development, and repetitive or highly focused behaviors or interests. The wide variability in how these signs present is why it’s described as a spectrum.

ADHD centers on patterns of inattention, hyperactivity, and impulsivity rather than the core social-communication differences described here. Rett syndrome has a distinctive pattern of early development followed by regression and specific hand-wringing movements, which sets it apart from the general early signs of autism. Asperger’s syndrome is an older label now folded into autism spectrum disorder, but the description here—early social-communication differences with possible earlier diagnosis—aligns with ASD.