Excerpt from: Autism Speaks (click for full article)
This is an important question. Mood disorders – including depression – do appear to be more common in those with developmental disabilities than in the general population.
However, diagnosing depression in those with autism represents a challenge that dates back to Leo Kanner’s original description of “infantile autism,” in 1943.
Kanner described a disturbance of “affective contact” in those with autism. Clinicians use the term “affect” to describe how someone’s emotional state appears to others. In other words, does the person look depressed or anxious? This can be different from “mood.” Mood refers to how someone actually feels inside.
Affect and mood are not always aligned. For example, someone’s expression may appear flat and register little reaction. However, that person may say that he or she feels fine. Clinicians refer to this as an “incongruence of affect and mood.”