[Posted on 27 March, 2019 by Maj-Britt Posserud]
In the Diagnostic and Statistical Manual, most psychiatric disorders require impairment in order to fulfil diagnostic criteria: «Symptoms cause clinically significant impairment in social, occupational, or other important areas of current functioning». The International Classification of Disorders does not list functional impairment as an independent criterion but in clinical practice, one rarely makes a diagnosis of autism or other neuropsychiatric disorders without functional impairment. Naturally it is easy to think that if there is no problem, there is no use for a diagnostic label, but it is not so simple, because impairment is a very challenging concept.
Who decides whether there is impairment? Who should report impairment? How much impairment should there be to call it «impairment»? What about discrepancies between informants? Parents may report a problem, but not the child or the teacher. A child may suffer in silence and not report problems.
Another challenge with impairment is that it is contextual, and therefore variable; depending on context. This creates the paradox that while autism should be based on permanent traits, present from early childhood, the actual fulfilment of diagnostic criteria may be on and off, depending on the contextual situation of the individual. It creates a conundrum for the clinician who may clearly see the trait in a child, but nobody is reporting impairment at that time. Years later maybe the adolescent is feeling different, not understanding why he or she always feels out of place. «But it can’t be autism, because that psychiatrist didn’t say anything about autism when I was a kid.» Or the adult psychiatrist/physician may think that it cannot be autism because it was not diagnosed in child and adolescent mental health even though he was assessed there as a child.
As many individuals with autism and ADHD have several problems, it is not so easy to know what is actually causing the impairment. There may be impairment due to the comorbid anxiety and language problems, but not because of the social oddities and repetitive interests.
The distinction between impairment and symptoms causes a lot of confusion for people. It is difficult to explain why a person can still have autism, even though extensive assessment in childhood did not conclude with an autism diagnosis.
Finally, and perhaps most importantly, the functional impairment criterion may also be stigmatizing, as the diagnosis by definition is a problem. Temple Grandin’s mother stressed «Different, not less» but the diagnostic criteria seem to say «Different and impaired». Just being different is not a diagnosis, and most of us would argue that it shouldn’t be. You shouldn’t get a diagnosis if you don’t need it. But what if you need it later?