Differential Diagnosis and Co-morbidity in Autism Diagnosis

Dr. Ozonoff presents many ways how co-morbidity can complicate the assessment and differential diagnosis of ASD.  Dr. Ozonoff starts off with a great example of the Occam’s Razor that says that all other things being equal, the simplest solution is the best solution.  For example, if the child has hand flapping but doesn’t have social or communication difficulties it would be a Stereotypic movement disorder not autism.  Dr. Ozonoff also goes on to say that treatment for just autism will not treat other difficulties the person may have and may sometimes have a more negative impact if left untreated.  So, when diagnosing someone with ASD it’s very important to see if other diagnoses are needed. 

Dr. Ozonoff  goes on to give great diagnostic considerations to think about when seeing if co-morbidity is occurring.  The number one consideration is if there is a change in function from baseline.  Meaning an onset of new symptoms or worsening of symptoms already present, lack of response to usually effective treatments, and/or signs of problems outside autism spectrum.  A child will present with symptoms of autism before age 3 but very often will present with other symptoms as the child gets older.  If other symptoms become present after age 3, this may indicate that there are other things going on.

Although Dr. Ozonoff doesn’t specifically list ways to deal with co morbidity with a functional assessment, she does give very specific guidelines one consider when looking into co morbidity. She states some Diagnostic Considerations below:

Consistency and pervasiveness of symptoms

Developmental history

Age of symptom onset (autism prior to age 3, most other symptoms don’t develop before age 3)

Package of symptoms – waxing and waning then something else is going on versus autism

Form and quality of symptoms

Are difficulties limited to those plausibly encompassed by DSM autism criteria or do they extend beyond

The major lesson I will take from the presentation is the chart she presented.  This chart will be very helpful when looking to see if a person has ASD, ASD + ____, a different diagnosis, or no diagnosis.  I attempted to re-create the chart as best as I could so I can keep it and refer to it often.

So, with the diagnostic considerations and the chart, I feel that I am better equipped now when performing a functional assessment and considering co morbidity.