Autism is frequently misdiagnosed, often as a mental health condition rather than a neurodevelopmental condition. One of the barriers to correct diagnosis, is that clinicians rarely consider autism in the differential, and when they do, they often don't have the expertise to assess for the condition.
One of the most common misdiagnostic labels is bipolar disorder. Everyone on the autism spectrum will have difficulty with emotional and behavioral regulation (staying calm and even without swinging between states).
Some on the spectrum swing between calm states and "fight" states including meltdowns, outbursts, or arguments. Others swing to "flight" states or to "freeze" states. Individuals who show "fight states" appear most likely to be misdiagnosed with bipolar disorder. Individuals with flight or freeze behaviors are more likely to be misdiagnosed with other conditions like agorophobia, social anxiety, or neurologic spells (like nonepileptic seizures).
One of the reasons that autism is misdiagnosed is that it is a big picture diagnosis with many neurologic features. As seen in the picture below, autism spectrum disorder has multiple features that may overlap with other conditions with a smaller symptom profile.
In the diagram, each of the diagnoses from 1-5 have all of the diagnostic criteria met. The problem isn't that the criteria aren't met for the diagnoses; the problem is that the characteristics are "better explained" by a diagnosis that includes all the features in one.
The DSM-5 manual notes that we should only make a diagnosis if the characteristics "are not better explained by a different diagnosis." Clinicians should be ruling out autism first, and then considering diagnoses with fewer features (like bipolar, obsessive compulsive disorder, social anxiety, etc).
Correct diagnosis is important! It should drive the most helpful recommendations. Click here for a free video from Dr. Regan about why correct diagnosis is important.