[tejohnso]

> Two children diagnosed with the disorder can have no overlapping symptoms.

Is there a precedent for this with other disorders? Seems to me that if there are no overlapping symptoms, it should be a separate disorder. Even if it's just arbitrary naming like "Type X" as in diabetes.

[dwringer]

This might not be the most authoratative source, and I'm no medical expert, but this overview from Encyclopedia Britannica[1] nicely describes the diversity in how diseases are classified (I know we aren't using the term "disease" here but the concepts are presumably related in practice - I found this summary informative but welcome any informed corrections):

> The most widely used classifications of disease are (1) topographic, by bodily region or system, (2) anatomic, by organ or tissue, (3) physiological, by function or effect, (4) pathological, by the nature of the disease process, (5) etiologic (causal), (6) juristic, by speed of advent of death, (7) epidemiological, and (8) statistical. Any single disease may fall within several of these classifications.

[1] https://www.britannica.com/science/human-disease/Classificat...

[DanBC]

> Seems to me that if there are no overlapping symptoms,

The full name is "Autistic Spectrum Disorder", so the name hints that there's a range of stuff happening.

To be autistic someone has to have problems with social communication, problems making or maintaining friendships, and fixed and repetitive interests.

Some people also have other stuff on top. These things are common with autism, but are not needed for the dx.

Alexithymia (the ability to recognise emotion in yourself and others) is one example. It's far more common in autistic people, but you don't need it to be autistic. Between 50% and 55% of autistic people have alexythimia. Sensory sensitivities are another. There are a range of these things that are more common in autistic people, but aren't needed for the dx.

And there's a lot of co-morbidity too. People with autism are more likely to have depression or anxiety or OCD. These aren't part of autism, but it's complicated to untangle what's going on. Is someone social isolated because they're depressed, or autistic, or is it a bit of both?

When you start looking at these other things it makes sense that autism might be an umbrella diagnosis.

[gowld]

And it overlaps with the diagnostic "Pervasive Developmental Disorder" in case you thought ASD wasn't a big enough tent.

[cbhl]

In the DSM 5, "Pervasive Developmental Disorder - Not Otherwise Sepcified" (PDD-NOS) and others (Asperger Syndrome) got refactored into a single unified Autism definition.

[projectramo]

I think there are precedents.

It happens because there is so much overlap in most patients, and symptoms tend to occur in clusters.

General delays in motor skills and language skills are quite prevalent in many conditions. If you google videos of kids with autism, you will see varied abilities.

I am hesitant to go into more detail because this is an area that causes a great deal of anxiety for parents and discussions are often sensitive. One surefire way to annoy a parent and get into an argument is to claim their kid does or does not have a condition that differs from their own opinion. (And I can see why it would bother them).

[avip]

IBS, asthma, schizophrenia, ADHD, and the list goes on and on.

[thaumasiotes]

> Is there a precedent for this with other disorders? Seems to me that if there are no overlapping symptoms, it should be a separate disorder.

Yes, this is a pretty normal way of doing diagnoses.

Specifically, many disorders are diagnosed according to the template "the disorder is present if the patient presents any X out of this list of Y symptoms". As long as X is less than half of Y, it's possible for two patients to "have" the disorder without sharing any symptoms.

"Have" is in scare quotes because, obviously, this state of affairs is an artifact of the diagnostic criterion. However, it's also possible for e.g. two people to host infections of HIV without sharing any symptoms -- one may have AIDS while the other is asymptomatic.

[gowld]

Imagine a power set of 2^n possible symptoms, that tend to occur together. Would you create 2^n diagnoses?