ibuysleep

In order to have autism, you need to show symptoms from early developmental period (around 2yrs). It's something that you have from birth, and it’s genetic (or very likely to be).

As for things that appear similar to autism, I made a list here, some may be caused by trauma and you might wanna look into them.

It's definitely not true today

False, the DSM-5 criteria requires it. It's actually more true today than it was in the past.

I was one of them

I was diagnosed 6 months ago.

Many people get diagnosed with autism as adults.

Correct, but in order to meet the criteria you must have also showed symptoms as a child. The symptoms don't have to be noticed during childhood, but they have to be present. Essentially, you must be able to recall being autistic as a child as well, and interviews of others are often done to further investigate if symptoms in young ages were present.

I just hate that so many friendships and opportunities were lost in my life due to undiagnosed autism

Agreed...

If the diagnostic criteria remained that strict

While I would be fine with the inclusion of 'acquired ASD' as a disorder, autism itself is a neurological disorder and is something that you are born with. If you suddenly develop symptoms in later years, the source of the issues would be different and thus the treatment methods may need to be different. For example - if ASD-like symptoms are somehow induced by trauma, treatments designed for PTSD or attachment disorders may be more successful than ones designed for autism. However, if the diagnosis is autism then everything would be focused on autism even though the underlying cause is different, which may lead to ineffective treatment.

It is true today, it’s part of the DSM-5 criteria. Actually, it is only true today - the old standard provided more leeway with PDD-NOS.

Strange though, I had to do more than just one test and interviews to get diagnosed - took a few months of appointments.

[deleted]

I see