You can prove CAPD really just as well as you can prove deafness.
A hearing test, where your individual elements of hearing are normal but in a test with more distraction, or a more general test, you fail.
I was actually diagnosed with CAPD before anything else by a good few years due to recurrent failing of the school hearing test, and when sent to an audiologist for further testing I would pass.
Sadly they only gave a note for preferential seating, and didn't explain to my mother what it was and made it seem like no big deal, no one realized it was causing me severe pain.
Anyway, if they trust a hearing test to be enough to prove someone is deaf, it should be enough for CAPD.
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Diagnosed autistic level 2, ODD, anxiety, dyspraxic, essential tremors, depression (Doubted), CAPD, hyper mobility syndrome
Suspected; PTSD (Treated, as my counselor did notice), possible PCOS, PMDD, Learning disabilities (Sure of it, unknown what they are), possibly something wrong with immune system (Sick about as much as I'm not) Possible EDS- hyper mobility type (Will be getting tested, suggested by doctor) dysautonomia