I hesitate to relate this, but getting a diagnosis isn't always a positive thing.
My childhood friend, now dead, became very eccentric and went for a test, we thought it a good idea so that she could get early treatment. But after a positive result of vascular dementia she was told she must wait until she became worse before she could be referred for treatment.
She just gave up!
Her DH pushed and pushed for treatment buy was only offered carers twice a week
She said her life was over, she stopped cleaning and cooking and working in her beloved garden, she just sat in her chair and stared out of the window.
No-one could help her - we tried everything we could think of. We asked and asked for treatment and in the end we were told we'd 'left it too late'!
We were gobsmacked.
Eventually she stopped eating, and died.
FOR HER it was a big mistake getting that diagnosis. Be careful how you handle this.