I noticed on HPD's website that the mental health check form has changed, or is this an old form?

dont know if its old or what, but i just used it last week and they accepted it

It appears to be a different form. The prior mental health release was quite similar to the regular medical release still being used. This also appears to have been released by the AG's office in September of 2013 and revised in February 2014. It is very similar to forms used by hospitals to request release of your Protected Health Information (PHI).

The duration or expiration statement seems to be oddly constructed and appears to be open ended until such time that you become disqualified to own firearms. This would, I believe, allow HPD to request your PHI at anytime, even if that request was not directly related to the registration of another gun.  It would also seem to suggest that since it was open ended, HPD could use it for any subsequent registration, so you shouldn't really have to fill out a new form for any new registrations.

That's just my opinion and IANAL...

Government invasion of privacy!