The Blue Badge scheme is to be extended later this year so that more people can qualify.

Although they don't say it in that article 'soon' means 30 August 2019.

People with hidden disabilities will soon be able to access Blue Badge parking permits, thanks to the rollout of new guidance today (June 15 2019).

For drivers or passengers with dementia, anxiety disorders or reduced mobility, the anticipation of travel difficulties such as finding a parking space can build on top of the stress of the journey itself.
However you should also note that:
While the new criteria will give clear and consistent guidelines on Blue Badge eligibility for the whole of England, not everyone with non-physical disabilities will qualify for a badge. It will be up to the relevant local authority to decide if an applicant meets the eligibility criteria, as is currently the case.
The change is also being linked to a "Crackdown on Blue Badge fraud and missuse".