I’ll give you the “lawyer answer” – it depends. All people who meet the ADA definition of disability are covered by the ADA in general, but they still may not have rights under particular sections of the ADA. For example, there is a section of the ADA that deals only with employment discrimination. If a person with a disability is not employed and is not seeking employment, then that person would not necessarily be covered by that part of the ADA, although the person would be covered by other parts of the ADA.
For additional information, take a look at the following resources:
FAQ: What does "regarded as" having a disability mean?