Databases have controlled vocabularies and in order to find scholarly articles on your topic, you need to use the same vocabulary as the database. Look for a link to thesaurus, subject headings, etc.
Here are some keywords and phrases you could use:
Example: elderly AND "Native Americans" AND "health care"
Reminder: Use quotes when searching phrases except in PubMed
health care (noun): a set of actions by a person or persons to maintain or improve the health of a patient/consumer
healthcare (noun or adjective): a system, industry, or field that facilitates the logistics and delivery of health care for patients/consumers