When creating a search string it's best to think of a comprehensive set of related terms.
For example terms related to 'elderly' :
- elder* (use an asterisk to search for various forms of the word)
- aged
- "older persons" (use quotes to search for multiple words together as a term)
- geriatric
- senior citizen
- old
To add on other search topics use the word 'AND', use the word 'OR' between all the related terms
For example, here is a comprehensive search string :
(elder OR aged OR "older persons" OR geriatric OR "senior citizen*" OR old*) AND (hypertension OR "high blood pressure") AND ("health literacy" OR "health communication" OR "consumer health" OR "community health" OR "community care")