Here is an example of the subject terms listed for a systematic review found in PsycINFO, "Primary care screening for and treatment of depression in pregnant and postpartum women: Evidence report and systematic review for the US Preventive Services Task Force" (2016).
The controlled vocabulary system for PubMed is MeSH: Medical Subject Headings. Using MeSH in combination with keywords is the most effective way to search PubMed.
For example, here are some MeSH terms for:
Adults: Adult (A person having attained full growth or maturity. Adults are of 19 through 44 years of age. For a person between 19 and 24 years of age, YOUNG ADULT is available.)
Screening: Mass Screening (Organized periodic procedures performed on large groups of people for the purpose of detecting disease.)
Major depression: Depressive Disorder, Major (Marked depression appearing in the involution period and characterized by hallucinations, delusions, paranoia, and agitation.)
Search using MeSH from the National Library of Medicine in the PubMed database:
Copyright @ The Regents of the University of California. All rights reserved.