Example PubMed searches:
If you type "ketamine depression" into the PubMed search box, you'll see over 1300 results. Many of them will be relevant, but you'll also run into many irrelevant results. For instance, ketamine is used in anesthesia, and you'll find it mentioned in the same abstract as a term like "respiratory depression" - which probably isn't what you're looking for.
MeSH will give you more targeted results. If we combine the MeSH terms for these two concepts like so: "Ketamine"[Mesh] AND ("Depressive Disorder"[Mesh] OR "Depression"[Mesh]) we narrow down the 1300+ results to only about 300. Want to restrict your search to even more specific, more targeted results? Instead of using the regular [Mesh] field, we can specify that we only want to see MeSH terms that are tagged as the MAJOR topic of an article - in other words, the concept isn't just discussed in the paper, it's the actual point of the research. If we restrict our MeSH search to only [Majr] topics, we narrow it down still further to about 230 results: "Ketamine"[Majr] AND ("Depressive Disorder"[Majr] OR "Depression"[Majr])
How do you determine who is depressed? Depression screening is an important method of identifying people who need mental health services support. Screening recommendations and instruments vary according to the population (pregnant women, older adults, children and adolescents, etc) and the screening environment (primary care clinic, oncology office, etc).