How Can I Use MeSH to Narrow My Search Results?
MeSH Major Topics
A MeSH Major Topic is one of the main topics discussed in an article. In the list of MeSH Headings assigned to a citation that appear in the PubMed record, a MeSH Major Topic is denoted by an asterisk (*) on the MeSH term or MeSH/Subheading combination. See the Sidebar below to answer the question "Why is the MeSH Major Topic Asterisk Sometimes on the Heading and Sometimes on the Subheading?"
For example, this citation is indexed with these MeSH Major Topics: SARS-CoV-2/immunology and Single-Cell Analysis/methods.
To search for a MeSH Heading as a MeSH Major Topic, use the [majr] tag.
For example, searching PubMed with Gastrointestinal Microbiome[majr] will return results with Gastrointestinal Microbiome[MeSH] as a major topic.
![Search details for Gastrointestinal-Microbiome[majr] showing that it is a MeSH Major Topic](img/Gastrointestinal-Microbiome.png)
Exercises
Sidebar - Why is the MeSH Major Topic Asterisk Sometimes on the Heading and Sometimes on the Subheading?
The placement of the asterisk indicates which concept is one of the main topics of the article. If that concept is described by the heading, overall, the asterisk will be applied to the heading. For example, an article about sleep initiation and maintenance disorders that discusses drug therapy but where drug therapy is not a main point of the article would be indexed with:
> Sleep Initiation and Maintenance Disorders* / drug therapy
If the heading/subheading combination describes the main topic, the asterisk is placed after the subheading. For example, an article that is mainly about drug therapy for sleep initiation and maintenance disorders will be indexed with:
> Sleep Initiation and Maintenance Disorders / drug therapy*
This placement does not affect PubMed searching. A search of either:
- Sleep Initiation and Maintenance Disorders[majr]
- Sleep Initiation and Maintenance Disorders/drug therapy[majr]
will retrieve both records, regardless of where the asterisk is applied.
This means that occasionally your search for a heading/subheading combination as a major topic will retrieve records where the major topic is the main heading and not the heading/subheading combination.