Researchers at the Icahn School of Medicine at Mount Sinai, in collaboration with colleagues from a number of other universities and research centers in the United States, have uncovered a possible RNA-related clue that may provide an explanation for why approximately twice as many women as men are diagnosed with chronic depression.
In the research report that was submitted to and accepted for publication by the journal Science Advances, the group discusses the link between long non-coding RNA (lncRNA) and depression.
Previous studies have shown that the function of RNA is to support the production of proteins by genes. In addition, it has been shown that lncRNA may interact with DNA, certain proteins, and other RNAs in order to regulate further forms of gene expression that are not fully understood.
FEDORA is a sort of long noncoding RNA that was the focus of this latest investigation by the researchers. Earlier work had shown that this particular lncRNA may have some relation to depression. As part of their studies, they examined the brains of recently deceased persons, paying particular attention to those who had suffered from persistent depression throughout their lives.
The scientists compared the amounts of FEDORA in women and men who were diagnosed with chronic depression to those who had not received such a diagnosis. In addition, they looked at individuals who had not received such a diagnosis. They also investigated the differences between those who had been given ketamine as a treatment for their depression and those who had not. They discovered the greatest levels of FEDORA among female patients who were already diagnosed with persistent depression. In addition, they discovered decreased amounts in these women while they were on ketamine.
The researchers also evaluated the levels of FEDORA in patients who were still living by drawing blood samples from them. They discovered that the levels of FEDORA in females who were experiencing depression were greater than the amounts in females who were not experiencing depression and in men in general.
The researchers then genetically modified test mice to express greater than usual quantities of lncRNA and discovered that doing so led to higher levels of FEDORA as well as increased symptoms of both anxiety and sadness; however, this was only seen in the female mice.
The findings of the researchers lead them to conclude that differences between genders, rather than disparities in hormone levels, are the most plausible explanation for the gender disparities they discovered.