New research on a brain chemical involved in development sheds light on why some individuals may be predisposed to anxiety. It also strengthens understanding of cellular processes that may be common to anxiety and depression, and suggests how lifestyle changes may help overcome both.
The animal study, in the May 13 issue of The Journal of Neuroscience, shows an important role for fibroblast growth factor 2 (FGF2), a chemical important in brain development, in anxiety. The findings advance understanding of cellular mechanisms involved in anxiety and illuminate the role of neurogenesis, or cell birth and integration in the adult brain, in this process. Together, these findings may offer new drug targets for the treatment of anxiety and potentially for depression as well.
According to the National Institute of Mental Health, approximately 40 million Americans adults have anxiety disorders, and 14.8 million suffer from major depression. These disorders often co-occur: people with anxiety frequently also have depression, and research suggests that the two disorders may share common causes. Previous human studies led by the senior author, Huda Akil, PhD, at the University of Michigan and her collaborators in the Pritzker Consortium, showed that people with severe depression had low levels of FGF2 and other related chemicals. However, it was unclear whether reductions in FGF2 were the cause or effect of the disease.
This new study, led by Javier Perez, PhD, also at the University of Michigan, examined FGF2 levels in rats selectively bred for high or low anxiety for over 19 generations. Consistent with the human depression studies, the researchers found lower FGF2 levels in rats bred for high anxiety compared to those bred for low anxiety.
The study also suggests that environmental enrichment reduces anxiety by altering FGF2. Other researchers have shown that anxiety behaviors in rats can be modified by making changes to their environment, perhaps akin to lifestyle changes for people. Perez and colleagues found that giving the high-anxiety rats a series of new toys reduced anxiety behaviors and increased their levels of FGF2. Furthermore, they found that FGF2 treatment alone reduced anxiety behaviors in the high-anxiety rats.