Statistics from the National Institute of Mental Health show almost 20% of all adults in the United States suffer from an anxiety disorder, with a higher prevalence in women (23.4%) than men (14.3%). Anxiety disorders are more prevalent in adolescents, with 38% of females and 26% of males suffering from some sort of disabling anxiety.
The Mayo Clinic defines anxiety disorders as “Experiencing occasional anxiety is a normal part of life. However, people with anxiety disorders frequently have intense, excessive and persistent worry and fear about everyday situations. Often, anxiety disorders involve repeated episodes of sudden feelings of intense anxiety and fear or terror that reach a peak within minutes (panic attacks).”
A recent paper (https://doi.org/10.1016/j.celrep.2019.09.045) by the labs of Dimitri Tränkner and Mario Capecchi at the University of Utah showed certain lineage of microglia cells in the brain suppressed obsessive compulsive disorder (OCD) and anxiety in mice. They showed that anxiety and OCD in mice seems to be caused by levels of female sex hormones. These behaviors are driven by the homeobox transcription factor Hoxb8. Hoxb8 KO mice exhibited extreme coat loss and spent more time grooming than Hoxb8 mice. Female KO mice exhibited very high levels of stress glucocorticoid hormones. As expected, the female sex hormones progesterone and 17β-estradiol were higher in females than males. Treatment of the mice with trilostane, an inhibitor of 3β-hydroxysteroid dehydrogenase, reduced anxiety-like behavior and stress levels. Injection of progesterone and estradiol into male mice caused higher levels of coat loss due to over-grooming and anxiety.
All stress and sex hormones were measured with Arbor Assays ELISA kits for cortisol, K003-H1/H5, progesterone, K025-H1/H5, and 17β-estradiol, K030-H1/H5, with normalization to urinary creatinine, K002-H1/H5.
The finding of microglia Hoxb8 linked relationships to OCD and anxiety-related behaviors needs further exploration as the disorders are related but follow separate etiologies.