Worldwide, over 350 million people of all ages suffer from depression, according to the World Health Organization. People suffering from depression also suffer from anxiety symptoms and thus, anxiety and depressive disorders have become a major cause of disability. Anxiety and depression show a close association with subsequent substance abuse. It has previously been shown that anxiety and depression are heritable traits and that genes also determine if a person will develop stress-related disorders in later life.
The researchers in the current study endeavored to understand the specific regions in the brain that are responsible for the heritable traits of anxiety and depression. The scientists used 592 young rhesus monkeys part of a multi-generational family. They exposed young monkeys to situations that a child would encounter, such as meeting with a stranger who doesn’t make eye contact. Brain imaging studies commonly done in humans (positive emission tomography or PET) were performed in the monkeys during the meeting with strangers. Detailed studies, termed “genetic correlation,” were conducted on how anxiety-related behavior ran in a family. The results show that
- Over-activity of the prefrontal-limbic-midbrain circuit is heritable and is directly associated with extreme anxiety in early childhood and depression-anxiety later in life
- The three regions involved in anxiety and depression are survival related brain regions, namely
o Brain stem- the most primitive part of the brain
o Amygdala- the limbic fear centero Prefrontal cortex- the seat of intelligence and higher level reasoning (fully developed only in humans and primates)
- The function of brain structure, and not its size, was inherited from parents to offspring
Regarding the findings, the senior author of the research publication Dr. Ned Kalin said to University of Wisconsin-Madison News, “Basically, we think that to a certain extent, anxiety can provide an evolutionary advantage because it helps an individual recognize and avoid danger, but when the circuits are over-active, it becomes a problem and can result in anxiety and depressive disorders.”
Understanding that parents pass on anxiety to children and knowing the exact areas of impact in the brain gives researchers an advantage in designing therapeutics for specific targets. Dr. Kalin says, “Now that we know where to look, we can develop a better understanding of the molecular alterations that give rise to anxiety-related brain function. Our genes shape our brains to help make us who we are.
Brain imaging shows how children inherit their parents' anxiety. (n.d.). Retrieved July 11, 2015, from http://www.news.wisc.edu/23879
Fox, A., Oler, J., Shackman, A., Shelton, S., Raveendran, M., Mckay, D., . . . Kalin, N. (2015). Intergenerational neural mediators of early-life anxious temperament. Proceedings of the National Academy of Sciences USA. 201508593
Depression. (n.d.). Retrieved July 11, 2015, from http://www.who.int/mediacentre/factsheets/fs369/en/
Substance Abuse | Anxiety and Depression Association of America, ADAA. (n.d.). Retrieved July 11, 2015, from http://www.adaa.org/understanding-anxiety/related-illnesses/substance-abuse
Lamb, D., Middeldorp, C., Beijsterveldt, C., Bartels, M., Aa, N., Polderman, T., & Boomsma, D. (2010). Heritability of Anxious-Depressive and Withdrawn Behavior. Journal of the American Academy of Child & Adolescent Psychiatry, 49(3), 248-255.
Franić, S., Middeldorp, C., Dolan, C., Ligthart, L., & Boomsma, D. (2010). Childhood and Adolescent Anxiety and Depression: Beyond Heritability. Journal of the American Academy of Child & Adolescent Psychiatry, 49(8), 820-829.