February 25, 2020

Research study examines brain development among adolescents for potential predictors of anxiety

Approximately 40 million adults in the United States are affected by an anxiety disorder, according to the Anxiety and Depression Association of America. Anxiety disorders — including generalized anxiety, social anxiety, obsessive-compulsive disorder, posttraumatic stress disorder (PTSD) and others — are the most common mental illness in the country. Although anxiety disorders are manageable, many go undiagnosed or unrecognized — and they frequently begin during adolescence.

A research study led by Hilary Marusak, assistant professor of psychiatry and behavioral neurosciences in Wayne State University’s School of Medicine, will examine adolescent brain development to better understand how the brain regulates fear. The five-year study, funded by the National Institute of Mental Health (Endocannabinoids and the Development of Extinction Recall Neural Circuitry in Adolescents), will monitor the brain development of adolescents between the ages of 10 and 17 by measuring blood samples and brain imaging.

While experiencing fear is natural and may be helpful in the face of imminent danger, it can be detrimental when fear interferes with daily life. For example, individuals with anxiety or PTSD can powerfully re-experience past memories of trauma, or experience symptoms of fear or anxiety — for example,  an elevated heart rate — to people, places or situations that only resemble past traumas.

Marusak’s team has previously shown that the brain systems that regulate fear are immature during childhood, and their current study will focus on adolescence. Adolescence is a critical time for brain development because it is the period where anxiety disorders begin to emerge.

Marusak’s team is especially interested in the development of the endocannabinoid system, a recently discovered system in the body that is of great medical interest. Interestingly, scientists discovered the compound that binds to the system in the body before they actually discovered the system. In the 1960s, scientists discovered the molecule THC — the primary psychoactive compound in cannabis (marijuana) — and, years later, the system in the body that THC binds to — the endocannabinoid system — was discovered. Scientists have only recently found that the body creates its own THC-like molecules, or “endocannabinoids,” and these molecules have receptors throughout the brain and are essential for controlling how the body responds to fear and anxiety.  

“The endocannabinoid system changes very dynamically during adolescence, before stabilizing into adulthood,” Marusak said. “Identifying a relationship between this system and potential indicators of anxiety would enable earlier treatment and possibly prevention.”  For example, this study may provide new ways to prevent anxiety in youth who are at high risk. “We know that childhood trauma is a huge risk factor for anxiety, which is influenced by fear regulation and tends to be chronic into adulthood,” Marusak said. “Previous studies indicate that the endocannabinoid system is critical in fear regulation, which is a skill developed between childhood and adolescence. Mapping out how this system develops during that critical stage can provide significant insight into treatment and prevention of adolescent anxiety.” 

In addition to helping find new ways to prevent and treat anxiety disorders, Marusak’s study has future implications related to the effects of cannabis on adolescent brain development.

“There’s still a lot of research to be done about the effect of cannabis on the developing brain, but we do know that THC can change signaling within the brain’s endocannabinoid system, which could have lasting effects on brain development and the ability to regulate fear and anxiety,” she said.

To learn more about Marusak’s work and additional research related to childhood brain development and the impact of stress and trauma, visit Wayne State’s THINK Lab.

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