The Origins of Anxiety: Studies in Behaviour and Brain Chemistry

It’s normal to experience feelings of worry and fear as a response to stressful situations, as well as physical symptoms such as increased heart rate and difficulty sleeping. For people living with anxiety disorders, however, such feelings can start to take over their lives and don’t necessarily have a rational trigger. Despite around one in five adults suffering from such disorders, little is known about how they actually work on a neurological level. Hence, medication used to treat anxiety disorders control symptoms (for example by increasing levels of serotonin) rather than eliminating any underlying neurological cause.

A recent study, however, has contributed to our understanding of the brain chemistry behind anxiety. Scientists at the University of Wisconsin School of Medicine and Public Health studied rhesus monkeys using MRI scanners to analyse early indicators of a susceptibility to anxiety disorders later in life. Led by Dr Ned Kalin, the researchers identified areas of the brain that may contribute to anxious behaviour patterns early in life; for example, the central extended amygdala, part of the brain’s reward system. Activity in this region has been shown to correlate with anxious behaviour; by analysing these tightly-woven networks, it is possible to estimate an individual’s overall chance of developing anxiety disorders.  

To test this, the team analysed each monkey’s anxiety level by introducing a human and observing their stress response. They also measured levels of cortisol as another indicator of stress. They then compared this assessment to the results found using MRI technology. As they predicted, monkeys who displayed more anxious behaviour were also found to have increased activity in the relevant elements of the central extended amygdala network. Because the monkeys used in the study were all related to each other to a greater or lesser extent, researchers knew exactly the family connections between all individuals and could calculate to what extent anxiety is hereditary. They found that interplay between Ce and BST, two different nuclei involved in the amygdala network, is highly hereditable. Understanding the hereditary element of anxiety disorders and how early indicators can predict later mental health could eventually point towards new methods of treatment and prevention.

Applicants for Psychology, Medicine, or related fields may wish to think about how such studies could contribute to our understanding of how to treat anxiety and other psychological disorders. Students could also consider the balance between neurological and environmental factors in the development, prevention, and treatment of such disorders