Introduction 

It isn’t tricky for college students to name the many aspects of their wellbeing that change between a usual week and finals week. During the dreaded exam week, stress is a universal experience. It’s the elephant in the room that makes the air zing. However, stress doesn’t impact all people equally (Enns et al., 2018). While many are overwhelmed by intense panic attacks and a sense of impending doom, others seem virtually unchanged from their baseline. Why does every student experience stress differently? 

A group of researchers from Turkey investigated the neurobiological underpinnings of varying stress responses in their 2020 publication in the Folia morphologica journal. They hypothesized that the anatomical size of the amygdala––the brain’s “emotional center” – impacted how drastically a student’s stress response increased between a typical day and exam day. Hypothetically, the larger the amygdala, the greater the stress response (Canbolat et al., 2020). They attempted to correlate the size of the amygdala seen on MRI scans with an increase in concentrations of stress hormones in saliva and levels of stress perceived by students. Researchers observed a correlation between students’ perceived levels of stress and their saliva cortisol concentrations, both of which increased around an exam date. However, an increased size of the amygdala didn’t seem to intensify one’s stress response. 

Background  

The amygdala is commonly known as the brain’s emotional center (Janak et al., 2015).  Evolutionarily, it is one of the oldest brain regions (Roxo et al., 2011). The amygdala’s role in a visceral stress response is thought to have been vital in keeping ancient humans safe from deadly enemies––like tigers! In response to dangerous situations, i.e., a tiger, the amygdala can stimulate the hypothalamic-pituitary-adrenal (HPA) axis, which converts neural signaling into a release of hormones within the body (Herman et al., 2016). One such hormone is cortisol. Cortisol, also known as the “stress” hormone, can  be used to measure the body’s reaction to external stressors. However, there (usually) is no tiger to run away from or fight amid a modern college campus. So, the amygdala clings onto other external stressors––like final exams! 

Methods 

Magnetic Resonance Imaging (MRI) uses powerful magnets to take images of  anatomical structures (Farah et al., 2018). In Canbolat et al.'s study, MRI was used to gauge the size of students' amygdalae. Researchers measured stress in two ways: testing for cortisol concentrations in saliva and asking students to reflect on their perception of stress using a questionnaire. The State Trait Anxiety Inventory-I (STAI-I) questionnaire was used, which helps determine anxiety levels in research studies (Ceylan et al., 2019).  The researchers selected a day they considered not stressful: 20 days before an exam.  They collected a saliva sample to test for cortisol concentrations and administered the questionnaire to establish a baseline. One day before an exam, students underwent MRI scans of their brains. On the day of the exam, saliva samples were collected again, along with questionnaire responses. Correlations between the three variables (cortisol levels, questionnaire scores, and amygdalae sizes) were evaluated. Students who had a drastic increase in cortisol levels and/or questionnaire scores were considered "high stressors,"  and those with a less severe increase were "low stressors" (Canbolat et al., 2020). Sizes of amygdalae were then compared between the high stressor and low stressor groups. 

Results 

Sixty-three male students participated in the study. On the day of an exam, both STAI-I  scores and cortisol levels in the saliva increased significantly compared to baseline values collected 20 days prior. However, the severity of that increase did not correlate with the size of students’ amygdalae. “High stressors” did not appear to have reliably larger amygdalae compared to “low stressors.” These findings suggest that the size of  one’s amygdala was not related to the level of stimulation of the HPA axis nor the perception of stress. 

Discussion 

Even though Canbolat et al.’s findings haven’t supported their hypothesis, their 2020 study was just as much a step forward in the field of neuroscience as studies that have supported their hypotheses. Regardless of findings, all science needs to be commended and promoted. Canbolat et al.’s results suggest that the size of the amygdala may not be the key to explaining its relationship with stress. Research into other correlations between stress and the amygdala’s structure or function is necessary. For instance, studies exploring chronic stress and the brain’s circuitry suggest that chronic stress can cause changes in the wiring of neurons within the amygdala (Liu et al., 2020). Zhang et al.’s findings indicate that chronic stress might create far too many new neural connections, making the amygdala hyperactive (Zhang et al., 2019). In other studies, exposure to chronic stress was shown on MRI scans to cause structural changes to the amygdala (Hölzel et al., 2010, McEwen et al., 2016). These are perhaps a few novel avenues that future studies may want to spend more time exploring. 

[+] References

[+] Other Work By Anastasiya Kozlovska