Brain imprints in the prediction of risk and symptoms of depression

By Tara Chand

Depression is like a persistent cloud that hangs over someone's emotions and thoughts. It's not just feeling sad occasionally; rather, it's a complex mental health condition characterized by prolonged feelings of sadness, hopelessness, and loss of interest in things that used to bring joy. Unfortunately, it is a mental health condition that affects millions of people worldwide and it's a complex interplay of biological, psychological, and social factors. By studying it, we gain insights into how these elements influence each other, leading to more effective interventions and improved mental health outcomes. Even though the symptoms of depression might come and go, a recent study published in Nature by Charles J. Lynch and colleagues, suggests that the way the brain is wired may remain the same throughout life, even when someone is not feeling depressed. So how does the brain change and how are the connections between different brain regions stronger or weaker?

Charles J. Lynch and colleagues utilized advanced brain imaging techniques to study individuals with symptoms of depression. Instead of scanning people only once, they took multiple scans over a long period (up to 62 times over a year and a half). This allowed them to see how the brain’s connections change over time with depression. 

These connections were examined using resting-state brain magnetic resonance imaging (rs-fMRI). During rs-fMRI, the scanner detects spontaneous fluctuations in blood flow changes within the brain (BOLD signal), which represent intrinsic brain activity. Researchers analyze these fluctuations to identify resting-state networks (RSNs). These RSNs are like interconnected neighborhoods of brain regions that tend to activate together. RSNs can be consistent across healthy people, different states of consciousness, and even across species.

Lynch and colleagues have found that a specific brain network called the salience network, which helps people focus on important things, is almost twice as large in people with depression compared to those without it. This difference in the structure of the brain network doesn’t seem to change even when a person’s mood improves. However, the strength of connections between brain areas of the salience network (e.g., nucleus accumbens and anterior cingulate cortex) changes in response to variations in mood over time.

Furthermore, to study the early prediction of depression, they explored the ABCD dataset and investigated children who were scanned before the age of 13 without depression during the scanning time but later developed depression symptoms. They found that the salience network was significantly larger in children who later developed clinically elevated symptoms of depression compared to children who did not. The study indicates that the expansion of the salience network has the potential to help predict susceptibility to depression symptoms. 

Currently, depression is largely diagnosed using questionnaires and interviews, but this research brings us one step closer to using brain scans to identify and understand depression more accurately. This study suggests that the expansion of the brain's salience network could indicate an increased risk of developing depression. It may be used to predict how and when depression symptoms might appear. 

Editor: Liwen Zhang
Visuals: Felipe Rivera

Source:
Lynch, C. J., Elbau, I. G., Ng, T., Ayaz, A., Zhu, S., Wolk, D., ... & Liston, C. (2024). Frontostriatal salience network expansion in individuals in depression. Nature, 1-10.

Brain Bites Sub-Team
Lead: Alejandra Lopez-Castro; Yohan Yee; Anna Matsulevits