Anxiety and your amygdala

Overall amygdala intrinsic functional connectivity network. Courtesy: UT Southwestern Medical Center/Qin et al

The amygdala is an almond-shaped set of neurons located deep in the brain’s medial temporal lobe somewhere behind our eyes. It plays a key role in responses associated with fear, anxiety, and processing emotions. It stands to reason that alterations in amygdala may reflect a higher anxiety.

Scientists at the Stanford University School of Medicine have published a report in the journal Biological Psychiatry that has found a link between the development of the amygdala during childhood and the development of anxiety problems.

“We know that early childhood anxiety has been linked to an increased risk for developing mood and anxiety disorders,” said lead researcher Shaozheng Qin from the department of psychiatry and behavioral sciences. “But we know very little about how early anxiety impacts the brain during a period in early childhood when anxiety-related traits begin to be reliably identifiable.”

Qin’s team studied 76 children between the ages of 7 and 9, a period in which the researchers say anxiety-related traits and symptoms can first be reliably identified. None of the children was determined to be clinically anxious. Rather, each child’s anxiety level was obtained through the parents’ reports on daily life experiences over 3 months. Finally, the children underwent non-invasive magnetic resonance imaging (MRI) scans of brain structure and function.

“We found that even in children as young as ages 7 to 9, high childhood anxiety is associated with enlarged amygdala volume and this enlargement is localized specifically to the basolateral amygdala,” said Qin.

They also found other brain functions that are affected within this region of the brain. Children who measured high on anxiety also showed increased connectivity between the amygdala and distributed brain systems involved in attention, emotion perception, and regulation said Qin. These effects are most prominent in the basolateral amygdala, the area involved in fear learning and processing emotions.

The scientists also developed an algorithm that could reliably predict the children’s anxiety level from the MRI measurements of amygdala volume and amygdala functional connectivity.

“Critically, machine learning algorithms revealed that levels of childhood anxiety could be reliably predicted by amygdala morphometry and intrinsic functional connectivity, with the left basolateral amygdala emerging as the strongest predictor,” he summarized.

The work aims to help scientists characterize altered brain systems as well as developing predictive biomarkers to help identify young children at risk for anxiety disorders.

Still, their findings have established a correlation, but not causation. “Our findings reflect only an association between childhood anxiety and amygdala volume and connectivity. It’s a bit of a chicken or egg situation at this point, since it’s unclear whether the anxiety alters the amygdala, or if an altered amygdala causes the anxiety,” Qin stated.

Either way, they are confident that understanding the influence of childhood anxiety on specific amygdala circuits, as identified in the study, will provide important new insights into the neurodevelopmental origins of anxiety in humans.
The next step is a longitudinal study to further determine how childhood anxiety impacts the development of emotion-related brain circuitry.

This piece originally appeared in Popular Science India. Reprinted with permission. Chhavi Sachdev reserves the right to be identified as its author.

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