Amygdala Size And Connectivity Linked To Childhood Anxiety

Risk factors in children for developing anxiety disorders and depression as adults include prolonged stress and anxiety, both in themselves, and in their mother.

Now, the degree of anxiety a young child is experiencing in daily life can be indicated by measuring the size and connectivity of the amygdala, a part of the brain associated with processing emotion, researchers at Stanford University have shown.

It was found that the larger the amygdala and the stronger its connections with other parts of the brain involved in perception and regulation of emotion, the greater the amount of anxiety a child was having.

Identifying Children at Risk of Anxiety Disorders

This does not necessarily mean that a young child with an enlarged and highly connected amygdala will inevitably go on to develop a mood disorder, says senior study author Vinod Menon, PhD.

“We are not at a point where we can use these findings to predict the likelihood of a child developing mood and anxiety disorders as an adult, but it is an important step in the identification of young children at risk for clinical anxiety,” Menon said.

76 children ages 7 to 9 were the subjects of the study.

“For the cognitive emotional assessments to be reliable, 7 years old is about as young as a child can be,” said Menon, who of the Child Health Research Institute at Stanford. “But the changes to the amygdala may have started earlier.”

Anxiety is a common emotional reaction to stress

Normally, anxiety helps us cope with difficult situations.

But sustained anxiety can lead to disabling conditions such as phobia, post-traumatic stress disorder and generalized anxiety disorder.

Studies of adults suffering from anxiety disorders have shown that they have enlarged, highly connected amygdalae.

Studies of animals placed in an environment causing chronic stress have determined that the animals’ amygdalae grew additional synapses and that synaptic connectivity increased in response to the resulting persistent anxiety.

What is the Amygdala?

The amygdala is an evolutionarily primitive part of the brain located deep in the temporal lobe. It comprises several subregions associated with different aspects of perceiving, learning and regulating emotions.

The basolateral amygdale is a subregion important for processing emotion-related sensory information and communicating it to the neocortex, which is the evolutionarily newer part of the brain.

This area is where Shaozheng Qin, PhD, lead author of the study, detected the enlargement.

Qin used magnetic resonance imaging to measure the size of the various subregions of the amygdala and functional MRI to measure the connectivity of those regions to other areas of the brain.

“The basolateral amygdala had stronger functional connections with multiple areas of the neocortex in children with higher anxiety levels,” according to Qin.

Four Neocortical Systems

Researchers pinpointed four functional neocortical systems that were affected.

One of the systems deals with perception, another with attention and vigilance, a third with reward and motivation, and the fourth with detection of salient emotional stimuli and regulation of emotional responses.

“All four of these core systems are impacted by childhood anxiety,” Qin said.

Menon said they were surprised that alterations to the structure and connectivity of the amygdala were so significant in the children with higher levels of anxiety, given both the young age of the children and the fact that their anxiety levels were too low to be considered clinical.

This study gives us significant insight into the developmental origins of anxiety, Qin added.

Understanding the influence of childhood anxiety on specific amygdala circuits, as identified in the study, may someday aid in the early identification and treatment of children at risk for anxiety disorders.

 

Amygdala subregional structure and intrinsic functional connectivity predict individual differences in anxiety during early childhood
BIOLOGICAL PSYCHIATRY
Qin, S., Young, C. B., Duan, X., Chen, T., Supekar, K., Menon, V.

Image Courtesy Medical Art Service, I. Christensen, Wellcome Images