Teen Depression May Be Linked to Hippocampus Size


Teen suicide is one of the most disturbing problems America faces. Why is it often so unpredictable? Why are some teens simply better able to handle life’s challenges than others?

Contrary to popular belief, it’s not just about having good parents and strong role models, although those things also have proven very important.

The hippocampus is highlighted here. Credit: decade3d/123RF Stock Photo

Research published in the journal Clinical Psychosocial Science this week determined that besides environment, the size of an adolescent’s hippocampus — the area of the brain that deals with emotions — also plays a role in depression.

“Adolescents with larger versus smaller hippocampal volumes showed heightened sensitivity in their depressive symptoms to a protective factor inside the home (sense of family connectedness) and a risk factor outside the home (community crime exposure),” the authors concluded in the abstract.

The authors, from the University of California Davis, studied adolescents with Mexican-American backgrounds. They chose to study this group because they are at particularly high risk for depression.

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Previous studies have linked small hippocampal volumes with depression. “This study showed that a larger hippocampus may indicate a greater ability for adolescents to take advantage of the support in their environments and overcome fear, anxiety and depression,” according to a UC Davis news release.

Conversely, teens with a large hippocampus who are exposed to danger and who do not have a strong support network are more likely to respond negatively to fear and anxiety, leading to depression. That is because it is the part of the brain that deals with emotions.

Credit: kmiragaya/123RF Stock Photo

In essence, without the presence of emotions that affirm safety and security, the hippocampus can catastrophize feelings of fear and anxiety.

The authors reported the findings could have significant implications for better treatments, particularly as neuroimaging becomes more feasible in the diagnosis of mental illness.

The researchers followed 209 youths in their junior and senior years of high school. Their brains were scanned and the teens were monitored for depressive symptoms.

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“As adolescents with more severe depressive symptoms are at greater risk for developing clinically diagnosed depressive disorders in adolescence and beyond, our results have important implications for prevention and intervention strategies,” said Amanda Guyer, professor of Human Development and Family Studies at UC Davis.

Guyer said this means not only the potential for more targeted treatment strategies but also the possibility of identifying depression risk early on.

“Results elucidate complex brain-environment interplay in adolescent depression, offering clues about for whom and how social context plays a role,” the authors concluded.  

“These interactive effects uniquely predicted depressive symptoms and were greater for the left side, suggesting two independent social-contextual contributions to depression that were moderated by left hippocampal volume.”