Depression Tied to Small Hippocampus
An international team of scientists has published a study suggesting that people with a smaller hippocampus in their brains are more likely to suffer a major depression in their lives.
For their study, including 15 data sets from Europe, the U.S., and Australia, researchers from Australia analyzed magnetic resonance imaging (MRI) brain scans of about 9,000 participants. This group included 1,728 participants who had major depression and 7,199 healthy people. The research team also had access to clinical records of the participants with depression.
Their findings, published in the journal Molecular Psychiatry, found that people with depression had a significantly smaller hippocampus, which is the region of the brain associated with forming new memories. Secondly, they found that smaller hippocampus size was largely associated with recurrent depression; it occurred in about 65 percent of the major depressive participants. Research also revealed that those with depression before the age of 21 also had a smaller hippocampus and were more likely to have recurrent depression through adulthood.
But participants who had not experienced more than one episode of major depression–about 34 percent of those with depression–did not have a smaller hippocampus.
The findings underscore the need to treat depression when it first occurs, particularly in adolescents and young adults. The findings also support the theory of neurotrophic hypothesis – the idea that people with chronic depression have differences in brain biology, such as sustained higher levels of glucocorticoid, which shrinks the brain.