The Structural and Functional Brain Network in Early- and Later-Onset Depressive Disorder

Faye Womer, M.D.

Project Overview:

Depression is a common mental illness among all ages. It affected 19 million U.S. adults and adolescents in 2015. Worldwide, it affects approximately 350 million people. Despite improved recognition and treatment of depression, it continues to cause significant suffering and burden for individuals, their families, and society.

Depression cost the U.S. economy an estimated $210 billion in 2010. It is a major risk factor for suicide among all ages. Suicide rates have increased over the past decades, and suicide is now a leading cause of death among those of 10 to 64 years of age. Further advances in diagnosis and treatment of depression are needed. However, scientists are hindered in pursuit of such advances due to unanswered questions about how depression works in the brain.

What we know:

1. There are brain differences between those with depression and those without.
2. Brain networks are important in depression.
3. Brain changes may differ based on the age when depression first began.

Questions to be answered:

1. What is the brain network like in depression?
2. Is early-onset depression different than later-onset depression?

Answering these questions could provide important information for improving diagnosis and treatment in depression.

The proposed study aims to address these questions by looking at the structural and functional brain network in early- and later-onset depression using recently developed magnetic resonance imaging (MRI) techniques based on graph theory.

Progress Report:

Significant alterations in ALFF and ReHo were found in later-onset MDD, compared to age matched healthy controls (HC), primarily in the cuneus. No significant differences were found between early-onset MDD and age matched HC. FA was significantly decreased in the corpus callosum and cingulum in early-onset MDD, compared to age-matched HC. No significant differences were found between later-onset MDD and age-matched HC.

Distance-based FC analyses revealed no significant differences between MDD and HC in ages 13-21. In ages 22-29, short range FC was significantly decreased in temporal regions and the cuneus in MDD, compared to HC, while significantly increased short range FC was shown in frontal regions. Medium/long range FC was significantly increased in limbic and parietal regions in MDD, compared to HC. Ultra-long range FC was significantly increased in frontal, limbic, and occipital regions. For ages 30-45, short range FC was significantly decreased in frontal and parietal regions in MDD, compared to HC. Medium range FC was significantly decreased in frontal regions and significantly increased in the cuneus in MDD when compared to HC. Ultra-long FC was significantly increased in right frontal region and bilateral cuneus. Significant FA increases were observed in the cerebellar vermis and hemisphere in MDD compared to HC for ages 13-21 years. For ages 22-29, significant FA decreases were found in the corpus callosum and cingulum. No significant FA differences were shown for ages 30-45. Specifically, significant FA, compared to HC.

Findings indicate alterations in the structural and functional brain network in MDD across adolescence to adulthood. They indicate a greater role of short range connections in adult MDD than adolescent MDD. They also support the potential presence of multiple neural trajectories in MDD across the lifespan.

To read the full Progress Report, please click here.