November 20, 2013
Dr. Jinying Zhao is studying the causes of major depressive disorder. Photo: Paula Burch-Celentano
Tulane University has received a five-year $3.13 million grant from the National Institute of Mental Health to study the causes of major depressive disorder (MDD).
“Major depressive disorder is a devastating psychiatric disorder that affects millions of Americans,” says Dr. Jinying Zhao, associate professor of epidemiology at the Tulane School of Public Health and Tropical Medicine and principal investigator.
The research team wants to identify alterations of genetic makeup (“epigenetic” changes) that may cause the disorder. “Epigenetic changes are related to many psychosocial, behavioral and/or environmental factors,” says Zhao. “For MDD, stressful early life events are believed to play an important role in causing the disease through epigenetic mechanisms.”
The study hypothesizes that attachment of methyl compounds to specific regions of DNA (methylation) leads to development of MDD. Methyl groups involved in DNA methylation can be generated within the human body or consumed via leafy vegetables and other foods containing folic acid.
“Epigenetic modifications including DNA methylation could occur any time during a person’s lifespan, from as early as in utero to adulthood. Once modified, the gene will express differently (most of the time erroneously) which in turn causes disease,” says Zhao.
The researchers will compare the DNA of twin pairs only one of which has MDD. The study will include 180-200 twin pairs from the University of Washington Twin Registry, which has collected information from over 8,000 twin pairs. The researchers will look for patterns of methylation common to the DNA of twins with MDD but not in the DNA of twins without depressive disorder. “We expect to identify novel epigenetic markers associated with MDD,” says Zhao.
The researchers also will examine postmortem brain tissue of MDD patients to determine if the same associations are present.
“The work is expected to have an important impact,” says Zhao. “Genes with both differential methylation and expression are likely to provide novel targets for prevention, intervention and treatment for depression and its related psychiatric conditions in addition to advancing the fields of psychiatric genetics.”
Tulane University, New Orleans, LA 70118 504-865-5000 firstname.lastname@example.org