Experts say one in ten people around the world is affected by severe depression, a debilitating mental disorder that leaves them unable to work and enjoy life. Scientists say understanding the genetic causes of the disorder might considerably improve current treatments.
University of Pittsburgh psychiatry professor George S. Zubenko and his colleagues have been researching depression for nearly 15 years.
In their latest study, published in the Journal of Molecular Psychiatry, Dr. Zubenko's team set out to identify the gene or genes linked to the most serious form of the disorder, recurrent major depression.
The researchers collected blood samples from 100 men and women suffering from the illness and 100 people without it.
Dr. Zubenko says the purpose of the study was to see whether specific regions of the human genome, or map of the human genetic makeup, differ in depressed and non-depressed individuals. "Fortunately, for those of us who are interested in identifying genes that contribute to serious clinical disorders, there are a large number of relatively closely spaced variations of the human genome that can be used as lamp posts to illuminate variations of the human genome from individual to individual," he said.
The University of Pittsburgh researchers found that 19 regions of the genome were associated with depression. Interestingly, men and women shared only three such regions. The remaining 16 regions were linked to depression in either males or females but not in both.
If replicated, these findings could provide a biological foundation for the fact that women are two times more susceptible to depression than men.
Dr. Zubenko says the findings might some day result in more precise, individualized treatments for depression, which at the present time are fairly random. "In current practice, the choice of a particular antidepressant for a patient is largely a hit or miss proposition that often leads to multiple medication trials before depression remits [goes away]. Side effects are common and can be debilitating," he said.
Brown University psychiatrist Louis Marino agrees. He says that understanding the genetic layout of depression can help mental health professionals with their diagnosis and treatment of the disorder.
"As we better characterize depression at a molecular level, we will find new opportunities for drug development. We might also be able to identify some of the people who are at greater risk for developing recurrent major depression. This will allow us to treat them earlier so that there is less suffering," said Mr. Marino.
The World Health Organization estimates that major depression is ranked second only to heart disease as a source of disability worldwide.
Current treatments work in the majority of cases, but experts like Dr. Zubenko would like to see the development of improved antidepressants with fewer side effects, something he and other scientists believe is now possible with the aid of genetic research.