Towards a Better Diagnosis and Treatment of Depression
09 June 2010
"The question we ask is very relevant to Singapore where the lifetime incidence of depression is eight per cent of the general population."
Dr Zhang Xiaodong of the Duke-NUS Graduate Medical School.
UNDERSTANDING DEPRESSION: The research led by Dr Zhang Xiaodong of the Duke-NUS Graduate Medical School Singapore explores the interactions between stress and the serotonin system in depression
A study by Dr Zhang Xiaodong of the Duke-NUS Graduate Medical School is set to better understand the interactions between stress and the serotonin system in depression. This could eventually lead to a better way of diagnosing and managing depression.
"The question we ask is very relevant to Singapore and in other places as well. In Singapore, the lifetime incidence of depression is eight per cent of the general population. As a comparison, in Western countries for instance, the lifetime incidence of depression is 12 per cent in men and 20 per cent in women," said Dr Zhang.
For this research, he was recently awarded funding by the Agency for Science, Technology and Research's (A*STAR) Biomedical Research Council. The grant call aimed to support the translation of laboratory discoveries to potential clinical therapies for diseases prevalent in Singapore and the region.
Typically, patients suffering from depression have a lower level of serotonin. Selective serotonin reuptake inhibitors (SSRI) such as Prozac were developed to prevent the serotonin from being absorbed again by a specific protein. The SSRI can increase extracellular serotonin levels and help alleviate certain symptoms experienced by patients. In more serious cases, electroconvulsive therapy (ECT) is administered to patients.
Dr Zhang said that currently, while all patients are treated with antidepressants, only a certain percentage of patients respond to antidepressants. "Our laboratory is interested in studying the genetic and environmental factors that may affect or contribute to depression. Once we understand the biological pathway, we can help to develop new pharmacological intervention in the treatment of depression. For diagnosing depression, biomarker or genetic screening can be done," said Dr Zhang.
On the research methodology, he explained: "Most of the previous studies examined white type mice which were either under or not under stress, but had no genetic defect. In our study, we are looking at these typical groups of mice, and expanding our observations to also include mice with genetic defects. Dr Zhang's research will measure how mice respond to acute and chronic stress and assess their behavioural and biological changes accordingly.
Dr Zhang was already pursuing the study of depression while at Duke University in the United States as a Research Fellow at Prof Marc Caron's laboratory. Dr Zhang was drawn to learning more about psychiatric disorder. He was part of the research team which proved that Tryptophan Hydroxylase-2 (TPH2) controls brain serotonin synthesis. He went on to collaborate with researchers of the psychiatry department at Duke University to genotype a very small cohort of severely depressed patients and found a rare mutation where there was a decrease in brain serotonin by 80 per cent.