Scientists from Pennsylvania’s University of Pittsburgh searched for chromosomal regions that harbor genes affecting susceptibility to severe depression – the second leading global cause of disability worldwide.

The team, led by Dr George Zubenko, a professor of psychiatry at the university’s school of medicine, looked at the genetic markers from 100 men and women with recurrent, early-onset major depressive disorder (RE-MDD).

These were compared with the same number of people who had no history of the disease.

Out of 19 chromosomal regions that were associated with the development of RE-MDD, 16 were “significantly” associated with the disorder in either men or women, but not when both sexes were combined.

Dr Zubenko says that the findings suggest sex-specific differences that determine resistance to stressful events.

And the team believe that genetic factors may also contribute to differences in the symptoms of clinical depression in men and women, variable treatment responses and the development of additional psychiatric disorders such as anxiety, alcoholism and substance misuse.

Major depression is unlikely to represent a single disease with a unitary cause, according to Dr Zubenko. “Instead, clinical depression is probably more like anemia. Both of these disorders are defined by a collection of clinical features that result from different causes in different people,” he said.

“Treatment or prevention efforts are usually most successful when they are aimed at the specific causes of the disorder.”

He said that further research should involve complementary genetic methods and independent populations.

“The identification and characterization of these genes and their products will provide new opportunities for drug development and disease prevention, and new information about the biology of mood and its regulation,” added Dr Zubenko.

However, he explained that the cost of the research in terms of time and resources means that it will be unlikely to have an impact on clinical care for people with depression within the next 10 years.

The Depression Alliance welcomed the research but expressed its continuing concern that as many as 75 per cent of depression cases remain unrecognized and untreated in the UK.

Reference: Zubenko et al, American Journal of Medical Genetics, April 2002

© Health Media Ltd 2002
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