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Genetic Basis for Depression
« on: 2003-07-17 23:54:09 » |
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Gene Causes Depression After Stress, Study Finds
Source: Reuters Asia
Authors: Maggie Fox, Health and Science Correspondent
Dated: 2003-07-17
WASHINGTON (Reuters) - Having a short version of a certain gene may make people more susceptible to depression after stressful events such as losing a job or a loved one, researchers said on Thursday.
People only have to inherit one copy of the gene, from either parent, to become more vulnerable to depression, the researchers in Britain, New Zealand and the United States found.
The finding, published in Friday's issue of the journal Science, could be the first to show stress as an environmental factor in causing disease, they said.
Stress, such as divorce or illness, is a well-known cause of depression -- one of the five leading causes of disability in the world.
"However, not all people who encounter a stressful life experience succumb to (depression)," the researchers wrote.
They set out to find a gene and looked at the 5-HTT or serotonin transporter gene, because the protein it controls is affected by well-known anti-depression drugs called selective serotonin reuptake inhibitors.
Serotonin is a message-carrying chemical linked with mood.
The 5-HTT gene, also known as the serotonin transporter gene, controls the recycling of the chemical messenger.
PRIME SUSPECT
"Since the most widely prescribed class of antidepressants act by blocking this transporter protein, the gene has been a prime suspect in mood and anxiety disorders," the U.S. National Institute of Mental Health, which helped fund the study, said in a statement.
Dr. Avshalom Caspi and Dr. Terrie Moffitt, of both the University of Wisconsin and King's College London, and colleagues, followed 847 Caucasian New Zealanders, born in the early l970s, from birth into their 20s.
About 17 percent of them had carried two copies of the stress-sensitive short version of 5-HTT, 31 percent had two copies of the longer version of the gene and 51 percent had one of each.
The research team also kept tabs on potentially stressful life events involving employment, money, housing, health and relationship woes among the volunteers from ages 21 to 26.
At 26, 17 percent of the participants had a diagnosis of major depression in the past year and three percent had either tried or thought about committing suicide.
Of those who had more than one big stressful event, 43 percent who had at least one short version of the 5-HTT gene developed depression, the researchers found.
That compared to just 17 percent who had two long copies.
The researchers also found that volunteers mistreated as children were more likely to become depressed. They reported last year that a gene for the enzyme monoamine oxidase A, also a target of antidepressants and associated with 5-HTT, affected a child's response to mistreatment.
This would not be the first gene linked with depression. Earlier this month a team at the University of Pittsburgh said they had identified 19 different genetic areas linked with depression.
Depression is a complex disease, affecting an estimated 120 million people worldwide.
The National Institute of Mental Health says that 16 percent of Americans -- more than 30 million people -- will suffer major depression at some point in their lives, costing employers more than $30 billion in lost productivity.
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