American scientists say they are closer to understanding why some mothers suffer post-natal depression. This could lead to better treatments for the disorder
In a study they found mice lacking a chemical receptor in their brains developed similar symptoms. The research, published in Neuron suggests the receptor helps stop brain cells firing too often in response to changes in hormone levels during pregnancy and birth.
Between 5% and 25% of all new mothers are thought to suffer some form of post-natal depression, and can find it hard to bond with thier baby and to cope with the demands of being a parent.
The precise reasons why some women develop it and some do not are uncertain, but the team at the University of California in Los Angeles say that at least they have some answers.
They studied a part of the brain which they already knew was involved with regulating mood and anxiety and found that a chemical called GABA can decrease the activity of certain nerve cells after coming into contact with receptors on that cell's surface.
The scientists from Calafornia noticed that a particular type of this receptor appeared to be highly active during pregnancy and the period after birth in mice. Their theory is that this variety of receptor might help, in normal circumstances, to keep control over the brain's response to huge hormonal changes during and immediately after pregnancy. Failure to do this effectively may be the root of some post-natal mood problems.
When they tested their theory on mice who'd been bred to have fewer of these receptors, they found that the genetically-altered mice behaved like mothers with post-natal depression, being more lethargic, and ignoring their newborn pups.
When the mice were given a drug known to boost the function of these receptors, the symptoms eased and the baby deaths fell.
Dr Delia Belelli, from the University of Dundee, who has studied the role of GABA in mood disorders for more than two decades, said it was possible that the drug used to boost receptor function might have a role in treatment of women.
She said: "It is fascinating to see something like this coming out after we have speculated about it for all this time. What they are suggesting is not surprising, and could in theory be applied not only to post-natal depression but to other mood disorders, such as those during the menstrual cycle in women."
August 2008
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