How Antidepressants May Subtly Alter a Growing Baby’s Brain
By Susan Gaidos, from Science News June 5, 2010
The newer class of anti-deperessants (SSRIs) work by changing how the brain manages a neurotransmitter called Serotonin. The SSRIs work by blocking the 5-HTTT protein. There is no conclusive research about how changing serotonin levels of the mother’s brain affect a baby in her womb. The paragraphs below were written by Susan Gaidos after she reviewed some basic research on how serotonin levels effect brain development in lower animals. Nobody knows if the same applies to humans, but this article suggests that when a pregnant mother takes anti-depressants it may well have lasting effects on the child she is carrying, making him or her more susceptible to anxiety throughout life.
“Changing the level of serotonin in the growing brain by blocking the reuptake process may alter the way these sensory systems develop, a growing number of animal studies suggest. SSRIs can readily cross the placenta, which nourishes the fetus, and the drugs are also detectable in breast milk and in breast-fed children.
“In 2004, Columbia University scientists showed that both mice exposed to SSRIs and mice engineered to lack a gene for the 5-HTT protein grew up to exhibit anxiety traits in adulthood, such as a reluctance to eat in or explore unfamiliar places. [SSRIs work by blocking the production of 5-HTT protein.]
“The levels of serotonin early in development may help determine how the serotonin system responds throughout life, he says. “Which brings with it the fact that if you change that level of serotonin in some artificial way, by taking drugs or experiencing stress, then those circuits could be forever altered.”
“Since then, studies have found faulty brain organization in mice lacking the 5-HTT protein.
“Serotonin may play another important role in growing brains: Organizing the circuitry by which the chemical itself operates throughout life. Serotonin is so essential to life that critters — from flies to frogs to humans — set up elaborate distribution systems to ensure its flow throughout the central nervous system. This is achieved, in part, by parceling out the sites where serotonin is released. But scientists have wondered how a developing brain knows what the density of release sites should be.
“One possibility is that the sites are set up according to how much serotonin is in the system, says neuroscientist Barry Condron of the University of Virginia in Charlottesville. So neurons producing serotonin would have their own receptors that sense how much of the neurotransmitter is out there and adjust accordingly. A lack of serotonin would prompt more release sites to grow; too much would cause release sites to retract.
“During development, when the serotonin system is “under installation,” it may be especially sensitive to serotonin levels in the brain, Condron says. In 2005, he and then doctoral student Paul Sykes found that developing flies were quick to adjust the number of release sites in response to changes in serotonin levels. But the response depended on the timing: Adding serotonin to the system decreased the overall density of release sites in older larvae, while increasing the density in very young larvae.
“It’s all about timing,” Condron says. “There’s a fine ballet of timing in serotonin levels and the need for the neurochemical during various stages of development.”