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Vol. LXVI, No. 23
November 7, 2014
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Digest

Rapid Agent Restores Pleasure-Seeking Ahead Of Other Antidepressant Action

A drug being studied as a fast-acting mood-lifter restored pleasure-seeking behavior independent of—and ahead of—its other antidepressant effects, in an NIH trial. Within 40 minutes after a single infusion of ketamine, treatmentresistant depressed bipolar disorder patients experienced a reversal of a key symptom—loss of interest in pleasurable activities—which lasted up to 14 days. Brain scans traced the agent’s action to boosted activity in areas at the front and deep in the right hemisphere of the brain.

“Our findings help to deconstruct what has traditionally been lumped together as depression,” explained Dr. Carlos Zarate of NIMH. “We break out a component that responds uniquely to a treatment that works through different brain systems than conventional antidepressants— and link that response to different circuitry than other depression symptoms.”

This approach is consistent with NIMH’s Research Domain Criteria project, which calls for the study of functions—such as the ability to seek out and experience rewards—and their related brain systems that may identify subgroups of patients in one or multiple disorder categories. Zarate and colleagues reported on their findings Oct. 14 in the journal Translational Psychiatry.

Doubt Cast on Plans to Scale Up Preterm Birth Treatment in Low-Resource Settings

A study by an NIH research network calls into question plans to increase access to steroid treatment for pregnant women in low-resource settings at high risk for preterm birth.
A study by an NIH research network calls into question plans to increase access to steroid treatment for pregnant women in low-resource settings at high risk for preterm birth.

A study by an NIH research network calls into question plans to increase access to steroid treatment for pregnant women in low-resource settings at high risk for preterm birth. The study, published online in The Lancet, concluded that the treatment—a standard, life-saving practice in high-income countries such as the United States—could potentially cause harm in low-resource settings where many births take place outside the advanced-care hospitals that are standard in high-income countries.

The researchers are uncertain as to why the therapy did not offer the clear benefit in the low-income countries that it provides to preterm infants in high-income countries. Potential reasons range from some unknown aspects of the intervention itself—the methods the researchers devised to teach local birth attendants how to administer the drug outside hospital settings—to the possibility that, despite enhanced lung function, preterm infants may simply be in greater need of the advanced hospital care common in high-income countries.

The steroid therapy works by triggering the lungs of a preterm infant to mature so that he or she can absorb oxygen. The treatment has been proven to increase the survival rate of preterm infants in high- and middle-income countries. Steroid treatment is routinely prescribed to women at risk of giving birth before the 34th week of pregnancy in the U.S. and in other highincome countries. Because of its proven effectiveness in the high-income countries, health care workers have begun efforts to increase access to women in low-resource settings in low- and middle-income countries. The study— undertaken as a test to determine the feasibility of providing the treatment in low-resource settings—enrolled women considered at risk for preterm birth in several countries in Africa, Asia and Central and South America.

“Many public health experts had believed steroid therapy before birth would save as many lives in low-resource settings as it does in high-income countries,” said study author Dr. Marion Koso-Thomas of NICHD. “These results are extremely disheartening, but they underscore the critical importance of studying even an established treatment before introducing it to a new setting.”

Scientists Sniff Out Unexpected Role for Stem Cells in the Brain

For decades, scientists thought that neurons in the brain were born only during the early development period and could not be replenished. More recently, however, they discovered cells with the ability to divide and turn into new neurons in specific brain regions. The function of these neuroprogenitor cells remains an intense area of research. NIH scientists report that newly formed brain cells in the mouse olfactory system—the area that processes smells—play a critical role in maintaining proper connections. The results were published in the Oct. 8 issue of the Journal of Neuroscience.

“This is a surprising new role for brain stem cells and changes the way we view them,” said study lead author Dr. Leonardo Belluscio of NINDS. He teamed up with Dr. Heather Cameron of NIMH to better understand how the continuous addition of new neurons influences the circuit organization of the olfactory bulb.

The olfactory bulb is located in the front of the brain and receives information directly from the nose about odors in the environment. Neurons in the olfactory bulb sort that information and relay the signals to the rest of the brain, at which point we become aware of the smells we are experiencing. Olfactory loss is often an early symptom in a variety of neurological disorders, including Alzheimer’s and Parkinson’s diseases.

In a process known as neurogenesis, adult-born neuroprogenitor cells are generated in the subventricular zone deep in the brain and migrate to the olfactory bulb where they assume their final positions. Once in place, they form connections with existing cells and are incorporated into the circuitry.—compiled by Carla Garnett


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