Protective Gene Keeps Abused Children’s Minds Safe


People who had been abused as children and who carried the most protective forms of the gene, called corticotropin-releasing hormone receptor one (CRHR1), had markedly lower measures of depression, compared with people with less protective forms, the researchers found in a recent study.

The findings could guide doctors in finding new ways to treat depression in people who were abused as children, says senior author Kerry Ressler, MD, PhD, assistant professor of psychiatry and behavioral sciences at Emory University School of Medicine. [...]

The study also supports previous evidence that corticotropin-releasing hormone (CRH) and related hormones play a role in depression. Other studies have found increased levels of CRH and altered levels of its receptor in the brains of patients with depression.[...]

The receptor for a hormone acts like a receiver or radar dish for messages sent between cells. CRH stimulates the pituitary gland to release another hormone, adrenocorticotropin, which in turn induces the release of cortisol from the adrenal cortex.

Extreme stress in childhood can over-activate this cascade of hormones, increasing the risk of depression in adulthood, Dr. Ressler says.

“Our results suggest that genetic differences in signals mediated by CRH may amplify or soften the developmental effects that childhood abuse can have — effects that can raise the risk of depression in adults,” he says.

In the study, scientists began by interviewing more than 470 adults and testing their DNA, looking for alternative spellings or SNPs (single nucleotide polymorphisms) in several parts of the CRHR1 gene.

This first group was mostly black and a majority had a monthly income less than $1,000. The researchers measured their symptoms of depression and had them answer questionnaires about childhood trauma. Their responses were categorized as low, mild, moderate and severe.

Overall, people with a history of moderate or severe child abuse had depression symptoms that averaged about double the level of those with low or mild child abuse scores.

Roughly 30 percent of the group had variations in the CRHR1 gene that together appeared to be protective if moderate to severe abuse had occurred. People who had inherited two copies of the most protective forms of the gene, or “haplotypes,” had average depression symptoms that were about half those of people who had not inherited those haplotypes. A haplotype comprises several SNPs that frequently appear together.

These differences in depression symptoms were only seen in people with histories of moderate to severe abuse; depression levels were not significantly different in people with low to mild abuse.

The most significant SNPs appear in the part of the gene preceding the region that encodes the receptor protein, suggesting that the variations may affect its regulation rather than the composition of the protein, the authors say.

The findings were strengthened when the researchers repeated the study in 199 white, middle-income adults and came up with similar results, suggesting that the genetic variations act in a way that is independent of ethnic background or economic status. (Source: Eurekalert)

Corticotropin-releasing hormone is a hormone created by the hypothalamus, a part of the brain important to the circadian rhythm. I’d like to find out if this gene alteration is present higher in populations that have endured generations of abuse. (As an adaptive mechanism)


Video Games More Rewarding to Men


It’s a stereotype now backed by scientific research: men like video games more than women.

Allan Reiss, MD, and his colleagues have a pretty good idea why your husband or boyfriend can’t put down the Halo 3. In a first-of-its-kind imaging study, the Stanford University School of Medicine researchers have shown that the part of the brain that generates rewarding feelings is more activated in men than women during video-game play. [...]

“The females ‘got’ the game, and they moved the wall in the direction you would expect,” said Reiss, who is director of the Center for Interdisciplinary Brain Sciences Research. “They appeared motivated to succeed at the game. The males were just a lot more motivated to succeed.”

After analyzing the imaging data for the entire group, the researchers found that the participants showed activation in the brain’s mesocorticolimbic center, the region typically associated with reward and addiction. Male brains, however, showed much greater activation, and the amount of activation was correlated with how much territory they gained. (This wasn’t the case with women.) Three structures within the reward circuit – the nucleus accumbens, amygdala and orbitofrontal cortex – were also shown to influence each other much more in men than in women. And the better connected this circuit was, the better males performed in the game. (Source: Scienceblog)