Friday, July 31, 2015

Women dependent on cocaine or meth have less grey matter

New SCIENTIST
DAILY NEWS

14 July 2015

Women dependent on cocaine or meth have less grey matter

The size of a woman’s grey matter could depend on her dependence (Image: Piotr Powietrzynski/Getty)

Don’t do drugs, kids. Especially if you’re female. Women dependent on stimulants like cocaine and methamphetamine appear to have less grey matter, even after they stop using them. Weirdly, men’s brains don’t show this difference.

The brain regions most affected are those involved in reward, emotion and learning – although it isn’t clear yet whether the smaller than average size of these brain areas could be a cause or effect of addiction. Jody Tanabe, at the University of Colorado Hospital in Aurora, hopes these results will help lead to a better understanding of sex differences in substance abuse, and better, more distinct treatments for women.

Tanabe’s team used MRI scans to measure the brain volumes of 59 people previously dependent on stimulants and compared them with people who have never been dependent on these kinds of drugs. On average, the 28 women who had formerly been dependent on a stimulant drug had a smaller volume of grey matter in their prefrontal cortices, temporal lobes, insulae and other regions. This effect was not seen in men.

Shrinking brains

The women who had been addicted also differed in their personalities – on average, they were more impulsive and more reward-driven. We already know that women respond differently to stimulants: they start taking the drugs earlier, use larger quantities and may have more difficulty quitting. It’s possible that this pattern of female addiction could be linked to the brain size difference.

However, it’s unclear whether less grey matter causes female addictive behaviours, or if addiction might shrink these brain regions. “The question of causality is complex. There is evidence for both pre-existing and post-drug changes in brain structure and function,” says Tanabe.

Mitul Mehta from King’s College London says longitudinal studies, which follow the same people over time, are necessary to untangle the causes and effects before any treatment decisions could be based on this research.

Currently, men and women receive the same treatment for stimulant dependence. Kelly Cosgrove from Yale University suggests that the female brain may be more vulnerable to toxic effects of drugs and this study “would suggest extended treatment is necessary – perhaps more so for women”.

Journal reference: Radiology, DOI: 10.1148/radiol.2015142541

As for men - see also
men-who-watch-porn-have-less-brain-grey-matter

Wednesday, July 29, 2015

Female and Male mice process pain differently

NATURE NEUROSCIENCE | BRIEF COMMUNICATION

Male and female mice use different types of immune cell to process chronic pain.

Studies of male mice have shown that immune cells called microglia in the spinal cord have an important role in chronic pain. To see whether this is the same in female mice, a team led by Jeffrey Mogil at McGill University in Montreal and Michael Salter at the University of Toronto, both in Canada, induced chronic pain in both sexes. The team then used drugs or antibodies to reduce microglia function. Whereas pain responses were reduced in the males, females were unaffected and instead recruited a different type of immune cell, called a T cell. This difference was linked to testosterone, which could make T cells less able to mediate pain in the males, leading to their use of microglia instead.

article

NEUROIMMUNOLOGY

For females, a different path to pain

Kristen L. Mueller

The immune cells underlying pain responses may differ between males and females

Chronic pain affects more women than men. To better understand why, Sorge et al.compared the mechanisms that underlie neuropathic pain in male and female mice. Previous studies suggested that immune cells called microglia trigger pain sensitivity in response to nerve injury. Surprisingly, blocking microglia genetically or pharmacologically reduced pain in male but not in female mice. This sex-specific response depended on testosterone—blocking microglia alleviated pain in testosterone-treated females but not in castrated mice. Lymphocytes, rather than microglia, appeared to promote pain in female mice. These results suggest that scientists may need to examine sex-specific responses when testing new treatments for pain and other neurological diseases involving immune cells.

Dutee Chand, Female Sprinter With High Testosterone Level, Wins Right to Compete

By JOHN BRANCHJULY 27, 2015

Dutee Chand did not follow recommendations that she take hormone-suppressing drugs or have surgery to limit her amount of testosterone. "I want to remain who I am and compete again," she said.CreditGraham Crouch for The New York Times

The final appeals court for global sports further blurred the line separating male and female athletes on Monday, ruling that a common factor in distinguishing the sexes — the level of natural testosterone in an athlete’s body — is insufficient to bar some women from competing against females.

The Court of Arbitration for Sport, based in Switzerland, questioned the athletic advantage of naturally high levels of testosterone in women and therefore immediately suspended the practice of “hyperandrogenism regulation” by track and field’s governing body, the International Association of Athletics Federations. It gave the organization, known as the I.A.A.F., two years to provide more persuasive scientific evidence linking “enhanced testosterone levels and improved athletic performance.”

The court was ruling on a case, involving the Indian sprinter Dutee Chand, that is the latest demonstration that sex is part of a spectrum, not a this-or-that definition easily divided for matters such as sport. It also leaves officials wondering how and where to set the boundaries between male and female competition.

Sex Differences in the News