Thinking with your gut

Via Science Daily:

For the first time, researchers at McMaster University have conclusive evidence that bacteria residing in the gut influence brain chemistry and behaviour.

The findings are important because several common types of gastrointestinal disease, including irritable bowel syndrome, are frequently associated with anxiety or depression. In addition there has been speculation that some psychiatric disorders, such as late onset autism, may be associated with an abnormal bacterial content in the gut.

“The exciting results provide stimulus for further investigating a microbial component to the causation of behavioural illnesses,” said Stephen Collins, professor of medicine and associate dean research, Michael G. DeGroote School of Medicine. Collins and Premysl Bercik, assistant professor of medicine, undertook the research in the Farncombe Family Digestive Health Research Institute.

The research appears in the online edition of the journal Gastroenterology.

For each person, the gut is home to about 1,000 trillion bacteria with which we live in harmony. These bacteria perform a number of functions vital to health: They harvest energy from the diet, protect against infections and provide nutrition to cells in the gut. Any disruption can result in life-threatening conditions, such as antibiotic-induced colitis from infection with the “superbug” Clostridium difficile.

Working with healthy adult mice, the researchers showed that disrupting the normal bacterial content of the gut with antibiotics produced changes in behaviour; the mice became less cautious or anxious. This change was accompanied by an increase in brain-derived neurotrophic factor (BDNF), which has been linked to depression and anxiety.

When oral antibiotics were discontinued, bacteria in the gut returned to normal. “This was accompanied by restoration of normal behaviour and brain chemistry,” Collins said.

To confirm that bacteria can influence behaviour, the researchers colonized germ-free mice with bacteria taken from mice with a different behavioural pattern. They found that when germ-free mice with a genetic background associated with passive behaviour were colonized with bacteria from mice with higher exploratory behaviour, they became more active and daring. Similarly, normally active mice became more passive after receiving bacteria from mice whose genetic background is associated with passive behaviour.

While previous research has focused on the role bacteria play in brain development early in life, Collins said this latest research indicates that while many factors determine behaviour, the nature and stability of bacteria in the gut appear to influence behaviour and any disruption , from antibiotics or infection, might produce changes in behaviour. Bercik said that these results lay the foundation for investigating the therapeutic potential of probiotic bacteria and their products in the treatment of behavioural disorders, particularly those associated with gastrointestinal conditions such as irritable bowel syndrome.

Study claims testosterone dysfunction may cause autism, prevalence of ASD in males

There’s a lot of controversy on basically every aspect of autism research. Just 68 years ago, “autism” didn’t exist as a diagnosis. It would be another few decades before the condition was fully differentiated from schizophrenia. The full diversity of its expression and functionality was not be recognized until the 1980′s when Asperger syndrome was taxonomized. And ten years ago, it was believed only one in 500-1,000 people were on the spectrum. Now, roughly one in 110 children gets a diagnosis. It’s unclear whether more children are actually autistic, or if doctors’ perceptions and diagnostic tools are becoming keener, or if ASDs are being overdiagnosed.

Even more controversial is the sex distribution of ASD. Autism diagnoses are four times as common in boys than girls, leading to the perception that ASD are “male” disorders. This has been taken so far that even eminent researchers like Simon Baron-Cohen have suggested that autism is the hyperactive expression of “masculine” thinking-styles marked by decreased empathy and increased systemic rule-following (even though theories claiming significant sex-based cognitive differences are among the most controversial and contested hypotheses in all of psychology).

More distressingly, the “masculinization” of autism creates conscious and unconscious biases that blur even trained professionals’ recognition of ASD traits in women. Many girls on the spectrum are misdiagnosed with social anxiety disorder, OCD, or ADHD early in life. (This often deprives them of the understanding and support they need. Aspergian Rudy Simone has done much knowing and humane activism and writing on the subject.) Exactly how often these misdiagnoses occur is unknowable with our current information; so it’s impossible to say how close the “four-to-one” statistic is to reality.

Bear all this in mind and approach this New Scientist article  with skepticism. It summarizes a George Washington Medical Center paper claiming to have “explained” the ASD gender gap (which, I have argued, may not exist, or at least not to the extent that has been reported):

 Valerie Hu at the George Washington University Medical Center in Washington DC and colleagues studied a gene implicated in autism called retinoic acid-related orphan receptor-alpha (RORA). This gene controls a molecule that switches many subsequent genes on and off.Previous research has shown that RORA is important for development of the cerebellum and that the brains of people with autism expressed less of it than normal. Mice that likewise express less RORA than normal display symptoms that resemble autism in humans, such as repetitive behavioursand deficits in spatial learning.

To find out how RORA is affected by hormones, Hu’s team bathed human brain cells expressing the gene in either oestradiol – a form of the major female sex hormone oestrogen – or the male sex hormone dihydrotestosterone (DHT), which is derived from testosterone. They found that oestradiol enhanced the gene’s expression, whereas DHT suppressed it. The team also discovered that RORA regulates another gene which controls aromatase, an enzyme that converts testosterone to oestrogen. If RORA is under-expressed, then aromatase cannot function properly and testosterone will accumulate.In a whole organism, this excess testosterone may in turn further repress the expression of RORA, making matters worse.

Elevated levels of testosterone in the womb are thought to contribute to the development of autism. However, if the RORA gene is faulty in a female fetus, it would be less susceptible to a build-up of testosterone because the fetus has higher levels of oestrogen to begin with. What’s more, female sex hormones are likely to promote any RORA that is expressed, rather than further repress it.

“For a long time elevated fetal testosterone has been a proposed as risk factor for autism, but the problem is that there has been no molecular explanation,” says Hu. “Now we have evidence for a really exacerbating situation. What we have identified is an inhibitory feedback loop. That is what makes this so fascinating.”

Brett Abrahams, who studies autism at the Albert Einstein College of Medicine in New York, says the study is “very cool”. He says that the commonness of autism in males is one of the key and unexplored areas of research into the condition.

“Elaborating a means of exploring this question is really to [this team's] credit. They have made an important contribution because although there have been previous attempts to look at relationship between genes known to modulate sex differences and autism, not much has come out of that.”

Joseph Buxbaum at the Seaver Autism Center at the Mount Sinai School of Medicine in New York is also impressed by the study, but cautions that there is still limited evidence for the “extreme male brain” hypothesis. Furthermore, he says, the nature of autism varies from person to person: “It is very unlikely there will be a single pathway.”

Giffords’ prognosis

Via MSNBC’s  JoNel Aleccia:

“She’s still critically ill,” said Dr. Alex Valadka, a neurosurgeon and spokesman for the American Association of Neurological Surgeons. “We get excited when people hold up a couple of fingers, but that’s a long way from higher functioning.”

Doctors at University Medical Center in Tucson, Ariz., said they were cautiously optimistic about Giffords’ prognosis a day after she was shot at point-blank range at a public gathering in a supermarket parking lot. Dr. G. Michael Lemole Jr., chief of neurosurgery, said he removed a large piece of Giffords’ skull to accommodate swelling caused after the bullet traveled — back to front — the entire length of the left side of her brain.

Lemole said Giffords is likely to remain in intensive care for a week or so, in the hospital for a couple more weeks and then face a long rehabiliation period. He didn’t want to speculate about her chances for recovery.

“We’ve seen the full gamut,” he said.

People who suffer penetrating traumatic brain injuries often develop paralysis and cognitive problems. The left side of the brain is typically responsible for speech and controls the right side of the body, Valadka explained, noting that most people are right-handed.

Giffords was fortunate that the bullet did not cross the geometric center of the brain, said Lemole. Early reports indicated she might have been shot in one temple with the bullet exiting the other, but Lemole said the single shot entered in the back and exited the front.

One is brought to mind of Phineas Gage; someone walked away from his accident, but it was not the Phineas Gage his intimates had known.

The body’s apprehension of music

The ear and the brain–specifically, the hypothalamus–are not the only parties involved. For some people, the skin is an active participant in appreciating music:

Some of us get the chills when hearing Handel’s exultant “Messiah” this time of year. For others, it’s the simple, yet joyful opening strains of Vince Guaraldi’s music at the start of “A Charlie Brown Christmas.” Or it might be Bing Crosby’s poignant “I’ll Be Home for Christmas” that triggers goose bumps. (Or for the sillier of us, his whimsical “Mele Kalikimaka” might just do it.)Well, it turns out that getting chills upon hearing music is an actual thing, you know, like scientists study. And a new report in the journal Social Psychology and Personality Science says that who gets music-induced chills and who doesn’t might depend on personality.

Musical chills, write the authors, from the University of North Carolina, are “sometimes known as aesthetic chills, thrills, shivers, frisson, and even skin orgasms [who knew?] … and involve a seconds-long feeling of goose bumps, tingling, and shivers, usually on the scalp, the back of the neck, and the spine, but occasionally across most of the body.”

The scientific explanation for chills is that the emotions evoked by beautiful or meaningful music stimulate the part of the brain called the hypothalamus, which controls primal drives such as hunger, sex and rage and also involuntary responses like blushing and goosebumps. When the song soars, your body can’t help but shiver.

Some people report lots of skin orgasms and some people say they never get them, but the personality trait “openness to experience” seems like a good predictor. (By “open to experience” the researchers seem to mean those people who enjoy art, good movies, aesthetic stuff.)

That’s what the North Carolina researchers wanted to test. So they took 196 people and assessed their music preferences; how often they experienced chills, goose bumps, hair standing on end and the like; their engagement with music (such as whether they played an instrument); and their personality types. The only personality trait with a significant impact on music-induced chills was indeed “openness.”

Genre, the style of music people listened to, didn’t seem to matter, though a deeper engagement with music in general did. So “Messiah,” Irving Berlin’s “White Christmas,” and your child’s rendition of “Oh Christmas Tree” might all give chills (though your kid’s singing might just be scary) if you’re the open type.