The Key to Reversing Autism May Be in the Microbiome
Part of the rise in autism is due to better diagnosis, but Dr. Emeran Mayer thinks it's something in our environment, and within us, that has played a role in causing this increase.
Dr Emeran Mayer is a world-renowned gastroenterologist and neuroscientist with 35 years of experience in the study of clinical and neurobiological aspects of how the digestive system and the nervous system interact in health and disease. His current research focus is on the role of the gut microbiota brain interactions in emotion regulation, chronic visceral pain, and in obesity. His research has been continuously supported by the National Institutes of Health.
Dr Mayer is a professor in the Departments of Medicine, Physiology and Psychiatry at the David Geffen School of Medicine at UCLA, executive director of the G Oppenheimer Center for Neurobiology of Stress and Resilience, and co-director of the CURE: Digestive Diseases Research Center at UCLA.
Emeran Mayer: Autism is both a devastating problem and it’s still a puzzle largely what causes or what has been causing the dramatic increase in the prevalence of this disease in the last 40 years or so. So it’s almost like an exponential increase. Part of that is really due to better diagnosis and the diagnostic criteria. But a lot of people think that something in our environment has played a role in causing this increase. And it’s worldwide. It’s not just in North America. It’s in Asia, it’s in Europe. So something environmental. The genes, the genetic risk factors for autism have obviously always been there but something else must have triggered it. So some people think it’s something in the diet and that is possible. It could also be something what we do to our gut microbes. So the use of antibiotics, the obsession with keeping things more and more sterile from the day we’re born, you know, throughout our lifetime.
So people have thought about this as potentially a change in microbial composition, diversity inside of us are a cause of this. There’s many observations that link the brain and the gut in autism. Clinically the majority of autistic children have digestive problems – constipation, abdominal pain, discomfort. Part of that is most likely due to the diet, the unique diet that autistic children self-select for. Many things are excluded from the diet that we normally would like fiber, fermented foods. And so it’s very possible that that plays a role. And there are people that have thought about this why do kids select such a diet. It seems to have to do a lot with the texture of foods. So very unique disturbance in the sensitivity for the texture, not so much for the content. So things that are soft are much preferred over crunchy and chewy things. And then, you know, people have started to look at the microbial composition. So they looked at the gut microbes in fecal samples from patients with autism and have found abnormalities.
The problem is most of those studies are small. They’re often not well controlled. We now understand that autism is a spectrum, autism spectrum disorder. And it probably contains several different subsets of patients. So if you just take a small number of patients, measure their gut microbes it’s, you’re likely to pick up variable patterns because it’s not a homogeneous group of patients. And the last thing that’s happened which has really drawn a lot of attention to it has been a study published a couple of years ago by a group at Cal Tech in California which showed that in an animal model of what’s called maternal immune activation – so where the mother undergoes an infection or immune activation during pregnancy. And then the offspring, the mother’s offspring shows altered social behavior. And there’s various tests that have been taken as animal behavior equivalents to human autism. Always, you know, a big chunk from something, from animal behaviors to something as complex as all the disturbances in autism. But that has received a lot of attention because in these animals that have these behaviors they have an altered gut microbial composition, produce different metabolites, particularly one metabolite that’s also been found in human patients. And they have a leaky gut. So they have immune activation in the gut and by treating these animals with – that’s the most intriguing. By treating them with a probiotic which is called B. fragilis, the investigators were able to reverse many of those behavioral changes and the gut abnormalities in these mice.
So this has triggered a tremendous interest now. There’s efforts underway to produce this probiotic and make it acceptable for human use. So it’s not a probiotic that you currently can get in your yogurt or cheese. It has to be approved. It has to be cultured. But clinical trials will happen in the next couple of years that will test this hypothesis. Can you actually by influencing the microbial composition reverse some of the changes either in terms of the gut dysfunction or cognitive and social interaction of these patients. One would assume that in humans the earlier you could start that therapy after delivery – this is clearly a developmental disorder that starts initially almost with imperceptible changes in the newborn and then gradually becomes clinically obvious. The earlier you could start this treatment, the more likely it would be beneficial. So autism in many ways is the prototypic brain-gut microbiome disorder. So this model is almost certainly going to lead to a better understanding and breakthroughs and diagnosis and therapy. But there’s still a ways to go.
So probiotic is a microbe with a demonstrated health benefit. So lots of microbes would qualify for this. We have 100 trillion of these microbes inside of our gut so many of those are potential probiotics that if you isolate them, culture them and then give them to humans – and that’s like with this B. fragilis. It’s produced in the context of infections and abscesses strangely. But it has been shown to have many beneficial effects also stimulating the immune system. That effect on autism appears to be different from the one that has been demonstrated earlier from its anti-inflammatory effect on the gut’s immune system. So it does exist. It just doesn’t exist in a form that is currently commercially available or that would be allowed by the FDA that you could put this into humans. So the trial was left to demonstrate the safety which most likely will be shown. But the FDA is fairly strict. Anytime you use a probiotic even the ones that are in commercially available products if you want to prove that a particular yogurt with its microbes is probiotic is beneficial for a disease condition you need to get FDA approval just like for any other drug which is a complex process, a time consuming process. And it’s kind of slowed the progress in this field of identifying microbes with potential health. So new microbes with potential health benefits.
The genetic risk for autism has always existed, but in the last 40 years the prevalence has risen dramatically – and not in any one location, but across all developed nations. Many researchers are looking to identify the trigger and, as a gastroenterologist and neurologist, Dr. Emeran Mayer is following the trail of evidence that points to the microbial composition of the digestive system and its relationship to the brain. The gut microbes of those with autism differs from people who aren’t on the autism spectrum, but so far many of the studies have not been sufficient to draw solid results. Dr. Mayer runs through one of the more compelling studies and explains how a yet unapproved strain of probiotic may be the answer to the decreasing the incidence of autism in the future. Dr. Emeran Mayer's most recent book is The Mind-Gut Connection: How the Hidden Conversation Within Our Bodies Impacts Our Mood, Our Choices, and Our Overall Health.
Dr Emeran Mayer's most recent book is The Mind-Gut Connection: How the Hidden Conversation Within Our Bodies Impacts Our Mood, Our Choices, and Our Overall Health
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Beards and perceptions of masculinity<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjU5OTg0MC9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTY0NzkxMjM3N30.cH-GqNwP5GVqvstgJWAhBPn1B_lYpVEAI0I7iax7EQw/img.jpg?width=1245&coordinates=0%2C1900%2C0%2C849&height=700" id="caae6" class="rm-shortcode" data-rm-shortcode-id="cb0a355a4e8e1899789bc45f3f7aef56" data-rm-shortcode-name="rebelmouse-image" />
Photo Credit: Wikimedia<p>The study used 919 American (mostly white) women ages 18-70 who rated 30 pictures of men they were shown with various stages of facial hair growth. The photographs depicted men with faces that had been digitally altered to look more feminine or more masculine, with a beard and without a beard. The women rated the men according to perceived attractiveness for long-term and short-term relationships. The study found that the more facial hair the men had, the higher the men were rated on their attractiveness, particularly for their suitability for a long-term relationship.</p><p>Part of this might be attributed to facial masculinity — i.e. protruding brow ridge, wide cheekbones, thick jawline, and deeply set narrow eyes — which conveys information to a woman about a man's underlying health and formidability. Women tend to associate more masculine faces with physical strength and social assertiveness. It can also indicate a man with a superior immune response. The researchers suggested that their findings favoring bearded men could be due to the fact that facial hair enhances the masculine facial features on a man's face, like creating the illusion of a thicker jaw line. This could communicate direct benefits to women like resources and protection that would enhance survival among mothers and their infants. In other words, while a beard doesn't mean superior genetics in and of itself, it might be a primitive, ornamental way of saying, "Hey girl, I'm a testosterone-fueled lean, mean, pathogen fighting machine." <br></p><p>It could also be that a beard becomes its own destiny. The researchers in this study cite prior research that found that by growing a beard, men felt more masculine and had higher levels of serum testosterone, which was linked to a higher level of social dominance. They also tended to subscribe to more old-school beliefs about gender roles in their relationships with women as compared to men with clean-shaven faces.<span></span><br></p>
What does disgust have to do with beard preference?<p>Obviously, not all women dig beards. The researchers were particularly interested in what traits make a women prefer bearded men over clean-shaven faces. They looked into several factors including a woman's disgust levels on various concepts, her desire to become pregnant, and her exposure to facial hair in her personal life. </p><p>According to the study, women who were not into facial hair were turned-off by potential parasites or other critters they imagined could be in the hair or skin. Women ranking high on this "ectoparasite disgust" scale might have viewed beards as a sign of poor grooming habits. However, women who ranked higher in levels of "pathogen" did find the bearded men to be desirable, possibly because they perceived beards as a signal of good health and immune function. An intriguing discovery in the study was links to morality. Women who displayed higher levels of "moral disgust," or feelings of repugnance toward taboo behaviors, were more likely to prefer hairy faces. The authors opined that this could reflect a link between beardedness, politically conservative outlooks, and traditional views regarding performances of masculinity in heterosexual relationships.</p>
Additional findings<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMjU5OTg1My9vcmlnaW4uZ2lmIiwiZXhwaXJlc19hdCI6MTYyNDI1NjUyOX0.P9B8WbmJR0q4nfzYZKbuNSA-2SAigVWJgrQE-_Gxlds/img.gif?width=980" id="49143" class="rm-shortcode" data-rm-shortcode-id="2ed3b1d6f20fc170bf2974646e565e8d" data-rm-shortcode-name="rebelmouse-image" />Giphy<p>The correlations that existed between married and single women's rating on the attractiveness of beards were not particularly clear, although the researchers noted that single and married women who wanted children tended to find beards more attractive than the women who didn't want children. They also found that women with bearded husbands found beards to be more attractive, which might indicate that social exposure to beards influences how desirable they are perceived of as being. Or it could be that men with wives who like beards grow beards.</p><p>It's important to note that culture plays a huge role in how attractive women perceive certain male characteristics as being. This study looked at a small, culturally specific group of American women, so no big, universal claims should be made about masculinity, facial hair, and male desirability to women. However, research like this is important in highlighting how human grooming decisions are driven by much more than fashion trends. Sociobiological, economic, and ecological factors all play a part in the way we choose to present ourselves.</p>
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