Is Dental Health Related to Mental Health?

smiling man and woman wearing jackets
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We may finally know what causes Alzheimer’s – and how to stop it

If you bled when you brushed your teeth this morning, you might want to get that seen to. We may finally have found the long-elusive cause of Alzheimer’s disease: Porphyromonas gingivalis, the key bacteria in chronic gum disease.

That’s bad, as gum disease affects around a third of all people. But the good news is that a drug that blocks the main toxins of P. gingivalis is entering major clinical trials this year, and research published today shows it might stop and even reverse Alzheimer’s. There could even be a vaccine.

Alzheimer’s is one of the biggest mysteries in medicine. As populations have aged, dementia has skyrocketed to become the fifth biggest cause of death worldwide. Alzheimer’s constitutes some 70 per cent of these cases and yet, we don’t know what causes it.

Bacteria in the brain

The disease often involves the accumulation of proteins called amyloid and tau in the brain, and the leading hypothesis has been that the disease arises from defective control of these two proteins.

But research in recent years has revealed that people can have amyloid plaques without having dementia. So many efforts to treat Alzheimer’s by moderating these proteins have failed that the hypothesis has been seriously questioned.

However evidence has been growing that the function of amyloid proteins may be as a defence against bacteria, leading to a spate of recent studies looking at bacteria in Alzheimer’s, particularly those that cause gum disease, which is known to be a major risk factor for the condition.

Bacteria involved in gum disease and other illnesses have been found after death in the brains of people who had Alzheimer’s, but until now, it hasn’t been clear whether these bacteria caused the disease or simply got in via brain damage caused by the condition.

Gum disease link

Multiple research teams have been investigating P. gingivalis, and have so far found that it invades and inflames brain regions affected by Alzheimer’s; that gum infections can worsen symptoms in mice genetically engineered to have Alzheimer’s; and that it can cause Alzheimer’s-like brain inflammation, neural damage, and amyloid plaques in healthy mice.

“When science converges from multiple independent laboratories like this, it is very compelling,” says Casey Lynch of Cortexyme, a pharmaceutical firm in San Francisco, California.

In new study, Cortexyme have now reported finding the toxic enzymes – called gingipains – that P. gingivalis uses to feed on human tissue in 96 per cent of the 54 Alzheimer’s brain samples they looked at, and found the bacteria themselves in all three Alzheimer’s brains whose DNA they examined.

The bacteria and its enzymes were found at higher levels in those who had experienced worse cognitive decline, and had more amyloid and tau accumulations. The team also found the bacteria in the spinal fluid of living people with Alzheimer’s, suggesting that this technique may provide a long-sought after method of diagnosing the disease.

When the team gave P. gingivalis gum disease to mice, it led to brain infection, amyloid production, tangles of tau protein, and neural damage in the regions and nerves normally affected by Alzheimer’s.

Cortexyme had previously developed molecules that block gingipains. Giving some of these to mice reduced their infections, halted amyloid production, lowered brain inflammation and even rescued damaged neurons.

The team found that at antibiotic that killed P. gingivalis did this too, but less effectively, and the bacteria rapidly developed resistance. They did not resist the gingipain blockers.

New treatment hope

Some brain samples from people without Alzheimer’s also had P. gingivalis and protein accumulations, but at lower levels. We already know that amyloid and tau can accumulate in the brain for 10 to 20 years before Alzheimer’s symptoms begin. This, says Lynch, shows P. gingivalis is a cause of Alzheimer’s, not a result.

Gum disease is far more common than Alzheimer’s. But “Alzheimer’s strikes people who accumulate gingipains and damage in the brain fast enough to develop symptoms during their lifetimes,” she says. “We believe this is a universal hypothesis of pathogenesis.”

Cortexyme reported in October that the best of their gingipain blockers had passed initial safety tests in people, and entered the brain. It also seemed to improve participants with Alzheimer’s. Later this year the firm will launch a larger trial of the drug, looking for P. gingivalis in spinal fluid, and cognitive improvements, before and after.

They also plan to test it against gum disease itself. Efforts to fight that have led a team in Melbourne to develop a vaccine for P. gingivalis that started tests in 2018. A vaccine for gum disease would be welcome – but if it also stops Alzheimer’s the impact could be enormous.

Journal reference: Science Advances

Is There a Calming Effect In Flickering Lights?

Aug 12, 2018  Andy CorbleyHERO_YI_PEN_LOY_KROTHONG_PanatFoto_Shutterstock

Alzheimer’s Disease, along with anxiety disorders, Parkinson’s, clinical depression, and other neurological diseases are notoriously difficult conditions to find treatment for. Because the diseases are not well understood, and therefore hard to target directly, many pharmaceutical options fail.

But a relatively new field of neurological treatment is opening up in the form of things like tACS (transcranial alternating current stimulation) and other non-invasive, non-drug methods.

For example, on March 2015, Li-Huei Tsai, a neuroscientist at MIT set up a tiny disco of flashing lights for some of the mice in her laboratory that had been engineered to develop increased amounts of an Alzheimer’s related brain-plaque called amyloid-β. They were later found upon dissection to be carrying far less – sometimes even none – of the plaque than was present before the disco parties began.

The experiment baffled Tsai; and even after checking the results multiple times, she had a hard time believing them. The strobe light within the little rodent dance party, which was tuned to 40 hertz, was designed to help manipulate the rodents’ brain waves and produce a large number of biological benefits, including the elimination of the amyloid-β forming proteins – and it worked.

RELATEDMagnetic Brain Treatment Erases Suicidal Thoughts in Dramatic Portion of Depressed Patients

“The result was so mind-boggling and so robust, it took a while for the idea to sink in, but we knew we needed to work out a way of trying out the same thing in humans,” Tsai told Nature. How can the simple repetitive flashing of lights help to suppress the development of things like Alzheimer’s disease? A brief look into brainwaves will help provide the clues.

When the neurons in your brain communicate with each other, electrical impulses, created by the flow of ions into and out of each cell can be observed on a computer as oscillating waves of electrical energy. Gamma-type brain waves flow at the highest frequency, and are less common in Alzheimer’s patients. These waves are observable when a person is in a period of deep sleep characterized by rapid eye movement (REM sleep).

Scientists believe the synchronized firing of neurons help sort out all the stimuli and sensory input into the correct centers of the brain for processing; taste, motor function, hearing, etc. Neurodegenerative diseases disrupt these brain wave oscillations and seem to deliver their pathologies through their own altering of brain waves; like Parkinson’s which impedes the natural suppression of the Beta-type brain wave leading to impeded motor function.

RELATEDAlzheimer’s Gene is Neutralized in Human Brain Cells for the First Time

Now, a growing body of evidence, including Tsai’s findings, offers the possibility of forestalling or even reversing the damage caused by such conditions without using a drug. More than two dozen clinical trials are aiming to modulate brainwaves in some way — some with flickering lights or rhythmic sounds, but most through applying electrical currents to the brain or scalp.

TACS, which involves the direct application of low-level electrical currents into certain parts of the brain, has been suggested to be even more effective than rodent (or human) disco parties of external stimulation. Emiliano Santarnecchi at Harvard Medical School in Boston, Massachusetts have been using tACS in research for years, and after seeing Tsai’s results, thought it a no-brainer to test the method on Alzheimer’s patients.


MOREThese Scientists Have Managed to Stop the Progress of Alzheimer’s in Animals

His team has begun an early clinical trial in which ten people with Alzheimer’s disease receive tACS for one hour daily for two weeks. A second trial, in collaboration with Tsai, will look for signals of increased microglia – unique and important immune cells designed just for the brain and nervous-system. According to earlier studies by Dr. Tsai, microglia can be made more active by brain wave manipulation, causing them to accelerate the speed and effectiveness in which they clean the brain and nervous system of debris. Results are expected from both trials by the end of the 2018.

The popular Radiolab podcast released an episode in 2014 titled “Nine-volt Nirvana,” in which they catalogued instances of tDCS (trans-cranial DIRECT current stimulation) being used to accelerate the learning processes of complex skills such as languages immensely, but also aiding in the quitting of smoking habits, the overcoming of depression, and even boosting rifle marksmanship.

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For Dr. Tsai, understanding the relationship between neurological diseases and the regulation of different brain wave oscillations is personal. The grandmother who raised her was affected by dementia and that confused face made a deep impact. Tsai is now giving everything she has to try and solve the mystery.


It Can Be Problematic When Hiding Your Smile

A genuine smile can be a greeting, a door opener, and initiate a contagious response. When we are embarrassed or ashamed because of missing, discolored, or crooked teeth, we lose a genuine asset to our interpersonal relationship building. Dental veneers can be a valuable tool in restoring your smile.

This New Medical Procedure Could Make Mercury Leak Out Of Your Fillings

content-1530099959-radiol-2018172597-fig1It’s relatively normal to be scared of going to the dentist. But what if we told you it could lead to a mouthful of mercury?

Researchers in Turkey published in the journal Radiology, showing that a new type of MRI scan has the slightly worrying effect of, er, making your fillings leak mercury into your mouth. Yes, it turns out a simple medical scan might give you a free helping of delicious heavy metals.

First, a quick recap: MRI – which stands for Magnetic Resonance Imaging – is a technique for scanning the body that has been around for nearly 50 years already. It relies, as the name suggests, on using strong magnetic fields to generate images of internal organs.

So how strong is a “strong magnetic field”? A standard MRI uses a magnetic field of 1.5T (Teslas – the unit of measurement for magnetic field strength). For comparison, the magnetic field surrounding the entire planet is only about 0.00005T. So, pretty strong.

But since the early 2000s, a new type of MRI scanner has been in commercial production – and it can produce magnetic fields of 7T and higher. In 2003, the FDA declared strengths of up to 8T a “non-significant risk”, and the new machines quickly proved popular for research and clinical use – despite concerns that not enough research had been done into their safety. In particular, researchers questioned whether enough was known about how the ultra-high magnetic fields would affect surgical and dental implants in patients.

This is where the new study comes in. The researchers took 60 “human teeth that had been extracted for various reasons”, which sounds very fine and not suspicious, and gave them all amalgam fillings – that’s the silver type you probably think of as a “normal filling”. They then divided the teeth into three groups: one underwent a normal 1.5T MRI scan, one had a 7T scan, and a control group had no scan at all. After nine days brewing in vials of artificial saliva, the amount of mercury that had leaked out of the teeth was measured and recorded.

The results were … not great. Although the mean amount of mercury that leaked in a normal MRI was a little higher than the control group, the teeth that had the ultra-high MRI scan had lost nearly five times as much. The researchers also noted that problems have been found with other dental implants, with gold and platinum crowns becoming hotter under the higher magnetic fields.

Despite the worrying results of the study, it’s important to remember that mercury-based fillings have been in common use for hundreds of years, and are declared safe by the FDA, the American Dental Association, the UK’s NHSHealth Canada and many more – and although ultra-high field MRI scans might be on their way, you’re unlikely to undergo one for a very long time.

How to Get a Picture-Perfect Wedding Smile

man in gray dress suit jacket embraces woman wearing wedding gown
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The first thing Larry Dougherty noticed about his dental school classmate Ana Paula Ferraz was her long, jet black hair. As Ana got to know Larry, she fell in love with his kindness and sense of humor.

After dental school, it was “I do” for the couple. Ana and Larry married in a small, 60-person wedding at an old estate home in Miami. One of their most special guests – the couple’s rat terrier Chi Chi, in full top-hat regalia – even rode to the wedding with Larry in the limo. “It was perfect,” Ana says. “We couldn’t stop smiling.” And they haven’t stopped since. Today, dentists Ana and Larry run their own practice and have some “been there, done that” advice to share for anyone getting ready to celebrate a wedding.

Whitening for the Wedding

The dress isn’t the only thing that’s white at many weddings. Some couples, including Ana and Larry, whiten their teeth for sparkling smiles on the big day. “If I were to whiten my teeth for a wedding, which I did, I would have a dentist do the whitening in an office,” Dr. Ferraz said. “That way, you can see results right away and not have to worry about placing whitening trays in your mouth every day.”

Because whitening can make your teeth feel more sensitive, Ana and Larry whitened their teeth a month before the big day. “We scheduled the appointment early to give our smiles time to adjust, which I recommend,” she says. “That way, by your actual wedding day, your teeth aren’t too sensitive.”

There are also some at-home options you can use, such as trays you can get from your dentist. You can also use whitening toothpaste or strips with the ADA Seal of Acceptance. That way, you know they are safe and effective. Ask your dentist which method is best for you, but above all, stay away from home remedies, which can actually do more harm than good.

Schedule a Dental Appointment Early On

“Weddings mark such momentous days in our lives, and our smiles are a big part of them,” Ana says. “The last thing you want to worry about is a toothache on your wedding day or on your honeymoon.”
If you don’t see a dentist regularly, the time leading up to your wedding can be a great time to start. Schedule an appointment a few months out to avoid painful and possibly expensive problems around your wedding. “I once cared for a patient whose wisdom teeth were infected less than two weeks before her wedding,” he says. “Having regular dental visits can help reduce your chances of a dental emergency or needing a procedure that close to the wedding.”  Need a dentist? Find one today!

Wedding Day Must-Haves

If your bridesmaids are putting together an emergency kit, there’s one item Ana recommends bringing along. “Have one of your bridesmaids carry floss and little compact mirror to make sure there’s nothing in your teeth and everything looks good,” she says. “That’s what I did.”
Regular brushing and cleaning between your teeth should help your breath stay fresh, but feel free to also pack some sugarless gum with the ADA Seal of Acceptance if you need a breath boost during the day. “Also, avoid food that can leave your breath not as fresh, like onions or garlic,” she says.

Commit to a Daily Dental Routine

Your wedding is just one small part of a long life with your partner. When it comes to your dental routine, don’t let it slide after tying the knot. Ana and Larry followed a healthy dental routine before the wedding.—and have kept up a sweet daily ritual together since then.  “We have our own little routine in the morning where we brush and floss together,” Ana says of her bathroom moments with Larry.

Sometimes, they even chat over the noisy buzzing of their electronic toothbrushes. “It can be hard to hear her but that doesn’t keep me from talking,” Larry says. “I always have something nice to say.”

Would You Like to Extend Your Existence?

A new nationwide study of obituaries has found that people with religious affiliations lived nearly four years longer than those with no ties to religion.

That four-year boost – found in an analysis of more than 1,000 obits from around the country – was calculated after taking into account the sex and  of those who died, two factors that have strong effects on lifespan.

The boost was slightly larger (6.48 years) in a smaller study of obituaries published in a Des Moines, Iowa, newspaper.

“Religious affiliation had nearly as strong an effect on  as gender does, which is a matter of years of life,” said Laura Wallace, lead author of the study and a doctoral student in psychology at The Ohio State University.

The study was published online today in the journal Social Psychological and Personality Science.

The researchers found that part of the reason for the boost in longevity came from the fact that many religiously affiliated people also volunteered and belonged to social organizations, which previous research has linked to living longer.

“The study provides persuasive evidence that there is a relationship between religious participation and how long a person lives,” said Baldwin Way, co-author of the study and associate professor of psychology at Ohio State.

In addition, the study showed how the effects of religion on longevity might depend in part on the personality and average religiosity of the cities where people live, Way said.

The first study involved 505 obituaries published in the Des Moines Register in January and February 2012. In addition to noting the age and any religious affiliation of those who died, the researchers also documented sex, marital status and the number of social and volunteer activities listed.

Results showed that those whose obit listed a religious affiliation lived 9.45 years longer than those who didn’t. The gap shrunk to 6.48 years after gender and marital status were taken into account.

The second study included 1,096 obituaries from 42 major cities in the United States published on newspaper websites between August 2010 and August 2011.

In this study, people whose obits mentioned a religious affiliation lived an average of 5.64 years longer than those whose obits did not, which shrunk to 3.82 years after gender and marital status were considered.

Many studies have shown that people who volunteer and participate in social groups tend to live longer than others. So the researchers combined data from both studies to see if the volunteer and social opportunities that religious groups offer might explain the longevity boost.

Results showed that this was only part of the reason why  lived longer.

“We found that volunteerism and involvement in social organizations only accounted for a little less than one year of the longevity boost that religious affiliation provided,” Wallace said. “There’s still a lot of the benefit of religious affiliation that this can’t explain.”

So what else explains how religion helps people live longer? It may be related to the rules and norms of many religions that restrict unhealthy practices such as alcohol and drug use and having sex with many partners, Way said.

In addition, “many religions promote stress-reducing practices that may improve health, such as gratitude, prayer or meditation,” he said.

The fact that the researchers had data from many cities also allowed them to investigate whether the level of religiosity in a city and a city’s “personality” could affect how religious  influenced longevity.

The findings showed that a key personality element related to longevity in each  was the importance placed on conformity to community values and norms.

In highly religious cities where conformity was important, religious people tended to live longer than non-religious people.

But in some cities there is a .

“The positive health effects of religion spill over to the non-religious in some specific situations,” Wallace said. “The spillover effect only occurs in highly religious cities that aren’t too concerned about everyone conforming to the same norms. In those areas, non-religious people tend to live as long as do religious .”

Way said there are limitations to the study, including the fact that it could not control for important factors related to longevity such as race and health behaviors. But a potential strength was that, unlike other studies,  was not self-reported, but was reported by the obituary writer.

Overall, the study provided additional support to the growing number of studies showing that  does have a positive effect on health, Wallace said.

 Explore further: Researcher studies the impact religion has on sleep quality

More information: Does Religion Stave Off the Grave? Religious Affiliation in One’s Obituary and Longevity. Social Psychological and Personality

This Precious Viral Picture Is Only Part of the Story

June 12 at 1:17 PM

For hours, Matt Sooter had been watching his two young children talk and play.

Maybe the conversation was about Queen Elsa or plastic Easter eggs — two topics his 4-year-old, Adalynn “Addy” Sooter, knew well. He doesn’t recall what the two were discussing that Saturday night at a hospice facility in Arkansas, where Addy lay dying after a long battle with Diffuse Intrinsic Pontine Glioma (DIPG), a rare tumor that starts in the brainstem.

But the father does remember the heart-wrenching moment that followed — when Addy’s 6-year-old brother, Jackson, told his younger sister good night for the last time.

Sooter, 29, said that Addy was tiring and that it was time for Jackson to head to sleep not far from his sister’s bedside. Jackson let his sister hold his hand, then he patted her forehead and said, “I love you.”

Sooter snapped a picture and posted it on Facebook on June 2 — capturing a heart-wrenching moment that has been shared across social media.

“A little boy should not have to say goodbye to his partner in crime, his play mate, his best friend, his little sister,” Sooter wrote in the post. “This isn’t how it’s supposed to be. But this is the broken world we live in.”

Sooter explained that his daughter’s symptoms were progressing quickly and urged family members and close friends to say their goodbyes.

He then asked for prayers for their family — specifically for Jackson.

“He doesn’t want to leave her side and we won’t make him,” he wrote.

Jackson knew that his sister had a tumor and that, if it kept growing, she would die. His father said that it made Jackson sad that his “sissy” would no longer be there but that he was glad “she was going to be with Jesus.”

Sooter said Tuesday in an interview with The Washington Post that about 20 minutes after Jackson tucked his sister in, her breathing changed — it became slower, more labored and more erratic. She opened her eyes a couple of times, but she was not coherent, Sooter said.

For the next several hours, Sooter and his wife, Chandra, sat on either side of their daughter’s bed. Then, just after 1 a.m. on June 3, Addy died.

They woke up Jackson about 4 a.m., deciding there was no reason to continue to stay at the hospice facility. It was time to go home, grieve and rest.

“We told Jackson that she had passed — that she was with Jesus and she wasn’t hurting anymore,” Sooter said. “He said ‘Goodbye, Sissy,’ and they went out to the car.”

Sooter posted a photo later that morning, showing Addy wearing a bright white sun hat.

“Our sweet little girl received the miraculous healing that we’ve all been praying for so long and ran into the arms of Jesus,” he wrote. “She passed from this life to the next just as she had lived: stubbornly but also peacefully, and surrounded by family. She wasn’t in any pain at the end.

“For those who were wishing to say goodbye I’m so sorry,” he added. “This all happened so much faster than we expected, but that in itself is a blessing because she suffered so little at the end.”

In 2016, the Sooters, from Rogers, Ark., noticed their daughter’s gait was a bit strange — she was swinging one of her legs instead of picking it up and planting it on the ground. The couple didn’t think much about it until her symptoms started to progress. The then-toddler soon started to lose coordination and motor function, her father said.

“She was still walking but only if she could hold your hand,” he said. “Otherwise, she would crawl.”

In November of that year, Addy was diagnosed with DIPG — a rare and incurable tumor that starts in the brain stem, which controls “breathing, heart rate and the nerves and muscles that help us see, hear, walk, talk and eat,” according to St. Jude Children’s Research Hospital. The hospital states that about 10 to 20 percent of pediatric brain tumors are DIPG.

For the next 19 months, Addy underwent 33 radiation treatments in Arkansas, then 10 experiential chemotherapy and immunotherapy treatments in Mexico to try to buy her more time, Sooter said.

But they also tried to enjoy the moments they had left with Addy — a Make-A-Wish vacation to Walt Disney World to meet her favorite “Frozen” queen and her first trip to the beach. Then, her father said, there were the little things that were on the 4-year-old’s “bucket list”: playing hide-and-seek and watching YouTube videos of people opening plastic Easter eggs and showing what was inside.

Eventually, the cancer spread to her spine. Her last week, the tumor in her back started pressing on the nerves in her spine, causing her pain, so her parents placed her in hospice care, Sooter said.

Following Addy’s death, her father said he and Chandra donated their daughter’s tumors to scientific research “in hopes of saving future children from a similar fate,” he wrote on Facebook. At Addy’s service Saturday in Rogers, her parents asked family members and friends to wear bright colors “or one of Addy’s favorite colors, pink, purple, or blue,” to celebrate her life.

Take A Walk On the Wild Side!

person standing in pathway
Photo by Lisa Fotios on

Want to Live a Longer Life? Science Says You Should Change the Way You Walk

It seems it’s wise to walk on the wild side.

Absurdly Driven looks at the world of business with a skeptical eye and a firmly rooted tongue in cheek. 

Health advice is everywhere.

Why, you probably have a Fitbit or an Apple Watch permanently attached to you, so that it can nag you into your optimal state.

It’s hard, though, to know all the right things to do.

The body has so many moving parts, after all.

Here, though, is some new advice from a group of scientists who studied walking.

Entitled Self-rated walking pace and all-cause, cardiovascular disease and cancer mortality: individual participant pooled analysis of 50 225 walkers from 11 population British cohorts, this piece of research suggests that walking simply isn’t enough to protect your health.

What may matter is how fast you walk.

The scientists say: “Walking at an average or brisk/fast pace was associated with a reduced risk of all-cause and CVD [Cardiovascular Disease] mortality, compared with reporting walking at a slow pace.”

One of the researchers, Emmanuel Stamatakis from the University of Sydney, wrote in the New Zealand Herald: “Compared to slow walkers, average pace walkers had a 20 percent lower risk of early death from any cause, and a 24 per cent lower risk of death from heart disease or stroke.”

You might be wondering just how fast you’re supposed to be walking.

A minimum of 6 kph — around 3.7 mph — is the minimum. You should feel slightly out of breath and just a little bit sweaty when you’re done.

A caveat is, of course, that this research depended on self-reported pace.

What seems clearer, though, is that strolling might be lovely for lovers, but doesn’t necessarily add to their health quotient.

Perhaps you, though, are an adherent of the 10,000 Steps theory.

You might believe that it’s the number of steps that matters, not the pace.

For you, I have bad news. That theory was, according to the British government, the invention of a Japanese pedometer manufacturer.

Life, like health, can seem like an arbitrary beast.

All one can suggest, therefore, is to try the walking on the wilder side thing and see if it makes any difference.

Oh, and cut down on the burgers, fries and ice cream.


It Could Be Healthy to Be Disgusted

A filthy first—the six common types of disgust that protect us from disease revealed

June 4, 2018, London School of Hygiene & Tropical Medicine
Credit: CC0 Public Domain

Disgust has long been recognised as an emotion which evolved to help our ancestors avoid infection, but now researchers have been able to show the human disgust system is likely to be structured around the people, practices and objects that pose disease risk.

This is the first time researchers have used the perspective of  to break the emotion of disgust into its component parts, and identify six common categories triggering disgust—the others being skin conditions such as having lesions or boils, food that is rotting or has gone off and having an atypical appearance such as deformity.

The researchers say these findings could help to target public health messaging, for example to encourage handwashing with soap or to counter the stigma associated with sickness.

The study, led by the London School of Hygiene & Tropical Medicine (LSHTM), surveyed more than 2,500 people online, listing 75 potentially ‘disgusting’ scenarios they might encounter, ranging from people with obvious signs of infection, pus-filled skin lesions and objects teeming with insects, to listening to sneezes and defecation in the open. Participants were asked to rate the strength of their disgust response to each scenario on a scale ranging from ‘no disgust’ to ‘extreme disgust’.

Of all the scenarios presented, infected wounds producing pus were rated as the most disgusting. The violation of hygiene norms—such as having bad body odour, was also found to be particularly disgusting.

By analysing participants’ responses, researchers were able to identify the six common categories of disgust, which each relate to regularly occurring types of infectious disease threat in our ancestral past. Historically for example, eating rotting food could have led to diseases like cholera, close contact with unhygienic people could have transmitted leprosy, promiscuous sexual practices could have put an individual at risk of syphilis and contact with open wounds could have led to the plague or smallpox infection.

The results confirm the ‘parasite avoidance theory’, in which disgust evolved in animals, encouraging them to adopt behaviours to reduce the risk of infection. This behaviour is replicated in humans where disgust signals us to act in specific ways, which minimise the risk of catching diseases.

Professor Val Curtis, senior author at LSHTM said: “Although we knew the emotion of disgust was good for us, here we’ve been able to build on that, showing that disgust is structured, recognising and responding to infection threats to protect us.

“This type of disease avoidance behaviour is increasingly evident in animals, and so leads us to believe it is evolutionarily very ancient.

“Increasing our understanding of disgust like this could provide new insights into the mechanisms of disease avoidance behaviour, and help us develop new methods to keep our environments, fellow animals and ourselves healthy.”

Interestingly, the survey results showed that there were gender differences in reactions to the disgusting scenarios that were presented, with women rating every category more disgusting than men. This is consistent with the fact that men are known to indulge in riskier behaviour than women, on average. The categories women in the study found most disgusting were risky sexual behaviour and animals carrying disease.

Before the study, the team predicted that types of disgust would correspond directly to categories of disease threat. However, they found that the types of disgust in the brain were more closely linked to the actions that people need to take to avoid disease—for example by not touching oozing skin lesions or approaching people with bad body odour. This corresponds to an evolutionary view of the emotions which are for action; emotions make us do things that put us in a better state with respect to our survival and reproduction.

Micheal de Barra, who co-led the research at LSHTM and now lectures Psychology at Brunel University London, said: “Although we only really came to understand how diseases transmit in the 19th century, it’s clear from these results that people have an intuitive sense of what to avoid in their environment. Our long coevolution with disease has ‘wired in’ this  of what can cause infection.”

Researchers say the findings could be used to develop instruments for measuring disgust, to investigate how disgust might vary across cultures and to understand how moral disgust, for example, relates to disease .

 Explore further: Disgust is way of communicating moral rather than self-interested motivation

More information: Curtis V, de Barra M. 2018. The structure and function of pathogen disgust. Philosophical Transactions of the Royal Society BBiological SciencesDOI: 10.1098/RSTB.2017.0208

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There Is A Way To Start Your Day

Occasionally, I wake up in the morning and it seems as if there is not a really good reason to get out of bed. Maybe it was the dream that I just had, or the problems of the past, or maybe the mistakes of my thoughts translated into words. What I have found is that if I linger on the errors of the past, it does not go well with the new day. I do try to learn and grow from what may have been imperfection, but each new day brings its own challenges, problems, and joys.


When we dwell too long our failures, we can lose sight of our destination and miss out on the full enjoyment of our successes and accomplishments. Take time to enjoy the new day!