Once a week.
Subscribe to our weekly newsletter.
Could a pathogen be the cause of Alzheimer’s disease?
Although we’ve had compelling evidence of this for decades, the pathogen hypothesis is finally being taken seriously.
Dementia has been with humanity for a long time. Records indicate ancient Greek and Roman physicians recognizing it, although at that time it was considered a natural part of aging. This attitude lasted for a long time. Alzheimer’s was only discovered as a pathology in 1906, by one Dr. Alois Alzheimer. Though much has been invested in understanding the condition, we still don’t know what causes it or how to cure it.
Today, about 5.5 million Americans live with the neurodegenerative disorder. By 2050, that number could be as high as 16 million. Besides the tremendous blow it delivers to the patient and their family, it also puts a terrible strain on the healthcare system.
Today, dementia sucks down $162 billion per year. Thanks to the “silver tsunami,” or the tremendous baby boomer generation climbing up into old age, dementia could cost the nation as much as $1.1 trillion by midcentury. As a result, Alzheimer’s research has increased dramatically in recent years. So what have we found so far?
We know that sticky globules called amyloid-beta plaques buildup in the brain and as they do, they begin to inhibit proper functioning. The more plaque accumulates, the more faculties a person loses, including chunks of memory, and over time the ability to make plans, drive, cook, bathe, dress one’s self, and eventually, even speak. These globules are aided by tangles of a protein called tau, which block nutrients from passing through neurons’ cell walls, essentially starving them. While tau tangles play an important role, the buildup of amyloid beta plaque is considered the main driver of the disease.
An artist’s conception of amyloid beta plaques. Credit: The National Institute on Aging.
For the last 40 years, a minority of researchers have considered the notion that a pathogen might be behind Alzheimer’s disease. Since the ‘90s, only a few labs across the US have been researching different pathogens which might be associated with the disorder. Note that few microbes can cross the blood-brain barrier—a special protective border which blocks harmful pathogens from entering the brain.
In 2011, Judith Miklossy and fellow researchers at the International Alzheimer’s Research Center, found evidence of spirochetes—a bacteria which can cross the blood-brain barrier, in the brains of former Alzheimer’s patients. This is a type of bacteria responsible for syphilis and Lyme’s disease, and is also known to cause all kinds of neurological issues if such diseases are left untreated, long-term.
In Miklossy’s work, Borrelia burgdorferi—the species of spirochete that causes Lyme, was identified in 451 out of the 495 Alzheimer’s-riddled brains they examined. Yet, her work at the time was derived by other researchers and until recently, she had difficulty securing funding.
Now however, with many promising new drugs proven ineffective, the field is looking for a new direction to explore, and this may be it. Dermatology professor Herbert Allen of Drexel University, suggested that if Alzheimer’s is indeed an infection, then a biofilm—a bacterial colony that huddles together in order to repel the immune system, could be considered evidence for the presence of an Alzheimer’s-causing bacteria.
These have been found in brains affected by Alzheimer’s. Amyloid plaque buildup therefore could be evidence of an immune response. The person might be infected with a certain kind of spirochete years or even decades earlier, which lies dormant, until the time it deems necessary to become active. This happens with syphilis and sometimes with Lyme.
One interesting finding has been that neurosurgeons performing procedures on those with the neurodegenerative condition, are actually more likely to fall victim to the Alzheimer’s themselves. A 2010 society of neurosurgeons report, found that their members were six times more likely to die from Alzheimer’s than any other condition. Yet currently, the medical establishment considers Alzheimer’s to be non-communicable.
Photomicrograph depicts a Treponema pallidum bacterium, a spirochete (5-15 micrometers long) which causes syphilis. Credit: Public Domain Files.
These days, two Harvard researchers have been looking into whether Alzheimer’s might originate with a colony of bacteria in the brain. To find out, they’ve had to launch a larger initiative. Assistant Professor of Neurology Robert Moir, teamed up with Professor of Child Neurology and Mental Retardation Rudolph Tanzi, both of Harvard Medical School and Massachusetts General Hospital.
They’re leading The Brain Microbiome Project, to find out what bacteria can be found in the brain and which are friendly and which aren’t. In a 2010 study, the duo proved that amyloid beta plaque is in fact an antimicrobial peptide.
Tanzi told The Daily Beast,
Turns out, our most ancient immune system, before we had adaptive immunity, had little baby proteins, antimicrobial peptides, and when they saw bacteria or a virus or a fungus, they would stick to it and clump it up into a ball and the peptide would grow into a spiral like spaghetti and trap it like a fly trapping a seed, and that is one of the most classic ways that our primitive innate immune system protects us.
The theory still has critics. There may be another reason for their outspokenness, besides the usual concerns. “The things creeping around in the brain will scare the heebie-jeebies out of you,” Moir told The Harvard Gazette. If an infection does prove to be the source of Alzheimer’s, we should be able to recognize it easily and wipe it out, before any neurological damage takes place, which means the end of Alzheimer’s as we know it.
Could a virus be causing Alzheimer’s? To hear more about that theory, click here.
All this from a wad of gum?
- Researchers recently uncovered a piece of chewed-on birch pitch in an archaeological dig in Denmark.
- Conducting a genetic analysis of the material left in the birch pitch offered a plethora of insights into the individual who last chewed it.
- The gum-chewer has been dubbed Lola. She lived 5,700 years ago; and she had dark skin, dark hair, and blue eyes.
Five thousand and seven hundred years ago, "Lola" — a blue-eyed woman with dark skin and hair — was chewing on a piece of pitch derived from heating birch bark. Then, this women spit her chewing gum out into the mud on an island in Denmark that we call Syltholm today, where it was unearthed by archaeologists thousands of years later. A genetic analysis of the chewing gum has provided us with a wealth of information on this nearly six-thousand-year-old Violet Beauregarde.
This represents the first time that the human genome has been extracted from material such as this. "It is amazing to have gotten a complete ancient human genome from anything other than bone," said lead researcher Hannes Schroeder in a statement.
"What is more," he added, "we also retrieved DNA from oral microbes and several important human pathogens, which makes this a very valuable source of ancient DNA, especially for time periods where we have no human remains."
In the pitch, researchers identified the DNA of the Epstein-Barr virus, which infects about 90 percent of adults. They also found DNA belonging to hazelnuts and mallards, which were likely the most recent meal that Lola had eaten before spitting out her chewing gum.
Insights into ancient peoples
The birch pitch was found on the island of Lolland (the inspiration for Lola's name) at a site called Syltholm. "Syltholm is completely unique," said Theis Jensen, who worked on the study for his PhD. "Almost everything is sealed in mud, which means that the preservation of organic remains is absolutely phenomenal.
"It is the biggest Stone Age site in Denmark and the archaeological finds suggest that the people who occupied the site were heavily exploiting wild resources well into the Neolithic, which is the period when farming and domesticated animals were first introduced into southern Scandinavia."
Since Lola's genome doesn't show any of the markers associated with the agricultural populations that had begun to appear in this region around her time, she provides evidence for a growing idea that hunter-gatherers persisted alongside agricultural communities in northern Europe longer than previously thought.
Her genome supports additional theories on northern European peoples. For example, her dark skin bolsters the idea that northern populations only recently acquired their light-skinned adaptation to the low sunlight in the winter months. She was also lactose intolerant, which researchers believe was the norm for most humans prior to the agricultural revolution. Most mammals lose their tolerance for lactose once they've weaned off of their mother's milk, but once humans began keeping cows, goats, and other dairy animals, their tolerance for lactose persisted into adulthood. As a descendent of hunter-gatherers, Lola wouldn't have needed this adaptation.
A hardworking piece of gum
A photo of the birch pitch used as chewing gum.
These findings are encouraging for researchers focusing on ancient peoples from this part of the world. Before this study, ancient genomes were really only ever recovered from human remains, but now, scientists have another tool in their kit. Birch pitch is commonly found in archaeological sites, often with tooth imprints.
Ancient peoples used and chewed on birch pitch for a variety of reasons. It was commonly heated up to make it pliable, enabling it to be molded as an adhesive or hafting agent before it settled. Chewing the pitch may have kept it pliable as it cooled down. It also contains a natural antiseptic, and so chewing birch pitch may have been a folk medicine for dental issues. And, considering that we chew gum today for no other reason than to pass the time, it may be that ancient peoples chewed pitch for fun.
Whatever their reasons, chewed and discarded pieces of birch pitch offer us the mind-boggling option of learning what someone several thousands of years ago ate for lunch, or what the color of their hair was, their health, where their ancestors came from, and more. It's an unlikely treasure trove of information to be found in a mere piece of gum.
The non-contact technique could someday be used to lift much heavier objects — maybe even humans.
- Since the 1980s, researchers have been using sound waves to move matter through a technique called acoustic trapping.
- Acoustic trapping devices move bits of matter by emitting strategically designed sound waves, which interact in such a way that the matter becomes "trapped" in areas of particular velocity and pressure.
- Acoustic and optical trapping devices are already used in various fields, including medicine, nanotechnology, and biological research.
Sound can have powerful effects on matter. After all, sound strikes our world in waves — vibrations of air molecules that bounce off of, get absorbed by, or pass through matter around us. Sound waves from a trained opera singer can shatter a wine glass. From a jet, they can collapse a stone wall. But sound can also be harnessed for delicate interactions with matter.
Since the 1980s, researchers have been using sound to move matter through a phenomenon called acoustic trapping. The method is based on the fact that sound waves produce an acoustic radiation force.
"When an acoustic wave interacts with a particle, it exerts both an oscillatory force and a much smaller steady-state 'radiation' force," wrote the American Physical Society. "This latter force is the one used for trapping and manipulation. Radiation forces are generated by the scattering of a traveling sound wave, or by energy gradients within the sound field."
When tiny particles encounter this radiation, they tend to be drawn toward regions of certain pressure and velocity within the sound field. Researchers can exploit this tendency by engineering sound waves that "trap" — or suspend — tiny particles in the air. Devices that do this are often called "acoustic tweezers."
Building a better tweezer
A study recently published in the Japanese Journal of Applied Physics describes how researchers created a new type of acoustic tweezer that was able to lift a small polystyrene ball into the air.
Tweezers of Sound: Acoustic Manipulation off a Reflective Surface youtu.be
It is not the first example of a successful "acoustic tweezer" device, but the new method is likely the first to overcome a common problem in acoustic trapping: sound waves bouncing off reflective surfaces, which disrupts acoustic traps.
To minimize the problems of reflectivity, the team behind the recent study configured ultrasonic transducers such that the sound waves that they produce overlap in a strategic way that is able to lift a small bit of polystyrene from a reflective surface. By changing how the transducers emit sound waves, the team can move the acoustic trap through space, which moves the bit of matter.
Move, but don't touch
So far, the device is only able to move millimeter-sized pieces of matter with varying degrees of success. "When we move a particle, it sometimes scatters away," the team noted. Still, improved acoustic trapping and other no-contact lifting technologies — like optical tweezers, commonly used in medicine — could prove useful in many future applications, including cell separation, nanotechnologies, and biological research.
Could future acoustic-trapping devices lift large and heavy objects, maybe even humans? It seems possible. In 2018, researchers from the University of Bristol managed to acoustically trap particles whose diameters were larger than the sound wavelength, which was a breakthrough because it surpassed "the classical Rayleigh scattering limit that has previously restricted stable acoustic particle trapping," the researchers wrote in their study.
In other words, the technique — which involved suspending matter in tornado-like acoustic traps — showed that it is possible to scale up acoustic trapping.
"Acoustic tractor beams have huge potential in many applications," Bruce Drinkwater, co-author of the 2018 study, said in a statement. "I'm particularly excited by the idea of contactless production lines where delicate objects are assembled without touching them."
Australian parrots have worked out how to open trash bins, and the trick is spreading across Sydney.
- If sharing learned knowledge is a form of culture, Australian cockatoos are one cultured bunch of birds.
- A cockatoo trick for opening trash bins to get at food has been spreading rapidly through Sydney's neighborhoods.
- But not all cockatoos open the bins; some just stay close to those that do.
Dumpster-diving trash parrots
In a study about these smart birds just published in Science, researchers define animal culture as "population-specific behaviors acquired via social learning from knowledgeable individuals."
Co-lead author of the study Barbara Klump of the Max Planck Institute of Animal Behavior in Konstanz, Germany says, "[C]ompared to humans, there are few known examples of animals learning from each other. Demonstrating that food scavenging behavior is not due to genetics is a challenge."
An opportunity presented itself in a video that co-author Richard Major of the Australian Museum shared with Klump and the other co-authors. In the video, a sulphur-crested cockatoo used its beak to pull up the handle of a closed garbage bin — using its foot as a wedge — and then walked back the lid sufficiently to flip it open, exposing the bin's edible contents.
Major has been studying Cacatua galerita for 20 years and says, "Like many Australian birds, sulphur-crested cockatoos are loud and aggressive." The study describes them as a "large-brained, long-lived, and highly social parrot." Says Major, "They are also incredibly smart, persistent, and have adapted brilliantly to living with humans."(Research regarding some of the ways in which wild animals adapt to the presence of humans has already produced some fascinating results and is ongoing.)
Clever cockie opens bin - 01 youtu.be
The researchers became curious about how widespread this behavior might be and saw a research opportunity. After all, says John Martin, a researcher at Taronga Conservation Society, "Australian garbage bins have a uniform design across the country, and sulphur-crested cockatoos are common across the entire east coast."
Martin continues, "In 2018, we launched an online survey in various areas across Sydney and Australia with questions such as, 'What area are you from, have you seen this behavior before, and if so, when?'"
Word gets around
Credit: magspace/Adobe Stock
Although the cockatoos' maneuver was reported in only three suburbs before 2018, by the end of 2019, people in 44 areas reported observing the behavior. Clearly, more and more cockatoos were learning how to successfully dumpster dive.
As further proof, says Klump, "We observed that the birds do not open the garbage bins in the same way, but rather used different opening techniques in different suburbs, suggesting that the behavior is learned by observing others." One individual bird in north Sydney invented its own method, and the scientists saw it grow in popularity throughout the local population.
To track individual birds, the researchers marked 500 cockatoos with small red dots. Subsequent observations revealed that not all cockatoos are bin-openers. Only about 10 percent of them are, and they are mostly males. The other cockatoos apparently restrict their education to a different lesson: hang around with a bin-opener, and you will get supper.
Thanks to the surveys, the researchers consider the entire project to be a valuable citizen-science experiment. "By studying this behavior with the help of local residents, we are uncovering the unique and complex cultures of their neighborhood birds."
The few seconds of nuclear explosion opening shots in Godzilla alone required more than 6.5 times the entire budget of the monster movie they ended up in.