Is Alzheimer's Research On the Wrong Track?
"The graveyard of hope." That's what experts call the quest for effective Alzheimer's treatments, a two-decade effort that has been marked by one costly and high-profile failure after another. Nearly all of the drugs tested target one of the key hallmarks of Alzheimer's disease: amyloid plaques, the barnacle-like proteins long considered the culprits behind the memory-robbing ravages of the disease. Yet all the anti-amyloid drugs have flopped miserably, prompting some scientists to believe we've fingered the wrong villain.
"We're flogging a dead horse," says Peter Davies, PhD, an Alzheimer's researcher at the Feinstein Institute for Medical Research in New York. "The fact that no one's gotten better suggests that you have the wrong mechanism."
If the naysayers are right, how could a scientific juggernaut of this magnitude—involving hundreds of scientists in academia and industry at a cost of tens of billions of dollars--be so far off the mark? There are no easy answers, but some experts believe this calls into question how research is conducted and blame part of the failure on the insular culture of the scientific aristocracy at leading academic institutions.
"The field began to be dominated by narrow views."
"The field began to be dominated by narrow views," says George Perry, PhD, an Alzheimer's researcher and dean of the College of Sciences at the University of Texas in San Antonio. "The people pushing this were incredibly articulate, powerful and smart. They'd go to scientific meetings and all hang around with each other and they'd self-reinforce."
In fairness, there was solid science driving this. Post-mortem analyses of Alzheimer's patients found their brains were riddled with amyloid plaques. People with a strong family history of Alzheimer's had genetic mutations in the genes that encode for the production of amyloids. And in animal studies, scientists found that if amyloids were inserted into the brains of transgenic mice, they exhibited signs of memory loss. Remove the amyloids and they suddenly got better. This body of research helped launch the Amyloid Cascade Hypothesis of the disease in 1992—which has driven research ever since.
Scientists believed that the increase in the production of these renegade proteins, which form sticky plaques and collect outside of the nerve cells in the brain, triggers a series of events that interfere with the signaling system between synapses. This seems to prevent cells from relaying messages or talking to each other, causing memory loss, confusion and increasing difficulties doing the normal tasks of life. The path forward seemed clear: stop amyloid production and prevent disease progression. "We were going after the obvious abnormality," says Dr. David Knopman, a neurologist and Alzheimer's researcher at the Mayo Clinic in Rochester, Minnesota.
"Why wouldn't you do that?" Why ideed.
In hindsight, though, there was no real smoking gun—no one ever showed precisely how the production of amyloids instigates the destruction of vital brain circuits.
"Amyloids are clearly important," says Perry, "but they have not proven to be necessary and sufficient for the development of this disease."
Ironically, there have been hints all along that amyloids may not be toxic bad boys.
A handful of studies revealed that amyloid proteins are produced in healthy brains to protect synapses. Research on animal models that mimic diseases suggest that certain forms of amyloids can ease damage from strokes, traumatic brain injuries and even heart attacks. In a 2013 study, to cite just one example, a Stanford University team injected synthetic amyloids into paralyzed mice with an inflammatory disorder similar to multiple sclerosis. Instead of worsening their symptoms—which is what the researchers expected to happen--the mice could suddenly walk again. Remove the amyloids, and they became paralyzed once more.
Still other studies suggest amyloids may actually function as molecular guardians dispatched to silence inflammation and mop up errant cells after an injury as part of the body's waste management system. "The presence of amyloids is a protective response to something going wrong, a threat," says Dr. Dale Bredesen, a UCLA neurologist. "But the problem arises when the threats are chronic, multiple, unrelenting and intense. The defenses the brain mounts are also intense and these protective mechanisms cross the line into causing harm, and killing the very synapses and brain cells the amyloid was called up to protect."
So how did research get derailed?
In a way, we're victims of our own success, critics say.
Early medical triumphs in the heady post-World War II era, like the polio vaccine that eradicated the crippling childhood killer, or antibiotics, reinforced the magic bullet idea of curing disease--find a target and then hit it relentlessly. That's why when scientists made the link between amyloids and disease progression, Big Pharma jumped on the bandwagon in hopes of inventing a trillion-dollar drug. This approach is fine when you have an acute illness, like an infectious disease that's caused by one agent, but not for something as complicated as Alzheimer's.
The other piece of the problem is the dwindling federal dollars for basic research. Maverick scientists find it difficult to secure funding, which means that other possible targets or approaches remained relatively unexplored—and drug companies are understandably reluctant to sponsor fishing expeditions with little guarantee of a payoff. "Very influential people were driving this hypothesis," says Davies, and with careers on the line, "there was not enough objectivity or skepticism about that hypothesis."
Still, no one is disputing the importance of anti-amyloid drugs—and ongoing clinical trials, like the DIAN and A4 studies, are intervening earlier in patients who are at a high risk of developing Alzheimer's, but before they're symptomatic. "The only way to know if this is really a dead end is if you take it as far as it can go," says Knopman. "I believe the A4 study is the proper way to test the amyloid hypothesis."
But according to some experts, the latest thinking is that Alzheimer's is triggered by a range of factors, including genetics, poor diet, stress and lack of exercise.
"Alzheimer's is like other chronic age-related diseases and is multi-factorial," says Perry. "Modulating amyloids may have value but other avenues need to be explored."
Stronger psychedelics that rewire the brain, with Doug Drysdale
A promising development in science in recent years has been the use technology to optimize something natural. One-upping nature's wisdom isn't easy. In many cases, we haven't - and maybe we can't - figure it out. But today's episode features a fascinating example: using tech to optimize psychedelic mushrooms.
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These mushrooms have been used for religious, spiritual and medicinal purposes for thousands of years, but only in the past several decades have scientists brought psychedelics into the lab to enhance them and maximize their therapeutic value.
Today’s podcast guest, Doug Drysdale, is doing important work to lead this effort. Drysdale is the CEO of a company called Cybin that has figured out how to make psilocybin more potent, so it can be administered in smaller doses without side effects.
The natural form of psilocybin has been studied increasingly in the realm of mental health. Taking doses of these mushrooms appears to help people with anxiety and depression by spurring the development of connections in the brain, an example of neuroplasticity. The process basically shifts the adult brain from being fairly rigid like dried clay into a malleable substance like warm wax - the state of change that's constantly underway in the developing brains of children.
Neuroplasticity in adults seems to unlock some of our default ways of of thinking, the habitual thought patterns that’ve been associated with various mental health problems. Some promising research suggests that psilocybin causes a reset of sorts. It makes way for new, healthier thought patterns.
So what is Drysdale’s secret weapon to bring even more therapeutic value to psilocybin? It’s a process called deuteration. It focuses on the hydrogen atoms in psilocybin. These atoms are very light and don’t stick very well to carbon, which is another atom in psilocybin. As a result, our bodies can easily breaks down the bonds between the hydrogen and carbon atoms. For many people, that means psilocybin gets cleared from the body too quickly, before it can have a therapeutic benefit.
In deuteration, scientists do something simple but ingenious: they replace the hydrogen atoms with a molecule called deuterium. It’s twice as heavy as hydrogen and forms tighter bonds with the carbon. Because these pairs are so rock-steady, they slow down the rate at which psilocybin is metabolized, so it has more sustained effects on our brains.
Cybin isn’t Drysdale’s first go around at this - far from it. He has over 30 years of experience in the healthcare sector. During this time he’s raised around $4 billion of both public and private capital, and has been named Ernst and Young Entrepreneur of the Year. Before Cybin, he was the founding CEO of a pharmaceutical company called Alvogen, leading it from inception to around $500 million in revenues, across 35 countries. Drysdale has also been the head of mergers and acquisitions at Actavis Group, leading 15 corporate acquisitions across three continents.
In this episode, Drysdale walks us through the promising research of his current company, Cybin, and the different therapies he’s developing for anxiety and depression based not just on psilocybin but another psychedelic compound found in plants called DMT. He explains how they seem to have such powerful effects on the brain, as well as the potential for psychedelics to eventually support other use cases, including helping us strive toward higher levels of well-being. He goes on to discuss his views on mindfulness and lifestyle factors - such as optimal nutrition - that could help bring out hte best in psychedelics.
Show links:
Doug Drysdale full bio
Doug Drysdale twitter
Cybin website
Cybin development pipeline
Cybin's promising phase 2 research on depression
Johns Hopkins psychedelics research and psilocybin research
Mets owner Steve Cohen invests in psychedelic therapies
Doug Drysdale, CEO of Cybin
How the body's immune resilience affects our health and lifespan
Story by Big Think
It is a mystery why humans manifest vast differences in lifespan, health, and susceptibility to infectious diseases. However, a team of international scientists has revealed that the capacity to resist or recover from infections and inflammation (a trait they call “immune resilience”) is one of the major contributors to these differences.
Immune resilience involves controlling inflammation and preserving or rapidly restoring immune activity at any age, explained Weijing He, a study co-author. He and his colleagues discovered that people with the highest level of immune resilience were more likely to live longer, resist infection and recurrence of skin cancer, and survive COVID and sepsis.
Measuring immune resilience
The researchers measured immune resilience in two ways. The first is based on the relative quantities of two types of immune cells, CD4+ T cells and CD8+ T cells. CD4+ T cells coordinate the immune system’s response to pathogens and are often used to measure immune health (with higher levels typically suggesting a stronger immune system). However, in 2021, the researchers found that a low level of CD8+ T cells (which are responsible for killing damaged or infected cells) is also an important indicator of immune health. In fact, patients with high levels of CD4+ T cells and low levels of CD8+ T cells during SARS-CoV-2 and HIV infection were the least likely to develop severe COVID and AIDS.
Individuals with optimal levels of immune resilience were more likely to live longer.
In the same 2021 study, the researchers identified a second measure of immune resilience that involves two gene expression signatures correlated with an infected person’s risk of death. One of the signatures was linked to a higher risk of death; it includes genes related to inflammation — an essential process for jumpstarting the immune system but one that can cause considerable damage if left unbridled. The other signature was linked to a greater chance of survival; it includes genes related to keeping inflammation in check. These genes help the immune system mount a balanced immune response during infection and taper down the response after the threat is gone. The researchers found that participants who expressed the optimal combination of genes lived longer.
Immune resilience and longevity
The researchers assessed levels of immune resilience in nearly 50,000 participants of different ages and with various types of challenges to their immune systems, including acute infections, chronic diseases, and cancers. Their evaluation demonstrated that individuals with optimal levels of immune resilience were more likely to live longer, resist HIV and influenza infections, resist recurrence of skin cancer after kidney transplant, survive COVID infection, and survive sepsis.
However, a person’s immune resilience fluctuates all the time. Study participants who had optimal immune resilience before common symptomatic viral infections like a cold or the flu experienced a shift in their gene expression to poor immune resilience within 48 hours of symptom onset. As these people recovered from their infection, many gradually returned to the more favorable gene expression levels they had before. However, nearly 30% who once had optimal immune resilience did not fully regain that survival-associated profile by the end of the cold and flu season, even though they had recovered from their illness.
Intriguingly, some people who are 90+ years old still have optimal immune resilience, suggesting that these individuals’ immune systems have an exceptional capacity to control inflammation and rapidly restore proper immune balance.
This could suggest that the recovery phase varies among people and diseases. For example, young female sex workers who had many clients and did not use condoms — and thus were repeatedly exposed to sexually transmitted pathogens — had very low immune resilience. However, most of the sex workers who began reducing their exposure to sexually transmitted pathogens by using condoms and decreasing their number of sex partners experienced an improvement in immune resilience over the next 10 years.
Immune resilience and aging
The researchers found that the proportion of people with optimal immune resilience tended to be highest among the young and lowest among the elderly. The researchers suggest that, as people age, they are exposed to increasingly more health conditions (acute infections, chronic diseases, cancers, etc.) which challenge their immune systems to undergo a “respond-and-recover” cycle. During the response phase, CD8+ T cells and inflammatory gene expression increase, and during the recovery phase, they go back down.
However, over a lifetime of repeated challenges, the immune system is slower to recover, altering a person’s immune resilience. Intriguingly, some people who are 90+ years old still have optimal immune resilience, suggesting that these individuals’ immune systems have an exceptional capacity to control inflammation and rapidly restore proper immune balance despite the many respond-and-recover cycles that their immune systems have faced.
Public health ramifications could be significant. Immune cell and gene expression profile assessments are relatively simple to conduct, and being able to determine a person’s immune resilience can help identify whether someone is at greater risk for developing diseases, how they will respond to treatment, and whether, as well as to what extent, they will recover.