Category: Neurology

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Can Total Joint Replacement Particles Reach the Brain?

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A study shows they do – but without causing cognitive decline

Photo by Towfiqu barbhuiya: https://www.pexels.com/photo/person-feeling-pain-in-the-knee-11349880/

Total joint replacement is a proven treatment to relieve chronic knee pain, but there have been concerns raised that particles from the device may migrate to the brain and cause memory problems. New research from Rush University shows that may not be a worry.

In a study published by Acta Biomaterialia, researchers found that particles in some people with total joint replacements traveled to the brain but did not cause cognitive decline.

Researchers did find an association of cobalt, a key element of most implants, with more Alzheimer’s disease pathology in the brain.

The particles, called wear debris, are caused by friction and movement in the joint, or, in some cases, corrosion. The newer materials used in joint replacements today make this less likely to occur.

“Implants have a very specific combination of metals such as cobalt, and when they show up together in one particle in the brain in the exact same composition that the implant is, we know it can’t come from any other source,” said Robin Pourzal, PhD, associate professor and director of implant materials analysis.

“For years, we’ve known that particles can deposit in tissues surrounding the joint, but this is the first study to look at the particles deposited in the brain.”

In working with Puja Agarwal, PhD, in the Rush Alzheimer’s Disease Center, the team took a closer look at what was happening cognitively in this group of people

The study included data collected among 701 deceased participants in the ongoing Memory and Aging Project conducted by David Bennett, MD, which include older adults residing in the greater Chicago area. The participants had no dementia at the beginning of the study and were followed annually with cognitive assessments using a 19-test battery, a standard collection of memory and thinking skill tests.

A total of 229 people in the study had a total hip, knee or shoulder replacement. The control group was made up of 472 people who had no total joint replacement. Due to a higher likelihood of the metal cobalt being found in total hip replacement, the participants were studied in two groups: 146 with hip replacements and 83 with knee or shoulder replacements. 

Pourzal notes that the collaboration was led by faculty members from the Department of Orthopedic Surgery, including leaders from Rush Orthopedic Research, in collaboration with colleagues from the Rush Alzheimer’s Disease Center and international partners.

“Total joint arthroplasty remains one of the most successful and life-changing interventions in modern medicine. But it does suggest that wear particles from the implant, particularly in certain hip replacements involving accelerated wear, may travel beyond the joint and warrant further study.”

Source: Rush University Medical Center

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Neuroscience Reports of Sex-dependent Effects Often Lack Evidence

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Photo by Daniil Onischenko on Unsplash

Studies in the behavioural and brain sciences reporting a major sex-dependent effect – that a drug, treatment or other intervention is more effective in one sex than another – are supported by appropriate evidence less than 25% of the time, an analysis finds.

The Proceedings of the National Academy of Sciences (PNAS) published the analysis of 200 recent articles with a claim of a sex- or gender-dependent effect in the title. The articles included studies on human and non-human subjects and spanned six brain-related research areas: behavioural sciences, clinical neurology, neurosciences, psychiatry, psychology and substance abuse.

“We found that studies in psychology had the highest rate of appropriate evidence – 39% of the published papers included statistical evidence to support the claim of a sex difference,” says Donna Maney, corresponding author of the study and professor of psychology at Emory University. “Research in neuroscience had the lowest rate of appropriate evidence, at just 18%.”

The low rate of appropriate evidence in neuroscience is particularly troubling, Maney says. She notes that claims of sex-dependent effects are more numerous in neuroscience, where such reports are currently being published at triple the rate seen in any other field.

“The high number of reports seen in neuroscience may be due to bias – neuroscientists looking harder for sex differences than other scientists,” Maney says. “But most current evidence shows that the brain is one of the least sexually differentiated organs in the body.”

Maney’s team was particularly alarmed by the number of calls for changes in clinical approaches that were based on faulty analyses. Many of the 200 articles they reviewed, for example, called for sex-specific approaches to suicide prevention, stress-related psychiatric disorders, substance-use disorder and psychopathy – all without providing statistical comparisons of effects across sex.

First author of the PNAS paper is Madeline Olivier, who did the work as an Emory student and has since graduated with a BS in psychology. 
 

Summary of findings

  • In 24% of the 200 papers, the effect compared statistically across sex and the results supported the claim of a sex-dependent effect.
  • In 9%, the researchers tested for a sex difference, but the results were missing.
  • In 9.5%, the sex difference in the effect was reported as not statistically significant, which was incompatible with the claim in the title.
  • In 57.5%, the sexes were not statistically compared — the researchers did not test the claim in the title at all.


A logical error 

Maney is a neuroscientist who studies hormonal and genetic influences on behaviour. For more than a decade, she has also focused on investigating how sex differences are tested for and reported in biomedical research. 

One issue she emphasises is that, instead of comparing the sexes directly with each other, researchers often test for the effect in each sex separately. Although it might make sense on the surface, the practice reduces the number of subjects to the point where a real effect can be missed. If the effect is detected in one sex but missed in the other, researchers are vulnerable to a logical error: that the effect differs between the sexes, when they have not been directly compared. 

To show that the sexes differ, females and males must be directly compared with each other in a statistical test. Most of the articles analysed by Maney and colleagues for the current PNAS paper did not do that. Instead, the researchers relied on the individual, within-sex tests – an invalid way of comparing the sexes that produces the illusion of a difference up to 50% of the time. “It’s no better than flipping a coin,” Maney says.

It’s also easy to miss true sex differences with a subgroup approach. For example, men and women could respond differently to a treatment but when the sample is divided in half and tested separately, the effect could be missed in both.

Maney cites the classic example of a large clinical trial showing that aspirin significantly reduced mortality from heart attacks. To illustrate the problem with the subgroup error, cardiologist Peter Sleight reanalysed the data by dividing participants into subgroups according to their astrological signs. Once the trial was split into 12 zodiac groups, the benefit of aspirin was no longer statistically detectable among the Libras and Geminis.

Sleight’s “findings” demonstrated how dividing a large group into subgroups can make a real effect disappear in some of the groups, even when the treatment is clearly beneficial. 

“This problem is not new,” says Maney. “I made the error myself until I learned about it. “Many researchers don’t receive training in how to test whether an effect differs between two groups.”
 

A simple solution

To provide evidence that an effect differs by sex, the effect must be statistically compared between males and females, Maney emphasises. Only that approach can show sufficient evidence for a sex difference.

She designed an open-source tool, housed on the web at sexdifference.org, to help guide researchers to verify sex-specific effects.

Maney’s interests extend beyond statistical sex comparisons.

“Ultimately,” she says, “I would like to see researchers not treat sex as the most important variable in a biomedical study. Variation in participants’ weights, ages or habits, for example, likely explains variation in the effect of a treatment better than which sex category they are in.”

Original written by Carol Clark

Source: Emory University

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Memory Decline Starts Earlier than You Think, New Research Suggests

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Researchers explore brain patterns through different ages to pinpoint where memories get mixed up

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Memory loss is usually thought of as something to address as a person ages. Slip-ups like forgetting someone’s name or recognising a familiar face but not remembering where you know them from are often viewed as issues that arise later in life.

New research by a team at Binghamton University reveals why memory shifts as we age – and that shift happens earlier in life than most people think, potentially at middle age.

“This is one of a growing list of studies highlighting that the period of middle age is really important for memory functioning and shouldn’t be ignored. For a long time, most studies have been focused on young adults versus older adults,” said Binghamton Associate Professor of Psychology Ian McDonough, co-author of a new study published in Cerebral Cortex.

McDonough and postdoctoral associate Destaw Mekbib tested a group of approximately 60 adults ages 18 to 74 by showing them faces paired with various objects and scenes. After a five-minute rest period, participants completed a memory test where they were prompted to pick the correct object or scene for each face – all while an MRI machine took readings of their hippocampal activity.

McDonough said the test mirrors how memories are formed. First, the brain records the new memory. Then, over a short period, the hippocampus replays the memory to stabilise it. Later, the brain retrieves the memory when needed.

The question the researchers had, however, was how aging affects the continuity of the information passing between those stages.

“We’re seeing a big decline in memory accuracy from the 20- to 30-year-old age group, to people in their 50s. Some of these hippocampal processes already start to decline by midlife,” McDonough said. “That suggests middle age is really a transition point.”

 Image Credit: Figure 1. Overview of the experiment. Reprinted from Mekbib and McDonough (2026), Cerebral Cortex, 36(7), bhag114, https://doi.org/10.1093/cercor/bhag114, used under CC BY-NC 4.0..

In the context of this research, middle-aged participants often paired a face with the wrong object or scene. They had recalled that they had seen it before, but not which pairing was correct, almost as an “I’ve seen something like this before” phenomenon. 

“It becomes hard because now all of these images on the screen during the test seem familiar,” McDonough said. “They know they’ve seen all of these before, but now what they have to remember is that specific link. And that’s where, as people age, they start to really show these errors.”

In comparing how younger and older people access memories, the researchers assumed that older adults would show weaker hippocampal activity, but this wasn’t exactly the case. What they did find was more interesting. When young adults made mistakes in the memory tests, it was because their brains were not activating the original memory patterns, which was expected.

However, when older adults made mistakes, their brains showed strong reactivation of those memory patterns. 

“The more they reactivate the hippocampus that’s consistent with encoding, the more likely they are to make these memory errors,” McDonough said. “So instead of that reactivation pattern being associated with better memory, it’s associated with those errors.”

McDonough said it’s not yet known why older adults can show strong hippocampal reactivation while making memory errors. Future follow-up studies could look at memory encoding, consolidation, and retrieval at the individual level, and explore how brain stimulation after learning impacts memory.

He noted that researchers should focus more on people in middle age, following them over many years, given this new information that memory can shift earlier in life.

“We really don’t have a good scientific understanding of what is happening in middle age, because the brain is not declining uniformly across this time, with some regions declining faster than others,” McDonough said. “Finding when those tipping points are is going to be important.”

Original written by David Hermanovitch

Source: Binghamton University

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Brain Activity Patterns may “Tag” Experiences for Later Memory Making During Sleep

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Theta oscillations during learning predicted which experiences were remembered after sleep

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The brain may “tag” experiences during learning to better consolidate the memory of them during sleep, according to a study published August 27th in the open access journal PLOS Biology by Dan Denis from the University of York, United Kingdom, and colleagues.

Most people do not remember every experience they’ve ever had. Instead, the brain consolidates some experiences – but not others – into long-term memory during sleep, suggesting that some experiences are “tagged” during learning for later encoding into memory.

To better understand how the brain selected experiences for later memory consolidation during sleep, the authors of this study collected data from 31 participants using electroencephalography (EEG) to measure patterns of brain activity. The participants learned sets of object-word pairs and were tested on them immediately and after a two-hour break. During one visit, participants were allowed to sleep, and in the other, they remained awake. As they learned and rested, the scientists analysed their EEG readings, matching the repetitive oscillations of brain activity during learning to those that were remembered after the participants’ sleep period.

The authors found that word-object pairs associated with theta oscillations between 3-8Hz during learning were more likely to be remembered after a period of sleep, but not after staying awake. The theta activity during learning predicted more coupling between slow neural oscillations during sleep and sleep spindles – bursts of brain activity. The slow oscillations and the sleep spindles were in turn associated with better memory performance after sleep. While the study only tested memory after two hours, and further studies would be needed to determine if memories persisted, the authors suggest that theta oscillations may indicate a mechanism by which the brain identifies experiences to consolidate into memories during sleep. 

The authors add, “How the brain decides what is important to remember and what can be forgotten is still a mystery. These new findings help to answer that question, by uncovering for the first time a signature of neural activity which instructs the brain which experiences to process during sleep and form into long-term memories.

“If we remembered everything that we experienced, our brains would quickly reach system overload. By selectively prioritising important events in our lives, be they emotionally salient or important for the future, we are able to use our past experiences to help guide our interactions in the world.

“Although it is typically adaptive to prioritise certain kinds of information, there are cases where this becomes maladaptive. For example, in depression, individuals tend to over allocate attentional resources to negative information, whilst disregarding or downplaying more positive experiences. Our new findings shed new light on the brain processes that dictate what is ultimately remembered, and may open new avenues for understanding and treating common mental health problems such as depression.”

Provided by PLOS

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Workers’ Pesticide Exposure Linked to 60-70% Heightened ALS Risk

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Increased risk of amyotrophic lateral sclerosis (ALS) associated with herbicides, insecticides
Men exposed to these chemicals may be twice as likely to develop ALS as unexposed men

Photo by Arjun Mj on Unsplash

Workplace exposure to pesticides (herbicides and insecticides) is linked to a 60-70% heightened risk of the most common form of motor neuron disease – amyotrophic lateral sclerosis, or ALS for short, finds a synthesis of the available evidence, published online in Occupational & Environmental Medicine.

Men who have been exposed to these chemicals may be twice as likely to develop the condition as those who haven’t been, the analysis indicates.

Although still relatively rare, the incidence of ALS – a progressive and rapidly fatal neurodegenerative disease for which there is no cure – has increased in recent years, note the researchers.

White the short term neurotoxic effects of pesticides, particularly insecticides, have been known for decades, there’s not a great deal of evidence on their potential long term neurotoxicity, they add.

In a bid to strengthen the evidence base, the researchers scrutinised research databases for relevant studies, including peer reviewed theses and scientific reports, on workplace exposure to pesticides and ALS, published between 1990 and 2025.

Eight case-control studies involving a total of 1734 cases of ALS, and 3 studies involving 457 cases of unspecified motor neuron disease, were retained for pooled data analysis from 767 initially screened articles.

This showed that compared with no exposure, any workplace exposure to pesticides was associated with a 60% heightened risk of ALS, based on the pooled data from 6 studies.

And based on the results of 3 studies, any exposure to high levels of pesticides was associated with a near tripling in risk compared with no pesticide exposure, whereas any exposure to lower levels was associated with a doubling in risk.

Compared with no exposure, exposure to herbicides was associated with a 70% heightened risk of developing the disease; exposure to either insecticides or fungicides was associated with a 60% heightened risk.

In studies that reported risk estimates stratified by sex, the pooled data analysis showed that exposed men were twice as likely as unexposed men (3 studies) to develop ALS.

But no increased risk was apparent in women who had been exposed to pesticides compared with those who hadn’t been.

The researchers highlight various limitations to their findings: the small number of available primary studies and their crude assessment of exposure, generally based on answers to a few limited questions.

“To strengthen the evidence on risk factors for ALS, primary studies particularly need methodological improvements on exposure assessment, on the selection of reference groups, and on adjustment for potential confounders, including analysis for interactions between risk factors,” they emphasise.

But they conclude: “The findings of this review add to the evidence that occupational exposure to pesticides may increase the risk of ALS and should encourage the implementation of interventions aimed at reducing exposure during occupational pesticide use.”

Source: The BMJ Group

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Researchers Create Microrobots to Repair Spinal Cord

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At the start and after three days: the top images show the uninjured spinal cord of a zebrafish; those in the middle show the injured spinal cord; and those at the bottom illustrate how the nerve cells grow thanks to the microrobots. (Image: ETH Zurich)

A research team from ETH Zurich and the University of Zurich (UZH) has developed a novel approach to treating spinal cord injuries: controllable microrobots deliver stem cells directly to the site of an injury, where they promote nerve cell regeneration. In animal experiments, this approach significantly improved mobility.

Spinal cord injuries can have devastating consequences for those affected. Nerve cells in the spinal cord rarely regenerate naturally, while scarring often prevents the regrowth of nerve fibres. Modern therapies attempt to influence implanted stem cells using electrical stimulation to promote the growth of new nerve cells. This approach has several drawbacks: it requires implanted electrodes, and the transplanted cells do not always survive or integrate properly into the existing tissue.

Cells and nanoparticles cleverly combined 

Researchers in Zurich are pursuing a new approach, which they have published in the journal Nature Materials. This involves combining therapeutic stem cells with magnetoelectric nanoparticles in such a way that the cells can be guided magnetically to the precise site of an injury and stimulate the stem cells to accelerate repair.

To achieve this, the researchers created a biohybrid microrobot, which combines living neural progenitor cells (NPCs) with a technical component in the form of specially engineered nanoparticles. The NPCs are derived from induced pluripotent stem cells (iPS cells), which are regular body cells reprogrammed in the laboratory to regain stem cell properties. These iPS cells have the potential to differentiate into various types of nervous system cells.

The nanoparticles consist of two layers: an inner layer that responds to magnetic fields and an outer layer that converts this response into electrical signals. By combining these special nanoparticles with the progenitor cells, the researchers fabricate what are known as NPCbots.

A lab the size of a chip

The researchers create the NPCbots in specialised labs on a surface measuring one square centimetre. This process can be illustrated graphically. “We place a reservoir in the centre where we trap the cells. Then we inject the nanoparticles and wait for the two components to bind,” explains Professor Salvador Pané i Vidal of the Multi-Scale Robotics Lab at ETH Zurich.

Illustration of how microrobots are fabricated on a lab-on-a-chip (LoC).  (Image: ETH Zurich)

After just thirty minutes, the NPCbots – each around six micrometres in size – are ready for use. “To scale up fabrication, we operate several lab-on-chip systems in parallel,” explains Hao Ye, senior scientist and the study’s first author. Depending on the test in question, the ETH researchers need hundreds of thousands of microrobots for cell-based studies and several million for animal experiments.

Injured zebrafish swim again

The team tested the NPCbots on zebrafish larvae with spinal cord injuries. The microrobots were injected precisely into the site of the fish’s injury, and electromagnetic fields were generated. For Pané Vidal, teamwork was vital to the experiment’s success: “Stephan Neuhauss and Jingjing Zang at the University of Zurich did extremely valuable work. They enabled us to demonstrate, in a well-characterised regenerative model system, how quickly cells differentiate using our method and how our bots repair the spinal cord.” In just three days, the zebrafish exhibited nearly normal swimming and exploratory behaviour.

Schematic illustration of nerve cell recovery in zebrafish and mice. (Image: ETH Zurich)

The researchers also tested the NPCbots on mice with completely severed spinal cords. Here, too, the results were very promising: after 28 days, the animals’ nerve cells had reconnected at the site of the injury. During this period, the treated mice exhibited increasingly normal movement patterns – their gait, stride length, coordination and exploratory behaviour improved significantly.

This result is particularly significant because, unlike in zebrafish, the mouse spinal cord does not normally regenerate. The treatment was well tolerated by the animals, with no evidence of any adverse effects or immune reactions. 

Success through minimally invasive stimulation 

These successes were made possible through electrical stimulation of stem cells, greatly enhancing their differentiation after transplantation. In this process, nanoparticles convert magnetic signals directly into electrical impulses that stimulate specific stem cells. When employing NPCbots, researchers need only apply external magnetic fields around the injury site, eliminating the need for implanted electrodes or cables in previous approaches. This is crucial because the spinal cord is extremely sensitive. “Microrobotic guidance makes the treatment more precise and minimally invasive,” Hao explains.

Magnetic fields are particularly well-suited for stimulating stem cells because they can penetrate tissue easily, and their frequency and field strength can be flexibly adjusted to the specific application. Once the progenitor cells have been stimulated and differentiated into nerve cells, the NPCbots essentially dissolve within the tissue. The researchers expect the nanoparticles to be stable and minimally reactive due to their barium titanate coating. Further studies will determine whether and how the particles are degraded or excreted over the long term.

The idea can be expanded as required

The results from animal experiments are extremely promising, but further research will be needed before NPCbots can be tested in humans. “In addition to many clinical aspects, we first need to test which magnetic fields work best in humans and determine the optimal stimulation duration,” Hao explains. Nevertheless, the researchers are already considering further applications: “The reproducible and scalable production of microrobots using our lab-on-a-chip system demonstrates that the platform’s application potential extends beyond basic research,” explains Professor Pané i Vidal. It could also be adapted for other biomedical applications – for example, in cardiology, oncology, wound healing and other targeted regenerative therapies. This could make these treatments safer, more controllable and more effective. 

By Franziska Schmid

Source: ETH Zurich

Categories : NeurologyTags :

Forgotten Memories Can Leave Silent Traces in the Brain

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Inaccessible memories can leave silent traces that reminders may revive or distort. Image generated by Johannes Felsenberg with the assistance of ChatGPT.

A forgotten memory is not always a vanished one. FMI neuroscientists investigating the fruit fly brain found that some memories become inaccessible while leaving a silent trace behind. The right reminder can bring them back, but misleading reminders can distort their recovery, producing false memories. The findings show how memories can be rebuilt from stored information and current clues, which may help explain why recall can sometimes alter what we remember.

Memory is not a perfect record. Some memories fade, while others remain hidden and can be brought back by reminders. But reminders can also distort what is remembered, and scientists still know little about how the brain accurately recovers memories or forms false ones.

In a new study, researchers in the group of Johannes Felsenberg trained fruit flies to associate one odour with mild electric shocks. Soon after training, the flies avoided that odour, but by 24 hours later the learned avoidance had faded. When the researchers later exposed the flies to the same odour as a reminder, the aversive memory was recovered, and the flies avoided the odour again.

The reminder only worked when key parts of the original setting, such as the chamber’s texture and lighting, were unchanged, suggesting that the fly brain used both the odour and its context to bring the memory back.

When the researchers looked inside the flies’ brain, they found that the original pattern of neural activity linked to the memory faded over time. At the same time, the memory left a silent trace in a different group of neurons. A specific reminder could reactivate this silent trace, restoring the brain activity that guides behaviour. These findings suggest that some forgotten memories are not erased but persist in the brain in a silent form that can later be recovered.

The team also showed how memory recovery can go wrong. During training, the flies had experienced a second odour that was not paired with shock. When researchers later used that harmless odour as the reminder, the flies began avoiding it too, as if it had predicted danger.

The neuronal pathways involved in forming the false memory were different from those used to recover the true memory. This suggests that, at least in flies, the brain may process recovered and distorted memories through distinct circuits.

This work does not show that fly memory is the same as human recollection, but it offers a circuit-level example of how remembering can depend on stored information, current cues and context, and why that process can sometimes distort past memories, the researchers say.

Source: Friedrich Miescher Institute for Biomedical Research

Categories : NeurologyTags :

From Flow to Function – When Brain Fluid Tells a Story

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Cerebrospinal fluid (CSF) protects the central nervous system (CNS). Credit: Scientific Animations Wiki CC-BY 4.0

Deep inside your brain, a clear liquid is constantly on the move. Cerebrospinal fluid (CSF) cushions the brain, delivers nutrients, removes waste and keeps pressure stable. Think of it as an internal tide, circulating through cavities in the brain and around the spinal cord to keep this delicate organ in balance. When that flow is disrupted, the consequences can be serious.

For decades, doctors have relied mainly on static brain scans to guide treatment. But structure tells only part of the story. Researchers at the University of Pretoria (UP) are now focusing on something more dynamic: how fluid actually moves.

Two of the most common neurosurgical conditions worldwide – brain tumours and hydrocephalus (a dangerous build-up of fluid in the brain) – are closely tied to disturbed CSF circulation. Tumours can block or distort the pathways through which fluid moves. Hydrocephalus represents a more obvious breakdown, where fluid accumulates and pressure rises. In both cases, symptoms such as headaches, problems with vision and neurological decline are not simply caused by the presence of disease, but by changes in pressure and pulsating flow inside the skull.

At the Brain Tumour and Translational Neuroscience Centre (BTC@UP), scientists are investigating an unexpected window into this hidden system – without inserting monitors into the brain: the eye.

Professor Llewellyn Padayachy, Head of the Department of Neurosurgery at BTC@UP explains: “The optic nerve, which connects the eye to the brain, is surrounded by the same protective layers as the brain itself. CSF flows along this nerve, meaning changes in brain pressure can subtly affect structures at the back of the eye. By using advanced, non-invasive eye imaging, researchers can detect signs of altered fluid flow and pressure without inserting monitors into the brain.”

This matters enormously for children with hydrocephalus and patients with brain tumours who require long-term monitoring. It offers a safer, repeatable way to track disease progression and treatment response. In low- and middle-income countries, where hydrocephalus is common but access to advanced imaging and neurosurgical infrastructure may be limited, such non-invasive tools could reduce reliance on costly technology while still delivering meaningful clinical insight.

The research also helps refine innovation. Modern shunts and endoscopic procedures increasingly aim to restore more natural fluid circulation rather than simply drain excess fluid. Objective eye-based markers provide measurable ways to evaluate whether these technologies truly improve flow.

While the link between the eye and brain pressure has long been recognised, what is new is the integration of advanced imaging, physiological modelling and continuous monitoring. This approach treats CSF flow as a living system, and shifts care from reacting to late damage towards detecting subtle change earlier.

Why this research matters

This work reframes brain disease through a simple but powerful idea: health depends on flow. By learning to read the movements of brain fluid, even through the eye, researchers are paving the way for safer monitoring, smarter surgery and more equitable neurological care worldwide.

Fast fact

The most common surgical treatment for hydrocephalus is the surgical placement of a shunt, which has one of the highest failure rates of any medical device on the market.

Provided by the University of Pretoria.

Categories : NeurologyTags :

Hitting a Nerve – in a Good Way: Vagus Nerve Calms Lung Inflammation

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Stimulating a nerve in the ear may alleviate lung inflammation in mice

In the mouse vagal ganglion, sensory neurons labeled from the auricular skin (green) and the lung (magenta) are located in close proximity (white circles). These findings suggest a possible anatomical basis for how sensation from the auricular skin may influence airway immune responses via nerves that directly supply the lung. (Rintaro Shibuya, Kim Lab, Icahn School of Medicine at Mount Sinai.)

Neuroimmunology, the study of interactions between the nervous and immune systems, is a rapidly growing field enabling new approaches for monitoring and treating inflammatory diseases. In a recent study, scientists showed that in mice, stimulating a nerve in the external ear may help to ease inflammation in the lungs. Based on these findings, which are published in Immunity, the researchers are designing a clinical trial to test a novel device for treating asthma.

“We are always looking for new therapeutics and devices that can kickstart the body and get it back to doing what it needs to do,” says senior and corresponding author Brian S. Kim of the Icahn School of Medicine at Mount Sinai in New York. “This research suggests a new way to target the body’s inflammatory pathways.”

Neuroimmunology took off after research revealed how the vagus nerve – the ‘information superhighway’ that connects the brain to major organs and controls their functions – helps to regulate the immune system.

“The vagus nerve is hardwired to be a homeostatic organ,” says Kim. “You can think of it like a rheostat that integrates everything and keeps it in check.”

For this study, the authors leveraged the unique characteristics of the auricular vagus nerve, the only branch of the vagus nerve that reaches the surface of the skin. This nerve is found in the cymba conchae, the small, bowl-shaped depression in the upper part of the outer ear.

“Given the strong connection between the lungs and the vagus nerve, we sought to use the lungs as a test case to study these mechanisms and see whether manipulating the auricular branch could modulate inflammation,” says Kim.

The team studied these connections in mouse models using several approaches, including chemogenetics and optogenetics, to see what happened when the auricular vagus nerve was stimulated in the presence of an allergen. Their work showed that stimulation of the nerve increased levels of a neurotransmitter protein called CGRPβ in the airway. This, in turn, reduced inflammation in the lung. When the nerve fibres were instead inhibited, airway disease was exacerbated.

“Our findings reveal a previously unrecognised neuroimmune reflex linking the skin and the lung,” says first author Rintaro Shibuya of Kyoto University. “I hope this work inspires new ways of thinking about vagus nerve biology and future bioelectronic and neuroimmune therapies for inflammatory diseases.”

Although the research is in early stages, the team says this approach has many potential applications for treating diseases characterized by inflammation, including pulmonary fibrosis, inflammatory bowel disease, and rheumatoid arthritis.

“We still don’t know the extent to which the effects of stimulating the auricular vagus nerve go beyond the airway, but it’s something we will continue to study in the lab,” says Kim.

Source: Kyoto University

Categories : Mental Health NeurologyTags :

Certain Mental Disorders Are Associated with Faster Brain Ageing

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Increased brain ageing was associated with dementia, addiction and psychiatric disorders like schizophrenia

Generated with Gencraft AI

People with dementia, mild cognitive impairment, alcohol addiction, or psychiatric disorders such as schizophrenia show increased brain ageing, each in specific patterns within the brain, according to a study published July 21st in the open access journal PLOS Medicine by Shile Qi from the Nanjing University of Aeronautics and Astronautics, China, and colleagues.

Some conditions can make the brain age faster. Scientists calculate how old the brain is relative to the body using the predictive age difference (PAD), the difference between chronological age and the age predicted by brain imaging, where a positive PAD indicates that ageing is accentuated or increased. To better understand how brain disorders and divergences might affect brain ageing, the authors of this study collected structure magnetic resonance imaging (MRI) data from 45 900 controls across several brain imaging banks, and compared them with those of 2698 patients with different brain conditions and differences, including attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), alcohol or tobacco addiction, Alzheimer’s disease (AD), mild cognitive impairment (MCI), schizophrenia, bipolar disorder or major depressive disorder.

The authors found that neurodegenerative disorders of AD and MCI had the largest association with a high PAD. Addiction and psychiatric disorders were also associated with increased PAD. In contrast, there were no differences in PAD between people with ADHD or ASD and controls.

The researchers also looked at PAD values in specific areas of the brain, and examined which genes showed increased expression in people with different brain conditions. The prefrontal cortex showed higher PAD across brain disorders. Higher PAD in the frontal and temporal lobes was associated with psychiatric disorders, while high PAD in the frontal and occipital cortex was associated with dementia. Addiction was connected with high PAD in the default mode network, and in the salience network and the putamen and thalamus. There were also differences in gene transcription that associated with specific conditions and divergences. While the results are correlational, and not causal, and while some conditions such as psychiatric disorders and addiction have high co-occurrence, the author suggest that understanding more about PAD could help provide biomarkers for commonly occurring brain disorders.

The authors add, “Different neurological disorders appear to leave different signatures on the brain ageing clock, which may help researchers better understand the neural and biological pathways involved in these conditions.”

Provided by PLOS