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Comment by Dr. Krishna Kumari Challa on September 2, 2025 at 7:29am

The reason why there are high levels of neutrophils in the meninges is unclear. One explanation could be that they are recruited by microglia, a type of immune cell unique to the brain.

Another possible explanation is that chronic stress may cause microhemorrhages, tiny leaks in brain blood vessels, and that neutrophils—the body's 'first responders'—arrive to fix the damage and prevent any further damage. These neutrophils then become more rigid, possibly getting stuck in brain capillaries and causing further inflammation in the brain.

These new findings show that these 'first responder' immune cells leave the skull bone marrow and travel to the brain, where they can influence mood and behavior.

Stacey L. Kigar et al, Chronic social defeat stress induces meningeal neutrophilia via type I interferon signaling in male mice, Nature Communications (2025). DOI: 10.1038/s41467-025-62840-5

Part 2

Comment by Dr. Krishna Kumari Challa on September 2, 2025 at 7:29am

Depression linked to presence of immune cells in the brain's protective layer

Immune cells released from bone marrow in the skull in response to chronic stress and adversity could play a key role in symptoms of depression and anxiety, say researchers.

The discovery—found in a study in mice—sheds light on the role that inflammation can play in mood disorders and could help in the search for new treatments, in particular for those individuals for whom current treatments are ineffective.

Around 1 billion people will be diagnosed with a mood disorder such as depression or anxiety at some point in their life. While there may be many underlying causes, chronic inflammation—when the body's immune system stays active for a long time, even when there is no infection or injury to fight—has been linked to depression. This suggests that the immune system may play an important role in the development of mood disorders.

Previous studies have highlighted how high levels of an immune cell known as a neutrophil, a type of white blood cell, are linked to the severity of depression. But how neutrophils contribute to symptoms of depression is currently unclear.

In research published in Nature Communications, a team of scientists  tested the hypothesis that chronic stress can lead to the release of neutrophils from bone marrow in the skull. These cells then collect in the meninges—membranes that cover and protect your brain and spinal cord—and contribute to symptoms of depression.

As it is not possible to test this hypothesis in humans, the team used mice exposed to chronic social stress. In this experiment, an 'intruder' mouse is introduced into the home cage of an aggressive resident mouse. The two have brief daily physical interactions and can otherwise see, smell, and hear each other.

The researchers found that prolonged exposure to this stressful environment led to a noticeable increase in levels of neutrophils in the meninges, and that this was linked to signs of depressive behavior in the mice. Even after the stress ended, the neutrophils lasted longer in the meninges than they did in the blood.

Analysis confirmed the researchers' hypothesis that the meningeal neutrophils—which appeared subtly different from those found in the blood—originated in the skull.

Further analysis suggested that long-term stress triggered a type of immune system 'alarm warning' known as type I interferon signaling in the neutrophils. Blocking this pathway—in effect, switching off the alarm—reduced the number of neutrophils in the meninges and improved behavior in the depressed mice.

Further analysis suggested that long-term stress triggered a type of immune system 'alarm warning' known as type I interferon signaling in the neutrophils. Blocking this pathway—in effect, switching off the alarm—reduced the number of neutrophils in the meninges and improved behavior in the depressed mice.

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Part 1

Comment by Dr. Krishna Kumari Challa on September 2, 2025 at 7:19am

In a second study, the working group also identified the changes in the brain that are associated with criminal behavior in frontotemporal dementia. This study was published in Human Brain Mapping.

Persons exhibiting criminal behavior showed larger atrophy in the temporal lobe, indicating that criminal behavior might be caused by so-called disinhibition, i.e., the loss of normal restraints or inhibitions, leading to a reduced ability to regulate one's behavior, impulses, and emotions.

Disinhibition can manifest as acting impulsively, without thinking through the consequences, and behaving in ways that are inappropriate for the situation.

One has to prevent a further stigmatization of persons with dementia. Of note, most offenses committed were minor, such as indecent behavior, traffic violations, theft, damage to property, but also physical violence or aggression occurred

Hence, sensitivity for this topic as possible early signs of dementia and earliest diagnosis and treatment are of the uttermost importance. Besides early diagnosis and treatment of persons affected, one has to discuss adaptations of the legal system, such as increasing awareness of offenses due to those diseases, and taking into account diseases in respective penalties and in jails, say the researchers.

 Matthias L. Schroeter et al, Criminal minds in dementia: A systematic review and quantitative meta-analysis, Translational Psychiatry (2025). DOI: 10.1038/s41398-025-03523-z

Karsten Mueller et al, Criminal Behavior in Frontotemporal Dementia: A Multimodal MRI Study, Human Brain Mapping (2025). DOI: 10.1002/hbm.70308

Part 2

Comment by Dr. Krishna Kumari Challa on September 2, 2025 at 7:17am

Criminal behavior in patients with dementia

Don't blame the criminals for everything they do. 

A suspected perpetrator who can barely remember his name, several traffic violations committed by a woman in her mid-fifties who is completely unreasonable and doesn't understand her behavior—should such cases be brought before a court? And how does the state deal with people who commit acts of violence without meaning to?

Those questions come to mind if one hears those examples from everyday clinical praxis with persons suffering from dementia. Neurodegenerative diseases might affect several functions of the brain, ranging from memory in Alzheimer's disease to behavior, such as in behavioral variant frontotemporal dementia, and to sensorimotor function in Parkinson's disease.

One of the most interesting consequences of these alterations is the fact that persons affected by these diseases might develop criminal risk behavior like harassment, traffic violation, theft or even behavior causing harm to other people or animals, even as the first disease sign.

If persons violate social or legal norms due to changes in behavior, personality and cognition, these incidents may have a substantial impact on this person's family and social surroundings and may lead to prosecution.

Researchers  investigated this problem in a broad meta-analysis that included 14 studies with 236,360 persons from different countries (U.S.A., Sweden and Finland, Germany and Japan). The work is published in the journal Translational Psychiatry.

Their systematic literature review revealed that criminal risk behavior prevalence is more frequent in early disease course than in the general population, but declines thereafter below population levels. Therefore, criminal behavior committed for the first time at mid-age could be an indicator of incident dementia, requiring earliest diagnosis and therapy.

The team shows that the prevalence of criminal risk behaviors was highest in behavioral variant frontotemporal dementia (>50%), followed by semantic variant primary progressive aphasia (40%), but rather low in vascular dementia and Huntington's disease (15%), Alzheimer's disease (10%), and lowest in Parkinsonian syndromes (<10%).

Criminal risk behavior in frontotemporal dementia is most likely caused by the neurodegenerative disease itself. Most of the patients showed criminal risk behavior for the first time in their life and had no previous records of criminal activity.

The prevalence seems to be more frequent in frontotemporal dementia and Alzheimer's disease in early disease course than in the general population before diagnosis, presumably in pre-stages, such as mild behavioral or cognitive impairment, but declines thereafter, finally leading to lower prevalence in dementia after diagnosis if compared with the general population.

The researchers also found that criminal risk behaviour is more frequent in men than in women in dementia. After diagnosis, men showed four times more criminal risk behaviour than women in frontotemporal dementia and seven times more in Alzheimer's disease.

Part 1

Comment by Dr. Krishna Kumari Challa on September 2, 2025 at 7:10am

Neuroscientists show for first time that precise timing of nerve signals determines how brain processes information

It has long been known that the brain preferentially processes information that we focus our attention on—a classic example is the so-called cocktail party effect.

In an environment full of voices, music, and background noise, the brain manages to concentrate on a single voice. The other noises are not objectively quieter, but are perceived less strongly at that moment.

The brain focuses its processing on the information that is currently relevant—in this case, the voice of the conversation partner—while other signals are received but not forwarded and processed to the same extent.

Neuroscientists provided the first causal evidence of how the brain transmits and processes relevant information. The work is published in the journal Nature Communications.

Whether a signal is processed further in the brain depends crucially on whether it arrives at the right moment—during a short phase of increased receptivity of the nerve cells. 

Nerve cells do not work continuously, but in rapid cycles. They are particularly active and receptive for a few milliseconds, followed by a window of lower activity and excitability. This cycle repeats itself approximately every 10 to 20 milliseconds. Only when a signal arrived shortly before the peak of this active phase did it change the behaviour of the neurons.

This temporal coordination is the fundamental mechanism of information processing. Attention makes targeted use of this phenomenon by aligning the timing of the nerve cells so that relevant signals arrive precisely in this time window, while others are excluded.

 Eric Drebitz et al, Gamma-band synchronization between neurons in the visual cortex is causal for effective information processing and behavior, Nature Communications (2025). DOI: 10.1038/s41467-025-62732-8

Comment by Dr. Krishna Kumari Challa on September 2, 2025 at 7:04am

Scientists find that ice generates electricity when bent

A new study  reveals that ice is a flexoelectric material, meaning it can produce electricity when unevenly deformed. Published in Nature Physics, this discovery could have major technological implications while also shedding light on natural phenomena such as lightning.

Frozen water is one of the most abundant substances on Earth. It is found in glaciers, on mountain peaks and in polar ice caps. Although it is a well-known material, studying its properties continues to yield fascinating results.

An international study has shown for the first time that ordinary ice is a flexoelectric material.

In other words, it can generate electricity when subjected to mechanical deformation. This discovery could have significant implications for the development of future technological devices and help to explain natural phenomena such as the formation of lightning in thunderstorms.

The study represents a significant step forward in our understanding of the electromechanical properties of ice.

The scientists  discovered that ice generates  electric charge in response to mechanical stress at all temperatures. In addition, they identified a thin 'ferroelectric' layer at the surface at temperatures below -113ºC (160K).

This means that the ice surface can develop a natural electric polarization, which can be reversed when an external electric field is applied—similar to how the poles of a magnet can be flipped. The surface ferroelectricity is a cool discovery in its own right, as it means that ice may have not just one way to generate electricity, but two: ferroelectricity at very low temperatures, and flexoelectricity at higher temperatures all the way to 0 °C.

This property places ice on a par with electroceramic materials such as titanium dioxide, which are currently used in advanced technologies like sensors and capacitors.

One of the most surprising aspects of this discovery is its connection to nature. The results of the study suggest that the flexoelectricity of ice could play a role in the electrification of clouds during thunderstorms, and therefore in the origin of lightning.

It is known that lightning forms when an electric potential builds up in clouds due to collisions between ice particles, which become electrically charged. This potential is then released as a lightning strike. However, the mechanism by which ice particles become electrically charged has remained unclear, since ice is not piezoelectric—it cannot generate charge simply by being compressed during a collision.

However, the study shows that ice can become electrically charged when it is subjected to inhomogeneous deformations, i.e. when it bends or deforms irregularly.

X. Wen et al, Flexoelectricity and surface ferroelectricity of water ice, Nature Physics (2025). DOI: 10.1038/s41567-025-02995-6

Comment by Dr. Krishna Kumari Challa on September 2, 2025 at 6:58am

Why male embryos grow faster

Researchers have uncovered the genetic triggers that cause male and female bovine embryos to develop differently, as early as seven to eight days after fertilization. The breakthrough in basic science has implications for human health—such as drug development and in vitro fertilization—and for bovine health and dairy industry sustainability.

Scientists have known since the 1990s that male embryos of multiple mammalian species, including humans, grow faster than female embryos, but until now, the underlying reasons were unclear.

In a paper, published in Cell & Bioscience,  scientists grew bovine embryos in petri dishes, then analyzed their genetic sex and RNA sequencing, which shows how genes are being expressed.

They discovered significant sex differences in gene regulation: male embryos prioritized genes associated with energy metabolism, causing them to grow faster than their female counterparts. Female embryos emphasized genes associated with sex differentiation, gonad development and inflammatory pathways that are important for future development.

Understanding these fundamental sex differences at the genomic and molecular levels is critically important to improving in vitro fertilization (IVF) success in humans and cows, and in developing treatments that will work for both men and women.

Meihong Shi et al, Sex-biased transcriptome in in vitro produced bovine early embryos, Cell & Bioscience (2025). DOI: 10.1186/s13578-025-01459-x

Comment by Dr. Krishna Kumari Challa on September 2, 2025 at 6:52am

Longevity gains slowing with life expectancy of 100 unlikely, study finds

A new study  finds that life expectancy gains made by high-income countries in the first half of the 20th century have slowed significantly, and that none of the generations born after 1939 will reach 100 years of age on average.

Published in the journal Proceedings of the National Academy of Sciences, the study analyzed life expectancy for 23 high-income and low-mortality countries using data from the Human Mortality Database and six different mortality forecasting methods. 

The unprecedented increase in life expectancy we achieved in the first half of the 20th century appears to be a phenomenon we are unlikely to achieve again in the foreseeable future. In the absence of any major breakthroughs that significantly extend human life, life expectancy would still not match the rapid increases seen in the early 20th century even if adult survival improved twice as fast as we predict.

From 1900 to 1938, life expectancy rose by about five and a half months with each new generation. The life expectancy for an individual born in a high-income country in 1900 was an average of 62 years. For someone born just 38 years later in similar conditions, life expectancy had jumped to 80 years on average.

For those born between 1939 and 2000, the increase slowed to roughly two and a half to three and a half months per generation, depending on the forecasting method. Mortality forecasting methods are statistical techniques that make informed predictions about future lifespans based on past and current mortality information. These models enabled the research team to estimate how life expectancy will develop under a variety of plausible future scenarios.

Researchers forecast that those born in 1980 will not live to be 100 on average, and none of the cohorts in their study will reach this milestone. This decline is largely due to the fact that past surges in longevity were driven by remarkable improvements in survival at very young ages.

At the beginning of the 20th century, infant mortality fell rapidly due to medical advances and other improvements in quality of life for high-income countries. This contributed significantly to the rapid increase in life expectancy. However, infant and child mortality is now so low that the forecasted improvements in mortality in older age groups will not be enough to sustain the previous pace of longevity gains.

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While mortality forecasts can never be certain as the future may unfold in unexpected ways—by way of pandemics, new medical treatments or other unforeseen societal changes—this study provides critical insight for governments looking to anticipate the needs of their health care systems, pension planning and social policies.

Although a population-level analysis, this research also has implications for individuals, as life expectancy influences personal decisions about saving, retirement and long-term planning. If life expectancy increases more slowly, as this study shows is likely, both governments and individuals may need to recalibrate their expectations for the future.

José Andrade et al, Cohort mortality forecasts indicate signs of deceleration in life expectancy gains, Proceedings of the National Academy of Sciences (2025). DOI: 10.1073/pnas.2519179122

Comment by Dr. Krishna Kumari Challa on September 2, 2025 at 6:40am

Super corals could help buy time for reefs in a warming world

Coral reefs are in crisis. Rising ocean temperatures driven by climate change are pushing these ecosystems to the brink, with mass bleaching events becoming more frequent and severe.

But what if nature already holds part of the solution?

New research led by UTS demonstrates that corals that naturally thrive in extreme environments, often referred to as "super corals," could be used in restoration efforts to protect vulnerable reef systems.

The research was published in the journal Science Advances and offers compelling evidence that these resilient corals can retain their heat tolerance even after being moved to more stable reef habitats.

Christine D. Roper et al, Coral thermotolerance retained following year-long exposure to a novel environment, Science Advances (2025). DOI: 10.1126/sciadv.adu3858

Comment by Dr. Krishna Kumari Challa on September 2, 2025 at 6:36am

Rare seasonal brain shrinkage in shrews is driven by water loss, not cell death, MRI study reveals

Common shrews are one of only a handful of mammals known to flexibly shrink and regrow their brains. This rare seasonal cycle, known as Dehnel's phenomenon, has puzzled scientists for decades. How can a brain lose volume and regrow months later without sustaining permanent damage?

A study using noninvasive MRI has scanned the brains of shrews undergoing shrinkage, identifying a key molecule involved in the phenomenon: water. The work is published in the journal Current Biology.

In the experiments conducted by researchers, shrews lost 9% of their brains during shrinkage, but the cells did not die. The cells just lost water. 

Normally, brain cells that lose water become damaged and ultimately die, but in shrews, the opposite happened. The cells remained alive and even increased in number.

This finding solves a mystery—and opens up potential pathways for the treatment of human brain disease. Brain shrinkage in shrews matches closely what happens in patients suffering from Alzheimer's, Parkinson's, and other brain diseases.

The study also shows that a specific protein known for regulating water—aquaporin 4—was likely involved in moving water out of the brain cells of shrews. This same protein is present in higher quantities in the diseased brains of humans, too.

That the shrunken brains of shrews share characteristics with diseased human brains makes the case that these miniature mammals, with their ability to reverse brain loss, could also offer clues for medical treatments.

 Programmed seasonal brain shrinkage in the common shrew via water loss without cell death, Current Biology (2025). DOI: 10.1016/j.cub.2025.08.015. www.cell.com/current-biology/f … 0960-9822(25)01081-4

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