Welcome to Peer Review'd, where we break down the latest discoveries from the world of science. I'm your host, and today we're covering some incredible breakthroughs from Christmas week 2025—from reversing Alzheimer's in mice to eliminating forever chemicals, and even printing electrodes directly on human skin. Let's dive in.

We're starting with some remarkable news on the dementia front. Scientists have discovered that dementia may be driven in part by faulty blood flow in the brain, and they've found a way to fix it. The research shows that when a key lipid goes missing, blood vessels become overactive, disrupting circulation and essentially starving brain tissue of what it needs. But here's the exciting part: when researchers restored this missing molecule, normal blood flow returned. This opens up an entirely new treatment avenue—targeting vascular problems rather than just focusing on protein buildup in the brain.

And speaking of Alzheimer's, there's even more groundbreaking news. For the first time, scientists have actually reversed Alzheimer's in mice and restored their memory. This challenges the long-held assumption that Alzheimer's is irreversible. The key insight? Severe drops in the brain's energy supply help drive the disease. When researchers restored that energy balance, they saw something remarkable: brain damage was repaired, cognitive function returned, and Alzheimer's biomarkers normalized—even in advanced cases. While this is still in mice, it offers genuine hope that recovery might be possible in humans.

Shifting gears to environmental science, researchers have developed new technology that eliminates PFAS—those notorious forever chemicals found in water worldwide. What makes this breakthrough special is its speed and efficiency: the material works hundreds to thousands of times faster than current filters, and it works in river water, tap water, and wastewater. But it doesn't stop at just capturing these chemicals. The system actually breaks them down safely and then refreshes itself for reuse. It's a rare complete solution to a persistent pollution problem.

Now let's talk about space. Scientists are getting serious about asteroid mining by analyzing what these space rocks are actually made of. By studying rare meteorites that fall to Earth, researchers are uncovering clues about the chemistry and potential usefulness of carbon-rich asteroids. While large-scale mining is still far off, the study identifies specific asteroid types that could be promising targets, especially for extracting water—a crucial resource for future space exploration.

In medical technology, Swedish researchers have developed a method to print working electrodes directly on human skin using just visible light. This technique creates electrodes from conductive plastics without hazardous chemicals, which could transform medical monitoring and wearable electronics. Imagine temporary sensors that can be applied as easily as shining a light on your skin.

There's fascinating neuroscience news about how we sense temperature. Researchers discovered that our bodies use two completely different cold detection systems—one in the skin and another in internal organs. This explains why cold air, cold drinks, and cold surfaces create such different sensations. It's not just psychological; we literally have separate biological mechanisms for detecting external versus internal cold.

On the heart health front, scientists have identified an unexpected protector of cardiac aging: the vagus nerve. Maintaining the heart's connection to this nerve pathway appears to be a key defense mechanism. Research shows that restoring this nerve connection can protect heart cells and preserve heart strength long-term. It's a reminder that the brain-body connection goes deeper than we often realize.

In more sobering neuroscience news, McGill University researchers found that a single nerve injury can quietly reshape the immune system across the entire body. The preclinical research suggests these changes can be long-lasting and appear to differ between males and females. This finding could change how we think about treating common nerve damage from stretching, pressure, or cuts.

Researchers have also discovered why some children develop microcephaly, a condition where the brain is smaller than expected. An international team found that a microscopic flaw in the brain's cellular scaffolding—just one small mutation—can shape brain size for life. Understanding these mechanisms at the cellular level is crucial for eventually developing interventions.

There's a surprising finding about ADHD medications. Brain scans reveal that stimulants like Ritalin and Adderall may not work the way we thought. Rather than sharpening focus directly, they appear to improve performance by making the brain more awake and motivated. This shifts our understanding of how these widely-prescribed medications—taken by about three and a half million kids in the US—actually function.

In physics news, the KATRIN experiment has tightened constraints around sterile neutrinos, those elusive particles that might exist beyond the Standard Model. High-precision measurements strongly limit where these hypothetical particles could hide, narrowing the search for new physics. Neutrinos are already incredibly difficult to detect despite being among the most abundant matter particles in the universe, so every refinement in our measurements matters.

And in chemistry, researchers finally proved a "crazy" theory from 1958 about vitamin B1. They managed to create and stabilize a normally ultra-reactive molecule called a carbene in water for months—something long considered impossible. This validates decades-old theoretical work and opens new possibilities in chemistry.

On the food and climate front, researchers found that what we eat could decide the planet's future. Most people, especially in wealthy countries, are exceeding a food emissions budget needed to keep warming below two degrees Celsius. Beef alone accounts for nearly half of food-related emissions in Canada. But the good news is that small changes—less waste, smaller portions, fewer steaks—could add up to significant climate benefits.

There's also interesting research on social media perception. While platforms often feel overwhelmingly toxic, research finds that most harmful content comes from a tiny fraction of users who post frequently and loudly. Many Americans believe hostile behavior dominates online, but studies suggest most people are far more restrained than we perceive. It's a reminder that our impression of online spaces may be skewed by a vocal minority.

Finally, there's a thought-provoking piece on consciousness and computation. New work proposes biological computationalism—the idea that brains do compute, but not in the abstract, symbol-shuffling way of traditional computers. Instead, computation is inseparable from the brain's physical structure, energy constraints, and continuous dynamics. This reframes consciousness as something that emerges from a special kind of computing matter, not from running the right program. It's neither pure software nor pure biology, but something in between.

And one last note on the state of science itself: AI writing tools are supercharging scientific productivity, with researchers posting up to fifty percent more papers after adopting them. The biggest beneficiaries are scientists who don't speak English as a first language. But there's a downside—many AI-polished papers fail to deliver real scientific value, creating a growing gap between slick writing and meaningful results that's complicating peer review and research oversight.

That's all for this episode of Peer Review'd. From reversing dementia to mining asteroids, from printing electronics on skin to understanding consciousness itself, science continues to push boundaries in every direction. Thanks for listening, and we'll catch you next time with more discoveries from the cutting edge of research.