Hidden in the deepest laboratories of Washington University, neuroscientists have discovered what they believe is the brain’s ultimate secret—a mathematical “sweet spot” called criticality that could revolutionize how we understand learning, memory, and prevent Alzheimer’s disease before it even begins.
For decades, researchers have struggled to understand why some people are naturally gifted learners while others struggle, why Alzheimer’s patients can appear completely normal until cognitive collapse suddenly occurs, and why sleep seems so crucial for brain health. Now, groundbreaking research published in June 2025 reveals that all these mysteries may share a single, elegant explanation: the brain’s ability to maintain a delicate state called “criticality.”
This isn’t just another neuroscience theory. According to researchers at Washington University in St. Louis, criticality represents a unified framework that could transform how we diagnose, treat, and prevent neurological diseases—years before symptoms appear.
The Physics of Perfect Thinking
Dr. Keith Hengen, an associate professor of biology at Washington University, has spent years uncovering what he calls “a relatively simple set of mathematical principles” that govern the brain’s immense power. Working alongside physicist Dr. Woodrow Shew from the University of Arkansas, Hengen published their unified theory of brain function in the prestigious journal Neuron after conducting a meta-analysis of 140 datasets spanning over two decades of research.
The concept of criticality comes from physics, where it describes complex systems balanced precisely at the tipping point between order and chaos. Think of a sand pile: as you add grain after grain, the pile grows steeper until it reaches a critical angle—one grain away from an avalanche. At this razor’s edge, the system becomes maximally sensitive to change and capable of rapid, large-scale reorganization.
“Brains need to reach criticality to think, remember and learn,” Hengen explains. At this delicate balance point, neural networks become primed to gain new information and process it optimally.
What makes this discovery particularly remarkable is that criticality maintains the same mathematical properties whether you’re examining a handful of neurons or entire brain regions, and whether you’re looking at brain activity over milliseconds or hours. This scale-free nature matches our intuitive understanding of consciousness—our experiences span from split-second reactions to memories lasting decades, without any fundamental change in how we perceive them.
The Alzheimer’s Connection No One Saw Coming
Perhaps the most shocking implication of criticality theory is how it reframes our understanding of Alzheimer’s disease. Rather than focusing solely on amyloid plaques and tau tangles, Hengen argues that Alzheimer’s destroys something far more fundamental: the brain’s ability to maintain criticality.
“Alzheimer’s and other neurodegenerative diseases don’t just damage neurons, they break the brain’s general ability to compute by slowly dissolving criticality,” Hengen explained in the research. “As a brain moves further and further from criticality, it loses the ability to adapt and process information effectively.”
This framework explains one of Alzheimer’s most puzzling features: why patients often appear completely normal until they’ve lost many neurons. The brain has remarkable compensatory abilities that can mask functional problems even as criticality begins to erode. Traditional assessments miss these early stages because they focus on established cognitive endpoints that the brain desperately tries to maintain through neural workarounds.
Hengen describes it like “an engine that still runs but requires more fuel and generates more heat. By the time we notice memory problems or other symptoms, criticality has likely been compromised for years.”
Working with Dr. David M. Holtzman at WashU Medicine, the researchers discovered that tau protein buildup in Alzheimer’s directly disrupts criticality, providing the first clear link between the disease’s molecular hallmarks and cognitive collapse.
Revolutionary Early Detection and Prevention
The practical implications are staggering. Since criticality can be precisely measured using fMRI brain imaging technology, doctors could theoretically detect Alzheimer’s-related brain changes years before any symptoms appear.
“We’ve developed a mathematical way to measure how close the brain is to criticality,” Hengen said. “In combination with cutting-edge blood tests, we could identify people at risk and intervene before irreversible damage occurs.”
This early detection capability extends beyond Alzheimer’s. In collaboration with Dr. Deanna Barch at WashU Medicine, researchers are studying how criticality at birth determines cognitive development and learning abilities in childhood. Early findings suggest that children closer to criticality from birth are naturally better learners, potentially explaining much of the variability in academic performance between children.
“From the beginning, some kids are closer to criticality than others, which, based on our theory, suggests they are going to be better learners,” Hengen noted. While many external factors affect school success, criticality could explain an impressive amount of the differences between children’s cognitive abilities.
Sleep: The Brain’s Reset Button
One of the most immediately practical discoveries involves sleep’s role in maintaining brain health. In early 2024, Hengen and physicist Dr. Ralf Wessel found that sleep literally restores a state of criticality. By tracking brain activity over multiple weeks, they discovered that being awake and active gradually moves us away from criticality, while sleep acts like a neural reset button.
This insight transforms our understanding of why sleep deprivation is so damaging and why poor sleep increases Alzheimer’s risk. Previous studies have shown that people who don’t get adequate sleep—whether from shift work or chronic insomnia—face much higher rates of Alzheimer’s as they age.
The research team believes that targeted, intensive sleep-based therapy could help restore criticality and improve learning and memory in people with brain disease. In promising preliminary studies, mice bred to have Alzheimer’s symptoms became faster learners after targeted sleep interventions that reinforced criticality.
The Hidden Science of Genius
The criticality framework may also explain extraordinary human abilities. Hengen theorizes that people with exceptional talents—whether in art, mathematics, or athletics—might naturally maintain criticality in specific brain regions related to their gifts.
“We may find that someone who is an amazing artist, for example, might be extremely close to criticality in parts of the brain involved in creative ideation,” he explained. The research could even identify hidden talents in people who’ve never had the opportunity to discover them. “Maybe they never tried art, but we can see that the potential is there.”
This opens the possibility of using criticality measurements to identify optimal learning windows, personalize education approaches, and even guide career choices based on natural neural predispositions.
Measuring and Optimizing Your Brain’s Sweet Spot
While still in early research phases, the practical applications of criticality theory are rapidly expanding. The research team has developed mathematical methods to measure how close any brain is to its optimal state, potentially leading to:
- Personalized brain training programs designed to maintain or restore criticality
- Optimized sleep interventions tailored to individual neural needs
- Early intervention protocols for neurodegenerative diseases
- Cognitive enhancement strategies for healthy individuals
- Learning optimization based on personal criticality patterns
The Future of Brain Health
The implications extend far beyond individual health. Understanding criticality could revolutionize how we approach education, treat mental illness, and maintain cognitive function throughout aging. Rather than waiting for symptoms to appear, we could monitor and maintain optimal brain states throughout life.
Current research involves 250 monozygotic twins, 142 dizygotic twins, and 437 non-twin subjects to understand the genetic components of brain criticality and its relationship to cognitive function. This massive study could reveal whether some people are born with natural advantages in maintaining criticality, and whether these advantages can be enhanced or compensated for through targeted interventions.
Beyond Traditional Medicine
What makes this research particularly revolutionary is how it bridges multiple scientific disciplines. By combining insights from physics, biology, psychology, and mathematics, the criticality framework offers something unprecedented: a unified theory of how healthy brains work and what goes wrong in disease.
“There’s a common perception that the human brain is the most complicated thing in the universe,” Hengen said. “The brain is immensely powerful, but that power may arise from a relatively simple set of mathematical principles.”
This simplicity could be the key to solving complex neurological problems that have puzzled researchers for decades. Rather than focusing on the countless individual components that make up the brain, criticality theory suggests we should focus on the fundamental organizing principle that governs how all these components work together.
The Path Forward
The research team is actively working to translate these discoveries into clinical applications. With support from institutions spanning physics, biology, psychology, mathematics, and neuroscience, they’re developing practical tools that could soon move from laboratory to clinic.
Current priorities include:
- Developing standardized criticality measurement protocols for clinical use
- Creating targeted sleep interventions that restore optimal brain states
- Designing early intervention strategies for at-risk individuals
- Establishing criticality-based guidelines for maintaining cognitive health throughout life
Your Brain’s Hidden Potential
The discovery of brain criticality represents more than just scientific progress—it offers hope for a future where neurological diseases can be prevented rather than merely treated, where learning can be optimized rather than left to chance, and where the full potential of human consciousness can be unlocked through understanding its fundamental operating principles.
As research continues, the most profound realization may be that your brain’s incredible capabilities aren’t as mysterious as once believed. They emerge from a delicate, measurable balance that can be understood, maintained, and potentially enhanced through scientific intervention.
The brain’s sweet spot isn’t just a theoretical concept—it’s a tangible state that could hold the key to preventing Alzheimer’s, enhancing learning, and maintaining cognitive vitality throughout life. The secret is no longer hidden in the laboratory; it’s beginning to emerge into the light of practical application.
The question isn’t whether your brain has this optimal state—it’s whether you’ll have access to the tools to find it, measure it, and maintain it for life.
Sources
- Brain Criticality May Hold Key to Learning, Memory, and Alzheimer’s – Neuroscience News, June 29, 2025
- The brain’s sweet spot: How criticality could unlock learning, memory—and prevent Alzheimer’s – Science Daily, June 25, 2025
- A unified theory of the mind could be key to understanding brain function and neurological disease – Medical Xpress, June 24, 2025
- Is criticality a unified setpoint of brain function? – Neuron Journal, 2025
- A unified theory of the mind – Washington University in St. Louis, June 2025
- Why Brain Criticality Is Clinically Relevant: A Scoping Review – PMC Scientific Literature
- The Brain’s Best State: How “Criticality” Shapes Learning, Memory, and Disease – CogniFit Research Blog
This article is for informational purposes only and should not replace professional medical advice. Always consult with qualified healthcare providers regarding brain health and neurological concerns.
