Visualize the difference between a healthy brain and one with Alzheimer's

Alzheimer's brain changes may begin years before symptoms appear

The debilitating disorder degrades cognitive abilities. Its symptoms may start with subtle memory issues, but by the time patients notice any changes, neural changes may already be progressing, such as the accumulation of beta-amyloid plaques between neurons and tau protein tangles within them.

Alzheimer's can cause brain shrinkage of between 10% and 30%

While the exact cause of Alzheimer's is debated, the buildup of amyloid plaques and tau protein tangles is instantly recognizable in post-mortem examinations. The atrophy of brain cells caused by this molecular pileup leads to noticeable physical changes, including significant shrinkage in affected brain regions.

"Plaques" and "tangles" are top potential causes of Alzheimer's—but questions remain

The exact causes of Alzheimer's—and how to treat it—continue to be the subject of intense research. Two leading factors are amyloid beta plaques and tau protein tangles, which effectively pile up in the brain and interfere with neurons and cause cell death, which manifests as memory loss and other symptoms.

1440: Everything you need to know about Alzheimer's

What is Alzheimer's, and is it different from dementia? In short, yes—Alzheimer's is a specific brain disease that falls under the umbrella of dementia. However it is the most prevalent form of the condition, accounting for 60 to 80% of reported dementia cases.

How aging degrades neural functioning in the brain over time

Aging affects the brain perhaps more than any other organ in the body. Throughout life, the brain experiences radical shifts in the number of neurons, synaptic connections between neurons, and hormone levels that regulate our mood and processing.

Watch what depression does to the brain

This video explores the neurobiology of depression and why unraveling the complexities of this disease and its etiology will potentially improve treatments. Effective depression treatment, as this video highlights, can eventually make a depressed brain look like a healthy one on brain scans.

An Alzheimer's patient discusses her condition with children

Alzheimer's is a deadly disease that profoundly changes a person's abilities and personality, which makes it difficult to explain to kids. Responding to potentially uncomfortable questions with honesty (and relatable imagery) about the costs and nature of the disease goes a long way in fostering understanding.

Your brain appears to age in five distinct stages

Analysis of brain scans from about 4,000 people has helped scientists identify five major stages of our brain's maturation from birth to death. The pattern of connections inside our brains seem to shift, on average, at ages 9, 32, 66 and 83. (Some readers may experience a paywall.)

Poor sleep increases the risk of developing Alzheimer's

Brain imaging studies reveal poor sleep leads to production of amyloid beta proteins—molecules linked to Alzheimer’s—which are cleaned from the brain during high-quality sleep. These findings suggest conditions like sleep apnea and insomnia increase the risk of developing the disease.

Memory disorders disrupt the brain's ability to make, store, or recall memories

These disorders stem from reversible issues like vitamin deficiencies or irreversible causes such as stroke or dementia. Only one type of dementia—familial Alzheimer’s disease—is directly inherited and accounts for about 20% of Alzheimer’s cases.

Explore an interactive 3D model of the brain

The brain contains about 86 billion neurons—nervous system cells—and controls vital bodily functions via electrochemical signals. Neurons form circuits through axons, and different brain regions use these circuits to perform specific tasks.

Researchers are exploring neural links between Alzheimer's and autism

Recent DNA sequencing and molecular biology studies suggest that similarities in genes, neural circuitry and patterns of disease warrant further exploration to potentially better understand both conditions and how to treat them. (Some users may encounter a paywall.)

How ALS (Lou Gehrig’s Disease) might work, and what scientists are learning about it

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder that affects the nerve cells (neurons) controlling muscle movement. As the motor neurons degenerate, they stop sending signals to the muscles, causing progressive muscle weakness and, eventually, death. This three-minute animation focuses on the mechanisms within the motor neurons that cause them to degenerate. By understanding these mechanisms, researchers hope to one day find a cure for ALS.

An interesting perspective on whether (and how) brain size matters in cognitive ability

Some brains are bigger than others, but what is the relevance, if any, to brain size and intelligence? This Scientific American article explores the question and offers examples. It also visually compares frontal slices of several mammals' brains, showing that humans don't necessarily have the biggest cerebrums on the block.

Aging results from the cumulative breakdown of cellular and tissue processes

A cumulative breakdown of cellular and tissue processes combines to result in decreased organ function, disrupting the systems driving normal human physiology. This five-minute video provides a primer on the subject, complete with a discussion of risk factors, cellular changes, and potential future treatments in the fight against aging.

See the challenges of navigating Alzheimer's caregiving

This 2025 PBS documentary provides a window into the experiences of three families navigating the struggles and beauty of caregiving for a loved one with Alzheimer's.

Hearing loss is linked with brain volume reductions

The brain looks different as a result of hearing loss, with reductions in brain volume overall and in specific areas, and these changes are hypothesized to impact cognition. Exactly why hearing loss alters cognition is an active area of research, but theories include that the elevated cognitive load of straining to hear affects brain power available for thinking and memory and that hearing loss leads to social isolation which boosts dementia risk.

Take a quiz to discover your brain care score

Each year, nearly 800,000 Americans have a stroke. With such a high occurrence rate, you may be asking yourself what you could do now to prevent a future stroke. Researchers at Harvard collaborated to answer this question by coming up with a "Brain Care" scoring system. Take the quiz to learn the quality of your brain health today and pick up helpful insights to lower your risk of stroke and dementia well into the future.

How science explains déjà vu

Take a fun look at the science explaining the odd experience of déjà vu, which some theories suggest is actually a sign of a healthy brain.

How the buildings you occupy may affect your brain health

Beautiful spaces filled with light and natural motifs aren't just aesthetic, but likely key to your health. Researchers had study participants view photographs of two distinct buildings, one designed with more natural elements while the other featured more abstract shapes and lines. Using electroencephalograph readings of each participant, they discovered participants had less brain inflammation while viewing the "biophilic," or natural, architecture. Learn more about the interdisciplinary framework of so-called neuroarchitecture here.

What is the brain up to when the mind wanders?

As you stare into the distance while washing your home's seemingly never-ending pile of dishes, the brain activates its default mode network. This collection of "task-negative" brain regions associated with memory, reward, action consideration, and prediction alight with activity when humans mentally turn inward, possibly giving rise to the brain's ability to wander and humans' ability to construct internal narratives about the world.

Visualizing a stroke at the microscopic level

By far the most common type of stroke is what is known as an ischemic stroke. This occurs due to either an embolus (a blood clot that travels to the brain from elsewhere in the body) or a thrombus (a blockage that forms within the brain itself).

What happens to the brain during migraine?

Migraine is a neurological condition that can cause debilitating symptoms across various bodily functions. So, what exactly is happening in the brain during these attacks? This five-minute video briefly overviews the internal machinations behind the painful episodes. An incapacitating headache is a common symptom of migraine, though migraine can occur without any headache.

Patient H.M. revealed that the hippocampus was responsible for memory formation

Henry Molaison became a landmark case in psychology after surgery removed large portions of his hippocampus, leaving him unable to form new memories. Upon his death, Molaison's brain was sliced into 2,401 sections and digitized for research.

Visualizing cause of death over time in America

As people age, their life expectancy decreases, but the timing and speed of this decline have evolved over the years. Check out this chart which shows the shift in various causes of death of Americans over the last few decades. Data from the...

Recent research found that the brain doesn't seem to massively rewire following amputation—upending earlier beliefs about the cause of phantom limb pain.

Watch what the Ebola virus does inside our cells and organs in order to spread and survive.

Researchers believe the brain consolidates memories, processes emotions, and plans for the future during dream states

Against his wishes, Albert Einstein's brain was removed before his cremation, and the pathologist responsible stored it for decades in mason jars within a beer cooler.

Visualize how CRISPR-Cas9—a type of immune system used by single-celled organisms to attack invasive viruses—targets and makes precise changes to a gene's DNA.

Learn how your body is, scientifically, like a firework with its own slow, controlled burn.

Listen to an in-depth conversation on the links between Parkinson's disease and herbicide exposure and the challenging pace of scientific investigation.

Studies suggest when you sleep is as important as how much you get, and syncing with your circadian rhythms may lead to less fatigue and improved long-term health outcomes

Watch how algorithms can be designed to train themselves and self-improve without human input, to the point where the optimized code is too complex for programmers to understand.

Larger animals like giraffes, elephants, and blue whales have developed a unique defense against cancer, a phenomenon known as Peto's Paradox

Crows are believed to have intelligence on par with a seven-year-old child and demonstrate complex behaviors, from problem-solving with tools to recognizing human faces.

Fear or disgust related to clusters of holes and cracks, called trypophobia, may stem from evolutionary processes to help us avoid pathogens.

Radioactive elements can introduce software errors because the ionizing radiation they produce can detach electrons from atoms, and computer code relies on the distribution of electrons.

This poison ivy knowledge quiz—accompanied by photos of the plant's varied forms—may help you identify this common rash-inducing growth.

Explore the known asteroids, comets, and spacecraft involved in asteroid studies within our solar system with 'Eyes on Asteroids,' a 3D visualization from NASA.

In 1945, Surrealist artist Salvador Dalí and legendary animator Walt Disney began collaborating on a short film that was not completed until 2003, years after both men had died.

Explore an interactive map built from more than 100,000 survey responses on where people find joy in their lives

Explore the history, structure, and species of Australia's Great Barrier Reef with this interactive journey narrated by Sir David Attenborough.

According to the physics of black holes, our 4D reality may be a hologram—a projection of information coded on a 2D surface on the edge of the universe.

Gerrymandering works through two techniques: cracking opposing voters across districts to dilute their power, and packing them into a few to waste their votes in lopsided majorities.

The syncytiotrophoblast is the outer layer of the placenta and the largest human cell, spanning an area about twice that of a king-sized bedsheet.

See a 3D reconstruction of Tenochtitlan, the Aztec capital that was home to an estimated population of 200,000 to 400,000.

The Mona Lisa's celebrity status and repeated restorations have obscured what made the painting so revolutionary for its time

Power lines are dotted with large, brightly colored balls to improve the visibility of these thin wires to helicopters and small planes and help prevent potential crashes.

The Nasdaq's 'Magnificent 7' companies are responsible for roughly 40% of the Nasdaq 100 index's gains, while the remaining 93 companies account for the other 60%.