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

Explore this 1440 Original video offering a primer on Alzheimer's disease and what's known about its incidence, causes, and more.

Alzheimer's brain changes may begin years before symptoms appear.

Alzheimer's can cause significant brain shrinkage in the affected brain regions, including the hippocampus.

"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.

Scientists are reevaluating the causes of Alzheimer's beyond the amyloid hypothesis after numerous experimental drugs designed to target that theory have failed.

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.

These areas of the brain are hard-hit in depression—but the changes are reversible

Depressed brains can have certain characteristic changes, including an overactive amygdala, reduced hippocampus size, and changes to the thalamus and neuromodulating chemicals in the brain.

Poor sleep increases the risk of developing Alzheimer's, and a main reason appears to be that the brain disposes of toxic protein buildup during high-quality sleep.

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.

Depression changes the brain, causing distinct structural alterations visible on brain scans, but effective treatment can eventually make a depressed brain resemble a healthy one.

Five to ten percent of Alzheimer's cases are early-onset

Early-onset Alzheimer’s typically emerges around 40 to 50 years of age, with devastating effects. This video follows Brian, diagnosed with the disease at age 54, as he travels the country as an advocate for research and discusses the progressive mental fog of Alzheimer’s.

Early-onset Alzheimer's can appear as early as age 30, but estimates of its prevalence remain uncertain.

Your brain appears to age in five distinct stages, with the pattern of connections inside your brain shifting, on average, around ages 9, 32, 66, and 83.

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.

Alzheimer's disease is the leading cause of dementia and risks rise after age 65

Read this primer about Alzheimer's disease and learn what factors increase the risk of this form of dementia, including genetics, being a woman, and health conditions, including high blood pressure.

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.

Neurodegeneration is the process underlying dementia, but it may happen for myriad reasons, and its triggers are under investigation.

How Alzheimer's disease becomes fatal

Despite more than 100,000 people with Alzheimer's dying each year, the specific cause of death is not the disease itself. Often, secondary diseases arise from complications with the disease, including pneumonia, severe falls, malnutrition, or infection. Read more about the range of complications caused by Alzheimer's here.

Recent evidence raises the question of whether conventional wisdom about amyloid plaques and their connection to Alzheimer's is wrong.

Learn the differences between mild cognitive impairment and age-associated memory loss

Mild cognitive impairment is a condition in which people experience more thinking and memory problems than expected for their age. It's often associated with depression and anxiety. Daily routines, writing things down, and healthy lifestyle choices can help cope with the condition, but there's no cure. The condition elevates the risk of developing dementia and Alzheimer's.

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.)

Some dementia cases may be linked to treatable microorganism infections in the brain.

The first identification of Alzheimer's was made in 1906.

How Alzheimer's caregivers get pulled into their loved one's reality

Caregivers, most often children and spouses, do not just witness a family member's cognitive decline—they also often become drawn into it, navigating a world in which the typical rules of time, order, or logical continuity may not apply.

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.

Does our fear of Alzheimer's create stigma around its treatment?

Surveys suggest our fear of Alzheimer's as a disease outranks that of heart disease and cancer. This piece argues our fear of aging and the slipping away of our mental capacities make it more difficult to treat Alzheimer's compassionately.

'Susan's Brain': what happens to the brain during addiction

This engaging animation from Harvard Online breaks down the neuroscience of addiction through the story of “Susan’s brain,” demonstrating how addictive substances hijack normal reward pathways. Through clear visual metaphors and approachable narration, it explains complex brain chemistry in understandable terms.

There are two FDA-approved blood tests that may detect early Alzheimer's disease.

Alzheimer's in the United States is most prevalent in the South and the East.

Genetic blood test offers an estimated clock on when Alzheimer's symptoms may appear

The 2026 research finding from researchers at Washington University School of Medicine in St. Louis—if validated in broader populations—suggests that an already available blood test could estimate when Alzheimer's symptoms may begin within a margin of several years. The test detects a protein called p-tau217 found in blood plasma and the researchers incorporated the findings from that blood test into a statistical model to come up with the symptom timeline predictions.

Aging is a complex biological process affecting our cells, tissues, and organs.

Stress and the brain

While an acute stress response is a normal bodily function, the effects of chronic stress can be extremely damaging to the human body. This is particularly true with regard to the brain. This article explores the effects of stress on the human brain, including how chronic stress may lead to psychological conditions such as depression and memory loss.

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.

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.

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.

A brain scientist's experience with a stroke

What happens when a leading brain scientist has a stroke of her own? Dr. Jill Bolte Taylor recounts moment by moment watching her brain function slow and then cease, followed by a prolonged recovery. Through this experience, she details what she learned about the phenomenon of stroke and how it has impacted her research ever since.

A first-person account of receiving an Alzheimer's diagnosis

Having Alzheimer's is a bit like having a part of your brain sliced away each day, according to author Greg O'Brien. This 34-minute podcast episode introduces O'Brien and his co-host, author David Shenk, as the two embark on a multi-season conversation on Alzheimer's disease and O'Brien's diagnosis.

How depression affects the brain

Treatment for depression has historically hinged on the theory that the condition was caused by underactive or abnormal neurotransmitters, specifically serotonin and norepinephrine. This four-minute video by Yale Medicine details how these neurotransmitters didn't explain the symptoms of depression but, two other neurotransmitters involved in regulating mood and emotion did. GABA and glutamate, some of the brain's most plentiful neurotransmitters, may possibly be the source of depressive symptoms.

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.

What's with the teen brain, anyway

In this video NIDA explores the intriguing similarities between the processes of brain development and computer programming. This analogy helps us understand why toxic environmental factors like drugs, bullying, or lack of sleep strongly affect a teenager's life The information provided by this video can empower your children or students with information they need make better decisions.

Taxi and ambulance drivers appear to have the lowest risk of dying from Alzheimer's disease out of 443 occupations, which suggests that constant real-time navigation work strengthens the hippocampus and may help protect against the disease.

What sleep loss does to the brain

Proteins in the brain perform various critical functions, such as helping neurotransmitters function or enabling electrical activity in the organ. These proteins must fold in specific ways to perform their duties, similar to paper airplanes. Sleep deprivation contributes to the gathering of misfolded proteins that aren't shaped correctly for their roles and so accumulate in undesired spaces, such as in the gaps between neurons.

Dementia describes progressive memory issues that impact daily activities

Although Alzheimer's disease is sometimes thought of synonymously with dementia, there are multiple types of dementia, which manifest in memory loss and other symptoms that make it challenging to perform daily tasks. These types include Lewy Body dementia, vascular dementia, and frontotemporal dementia. Parkinson's disease is not a form of dementia, but this movement disorder can sometimes develop into issues with memory and a formal diagnosis of dementia.

Why vascular dementia develops

This type of dementia, the second most common form after Alzheimer's, develops due to microscopic bleeds and blood vessel blockages in the brain. The condition isn't curable but medications to help with blood clotting and high blood pressure are part of a suite of interventions designed to minimize damage to the brain.

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.

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.

How Alzheimer's disease affected one family as symptoms progressed

News program 60 Minutes interviewed a couple navigating aging and Alzheimer's over a 10-year period to illustrate the effects of the disease on their lives.

Read the original 1907 paper on the first known Alzheimer's patient, which was identified by Dr. Alois Alzheimer.

Prolonged stress impairs the prefrontal cortex

Burnout isn't just a feeling—it physically affects the brain. Prolonged stress impairs regions of the brain responsible for decision-making, emotional control, memory, and more. It can also lead to chemical imbalances, like reduced dopamine and norepinephrine levels, that worsen these effects.

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.