Sclerosis is the technical term for the lesions or plaques that form without myelin

Multiple sclerosis means 'many scars'

That's a reference to the scarring or lesions that occur in the brain, spinal cord, and elsewhere whenever the immune system has a flare-up. The immune system attacks the myelin because it incorrectly responds as if it's a threat, damaging the body's ability to transmit electrical signals effectively from areas of the body to the brain.

Remylination is a huge focus for treatment—especially among older adults

Our ability to build new myelin sheaths for nerves degrades with age. There have been research advances boosting cells that support these processes and clear away debris from degraded myelin, but not yet any medications to boost myelination itself, which would aid nerve signaling and preserve nerve function.

Age, stress, and neurological disorders can prevent memory formation and recall

Neurons transmit signals between one another at sites called synapses. Repeated interactions at these sites improve the efficiency of signal transmissions, making memories involving sensory data associated with those neurons easier to recall. Biochemical factors impacting these synaptic interactions affect memory quality.

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.

Scleroderma, which causes skin to harden and scar, has no FDA-approved treatment

It's an autoimmune disease that disproportionately causes worse complications in African American people for unknown reasons. It causes the body to overproduce collagen after the immune system attacks the body's own connective tissue, leading to excess collagen deposits and restricted blood circulation as small blood vessels are damaged. It can damage various organs, including the lungs.

Nerve axons become damaged by leprosy, so patients may lose feeling in their skin

Infection of the peripheral nerves—nerves outside the brain and spinal cord—is a known complication of leprosy. That damage can cause patients to lose their sense of touch and the ability to feel pain or temperature in affected areas, leading to accidental injury.

Necrosis is the unplanned death of cells and the tissue they comprise

If cells die prematurely due to a lack of blood flow, injury, or disease, they and their organelles can swell, leading to rupture of the surrounding cell membrane. This releases the cell's contents into the surrounding tissue, causing inflammation and damage to neighboring cells.

The rare but deadly time bomb lurking after a measles infection

Subacute sclerosing panencephalitis, also known as Dawson disease, is a progressive and fatal neurodegenerative condition caused by a dormant measles infection. Typically, patients recover from measles normally, with the symptoms of SSPE only appearing years or even decades later. The incidence rate in unvaccinated pediatric patients is estimated to be around one in 1,300.

Chronic lyme isn't a medically recognized diagnosis in conventional medicine

It describes a constellation of symptoms attributed to a persistent Lyme infection—meaning the bacteria have remained present even after antibiotics. It often occurs among people who have never received a positive test for Lyme. Doctors do recognize "post-treatment Lyme disease syndrome," however, which can include muscle and joint pain, fatigue, and cognitive difficulties after treatment for confirmed Lyme.

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).

Poliomyelitis is derived from Greek

Polio, formally called poliomyelitis, comes from the Greek words for gray (polios) and marrow (myelos)—a reference to the spinal cord tissue that, when infected by the virus, causes paralysis.

LSD's molecular structure closely resembles the neurotransmitter serotonin

Lysergic acid diethylamide (C20H25N3O) is a colorless, odorless, and flavorless chemical compound that can induce altered perception, mood, and cognition. One of its roles in the brain is as a serotonin agonist, meaning it enters serotonin receptors and triggers a fraction of the response the neurotransmitter would typically warrant.

Alzheimer's can lead to brain shrinkage, with an average of around 2% of volume reduction per year

As deposits build up under the eye, the retina bends with macular degeneration

The retina bends due to the accumulation of proteins and other materials beneath it. That's considered the milder "dry" form of macular degeneration. Another form, called "wet" macular degeneration, is caused by abnormal blood vessels leaking fluid into the eye, which can rapidly affect central vision.

How skeletal and smooth muscles differ

Skeletal and smooth muscles are two of the three muscle types found throughout the body. The former is attached to bones via tendons, enables limb movement, and is consciously controlled. The latter is found lining blood vessels and hollow organs (e.g., the intestines, stomach, and esophagus) and is managed by the autonomic nervous system, which means it's outside conscious control.

'Artificial embryos': The hidden steps in forming a spine

Somitogenesis is the process by which segmented body structures like vertebrae form in embryos. While the process is well understood in animals like mice or zebrafish it is difficult to study in humans. But now, researchers have created a model of somitogenesis, using pluripotent stem cells, called an axioloid.

Why say 'migraine' instead of 'migraines'?

Language choice can affect people's assumptions and beliefs about the subject at hand, which is why some would prefer "migraine" to be treated as a singular and plural noun. This American Migraine Foundation article examines the logic behind the grammar choice.

The term schizophrenia was coined by Swiss psychiatrist Eugen Bleuler in 1908

He launched the word during a lecture at the German Psychiatric Association in Berlin. In his talk he focused on the splitting of psychic functioning as a defining feature of the disease and noted it wasn't associated with dementia or factors like early puberty onset.

Sleep paralysis occurs when the body fails to 'unfreeze' in sync with waking

When the body falls into a deep enough phase of sleep, it paralyzes certain parts of itself so the brain can't force it to physically act out dreams. This well-known but little-understood phenomenon happens when the brain awakens early and typically results in haunting hallucinations and reports of supernatural terrors.

Breaking down various tongue disorders, from infections to genetics

Taste is one of our fundamental senses, but can be impeded by a wide variety of conditions including glossitis, angioedema, and black hairy tongue. Most are characterized by their color, shape, and sometimes change in function. Causes range from vitamin or mineral deficiencies to fluid accumulation, fungal infection, or more.

Carrier screening enables individuals without symptoms to see if they carry a gene for disease

Some conditions are autosomal recessive—meaning a person may carry a gene for that condition, but not have symptoms. Cystic fibrosis, sickle cell disease, and Tay-Sachs disease are examples of autosomal recessive diseases in which a person must inherit two copies of a nonfunctioning gene—one from each parent—to develop disease.

Cancer is typically described by one of five stages

Stage 0 is in situ, meaning abnormal cells haven’t spread, while Stage 1 is further progressed but remains localized to the origin. Stage 2 and 3 show increasing tumor size and spread to nearby lymph nodes or tissues. Stage 4 indicates metastasis, meaning cancer has spread to distant organs.

Is ice slippery because of amorphization—a chaos of molecules caused by sliding?

Traditional explanations cite three factors that make ice slippery: pressure, friction and so-called premelting. A fourth has been proposed in recent years: amorphization, that sliding along some surfaces creates molecular disorder, causing liquid-like behavior.

Anatomy of a healthy knee joint

To understand arthritis, study a normal joint. Where two bones come together, each is lined by a cartilage cap. These bones are linked together by strong ligaments. The inner juncture is lined by a joint capsule (synovial membrane) containing lubricating joint fluid between the two surfaces, allowing for near-frictionless motion.

Stereolithography uses light to fabricate objects in layers via chemical reactions

Specific locations in a tank of light-sensitive liquid resin are exposed to projected light, causing them to cure onto a build platform. The resulting cross-section of hardened plastic is moved slightly away from the light source, exposing it to resin once more, and the process repeats to produce successive layers.

Anhedonia, which means 'without pleasure' in Greek, is typical in major depressive disorder

This common symptom—a flat affect—results in previously enjoyable hobbies no longer bringing pleasure. People with anhedonia may also avoid social situations because they anticipate they'll bring no joy, not because of anxiety or fear.

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.

Ebola is a filovirus, meaning it resembles a thread under a microscope, though it sometimes twists and can resemble a bowl of spaghetti.

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.

Corals are themselves not coral reefs—the term refers to the tiny marine invertebrates that build the rigid reef.

Some researchers have labeled nomophobia, the fear of being without your phone, as 'the phobia of the 21st century.'

The hormonal disorder PCOS was renamed PMOS in 2026, a move designed to improve care and research by shifting the focus to the hormonal causes of this condition that affects 1 in 8 women.

Volcanoes 'die' when their supply of magma runs out, if they are shifted away from their underlying magma reservoir, or if they get clogged by collapsing or their magma cooling back into rock.

Tattoos remain visible on your skin thanks to immune cells called macrophages

About 2,000 US babies are born annually without some portion of their limbs, potentially leading to a lifetime of pricey prosthetics.

Read a deep dive on the 'all-purpose healing' peptide BPC-157.

The use of fungi to detoxify land and water—a process known as mycoremediation—has been used to clean up natural resources affected by the 2025 California wildfires.

Stars appear to twinkle because turbulence in the motion of molecules in Earth's atmosphere causes light to bend and wiggle rapidly on its way to the surface—a phenomenon called scintillation.

Poison ivy's characteristic rash is caused by an allergic response to an oily compound in the plant called urushiol.

Objects can be 3D printed with light by projecting 2D computerized tomography (CT) scans onto rotating cylinders of resin, which solidify upon exposure.

The Great Salt Lake's distinct dual coloration results from high-salinity organisms that only live in the northern portion and produce a purple protein.

Some Pokémon have been named after real and fictional organisms, while some real-world species have been named after Pokémon, such as Chilicola charizard and Binburrum zapdos.

See images of medical cases of firework injuries shared on this 'Instagram for doctors.' (Warning: Graphic content)

In 1939, baseball star Lou Gehrig delivered his inspirational 'Luckiest Man' speech after retiring due to the health condition that now bears his name.

The American Society of Civil Engineers' infrastructure report card gave the US a C in 2025, its highest grade since the project launched in 1998.

SpaceX's S-1 or 'prospectus' revealed many previously unknown details about the company, including its unprofitability despite doing $18.7B in revenue in 2025, exactly how many voting shares Elon Musk will have in the company (roughly 85%), and more.

Pure water does not conduct electricity because this flow of energy requires the movement of charged particles, and water is a neutral molecule.

Existentialist writer Jean-Paul Sartre coined the famous phrase 'Hell is—other people' in his play 'No Exit'

The word 'jazz' evolved from 'jasm,' 19th-century American slang for 'energy'

Some coin denominations have ridges etched on their sides, partly to prevent counterfeiting, in a practice called 'reeding.'