Neurodegenerative disease

Our brains use tiny cells to work. These cells help us move and think. Sometimes, these cells start to get hurt. They can even die. This is called a brain disease.

When cells die, the brain changes. It might get harder to walk. It might be hard to remember things. Some people have trouble with how they move.

One common disease is called Alzheimer's. It is very hard to fix. Doctors are looking for ways to help.

Getting older is a big risk. Many people get these diseases as they age. Scientists want to find new ways to keep our brains healthy.

Our brains use tiny cells called neurons to work. These cells help us think and move. Sometimes, these neurons are lost or die. This is called neurodegeneration. It is a way the brain breaks down over time.

There are many different types of these diseases. Alzheimer's is the most common one. It causes parts of the brain to shrink. This happens because of tiny clumps called amyloid plaques. These plaques are made from small pieces of protein.

Another common type is Parkinson's disease. It can make it hard to move or stay steady. It affects cells that use a tool called dopamine. Huntington's disease is another type. It is caused by a change in a gene. This can cause strange movements.

Some diseases, like Multiple Sclerosis, attack the protective coating on cells. This coating is called myelin. When myelin is lost, signals move more slowly. Scientists study these diseases to find new cures. Right now, most of these diseases cannot be cured. Getting older is the biggest risk factor for them.

Neurodegenerative diseases are a group of conditions that cause the steady loss of neurons. Neurons are the tiny cells that help our brains work. This loss is called neurodegeneration. As neurons are damaged, they may eventually die. This can happen at many levels in the brain. It can affect small parts of a cell or the whole system.

Scientists believe two main things contribute to this. One is called oxidative stress. The other is inflammation, which is when the body reacts to damage. Because we cannot yet reverse this loss, these diseases are called incurable. This makes them a very important area for medical research.

Different diseases work in different ways inside the body. In Alzheimer's disease, tiny clumps form in the brain. These are called amyloid plaques. They are made of small pieces of a protein called amyloid beta. This protein comes from a larger protein called amyloid precursor protein, or APP. Enzymes like beta secretase and gamma secretase cut the APP into smaller pieces. These pieces then gather into dense plaques.

In Multiple Sclerosis, the body's own immune system attacks the brain. It targets the myelin sheath, which is a protective coating on the neurons. When this coating is lost, signals move much slower through the nervous system.

Researchers have studied these diseases for a long time to find causes. For example, scientists found that mutations in the huntingtin gene cause Huntington's disease. This disease causes proteins to form clumps called inclusion bodies. These clumps can be toxic to the neurons. In 1993, researchers found specific mutations in the SOD1 gene for some cases of ALS. This disease causes the loss of both upper and lower motor neurons. Scientists also look at how proteins like alpha-synuclein move through cells. This helps them understand how Parkinson's disease might work.

There are many important facts and numbers regarding these diseases. Alzheimer's is the most common neurodegenerative disease. It has a 20% misdiagnosis rate. In clinical trials, new treatments for it have a 99.5% failure rate. Parkinson's is the second most common disorder. Its prevalence can range from 15 to 12,500 per 100,000 people. In 2019, an estimated 55 million people worldwide had dementia. This number is expected to grow to 139 million by the year 2050.

These diseases affect how we interact with the world every day. Some cause problems with movement, like the shaking seen in Parkinson's. Others cause dementia, which changes how people think and remember. Huntington's disease can cause a type of movement called chorea. Even rare diseases like Batten disease affect how children see and walk. The biggest risk factor for most of these conditions is simply getting older.

By studying how these cells break down, scientists hope to find new ways to help.

Neurodegenerative diseases are a group of conditions defined by the progressive loss of neurons. This process is known as neurodegeneration. As neurons suffer damage, they may eventually die. This damage can occur at many different levels of the brain's circuitry. It can happen at the molecular level or at a systemic level. Because there is currently no known way to reverse this loss, these diseases are considered incurable. Scientists believe two major factors contribute to this process: oxidative stress and inflammation.

Biomedical research has found many similarities between these different diseases. At the subcellular level, they often involve atypical protein assemblies, which is called proteinopathy. They also share the process of induced cell death. These similarities are important for science. They suggest that a new treatment for one disease might help improve other diseases as well. The scale of these conditions is massive. In 2019, an estimated 55 million people worldwide lived with dementia. Researchers predict this number will rise to 139 million by the year 2050.

Alzheimer's disease is the most common neurodegenerative disease. It is a chronic condition that causes the loss of neurons and synapses. This loss happens in the cerebral cortex and certain subcortical structures. This leads to gross atrophy, or shrinking, of the temporal lobe, parietal lobe, and parts of the frontal cortex. The pathology of Alzheimer's is characterized by amyloid plaques and neurofibrillary tangles. Plaques are made of small peptides called amyloid beta. These come from a larger protein called amyloid precursor protein, or APP. Enzymes like beta secretase and gamma secretase cleave APP into smaller fragments. These fragments then self-assemble into dense extracellular plaques.

Parkinson's disease is the second most common neurodegenerative disorder. It often causes bradykinesia, which is slow movement, as well as rigidity and tremors. This disease is characterized by the death of dopaminergic neurons in the substantia nigra. This is a specific region of the midbrain. In affected neurons, researchers observe alpha-synuclein-ubiquitin complexes in structures called Lewy bodies. It is thought that defects in protein transport machinery, such as RAB1, may play a role. Age remains the main known risk factor for Parkinson's. However, mutations in genes like SNCA, LRRK2, GBA, and MAPT can also increase risk.

Huntington's disease is a rare autosomal dominant disorder. It is caused by mutations in the huntingtin gene, known as HTT. This mutation causes a polyglutamine tract expansion. This results in a mutant version of the huntingtin protein. These mutant proteins form aggregates called inclusion bodies. These inclusion bodies may be directly toxic to cells. They can also damage molecular motors and microtubules. This interferes with axonal transport, which is the movement of materials through the neuron. This interference can prevent the transport of important cargoes like BDNF. The disease often affects the striatum first, leading to movements called chorea.

Multiple sclerosis, or MS, is a chronic demyelinating disease of the central nervous system. It is caused by an autoimmune attack on the body. This attack results in the loss of the myelin sheath on neuronal axons. The myelin sheath acts like insulation for the nerve. When it is lost, the speed of signal transduction decreases. This leads to cognitive and motor impairments. The disease progresses through episodes of increasing inflammation. This happens when antigens like myelin basic protein trigger an autoimmune response. This causes T cells, B cells, and macrophages to cross the blood-brain barrier and attack the myelin.

Other rare diseases also cause significant neurodegeneration. Amyotrophic lateral sclerosis, or ALS, involves the loss of upper and lower motor neurons. In some cases, mutations in the SOD1 gene are found. Research shows that SOD1 mutations may act on astrocytes, which are cells other than neurons. Batten disease is a rare group of lysosomal storage disorders. It is also called neuronal ceroid lipofuscinoses. It is often characterized by early vision loss and seizures. Finally, Creutzfeldt–Jakob disease is a prion disease. In this condition, misfolded proteins called prions aggregate in brain tissue and cause rapid dementia.