Neurodegenerative Diseases

What Are Neurodegenerative Diseases?

Neurodegenerative disease is a broad term that describes a large group of progressive conditions characterized by gradual damage to parts of the brain and spinal cord. The progressive nature of the diseases means that over time, they are associated with increased disability involving memory, behavior, or the ability to move muscles meaningfully.

Neurodegenerative diseases affect more than 50 million people worldwide and 7 million in the US alone. They generally affect people older than 65 years, but some, like amyotrophic lateral sclerosis (ALS), affect younger people.

Types of Neurodegenerative Diseases

Neurodegenerative disease is a term that describes a wide range of diseases of the brain and spinal cord with varied prognoses and levels of disability. In general, they fall into one of a few different categories.

Motor Neuron Diseases

Motor neuron diseases affect the neurons in the spinal cord that control muscles in the body. As these neurons die or become damaged, people experience difficulty walking and performing activities of daily living like cooking or bathing.

An example of a motor neuron disease is ALS, or Lou Gehrig’s disease.

Parkinsonism-type Diseases

Diseases in this category affect neurons in the brain that control movement. Typical symptoms are tremors and difficulty with coordination. People with these diseases may also have trouble walking and balancing.

Examples of this type of disease include Parkinson’s disease and atypical Parkinsonian disorders, including progressive supranuclear palsy (PSP) and multiple system atrophy (MSA).

Dementia-type Diseases

Diseases that cause dementia can affect many different regions of the brain, causing the neurons to become damaged or die. Symptoms of dementia-type diseases are variable but include difficulty with memory, mood, and the ability to focus.

One of the more common forms of dementia is Alzheimer’s disease, which is thought to be caused by an issue with protein accumulation in and around neurons. Chronic traumatic encephalopathy (CTE) is another type of dementia that results from repeated blows to the head caused by high-impact sports.

Demyelinating Diseases

When the insulation around neurons called myelin degrades, the speed of information traveling from one neuron to another slows down. Demyelinating diseases cause a progressive loss of myelin in the brain and spinal cord that can cause slower reaction times, difficulty with coordination, and problems with memory. Multiple sclerosis (MS) is one of the more common demyelinating diseases.

How Common Are Degenerative Brain Diseases?

The incidence of individual neurodegenerative disease varies significantly. Parkinson’s disease affects about 150 per 100,000 people in the US, whereas ALS affects only about 5 per 100,000 people. One of the rarer neurodegenerative diseases, Creutzfeldt-Jakob disease, which is a fetal brain disease, affects only about 1 per 1,000,000 people worldwide.

What Causes Neurodegenerative Diseases?

Neurodegenerative diseases are typically associated with many risk factors, including genetics and exposure to harmful substances. Recent research shows that most neurodegenerative diseases have more than one cause, resulting in a lifetime of increasing risk that culminates in disease later in life.

A handful of diseases are caused by mutations in a single gene that can be identified before symptoms arise, such as Huntington’s disease, a degenerative disease of neurons that control movement. Even in these cases, though, a combination of genetic tests, brain imaging, and symptom assessment is needed for a definitive diagnosis.

Parkinson’s disease, for example, has no known cause but may result from inflammation, exposure to chemicals like drugs or toxins in the environment, or issues with the brain’s ability to prevent the accumulation of proteins in neurons. Different people may have a similar progressive loss of neurons that causes the disease, but the disease could have different causes.

What Are the Complications of Neurodegenerative Diseases?

The complications of neurodegenerative diseases directly result from the types of neurons or cells in the affected brain region. For example, when motor neurons die, the ability to move is affected, whereas when cells that produce myelin die, the speed of movement is affected.

The area of the brain where the cells are degenerating can also determine the types of complications a person will experience. Each area of the brain is generally responsible for a different task, like speech, memory, coordination, and movement. When the neurons are located in one of these regions, the skills are affected. Parkinson’s disease, for example, is caused by a loss of neurons located near the middle of the brain that are responsible for stabilizing movements. Therefore, a complication of Parkinson’s disease is tremors or shaky movements of the body.

Can Neurodegenerative Diseases Be Prevented?

Most neurodegenerative diseases cannot be completely prevented, but the risk of developing one can be reduced. Steps to reduce this risk focus on limiting exposure to environmental chemicals and improving brain health by leading a healthy lifestyle.

Avoid Smoking

Smoking tobacco is a major avoidable risk factor for several types of cardiovascular disease and, recently, has been implicated in neurodegenerative disease. Damage to blood circulation in the brain may cause cellular issues that can lead to the loss of neurons over time.

Limit Alcohol Consumption

The role of alcohol in brain health has been explored for decades, and the message is fairly clear: small amounts of alcohol may be beneficial, while moderate or heavy use of alcohol, defined as more than two drinks a day for men and one drink a day for women, can be detrimental to brain health. Chronic moderate alcohol use could be toxic to the neurons that cause Parkinson’s disease and Alzheimer’s disease.

Get Enough Sleep

A study by the Biomedical Research Institute in Spain showed that lower amounts of sleep at night correlate with an increased risk of developing Alzheimer’s disease. The same study also reported that people who wake earlier in the morning are at lower risk of developing Parkinson’s disease.

Engage in physical activity

Exercise has may increase factors that promote the survival of neurons and reduce inflammation and substances that damage cells in the brain, thereby protecting the nervous system from diseases like Alzheimer’s and Parkinson’s disease. Conversely, a sedentary lifestyle can cause changes in the body that increase the risk of neurodegenerative diseases. The amount of exercise required can be as little as a 20-minute walk three times a week.

Eat A Healthy Diet

Diet can greatly impact mental health, and adherence to a Mediterranean diet has been associated with lower rates of dementia. This diet has a high intake of fish, grains, and nuts, with a low intake of red meat, saturated fat, and dairy.

What Can I Expect If I Have a Neurodegenerative Disease?

Neurodegenerative diseases vary widely in the way they progress; however, progression is to be expected. Some common symptoms of neurodegenerative diseases include:

• Memory issues or forgetfulness
• Confusion
• Agitation
• Sleep disturbances
• Mood changes
• Muscle spasms
• Weakness
• Pain

If you have a neurodegenerative disease, you will likely see a neurologist to receive a diagnosis and ongoing treatment that could include medicines to treat symptoms or referrals to other specialists that can support your mental health and daily function.

You may have an occupational therapist who can help with teaching you new ways of doing things that can preserve or increase your independence or a physical therapist to increase your strength or coordination. Speech therapists and psychologists may also be on your care team to help you with speech and mood disorders that might arise.

Generally, the level of support you need increases over time, but having a team in place soon after your diagnosis can ensure that more support is incorporated seamlessly when required.

What’s the Outlook for Neurodegenerative Diseases?

A large research effort has contributed to significant advances in supporting people with neurodegenerative diseases, with the National Institutes of Health providing over $5 billion in research funding in 2023 alone.

In recent years, research has focused on drug development, stem cell-based therapies to replace dead or dying neurons, and immunotherapies that attempt to block the damage caused by genetic mutations or environmental toxins. Other new developments involve PROTACs that address the disease-causing accumulation of proteins in and around neurons. Finally, approaches like gene therapy provide hope for modifying the genetic risk of developing neurodegenerative diseases.

How Do I Take Care of Myself or a Loved One with a Neurodegenerative Disease?

After being diagnosed with a neurodegenerative disease, whether it is yourself or a loved one, your doctor will put together a care team consisting of healthcare providers with expertise in the disease. They will provide education and support and, importantly, will be there for you as the required level of care increases. The care team will help you identify needs and resources for addressing issues as they arise to help the person be as independent as possible.

Assistive devices, such as electronic reminders for medicines or computers that help with speech, are available to support the person’s goals.

When Should I See My Healthcare Provider?

A healthcare provider should be consulted if you observe any changes in your ability to function daily. If your family has a history of neurodegenerative diseases, this should be shared with your healthcare provider, even if you don’t have symptoms. When in doubt, communicate what you are experiencing to your healthcare provider. They can assess whether a referral to a specialist would be beneficial and can help you track possible symptoms.