Chronic Degenerative Diseases Examples

Instructor: Amanda Robb

Amanda holds a Masters in Science from Tufts Medical School in Cellular and Molecular Physiology. She has taught high school Biology and Physics for 8 years.

In this lesson, we'll learn what a chronic degenerative disease is and what can cause it. We'll also go over some common examples and dive into the symptoms and treatments for each.

What Are Chronic Degenerative Diseases?

If you live somewhere where there's snow, you may be familiar with the wear and tear on the roads over time. Such wear and tear is particularly common during the winter, when ice and snow freeze the pavement, causing cracks as the underlying surface expands and contracts at a different rate than the asphalt. Plow trucks and salt also work to break apart the smooth surface. Even though it is unintended, the result is a patchy, pothole-ridden road in the spring.

A similar process happens in our body and it's called degenerative disease, but snow and ice aren't the culprit here. In degenerative diseases, parts of the body break down at a faster rate than normal over time. These might be caused by environmental factors or genetics, and some causes aren't fully understood yet. Below, we'll look at four major examples of degenerative diseases: Huntington's disease, Parkinson's disease, macular degeneration and osteoarthritis.

Huntington's Disease

Imagine a freight train barreling down on you. You know there is no way to stop it, and you can't outrun it. You close your eyes and prepare for the worst. Although this frightening situation is a thing of nightmares, patients with Huntington's disease experience a similar fear of their inevitable demise.

Huntington's disease is a genetic disorder that is present from birth that eventually causes death of brain cells, called neurons. The condition usually appears between ages 30 and 40, but it can manifest as early as age 20. Once the symptoms have started, there is no way to stop them and the person will eventually stop being able walking, speaking and swallow on their own.

At first, the patients might feel uncontrollable emotions and an inability to organize their thoughts. Jerky movements and problems with posture and balance also occur. Although no treatment can stop the disease, medications that help ease movement and psychiatric drugs that control emotional instability can help. Patients may also attend physical or speech therapy.

The pink highlight shows the striatum, the main part of the brain affected by the disease.
brain diagram

Parkinson's Disease

Parkinson's disease is another disease in which neurons die off over time. These neurons die in a specific location in the brain called the substantia nigra. This location controls motor function through the chemical dopamine. Neurons that make dopamine are killed off and, without these neurons, a person starts to experience tremors, or light shaking. The disease eventually develops into larger tremors as well as difficulty walking and swallowing. Most drug treatments for Parkinson's are all about increasing dopamine levels, since decreased dopamine is the major problem. Patients might also go to physical therapy to get help with walking.

Macular Degeneration

Picture two children playing at the park. One has a bright yellow ball and the other holds a soccer ball. They pose for their parent to take a picture. The image below shows two different versions of this image--people with macular degeneration see the picture on the right, while a person without this disease might see the clearer picture on the left.

Macular degeneration causes changes in vision.
vision in macular degeneration

Macular degeneration is a condition that occurs in many older people. With this disease, an important part of the retina called the macula breaks down over time. The macula may break down slowly, with no noticable symptoms for many years, or it may progress faster, causing relatively sudden blurred vision and black spots. Since the macula is in the middle part of the retina, the central vision is most affected. Macular degeneration won't cause full blindness by itself, but the extreme blurred vision in the center of the vision field can be problematic. Most treatments focus on prevention, such as by stopping smoking or taking certain vitamins. However, for very extreme cases, surgery can be an option.

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