Overview

Corticobasal degeneration (CBD) is a rare brain disease that can cause a collection of symptoms known as corticobasal syndrome (CBS). CBS symptoms include trouble with thinking, speaking, movement on one side of the body, poor coordination and stiffness.

Corticobasal degeneration happens when a protein called tau builds up in the brain. This buildup causes nerve cells to die and areas of the brain to shrink. While CBD is a common cause of CBS, these symptoms can be due to other conditions such as Alzheimer's disease or progressive supranuclear palsy.

Corticobasal degeneration affects the area of the brain that processes information and brain structures that control movement. People with this disease have trouble with movement on one or both sides of the body. Trouble with movement gets worse over time.

Symptoms also may include poor coordination, stiffness, trouble thinking and trouble with speech or language.

The only way to confirm CBD as the cause of CBS is to examine brain tissue after death, but exams and tests can help diagnose the condition during life.

There is no cure for CBD yet, but medicines and therapies can help to manage symptoms.

Symptoms

Symptoms caused by CBD can affect thinking, language, behavior and movement. Changes in thinking or behavior may appear before changes in movement. When these symptoms show up, they may be diagnosed as corticobasal syndrome (CBS). More tests may be needed to know if CBD is the root cause of CBS.

Mental processing symptoms may include:

  • Trouble with decision-making, planning or problem-solving. These also are known as executive function skills.
  • Memory changes.
  • Difficulty with visual and spatial awareness.
  • Not being able to do a learned task. This is known as apraxia.
  • Speech changes, such as slow and halting speech. This is known as aphasia.

Behavioral symptoms may include:

  • Depression, withdrawing or feeling like nothing matters.
  • Feeling irritable or agitated on a regular basis.
  • Acting out, also known as compulsivity.
  • Fixations on certain behaviors, such as putting objects in the mouth.
  • Marked increase in sexual desire.
  • Laughing for no reason.

Movement symptoms may include:

  • Trouble moving on one or both sides of the body, which gets worse over time.
  • Trouble with balance or coordination.
  • Stiffness.
  • Postures of the hands or feet that can't be controlled. For example, the hand may form a clenched fist.
  • Muscle jerks, or limbs that seem to move on their own.
  • Trouble swallowing.
  • Changes in eye movements.

Symptoms tend to get worse over time. Eventually, people with the disease lose the ability to walk. A wheelchair or other aids may be needed as movement declines. CBD can cause serious complications that often lead to death. Life expectancy with confirmed CBD can range from 2 to 12 years. But it tends to last between 6 to 8 years on average.

Causes

Corticobasal degeneration is due to a buildup of a protein called tau in brain cells. The buildup of tau may lead to the breakdown of the cells. This breakdown can lead to signs and symptoms of corticobasal syndrome.

Most people with CBS have CBD, but other causes are common. These include Alzheimer's disease, progressive supranuclear palsy, Pick's disease and Creutzfeldt-Jakob disease.

Risk factors

While risk factors for CBD aren't clearly understood, family genes may play a role. Differences in certain genes may raise the risk of CBD. These genes include MAPT and MOBP.

MAPT helps the body make tau. MOBP supports processes that create the protective covering of the nerves, called myelin. More research is needed to fully understand the connection between these gene changes and CBD.

Lifestyle choices or environmental factors do not seem to play a role in getting or preventing CBD.

Complications

People with corticobasal degeneration may develop serious complications. This is because CBD affects the body's functions that control breathing, swallowing and movement. Complications often lead to death.

Complications include:

  • Pneumonia.
  • Choking.
  • Blood clots in the lungs.
  • Sepsis, which is a dangerous response to an infection.
By Mayo Clinic Staff