Corticobasal degeneration (CBD)
Corticobasal degeneration (CBD) is a rare, progressive brain disease which is also known as corticobasal syndrome (CBS) or corticobasal ganglionic degeneration (CBGD).
What causes CBD?
Corticobasal degeneration is a loss of nerve cells in parts of the brain. The outer layer of the brain, the cortex, is severely affected and the basal ganglia area (a deep part of the brain) also sees deterioration. This brain damage is thought to be caused by a build-up of a protein called tau. In most people tau is broken down and never reaches high levels. In people with CBD it isn't broken down and forms harmful clumps in the brain.
CBD is a progressive disorder which usually develops in people between the ages of 50 and 70. It worsens over the course of 5 to 10 years. Unfortunately patients with CBD deteriorate to the point where they can no longer care for themselves. They often die from secondary medical issues such as pneumonia or severe infection.
The symptoms of CBD come on gradually and can be mistaken for stroke, Alzheimer's or Parkinson's disease. They include:
- Changes in language, slow and slurred speech
- Progressive numbness and loss of use of one limb
- Unintentional jerky movements of one limb or other parts of the body, tremors
- Difficulties with co-ordination, balance and movement
- Difficulty swallowing
- Muscle stiffness, rigidity
Symptoms vary from person to person and it's unlikely anyone would have all of the above symptoms.
As CBD progresses other limbs may become affected and a person with the disorder may experience short-term memory loss, difficulty with reading and counting, and problems planning ahead.
In its advanced stages CBD patients will no longer be able to care for themselves. They may experience extreme muscle stiffness and an inability to move one or more limbs. Their speech may deteriorate making it harder for them to be understood and they may have worsening dementia. They may blink uncontrollably and have increased difficulty swallowing.
On average, people with CBD live for around 8 years after their first symptoms appear.
There is no single test for CBD and so a diagnosis is made based on symptoms and by ruling out other, similar diseases. Tests and brain scans will be carried out and a diagnosis made or confirmed by a consultant with expertise in CBD. This will usually be a neurologist.
A patient may also undergo neuropsychological tests which look at memory, numbers, concentration and understanding language, words and pictures. Patients with CBD have a pattern of difficulties with these tests.
There are a number of ways to manage the symptoms of CBD but there is currently no cure and no treatment to slow its progress.
Patients may benefit from physiotherapy to help with movement and balance, and speech and language therapy for help with talking and swallowing difficulties. Occupational therapy may help with doing everyday tasks.
A number of drugs are available to help relieve individual symptoms, such as muscle stiffness and pain. However, doses should start low as people with CBD are often sensitive to the side effects of medication.