Corticobasal degeneration (CBD) is a rare type of parkinsonism that affects people from the age of 40, typically between the ages of 50 to 70. It tends to affect one side of the body more than the other initially, gradually spreading over the course of a few years.
CBD has similarities with Progressive Supranuclear Palsy (PSP). Some people with CBD go on to develop PSP, and vice versa.
CBD is a very individual condition and the symptoms each person experiences vary. As CBD is a progressive neurodegenerative condition, symptoms gradually become worse over time.
The most common symptoms are outlined below, but many people have only a few symptoms.
- difficulty controlling the limbs on one side of the body – often known as ‘alien limb’ syndrome – as arms or legs may seem to move independently
- numbness and loss of movement in one hand, making everyday tasks such as dressing, writing and eating difficult
- muscle stiffness (rigidity)
- shaking (tremor)
- jerky or awkward movement and spasms (dystonia)
- balance and co-ordination problems.
Speech and communication problems: slow and slurred speech.
Swallowing difficulties: eating, drinking and swallowing become progressively more difficult and food may ‘go down the wrong way’. This can lead to chest infections or pneumonia.
Cognitive and behavioural changes: thinking may become impaired, leading to memory problems and difficulty understanding and interpreting communication. It may also be difficult to carry out complex tasks that require planning ahead.
Changes in personality, such as apathy, irritability and interest in things previously enjoyed may be noticed by family and friends.
Diagnosis is usually based on the pattern of symptoms experienced and the exclusion of other conditions that may cause similar symptoms, such as Parkinson’s or stroke. Unfortunately, as with Parkinson’s, there is no single test or scan to diagnose CBD.
A diagnosis should be made by a specialist with experience of CBD, usually a neurologist. He or she may ask for a brain scan to rule out other causes, and they may also carry out tests to check memory, concentration and understanding of verbal communication.
CBD occurs when cells in specific parts of the brain – the cortex and basal ganglia - are damaged as a protein called tau builds up and over time causes harmful clumps. In normal brains, tau is broken down to avoid a build-up, but in CBD this does not happen.
It is thought there may be some weak genetic link too but the risk of other family members developing CBD is very low.
There is currently no cure or treatment to stop CBD’s progression but medication and various therapies can relieve symptoms and improve quality of life.
- Medication can improve movement, cognitive and behavioural problems.
- Physiotherapy can help with movement and balance problems.
- Speech and language therapy can help with swallowing and communication difficulties.
- An occupational therapist can advise on equipment and adaptations in the home, and can suggest strategies for carrying out daily tasks in order to retain as much independence as possible.