The symptoms typically become more severe over several years, although the speed at which they worsen varies.
As CBD reaches an advanced stage, muscle stiffness will continue to get worse. People with the condition may lose the ability to move 1 or more limbs. Some people are unable to walk and need a wheelchair or assistance to transfer (such as help getting into and out of bed).
Some of the main symptoms of CBD are outlined below. Most people with the condition won’t experience all of these.
Problems affecting the limb can include:
Walking, balance and co-ordination may get worse. Many people have problems with their speech, which will become slow and slurred.
As CBD progresses, it may eventually start to cause problems in your other limbs.
Other problems people with advanced CBD can experience include:
CBD typically affects one of the limbs at first. This is usually a hand or arm, but sometimes a leg.
The condition tends to develop gradually, which means it can be mistaken for another condition at first – such as Parkinson’s disease, dementia or a stroke.
We would like to thank Prof Carlo Colosimo (Università La Sapienza, Rome, Italy) for his help in reviewing this infomation.
A diagnosis should be made by a specialist with experience in 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.
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.
Speech and communication problems: slow and slurred speech.
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.
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.
Content last reviewed: March 2020