People with corticobasal degeneration (CBD) develop a range of difficulties with movement, speech, memory and swallowing.

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.

The symptoms typically become more severe over several years, although the speed at which they worsen varies.

Some of the main symptoms of CBD are outlined below. Most people with the condition won't experience all of these.

CBD typically affects one of the limbs at first. This is usually a hand or arm, but sometimes a leg.

Problems affecting the limb can include:

• a clumsy or "useless" hand
• muscle stiffness
• shaking hands (tremors) and muscle spasms (dystonia)
• loss of feeling
• feeling like the limb doesn't belong to you (an "alien" limb)

Some people also develop problems with walking and co-ordination.

As CBD progresses, it may eventually start to cause problems in your other limbs.

Walking, balance and co-ordination may get worse. Many people have problems with their speech, which will become slow and slurred.

Some people with CBD also have dementia, although this doesn't always occur, symptoms may include:

• problems recalling words, reading and using correct language (aphasia)
• short-term memory loss
• problems carrying out tasks that require planning or thinking ahead
• problems coping with sudden and unexpected situations
• difficulty with numbers and counting
• difficulty seeing things, or knowing where things are located (such as furniture)

It's also common for someone with CBD to experience personality changes, such as becoming apathetic, irritable, agitated or anxious.

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).

Other problems people with advanced CBD can experience include:

• worsening speech problems, which can make it hard for others to understand them
• uncontrollable blinking
• worsening dementia, meaning constant care may be needed
• increasing dysphagia (swallowing problems), which may mean a feeding tube is required

As a result of swallowing problems, many people with CBD develop chest infections caused by fluid or small food particles falling down into their lungs, or aspiration pneumonia, which can be life-threatening.