A rare neurodegenerative condition
Corticobasal degeneration (CBD) is a brain condition that causes stiffness, clumsiness and jerky movements, often starting on one side.
It can also lead to changes in thinking, language or behaviour. Symptoms usually begin with a limb feeling awkward or stiff and tend to worsen over years, eventually affecting both sides of the body.
What is corticobasal degeneration?
Corticobasal degeneration is a condition in which movement difficulties and changes in thinking, language or behaviour occur together, reflecting damage across connected brain regions on one side of the brain more than the other, at least initially. The clinical picture arising from this underlying disease is often referred to as corticobasal syndrome, defined by which features are most prominent:
- classic corticobasal syndrome – asymmetric stiffness, clumsiness and jerky movements (myoclonus) affecting one limb, sometimes with the affected limb feeling as though it is not part of the body or moving on its own (alien limb phenomenon)
- progressive apraxia presentation – difficulty planning and carrying out familiar, purposeful movements (apraxia), such as using tools or dressing, despite normal strength
- behavioural or language-led presentation – changes resembling frontotemporal dementia or primary progressive aphasia can occur, with corticobasal degeneration as the underlying cause.
Both movement and cognitive features share several common symptoms, which can include:
- a limb that feels foreign or moves involuntarily (alien limb phenomenon)
- brief muscle jerks (myoclonus) in the affected limb
- changes in language, planning or behaviour
- difficulty with planned, purposeful movement (apraxia)
- stiffness and clumsiness in one limb, spreading over time.
Over time, corticobasal degeneration typically affects:
- movement, coordination and stiffness, spreading to affect both sides of the body
- purposeful movement and coordination (apraxia)
- language, planning and behaviour
- balance and walking, later in the condition
- swallowing and speech, later in the condition.
What happens in the brain?
Corticobasal degeneration is associated with a build-up of abnormal tau protein inside brain cells, a process known as a tauopathy, leading to progressive shrinkage and dysfunction in the brain’s cortex and basal ganglia, typically more pronounced on one side. Because these regions control movement planning, coordination, and aspects of language and behaviour, corticobasal degeneration typically produces a combination of asymmetric motor symptoms and cognitive or language changes.
As corticobasal degeneration and progressive supranuclear palsy both involve abnormal tau protein, the two conditions are sometimes grouped, even though the pattern and distribution of brain involvement differ.
What increases the risk of corticobasal degeneration?
CBD’s exact cause isn’t fully understood, but some factors are linked to a higher chance of developing it. Since it is rare, researchers are still exploring what triggers the condition.
Factors that can’t be changed include:
- age – CBD typically develops in people in their 60s and 70s, and risk increases with age
- genetics – most cases occur sporadically, without a family history; a genetic variation in the MAPT gene, which relates to tau protein, has been linked to a modestly increased risk in some studies, though carrying this variation doesn’t mean a person will develop CBD.
Factors that may play a role, with less well-established evidence than for conditions like vascular dementia or Alzheimer’s disease, include:
- environmental exposures – some research has explored potential links to certain environmental factors, though no specific exposure has been confirmed as a clear cause
- general brain health – cardiovascular health and lifestyle factors have drawn some research interest as possible influences on symptom severity, though this hasn’t been clearly established for CBD specifically.
CBD is rare and its underlying cause isn’t fully understood, so there’s currently no known way to prevent it from developing, and no strong evidence-based lifestyle intervention has been shown to reduce risk.
Common patient questions
No. Corticobasal degeneration can resemble Parkinson’s disease due to stiffness and slowness, but it usually:
- causes more asymmetric symptoms (affecting one side much more than the other)
- has additional features such as apraxia or alien limb phenomenon
- responds poorly or only briefly to standard Parkinson’s medications.
Not always, but changes in thinking, language or behaviour are common, either alongside or sometimes before the movement symptoms become prominent. The pattern varies between people, depending on which brain regions are affected first.
No. Corticobasal degeneration is not typically considered an inherited condition, and it usually occurs without a family history.
While no cure exists, managing symptoms through a team approach can help maintain safety and quality of life, offering reassurance and support.