Corticobasal Degeneration – Symptoms and Causes
Overview
Corticobasal degeneration (CBD) is a rare brain disorder that damages nerve cells and causes areas of the brain to shrink. This condition typically affects people between 50 and 70 years old and gets worse over time.
The condition is sometimes confused with Parkinson’s disease because they share some symptoms. However, CBD doesn’t respond well to Parkinson’s treatments, which helps doctors tell them apart.
Symptoms
Corticobasal degeneration (CBD) develops gradually, often starting around age 60. Symptoms typically begin on one side of the body and eventually affect both sides.
People with CBD often experience stiffness, shakiness, and difficulty controlling arm or leg movements on one side. The affected limb may feel alien or perform unwanted movements, a symptom called “alien limb phenomenon.”
Balance problems and falls become common as the disease progresses. Some individuals develop jerky movements or fixed postures in their limbs.
Speech difficulties occur in many cases. Words may become slurred or the person might struggle to find the right words. Swallowing problems can develop later in the disease.
Common symptoms include:
- Muscle stiffness and rigidity
- Poor coordination
- Slow movements
- Difficulty with fine motor tasks
- Involuntary muscle jerks or twitches
- Impaired balance and walking
- Speech and language problems
- Difficulty swallowing
Thinking and memory problems may appear as the condition advances. Some people experience changes in behavior, personality shifts, or emotional difficulties. Depression can develop in response to the challenges of living with CBD.
Causes
Corticobasal degeneration (CBD) happens when brain cells degenerate and die over time. The exact cause remains unknown, but scientists have identified several factors that play a role in this rare brain disorder.
At the cellular level, CBD involves the buildup of an abnormal protein called tau. This protein normally helps maintain the internal structure of brain cells.
In CBD, tau proteins cluster together and form deposits that damage cells, particularly in areas controlling movement.
Genetic factors may contribute to CBD development. While it’s not typically inherited, researchers have found mutations in a gene called MAPT (microtubule-associated protein tau) in some cases. These mutations affect how tau protein works in the brain.
Age stands as the main risk factor for CBD. Most people develop symptoms after age 60, with the condition rarely appearing before age 40.
Unlike some other neurological disorders, CBD doesn’t seem to have clear environmental triggers, though researchers continue exploring this possibility.
CBD belongs to a group of conditions called “tauopathies,” which include other neurodegenerative disorders like progressive supranuclear palsy and certain forms of frontotemporal dementia. These conditions share the common feature of abnormal tau protein accumulation.
Complications
Corticobasal degeneration (CBD) leads to several complications as the disease progresses. These problems often worsen over time and can significantly impact daily life.
People with CBD commonly experience difficulty with movement and balance. Falls become more frequent, raising the risk of serious injuries like fractures and head trauma. As mobility decreases, patients may need walking aids or eventually a wheelchair.
Speech and swallowing problems create additional challenges.
Difficulty swallowing (dysphagia) increases the risk of:
- Choking
- Malnutrition
- Dehydration
- Aspiration pneumonia
Muscle rigidity and contractures can cause pain and discomfort. These physical symptoms often limit independence in daily activities like dressing, bathing, and eating. Most patients require increasing assistance as the disease advances.
Cognitive decline affects judgment and safety awareness. Memory loss, confusion, and reduced problem-solving skills make living alone unsafe for many patients. Family members frequently need to take over financial and healthcare decisions.
The emotional impact shouldn’t be overlooked. Depression and anxiety are common in CBD patients, partly due to awareness of their declining abilities. Some patients develop apathy or personality changes that strain relationships with caregivers.
