Cerebral Amyloid Angiopathy
Amyloid buildup that weakens small brain blood vessels
Quick Facts
- Type: Small-vessel brain disease
- Main protein: Amyloid beta
- Main risk: Bleeding in the brain
- Most affected: Older adults
Overview
Cerebral amyloid angiopathy, or CAA, is a condition in which a protein called amyloid beta gradually deposits in the walls of the small and medium blood vessels of the brain and its surface. As the protein builds up, the vessel walls become brittle and prone to leaking or bursting. This makes CAA an important cause of bleeding in the brain, particularly in older adults.
CAA most often affects people in later life, and the risk rises with age. It is also closely related to Alzheimer's disease, because both involve the same amyloid protein, although a person can have one condition without the other. CAA can lead to sudden bleeding strokes, small areas of bleeding that accumulate over time, and gradual changes in thinking and memory. There is no cure, so care focuses on lowering bleeding risk and managing symptoms.
Symptoms
The symptoms of cerebral amyloid angiopathy depend on whether bleeding occurs and where it happens in the brain.
- Sudden severe headache, weakness, numbness, or speech difficulty if a larger bleed occurs
- Brief, recurring episodes of tingling, numbness, or visual changes that spread across part of the body
- Gradual decline in memory and thinking over time
- Confusion or difficulty with attention and planning
- Seizures in some cases
Many small bleeds cause no obvious symptoms and are found only on brain imaging.
Causes
CAA is caused by the buildup of amyloid beta protein in the walls of brain blood vessels. Over time this weakens the vessels so they are more likely to leak or rupture. Why amyloid accumulates is not fully understood, but advancing age is the strongest factor.
Most cases occur sporadically in older adults and are not directly inherited. Rare familial forms are linked to specific gene changes and can appear at younger ages. The condition is not caused by lifestyle and is not contagious, though factors that raise blood pressure or thin the blood can increase the chance of bleeding.
Risk Factors
- Older age, the strongest risk factor
- Alzheimer's disease, which shares the same amyloid protein
- Certain inherited gene variants in rare familial forms
- Use of blood-thinning medications, which raises the risk and severity of bleeding
- Uncontrolled high blood pressure, which adds to bleeding risk
Diagnosis
Diagnosing CAA can be difficult because a definite diagnosis requires examining brain tissue, which is rarely done. In practice, doctors rely on the clinical picture and imaging.
- MRI of the brain: Special sequences can reveal tiny old bleeds and surface bleeding patterns typical of CAA.
- CT scan: Used urgently to detect a new brain bleed.
- Clinical assessment: A pattern of bleeding in the outer brain regions in an older adult supports the diagnosis.
- Other tests: Cognitive testing and, in selected cases, additional studies to assess amyloid.
Treatment
There is currently no treatment that removes amyloid from brain vessels, so care aims to reduce the risk and impact of bleeding.
- Blood pressure control: Keeping blood pressure well managed lowers the chance of bleeding.
- Careful use of blood thinners: Doctors weigh the risks carefully, since these medicines can increase bleeding in CAA.
- Stroke care: Emergency treatment and rehabilitation if a brain bleed occurs.
- Seizure treatment: Medication if seizures develop.
- Supportive care: Help with memory, thinking, and daily function, and safety planning to prevent falls.
Prevention
CAA itself cannot be prevented, but steps can lower the chance of a serious bleed.
- Keep blood pressure within the range your doctor recommends
- Discuss the risks and benefits of any blood-thinning medication with your doctor
- Avoid excessive alcohol
- Reduce fall risks at home, since head injuries can trigger bleeding
- Attend regular follow-up if CAA has been identified
When to See a Doctor
See a doctor if you notice gradual changes in memory or thinking, or brief recurring episodes of numbness or visual disturbance. Call emergency services immediately for signs of a stroke or brain bleed:
- Sudden severe headache unlike any before
- Sudden weakness or numbness, especially on one side
- Trouble speaking, understanding, or seeing
- Sudden loss of balance, confusion, or a seizure
Frequently Asked Questions
What causes cerebral amyloid angiopathy?
CAA is caused by buildup of a protein called amyloid beta in the walls of small brain blood vessels, which makes them fragile and prone to bleeding. Advancing age is the strongest factor, and most cases are not inherited.
Is cerebral amyloid angiopathy the same as Alzheimer's disease?
No, but they are related. Both involve the amyloid beta protein, and the two conditions often occur together. However, a person can have CAA without Alzheimer's disease, or Alzheimer's without significant CAA.
Why does CAA cause bleeding in the brain?
Amyloid deposits weaken the walls of small brain blood vessels, making them brittle. These fragile vessels are more likely to leak or rupture, which can cause small bleeds that build up over time or larger, sudden bleeding strokes.
Can cerebral amyloid angiopathy be treated?
There is no treatment that clears amyloid from the vessels. Care focuses on controlling blood pressure, carefully weighing blood-thinning medicines, treating any bleeding or seizures, and supporting memory and daily function.
Should people with CAA avoid blood thinners?
Blood-thinning medicines can raise the risk and severity of brain bleeding in CAA, so doctors weigh their use very carefully. The decision depends on each person's overall situation and should be made with a doctor, never stopped on your own without advice.
References
- National Institute of Neurological Disorders and Stroke (NINDS).
- Mayo Clinic. Cerebral amyloid angiopathy.
- MedlinePlus, U.S. National Library of Medicine. Stroke.
- American Stroke Association. Hemorrhagic stroke.