Some changes in cognitive abilities (such as thinking, learning, and remembering) are common as healthy people age. In people with certain conditions, cognitive decline might be more severe and rapid. Cerebral amyloid angiopathy (CAA) is a form of amyloidosis that affects the brain, and it’s an important cause of abnormal mental decline.

If you’re already living with amyloidosis, you may have heard about the connection between dementia or Alzheimer’s disease and amyloidosis. Members of MyAmyloidosisTeam have expressed concern about this connection. “Can amyloid protein spread to your brain?” asked one member. Another shared, “My husband has been told that he has amyloidosis of the brain. Has anyone heard of this?”

Read on for more details about CAA including what causes it, who’s most likely to develop it, common symptoms, and how it’s diagnosed and treated.

What Is Cerebral Amyloid Angiopathy?

When you’re living with amyloidosis, amyloid protein clumps up and sticks to different organs in your body. These clumps are called amyloid deposits or fibrils. Over time, they can make it difficult for the organ to function. Amyloid deposits can affect your heart, liver, and other organs.

In cerebral amyloid angiopathy, a protein called amyloid beta starts to build up in the brain. Amyloid beta is a very small protein called a peptide. Amyloid beta deposits can get stuck in cerebral blood vessel walls. They can also build up in tissues around the brain called leptomeninges. These deposits cause cerebral hemorrhages (brain bleeds). You might also hear these bleeding episodes called hemorrhagic strokes. People often don’t notice any symptoms when these hemorrhages are small. But when brain bleeds are larger, people can begin to experience neurological symptoms, such as confusion or trouble speaking.

Can CAA Spread to the Body?

CAA is a type of localized amyloidosis that usually only occurs in the brain. People with CAA don’t usually have amyloid beta deposits in other organs.

Can Amyloidosis Spread to the Brain?

People with amyloidosis in other organs might wonder if it can spread to the brain. Unfortunately, there isn’t much research on this topic. A 2022 study found that people with amyloidosis were about three times more likely to experience a brain bleed compared with the general population. Researchers aren’t sure what causes this increased risk. We need more studies to understand how systemic amyloidosis affects the brain.

Who Gets Cerebral Amyloid Angiopathy?

Scientists don’t yet understand why some people develop cerebral amyloid angiopathy. Sometimes, CAA is passed down in families. In other people, CAA develops spontaneously. The older you are, the higher your chance of developing CAA.

Studies estimate that between 23 percent and 29 percent of people older than 50 have moderate to severe CAA. Researchers have found a link between CAA and a protein called apolipoprotein E (APOE). Studies have shown that APOE is important in controlling what amyloid beta does in the brain. Having a particular version of the APOE gene called the epsilon4 allele is a risk factor for developing CAA. About half of people with CAA have some higher-risk version of APOE.

Hereditary CAA, also called inherited CAA, is very rare. It’s caused by mutations in different genes that control amyloid beta. The National Institute of Health estimates that fewer than 1,000 people in the U.S. have hereditary CAA. There are many different kinds of hereditary CAA. These subtypes include the Dutch type, the Icelandic type, and the Danish type.

What Are the Symptoms of Cerebral Amyloid Angiopathy?

Cerebral amyloid angiopathy-related hemorrhages in the brain cause the neurological symptoms people experience. If there’s only a small amount of bleeding, you might not even notice anything. This is a silent microbleed or microhemorrhage. Larger hemorrhages begin to harm brain tissue and lead to noticeable symptoms. Below, we discuss the common symptoms of CAA.

Gradual Neurological Symptoms

With microbleeds, symptoms can be more gradual as brain tissue builds up damage. These symptoms include:

• Episodes of confusion
• Headaches that come and go
• Cognitive decline (gradual loss of mental function)
• Dementia
• Memory loss
• Seizures

Sudden Neurological Symptoms

When a larger hemorrhage occurs, the symptoms can resemble a stroke. During a hemorrhage, you may experience some of these symptoms:

• Headache, especially in one part of the head
• Vision changes, including double or decreased vision
• Drowsiness
• Weakness and paralysis (inability to move)
• Difficulty talking
• Sudden confusion or delirium
• Seizures

Cognitive Impairment

People with CAA tend to experience short- and long-term problems with mental function. A brain bleed can cause a sudden decrease in cognitive function. Brain tissue damage from CAA-related hemorrhaging can also lead to cognitive impairment.

Amyloid beta deposits can also make it difficult for brain tissue to get enough oxygen to function well. This condition of reduced blood flow is called cerebral ischemia. Too little blood flow and oxygen leads to the faster breakdown of the brain cells called neurons. This process is called neurodegeneration, and it happens to everyone as we get older. But people with CAA may experience it faster. Studies show that people with CAA are more likely to develop vascular dementia and Alzheimer’s disease. Vascular dementia is a type of dementia caused by too little blood flow and oxygen to the brain.

People experiencing cognitive impairment may have the following neurological symptoms:

• Forgetfulness and memory loss
• Confusion
• Difficulty doing daily tasks, such as driving to the grocery store or mailing a letter
• Mood and personality changes, such as becoming more suspicious or scared
• Difficulty recognizing familiar faces
• Difficulty participating in conversations

It’s important that people living with CAA have long-term follow-up and monitoring. This will help their medical team manage these mental changes.

How Is Cerebral Amyloid Angiopathy Diagnosed?

Like other forms of amyloidosis, your doctor may need a biopsy — a sample of tissue — to be sure you have CAA. But imaging tests can show brain bleeds and deposits of amyloid beta. This may lead your doctor to suspect CAA. These imaging tests can include:

• CT and MRI scans for hemorrhages
• Positron emission tomography (PET) scans for deposits of amyloid beta

How Is Cerebral Amyloid Angiopathy Treated?

Right now, there is no effective treatment for cerebral amyloid angiopathy. Your medical team’s goal is to reduce the frequency and amount of cerebral hemorrhaging. This will also help control the symptoms you experience. For example, high blood pressure, or hypertension, is a risk factor for hemorrhages.

One special consideration for people with CAA is how this condition impacts their ability to take drugs to prevent blood clots. These drugs are called anticoagulants or blood thinners. Blood thinners are often used for other conditions common in older people. But blood thinners can also worsen cerebral amyloid angiopathy-related hemorrhages. Your medical team will carefully assess the risks of anticoagulants.

In addition, drugs that act on the immune system have been researched as possible treatments for some forms of CAA that involve inflammation. Treatments studied so far have included glucocorticoids (or simply steroids), methotrexate, and other drugs that reduce the immune response.

If you’re interested in participating in research for cerebral amyloid angiopathy treatments, ask your neurologist whether there are any clinical trials you might be eligible to join.

Talk With Others Who Understand

MyAmyloidosisTeam is the social network for people with amyloidosis and their loved ones. On MyAmyloidosisTeam, members come together to ask questions, give advice, and share their stories with others who understand life with amyloidosis.

Are you living with cerebral amyloid angiopathy? Do you wonder if amyloidosis is affecting your brain? Share your experiences in the comments below, or start a conversation by posting on MyAmyloidosisTeam.