Amyloidosis can interfere with the function of organs throughout the body, resulting in symptoms such as swelling, fatigue, shortness of breath, and diarrhea. The condition does not, however, cause dementia — characterized by impairment of brain functions. Nevertheless, there is a connection between amyloidosis and dementia.

Amyloidosis is caused by an abnormal buildup of particular proteins, called amyloids, in different organs. The buildup may lead to organ damage, and in severe cases, organ failure.

Dementia results from damage to brain cells — and scientists have found that people with Alzheimer’s disease (a type of dementia) have amyloid deposits in the brain. Some doctors believe that these deposits are responsible for the brain damage that leads to dementia. However, research has not yet proven that to be the case.

In short, amyloidosis and dementia share a trait in that they are both linked to abnormal amyloid protein deposits. However, not all scientists are confident there is a direct causal relationship between them.

To better understand the relationship, let’s take a closer look at amyloidosis, dementia, and other connections between the two.

What Is Amyloidosis?

Amyloidosis is a rare disease that is classified into several different types. With amyloidosis, amyloid proteins misfold and form clumps called amyloid plaques, fibrils, or deposits. These deposits build up in different organs and stop them from functioning properly.

Different types of amyloidosis may affect different organs. The condition also may affect one organ or multiple organs at the same time. Affected organs may include the:

• Kidney
• Heart
• Liver
• Spleen
• Stomach or intestines
• Nervous system

Amyloidosis can have a variety of nonspecific symptoms, including:

• Irregular heartbeat
• Diarrhea and constipation
• Severe fatigue
• Shortness of breath
• Weight loss

Symptoms vary widely from person to person, depending on which organs are affected. This can sometimes make amyloidosis difficult to diagnose.

What Is Dementia?

Dementia is a general term that covers a range of neurodegenerative diseases, including Alzheimer’s disease. Neurodegenerative diseases are diseases of the central nervous system that cause nerve death (neurodegeneration) and affect cognitive function. Dementia describes memory loss, cognitive impairment, and the loss of other thinking abilities, potentially disrupting a person’s daily life severely.

Unlike amyloidosis, dementia mainly affects the brain and not other organs. Initial symptoms of dementia include problems with short-term memory and with carrying out daily activities, such as paying bills, preparing dinner, and remembering appointments. Symptoms of dementia are progressive, which means that they get worse over time. In some cases, symptoms may progress rapidly.

Causes of Amyloidosis and Dementia

Both amyloidosis and dementia involve deposits of amyloid protein, but the driving forces behind the buildup appear to be different between the conditions.

Amyloidosis Causes

Researchers understand much about the causes of amyloidosis and its characteristic buildup of amyloid proteins. Some varieties of the condition are hereditary. Transthyretin amyloidosis, for example, is hereditary and caused by gene mutations. Other types of amyloidosis are caused by outside factors, such as inflammatory diseases or long-term dialysis.

Studies have found some risk factors among people with amyloidosis, including:

• Being older than 50
• Having an inflammatory disease
• Experiencing chronic infections
• Having a family history of amyloidosis
• Having multiple myeloma (a type of blood and bone marrow cancer)
• Having a kidney disease that required dialysis treatment for longer than five years

Dementia Causes

Dementia, in general, is caused by damage to neurons, the nerve cells in the brain. When brain cells are damaged, so too are the connections between them. Lesions (scarring) from the damage can stop the affected region of the brain from functioning properly. For example, when brain cells are damaged in the region responsible for forming memories, memory loss may result.

Deposits of amyloid proteins are a hallmark of Alzheimer’s. Recent studies have found a correlation between the rate of amyloid buildup in the brain and cognitive decline. However, correlation is not the same as causation. It is not certain whether the buildup of amyloid proteins causes Alzheimer’s disease and dementia.

The Amyloid Hypothesis

Some researchers support something called the amyloid hypothesis as an explanation for why brain cells degenerate. The amyloid hypothesis suggests that the buildup of beta-amyloid — smaller particles of amyloid proteins — is the primary cause of Alzheimer’s. The hypothesis suggests that abnormal amyloid deposits disrupt communication between brain cells, which causes brain cells to die.

To test this hypothesis, some studies have examined the effectiveness of using anti-amyloid antibodies — immune proteins that fight against beta-amyloid proteins — to prevent buildup. In 2016, a clinical trial found that anti-amyloid antibodies reduced levels of beta-amyloids in the brain and decreased the rate of cognitive decline in people with mild or preclinical Alzheimer’s disease.

Although some researchers continue to explore the amyloid hypothesis, others don’t believe amyloid buildup is the primary cause of Alzheimer’s.

The Connection Between Amyloidosis and Dementia

The main biological similarity between amyloidosis and dementia is the abnormal buildup of amyloid proteins. In amyloidosis, that buildup occurs in organs such as the kidney, heart, or liver. In Alzheimer’s, the buildup occurs in the brain.

The difference is, the buildup of proteins has been shown to cause organ damage and failure in amyloidosis. With dementia, however, it is not yet certain whether those proteins are the cause of the brain damage.

Another commonality between amyloidosis and dementia is the role of age. Amyloidosis is more common in older adults over age 50. Similarly, the risk of dementia and Alzheimer’s disease increases with age.

Decreasing the Risk of Dementia With Amyloidosis

According to current research, there is no evidence that a person with amyloidosis would have an increased risk of dementia. For all people, though, it is important to focus on preventing dementia and strengthening your immune system. One study found that people who practiced four or five healthy lifestyle factors had a 60 percent lower risk of dementia as compared to people who followed none or only one of the factors. Lifestyle factors included:

• Eating a healthy diet
• Getting moderate to vigorous physical activity
• Not smoking
• Having light to moderate alcohol intake
• Engaging in cognitively stimulating activities

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 amyloidosis? Share your experience in the comments below, or start a conversation by posting on your Activities page.