How Does Multiple Myeloma Affect the Brain?

Multiple myeloma is a form of cancer that affects the plasma cells in the bone marrow − the soft, inner tissue of the bones. Plasma cells play a role in the body's immune function. When plasma cells begin to grow uncontrollably, as with multiple myeloma, they can affect the production of red and white blood cells and platelets.

Abnormal cell development can ultimately lead to symptoms of multiple myeloma. However, neurological signs can stem from many aspects of the disease, including:

• Hypercalcemia

• Anemia

• Infections

• Hyperviscosity Syndrome (HS)

• Central nervous system involvement

While multiple myeloma typically doesn’t directly affect the brain, it can cause neurological symptoms from its effects on other systems in the body. This includes changes in blood chemistry, as well as damage to organs like kidneys or bones which may lead to complications.

Multiple myeloma can also cause cognitive changes due to the release of proteins into the bloodstream. These proteins, called cytokines, are released from myeloma cells and can interfere with the function of the nervous system. This disruption may lead to confusion, memory loss, or difficulty concentrating.

Multiple myeloma presents in different ways, but the earliest symptoms usually relate to the bones. However, there are other early signs of multiple myeloma, including:

• Bone pain

• Back pain

• Shortness of breath

• Unexplained fatigue

• Bleeding or bruising easily

• Nausea

• Changes in bowel habits

• Appetite changes

• Frequent infections

In some cases, mental confusion can be a sign of multiple myeloma. The exact cause varies and may be because of accumulating proteins, high calcium levels or psychological factors.

The following are some possible causes of confusion in multiple myeloma patients.

Hypercalcemia

High blood calcium levels (hypercalcemia) can interfere with proper brain functioning and are made worse by dehydration. Patients with multiple myeloma can develop hypercalcemia due to the release of cytokines from cancer cells, fever and dehydration.

Signs of hypercalcemia include:

• Weakness

• Nausea or vomiting

• Fatigue or lethargy

• Confusion or memory loss

• Depression

Anemia

Anemia happens when the body does not produce enough healthy red blood cells. In multiple myeloma, anemia can occur due to a lack of production of red blood cells in the bone marrow. Anemia can lead to fatigue, confusion, and difficulty concentrating.

Infections

Infections are common in multiple myeloma patients because they often have weakened immune systems due to the imbalance of immune cells. Serious infections can lead to confusion and other neurological symptoms.

Examples of infections that may lead to neurological symptoms include:

• Pneumonia

• Urinary tract infection

• Septicaemia

• Meningitis

• Encephalitis

Hyperviscosity Syndrome (HVS)

Hyperviscosity syndrome (HVS) is a condition in which the blood has increased viscosity (thickness). This happens from an accumulation of monoclonal immunoglobulins, which is common in multiple myeloma. HVS can lead to confusion, headaches, dizziness, and vision problems.

Extramedullary Disease (EMD)

Extramedullary disease (EMD) in myeloma is a term used to describe the malignant cells grow outside the bone marrow. Sometimes this can be in the brain, spinal cord, lymph nodes, and other organs. In multiple myeloma, EMD in the brain may cause neurological symptoms due to changes in pressure levels in the brain. When it occurs, increased pressure in the brain can lead to changes in cognition, such as confusion or occasional seizures. Additionally, symptoms of myeloma growing the nervous system may include:

• Difficulty walking

• Numbness in the legs

• Headaches

• Vision disturbances

• Changes in behavior

Central Nervous System Involvement

Though rare, multiple myeloma can spread to the brain, leading to confusion and other neurological symptoms. An estimated 0.7% of those diagnosed with multiple myeloma will have central nervous system involvement, according to a 2019 study.

"Multiple myeloma can cause confusion because the cancer cells can migrate to the brain and spinal cord," said Sony Sherpa, MD, a holistic physician from Nature’s Rise in Sacramento, California. "When this happens, they can disrupt normal brain functioning by interfering with nerve signals, causing inflammation or chemical imbalances, and putting pressure on the brain."

Additionally, increased pressure on specific areas of the brain due to fluid accumulation in the skull may lead to confusion and other cognitive changes.

Other symptoms of multiple myeloma may include:

• Bones that break easily

• Lethargy

• Depression

• Extreme thirst

• Difficulty walking

• Numbness or tingling in the extremities (peripheral neuropathy)

• Headaches

• Changes in behavior

• Difficulty concentrating

• Weight loss

According to Dr. Sherpa, you should speak to your healthcare provider if you're experiencing any new or worsening mental confusion. Your doctor may suggest a CT scan or MRI to check for abnormalities within the brain. They may also suggest other tests to rule out infection or other causes of confusion.

If your mental confusion is determined to be related to multiple myeloma, your doctor will work with you to determine the best treatment approach for you.