Dementia with Lewy Bodies
Dementia is a condition that affects your ability to think, reason, and process information. It can also affect your personality and memory. Dementia is progressive, which means it continues to develop over time. There are several types of dementia with different causes.
Of the forms of dementia caused by degeneration of the tissues in the brain, dementia with Lewy bodies (DLB) is the second most common type after Alzheimer’s disease (AD). People with DLB have an accumulation of abnormal protein particles called Lewy bodies in their brain tissue. Lewy bodies are also found in the brain tissue of people with Parkinson’s disease (PD) and AD, although the Lewy bodies are generally located in different parts of the brain in these conditions.
The presence of Lewy bodies in DLB, PD, and AD suggests a connection among the conditions. But scientists haven’t yet figured out what the connection is.
Facts about DLB
DLB was first recognized as a diagnosis in the 1980s. Because the signs and symptoms of DLB resemble those of other forms of dementia, researchers think that the number of diagnoses is lower than the number of cases that actually exist.
According to the National Institute of Neurological Disorders and Stroke, DLB has three features that distinguish it from other forms of dementia:
Fluctuating effects on mental functioning, particularly alertness and attention, which may resemble delirium
Recurrent visual hallucinations
Parkinson-like movement symptoms, such as rigidity and lack of spontaneous movement
In DLB, memory problems often occur later in the progression of the disease.
Approximately 1.3 million people in the U.S. are affected by DLB, according to the Lewy Body Dementia Association.
Other than advanced age, no specific risk factors for DLB have been established. DLB generally appears between the ages of 50 to 85, but it has been seen in younger people. Men are affected by DLB slightly more often than women. If you have a family member with DLB, you are at a somewhat increased risk. Some studies have suggested that a healthy lifestyle might delay onset of dementia associated with increased age.
Causes of DLB
DLB is caused by degeneration of brain tissue. Lewy bodies in the brain affect substances called neurotransmitters. A neurotransmitter is a chemical that helps to transmit signals from one nerve cell to another.
One type of neurotransmitter is dopamine, which helps transmit signals that cause muscle movement. Lewy bodies interfere with the production of dopamine. A lack of dopamine causes movement problems such as those seen in PD.
Acetylcholine is another type of neurotransmitter found in the parts of the brain responsible for memory, thinking, and processing information. When Lewy bodies build up in these areas, they use up the acetylcholine, causing symptoms of dementia.
Signs and symptoms
DLB can be confused with other forms of dementia, but it also has features of a psychiatric nature, such as hallucinations and delirium.
The primary sign of DLB is a progressive decline in cognitive functions, such as memory, thinking, and problem-solving. The decline in cognitive function is enough to affect your ability to work and perform normal daily activities. Although memory may be affected, it isn’t usually as impaired as in someone with AD.
DLB is generally diagnosed when at least two of the following features are also present with dementia:
Fluctuations in attention and alertness. These fluctuations may last for hours or days. Signs of these fluctuations include staring into space, lethargy, frequent drowsiness, and disorganized speech. These fluctuations have been referred to as “pseudodelirium” because they are similar to delirium.
Visual hallucinations. These hallucinations recur and are very detailed. While the hallucinations may be upsetting to someone observing them, they generally don’t bother the person experiencing them. About 80 percent of people with DLB have visual hallucinations.
Movement symptoms consistent with PD. Such movement symptoms include slow movement, rigidity, and falls. Tremors may also be present, but not as pronounced as in a person with PD with dementia.
Additional signs and symptoms seen in DLB include:
Sleep disorder that affects REM sleep, causing vivid dreams with body movement
Dizziness, feeling lightheaded, fainting, or falling
The symptoms of DLB may resemble other conditions. Always see your doctor for a diagnosis.
The only definitive diagnosis of DLB can be made at autopsy, as there are no specific markers to indicate the presence of Lewy bodies. So, the diagnosis of DLB is made based on your medical history, a physical exam, and your symptoms.
In addition to a complete medical history and physical exam, your doctor may order some of the following:
Blood tests. These are to rule out conditions such as vitamin B12 deficiency and hypothyroidism, or a lack of thyroid hormones.
Computed tomography scan
Magnetic resonance imaging
Positron emission tomography (PET). PET may detect biochemical changes in an organ or tissue that can identify the onset of a disease process before anatomical changes related to the disease can be seen with other imaging tests.
Neuropsychological assessments. These tests assess mental functioning and include attention span, memory, language and math skills, and problem-solving skills.
Psychiatric evaluation. This may be done to rule out a psychiatric condition that may resemble dementia.
DLB has no cure. Treatment for DLB involves addressing the symptoms. Medications are most often used. Other treatments, such as supportive care, physical therapy, and behavioral interventions, may also be used.
It’s important that the doctor treating DLB is familiar with all aspects of the disease because other specialists are often involved. Because DLB shares features with AD and PD, those features will need to be treated. Many people with DLB, however, can’t tolerate some of the medications for AD or PD, so, caution must be used when prescribing certain medications for DLB.