What is Lewy Body Dementia?

Published in

Better Caregiving with Evva

6 min readApr 6, 2023

Lewy body dementia is a neurodegenerative disorder that affects millions of people worldwide. Often misdiagnosed or unrecognized due to its complex symptoms, researchers and medical practitioners are working tirelessly with the help of patients to learn more about the disease.

Alois Alzheimer with his co-workers: photo taken circa 1909–1910. Frederich H. Lewy is pictured top right. Source: Wikimedia Commons

Named after neurologist Frederich H. Lewy, M.D., it was discovered in research at Dr. Alois Alzheimer’s laboratory in the early 1900s. However, the first case of Lewy body dementia was not identified until the 1960s. Research on Lewy body dementia has lagged far behind other types of dementia due to the misconception that it was exceptionally rare.

Lewy body dementia is characterized by sudden changes in attention and alertness, visual or auditory hallucinations, and a decline in both mental ability and motor control. Patients with Lewy body dementia often exhibit Parkinson’s-like symptoms such as tremors and difficulty moving.

How is Lewy body dementia different from other types of dementia?

Lewy body dementia is different from other types of dementia in both its potential causes and the symptoms a patient can experience. Lewy body dementia is associated with a buildup of abnormal protein deposits in the brain, similarly to Parkinson’s.

Symptoms of Lewy body dementia

Here are a few characteristic symptoms of Lewy body dementia. The severity of each symptom depends on where in the brain has the largest build-up of abnormal protein deposits.

Cognitive changes: People with DLB often experience cognitive impairments that affect memory, attention, and executive function. They may have difficulty with problem-solving, decision-making, and planning.
Visual hallucinations: Hallucinations are a common feature of DLB, and people with this condition may see people, animals, or objects that aren’t actually there.
Parkinsonism: DLB can cause motor symptoms similar to Parkinson’s disease, including tremors, rigidity, and slowness of movement.
Sleep disturbances: DLB can cause sleep disorders such as REM sleep behavior disorder (RBD), which causes people to act out their dreams.
Fluctuating attention: People with DLB may have periods of alertness and clarity followed by sudden episodes of confusion and disorientation.
Mood and behavior changes: DLB can cause changes in mood and behavior, including depression, anxiety, agitation, and aggression.
Sensitivity to medications: People with DLB may be more sensitive to medications than those with other types of dementia, and some medications can worsen symptoms.

Other signs and symptoms can include:

Difficulty understanding visual information.
Malfunctions of the “automatic” (autonomic) nerve system, which regulates bodily functions such as perspiration, blood pressure, heart rate, digestion, and sexual response.
Memory loss can be considerable, but usually isn’t as severe as Alzheimer’s.

Lewy body dementia (LBD) and dementia with Lewy bodies (DLB)

You may come across two slightly different names with this type of dementia: Lewy body dementia and dementia with Lewy bodies. These terms are often used interchangeably, but there is a slight difference between them.

Lewy body dementia is an umbrella term used to refer to two similar diseases: dementia with Lewy bodies (DLB) and Parkinson’s disease dementia (PDD). Both diseases have very similar causes, and are known to cause a decline in a patient’s physical capabilities. The major difference between the two diseases lies in how quickly cognitive function declines after physical symptoms show up.

Defining LBD, DLB, and PDD

LBD (Lewy body dementia) is the umbrella term for DLB and PDD.
In both DLB and PDD, there is a gradual decline in motor function and physical capabilities.
In DLB (dementia with Lewy bodies), thinking and memory decline quickly (less than one year) after motor function begins declining.
In PDD (Parkinson’s disease dementia), thinking and memory decline long after (over one year) motor function declines.

Note that Parkinson’s disease dementia is not the same as Parkinson’s disease, because not all people with Parkinson’s develop dementia.

What we know about Lewy body dementia

The hallmark feature of Lewy body dementia is the presence of Lewy bodies in the brain, which are abnormal protein deposits that interfere with brain function. The main component of Lewy bodies, the alpha-synuclein protein, is present throughout the brain, but its normal role is unknown.

Proteins can interact with DNA to regulate gene expression, which is the process by which genetic information is used to create proteins and other molecules needed by cells.

Lewy bodies are a brain abnormality in Parkinson’s disease dementia and DLB. Many individuals with Parkinson’s eventually develop cognitive and reasoning impairments, and many people with DLB eventually develop movement symptoms such as stooped posture, tight muscles, a shuffling gait, and difficulty beginning movement. Therefore, we know that there is a big overlap between the two diseases. This suggests that there is an underlying abnormality that develops in how the brain processes the alpha-synuclein protein.

Many people with DLB and Parkinson’s dementia also exhibit plaques and tangles, which are typical brain abnormalities associated with Alzheimer’s disease. It is possible to have both DLB and Alzheimer’s at the same time, and in those cases symptoms will manifest much more quickly and severely.

Any combination of more than one cause of dementia is known as mixed dementia. Read more in our article on the different causes of dementia here.

What causes Lewy body dementia?

Although the exact cause of LBD and why lewy bodies accumulate is unclear, researchers are making progress towards discovering more about it every day.

We know Lewy body buildup impedes neurons that generate two important chemicals that function as messengers between brain cells. These two chemicals are acetylcholine and dopamine. Acetylcholine is essential for memory and learning. Dopamine is involved in behavior, cognition, movement, and sleep.

Researchers are also studying LBD’s risk factors. A risk factor is something that increases the likelihood of getting a disease. Some risk factors are under our control, while others are not. Like other types of dementia, the biggest risk factor is age. Research has not yet pointed to any lifestyle factors that may increase the likelihood of developing LBD.

However, certain diseases and health problems, including Parkinson’s disease and REM sleep behavior disorder, have been linked to an increased risk of LBD. With such a big overlap between PDD and DLB, we know that there is likely a cause that links the two together.

Although LBD is not considered a hereditary illness, having a family member with the condition may also raise a person’s risk of developing it. Variations in three genes — APOE, SNCA, and GBA — have been linked to an elevated risk, although the exact reason is unclear in a majority of cases.

Diagnosis of dementia with Lewy bodies

There isn’t one specific test that can definitively identify dementia with Lewy bodies. DLB is now considered a clinical diagnosis, which means it reflects a doctor’s best professional guess as to the cause of a person’s symptoms. A postmortem autopsy is the only way to definitively diagnose DLB.

Pre-diagnostic screening of DLB will be very similar to other dementia screenings, but may also include dopamine transporter imaging and sleep studies, as DLB is linked to both reduced dopamine levels and sleep disorders. Difficulties with physical movement will also point a doctor towards a DLB diagnosis.

As previously mentioned, most scientists believe that dementia with Lewy bodies and Parkinson’s disease dementia are two separate manifestations of the same underlying abnormalities with the protein alpha-synuclein processing in the brain. However, it’s still advised to treat DLB and Parkinson’s disease dementia as different illnesses.

Conclusion and Resources

Like most other forms of dementia, LBD cannot be cured. However, with proactive detection and treatment, it is possible to obtain treatment that will prolong a patient’s independence and quality of life for as long as possible.