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Lewy Body Dementia

What is Lewy Body Dementia?

Lewy body dementia (LBD) is a neurodegenerative disorder characterized by the presence of abnormal protein deposits called Lewy bodies in the brain. Lewy body dementia is a progressive and incurable condition that affects brain function, leading to a decline in cognitive abilities. It is the third most common cause of dementia, following Alzheimer’s disease and vascular dementia. LBD is named after Friedrich H. Lewy, the scientist who first discovered the abnormal protein structures in the early 1900s.

The hallmark feature of Lewy Body Dementia is the accumulation of Lewy bodies, which are microscopic protein deposits found in nerve cells of the brain. These deposits primarily consist of a protein called alpha-synuclein. The presence of Lewy bodies disrupts the normal functioning of brain cells and impairs communication between them.

Lewy Body dementia or dementia with Lewy Bodies is the lesser known relative of Parkinson’s disease (PD) and is a more challenging condition to treat compared to PD, but research is ongoing on treating the underlying causes.

Dementia with Lewy Bodies came into the national spotlight after news that actor and comedian Robin Williams was suffering from the disease. LBD is a neurodegenerative disorder manifested by cognitive decline causing difficulty with daily activities or higher-order tasks, plus parkinsonism (slowness, stiffness, tremor, instability due to low dopamine in the brain).


The cognitive issues that arise in DLB can include difficulty making decisions, slowed mental processing, short term memory deficits, and mental inflexibility. When these changes begin to interfere with higher-order tasks such as medication management, paying bills on time, and coordinating appointments, the patient is said to have dementia.

It is important to note that dementia and Alzheimer’s disease are not the same thing. Dementia can be caused by many different conditions, the most common of which are Alzheimer’s, vascular dementia, Parkinson’s disease, and DLB.

What sets DLB apart from other causes of dementia is the prevalence of hallucinations and delusions, as well as a sleep disorder called REM sleep behavior disorder.

Hallucinations and delusions

  • The hallucinations of DLB are typically visual; they may begin with a sense of a presence or shadow, typically in the periphery.
  • Other forms include illusions, where an everyday present object is mistaken for something else, such as a telephone wire taking on the appearance of a snake.
  • As the disease progresses, frank hallucinations can be seen, often appearing like an indistinct person, small child, or animal. Initially there is preserved insight, meaning the patient can tell there is no one or nothing there, but later in the disease, the distinction between reality and hallucination becomes difficult.
  • Auditory (sound) hallucinations can occur too, ranging from a soft murmur to indistinct voices.
  • Sometimes there can be more than one hallucination, and patients may comment on the presence of a group of people, sounding like the background noise of a dinner party.
  • Tactile hallucinations, causing the feeling of something such as bugs, are less common.

Delusions refer to fixed, false beliefs that are not based in reality. Examples can include paranoid delusions such as a spouse’s infidelity, people stealing from them; and delusions of reference, meaning a strong feeling that a person or a place is not what they seem. For example, a patient may feel that their wife is a different woman, or that their home is not actually their home. This is different from a loss of recognition or disorientation, and may take on a bizarre quality such as insisting that the furniture in the “false” home has been stolen or replicated from the “real” house. Arguing with the delusion tends to make things worse.

REM sleep behavior disorder

Also a core feature of DLB is the presence of REM sleep behavior disorder (RBD), typically preceding the cognitive and movement disorder by several years, even decades.

During REM sleep, when we dream, normally the only part of our bodies that move are our eyes – the rest of the body is paralyzed. This is why it’s known as Rapid Eye Movement (REM) sleep. In RBD, the body is not paralyzed during REM sleep. This can cause acting out of dreams, such as kicking and punching. Classically, the dreams can be quite violent, but the dreamer is not the primary aggressor, meaning he is defending against attack by a person or thing. In the process, the patient may kick, punch, yell out, or even attempt to strangle his bedfellow.

Patients are often not particularly bothered by RBD, but this symptom can be a safety concern for the patient as well as the bedfellow. RBD can be treated with melatonin and clonazepam. Safety measures can include having the bedfellow sleep in a different room, keeping the bed low to the ground, locking up firearms and removing anything that can be used as a weapon from the bedroom.

One striking manifestation of DLB is fluctuations of awareness. Patients may appear to be awake but not responsive, lasting for several minutes, then returning to baseline level of alertness. Typically, this will prompt an emergency evaluation to exclude stroke or seizure, and all testing is inconclusive. These types of episodes may occur infrequently and there is no known treatment.


The parkinsonism that develops in DLB includes symptoms of slowness, stiffness, shuffling gait, tremor, and imbalance.


The definitive diagnosis of DLB is, unfortunately, based on autopsy. Probable DLB is diagnosed based on the presence of dementia and two of the three core features: visual hallucinations, parkinsonism, and fluctuations of awareness.

Supportive features include REM sleep behavior disorder (RBD), as discussed above and sensitivity (bad reactions) to antipsychotic medications. Diagnostic testing can play a role, mainly in the use of DaTscan (which can differentiate between Alzheimer’s disease and DLB), and PET scan (which can show low metabolism in the occipital lobes, seen in DLB).

The main alternate diagnosis to DLB is Parkinson’s disease with dementia (PDD). In PDD, dementia begins years after onset of motor symptoms, and the movement symptoms typically respond well to levodopa. DaTscan cannot differentiate between PDD and DLB. In cases where it is difficult to differentiate between PDD and DLB, this handout from the Lewy Body Disease Association (LBDA) can help.


There are no treatments of DLB that are unique to the condition. Medications and treatments used to manage symptoms of parkinsonism, dementia, behavioral issues, and RBD are used based on testing in PD.

Physical therapy, occupational therapy, and exercise certainly play a role in the management of the motor symptoms of DLB.

PD Dementia

Avoidance of antipsychotic medications such as Seroquel (quetiapine), Zyprexa (olanzapine), Haldol (haloperidol), Risperdal (risperidone), and dopamine-blocking anti-nausea medications such as Reglan (metoclopramide) and Compazine (prochlorperazine) is key given the high likelihood of a negative reaction.

Acetylcholinesterase inhibitors such as Aricept (donepezil) and Exelon (rivastigmine) can be helpful for cognitive dysfunction and other behavioral symptoms.


The parkinsonism (slowness, stiffness, shuffling gait, tremor, imbalance) that develops in DLB is less responsive to levodopa compared to idiopathic (typical) PD. Sometimes there is a mild improvement, sometimes temporary, but no significant or dramatic improvements are seen with medication. Physical therapy, occupational therapy, and exercise certainly play a role in the management of the motor symptoms of DLB.

While there are no curative treatments for Lewy Body dementia at this time, at Pacific Neuroscience Institute we are confident that accurate diagnosis is the first step in research opportunities and improved treatment and prevention of progression.

Written and reviewed by:
We are a highly specialized team of medical professionals with extensive neurological and cranial disorder knowledge, expertise and writing experience.
Last updated: June 5, 2024