Dementia with Lewy bodies Q&A

What is Lewy body disease?

Lewy body disease is a progressive disease in which abnormal proteins called Lewy bodies accumulate extensively in the brain, and the number of neurons in the brain gradually decrease, although the cause is unknown. It is a relatively new disease that has come to be widely recognized since the late 1990s.

How many people have Lewy body disease?

Lewy body disease is the second most common cause of dementia after Alzheimer’s disease, and is as common as vascular dementia. Approximately 20% of patients with dementia have Lewy body disease.
The prevalence of Lewy body disease, i.e., percentage prevalence, is unclear.

What are the types of people that commonly have Lewy body disease?

Lewy body disease is common in the elderly aged around 75 to 80 years old.

Is Lewy body disease inherited?

Lewy body disease is not inherited, in principle.

What are the symptoms caused by Lewy body disease?

Lewy body disease causes a characteristic triad of symptoms,
i.e., 1) fluctuations in cognitive function, 2) repeated visual hallucinations, and 3) parkinsonian symptoms.

1. Fluctuations in cognitive function

Fluctuations in cognitive function: There are marked differences in the patient ability to recognize time, place and circumstances and in their ability to understand conversations, within each day and from day to day.

2. Repeated visual hallucinations

Visual hallucinations: The patients see things that are not actually present, and often say that they see people or children. Visual hallucinations most often occur at night.

3. Parkinsonian symptoms

Parkinsonian symptoms: These refer to some motor symptoms, such as stiff body or lack of facial expression, reduced body movements, clumsy movements, tremors of the hands, a forward-leaning posture, a tendency to lose balance, gait with short steps, and making a dash resulting in an inability to stop. Autonomic symptoms, such as orthostatic dizziness, syncope and constipation, may also occur.
In addition, delusions may occur, such as feeling the presence of someone, thinking that family members are fake, and thinking that he/she is not in his/her home.

Thus, patients with dementia with Lewy bodies develop various psychiatric symptoms and may receive therapeutic agents for delusions and auditory hallucinations of schizophrenia.
However, these antipsychotics are characterized by a tendency to cause adverse reactions.
In addition, some patients develop behavioral abnormalities during sleep, called “REM sleep behavior disorder,” from the very early stages.
REM sleep is one of the sleep “stages,” and people dream during REM sleep in most cases. Healthy people do not take action while dreaming, because the skeletal muscle tone is suppressed during REM sleep. However, patients with REM sleep behavior disorder actually perform actions while dreaming, because suppression of the muscle tone is impaired.

Although these patients also have forgetfulness, they generally have milder forgetfulness than patients with Alzheimer’s disease. There are differences in the type/severity of symptoms and the rate of progression among patients with Lewy body disease, i.e., some patients have more severe visual hallucinations and some have prominent parkinsonian symptoms.

What are the imaging findings?

Brain MRI shows generalized brain atrophy. Hippocampal atrophy is milder than that in Alzheimer’s disease. Cerebral blood flow single photon emission computed-tomography (SPECT) shows decreased blood flow in the parietal, temporal and occipital lobes. Since blood flow in the occipital lobe does not tend to decrease in Alzheimer’s disease, specialists pay attention to regional blood flow to this region to differentiate this disease from Alzheimer’s disease. Metaiodobenzylguanidine (MIBG) myocardial scintigraphy shows reduced uptake of the drug MIBG in the myocardium, which is also useful for the diagnosis of Lewy body disease.

What is the clinical course of Lewy body disease?

Patient types seem to vary according to the department that the patient visits. Patients in whom cognitive impairment, fluctuations in cognitive function or visual hallucinations occur first or are prominent often visit the neuropsychiatry department (e.g., our department). On the other hand, we think that patients with more severe parkinsonian symptoms often visit the neurology department. Although the course of Lewy body disease varies depending on which symptoms of the triad are prominent, it progresses more rapidly than Alzheimer’s disease and vascular dementia, and its entire course is thought to be less than 10 years.
Since there is no widely used classification for the severity of Lewy body disease, here, the severity is classified based on previous studies and our own and other specialists’ observations.

Early stage

Constipation, dysosmia, depressive symptoms and REM sleep behavior disorder are said to often appear first. Subsequently, disorganization, forgetfulness, and orthostatic dizziness (orthostatic hypotension) occur, and then, the triad (1. fluctuations in cognitive function, 2. repeated visual hallucinations, and 3. parkinsonian symptoms) appears. Cognitive impairment and fluctuations in cognitive function are more prominent in patients who visit the neuropsychiatry department, like our department. However, in these stages, the cognitive functions are maintained for a long time and orientation and understanding are maintained. Therefore, the patients have no problems in communicating with people around them. In most patients, forgetfulness is mild and not very prominent. Patients increasingly complain of visual hallucinations and optical illusions (they mistake clothes on a hanger for a human or a stain on the wall for a bug. Other symptoms, such as auditory hallucinations and delusions gradually become prominent. For example, a patient staying in his/her home says that he/she is not in his/her home or a patient says that his/her family members are fake. Patients may have delusions of persecution or delusional jealousy.

Intermediate stage

The parkinsonian symptoms become severe, making it difficult for the patient to walk. In addition, patients have longer stretches of poor cognitive function. Namely, they have poor orientation and impaired ability to understand, and therefore have difficulty in communicating with people around them and longer time-stretches of poor memory. In addition, their abilities continue to decrease even while they remain in reasonably good condition. Difficult-to-manage BPSD, including visual hallucinations and delusions, becomes prominent. Patients require assistance/support in daily life.

Late stage

The parkinsonian symptoms and cognitive impairment worsen further, and the patients need continual assistance in daily life.
Many patients are forced to use a wheelchair. Dysphagia becomes prominent. Fluctuations in cognition gradually become less, with the cognition remaining poor more or less throughout.

This site explains the early, intermediate and late stages, not including the most severe stage, wherein the patients are bedridden.
Early appropriate diagnosis and care planning allow prevention of psychiatric symptoms, such as persecutory delusions and behavioral abnormalities to some extent, and the patients need proactive support for activities of daily living (ADL).

What are the currently available treatments for Lewy body disease?

Unfortunately, there are no drugs available at present that can completely cure Lewy body disease or stop its progression. However, therapeutic agents for Alzheimer’s disease have been shown to be effective against decline or fluctuations in cognitive function or visual hallucinations in some cases. Therapeutic agents for Parkinson’s disease are used for parkinsonian symptoms.

Source of reference: To know dementia to feel relieved. A guide to dementia management according to symptoms (Medical Review Co., Ltd.)
Supervised by: Masatoshi Takeda
Authors: Hiroaki Kazui, Hiromichi Sugiyama, Shioko Bando

ページトップに戻る