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Lewy body dementia, also known as dementia with Lewy bodies, is the second most common type of progressive dementia after Alzheimer's disease. Protein deposits, called Lewy bodies, develop in nerve cells in the brain regions involved in thinking, memory and movement (motor control).
Lewy body dementia causes a progressive decline in mental abilities. People with Lewy body dementia might have visual hallucinations and changes in alertness and attention. Other effects include Parkinson's disease signs and symptoms such as rigid muscles, slow movement, walking difficulty and tremors.
Symptoms
Lewy body dementia signs and symptoms can include:
- Visual hallucinations. Hallucinations — seeing things that aren't there — might be one of the first symptoms, and they often recur. People with Lewy body dementia might hallucinate shapes, animals or people. Sound (auditory), smell (olfactory) or touch (tactile) hallucinations are possible.
- Movement disorders. Signs of Parkinson's disease (parkinsonian signs), such as slowed movement, rigid muscles, tremor or a shuffling walk can occur. This can lead to falling.
- Poor regulation of body functions (autonomic nervous system). Blood pressure, pulse, sweating and the digestive process are regulated by a part of the nervous system that is often affected by Lewy body dementia. This can result in sudden drops in blood pressure upon standing (orthostatic hypotension), dizziness, falls, loss of bladder control (urinary incontinence) and bowel issues such as constipation.
- Cognitive problems. You might have thinking (cognitive) problems similar to those of Alzheimer's disease, such as confusion, poor attention, visual-spatial problems and memory loss.
- Sleep difficulties. You might have rapid eye movement (REM) sleep behavior disorder, which can cause you to physically act out your dreams while you're asleep. This might involve behavior such as punching, kicking, yelling and screaming while sleeping.
- Fluctuating attention. Episodes of drowsiness, long periods of staring into space, long naps during the day or disorganized speech are possible.
- Depression. You might develop depression.
- Apathy. You might lose motivation.
Causes
Lewy body dementia is characterized by the abnormal buildup of proteins into masses known as Lewy bodies. This protein is also associated with Parkinson's disease. People who have Lewy bodies in their brains also have the plaques and tangles associated with Alzheimer's disease.
Risk factors
A few factors seem to increase the risk of developing Lewy body dementia, including:
- Age. People older than 60 are at greater risk.
- Sex. Lewy body dementia affects more men than women.
- Family history. Those who have a family member with Lewy body dementia or Parkinson's disease are at greater risk.
Complications
Lewy body dementia is progressive. Signs and symptoms worsen, causing:
- • Severe dementia
- • Aggressive behavior
- • Depression
- • Increased risk of falling and injury
- • Worsening of parkinsonian signs and symptoms, such as tremors
- • Death, on average about seven to eight years after symptoms start
Diagnosis
A diagnosis of Lewy body dementia requires a progressive decline in your ability to think, as well as at least two of the following:
- • Fluctuating alertness and thinking function
- • Repeated visual hallucinations
- • Parkinsonian symptoms
- • REM sleep behavior disorder, in which people act out their dreams during sleep
Autonomic dysfunction, which involves instability in blood pressure and heart rate, poor regulation of body temperature, sweating, and related signs and symptoms, supports a Lewy body dementia diagnosis. So does sensitivity to antipsychotic drugs, particularly first-generation antipsychotics such as haloperidol (Haldol). Medications like Haldol aren't used for people with Lewy body dementia because they can cause a severe reaction.
No single test can diagnose Lewy body dementia. The diagnosis is based the on signs and symptoms you have and ruling out other conditions that can cause similar signs and symptoms. Tests might include:
Neurological and physical examination
Your doctor may check for signs of Parkinson's disease, strokes, tumors or other medical conditions that can affect the brain and physical function. A neurological examination tests:
- • Reflexes
- • Strength
- • Walking
- • Muscle tone
- • Eye movements
- • Balance
- • Sense of touch
Assessment of mental abilities
A short form of this test, which assesses your memory and thinking skills, can be done in less than 10 minutes in your doctor's office. It's not generally useful in distinguishing Lewy body dementia from Alzheimer's disease but can determine whether cognitive impairment is present. Longer tests that take several hours help identify Lewy body dementia.
Blood tests
These can rule out physical problems that can affect brain function, such as vitamin B-12 deficiency or an underactive thyroid gland.
Brain scans
Your doctor might order an MRI or CT scan to identify a stroke or bleeding and to rule out a tumor. While dementias are diagnosed based on the medical history and physical examination, certain features on imaging studies can suggest different types of dementia, such as Alzheimer's or Lewy body dementia.
If the diagnosis is unclear or the signs and symptoms aren't typical, your doctor might suggest additional imaging tests, including these that can support a diagnosis of Lewy body dementia:
- • Fluorodeoxyglucose PET brain scans, which assess brain function.
- • Single-photon emission computerized tomography (SPECT) or PET imaging, which can determine whether dopamine transporter uptake is reduced in the brain.
Sleep evaluation
Your doctor might order a sleep evaluation called a polysomnogram to check for REM sleep behavior disorder or an autonomic function test to look for signs of heart rate and blood pressure instability.
Heart test
In some countries, doctors might also order a heart test called myocardial scintigraphy to check the blood flow to your heart for indications of Lewy body dementia. However, the test isn't used in the United States.
Emerging biomarkers
Research is ongoing into other indicators of Lewy body dementia. These biomarkers might eventually enable early diagnosis of Lewy body dementia before the full disease develops.
Treatment
There's no cure for Lewy body dementia but many of the symptoms can improve with targeted treatments.
Medications
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Cholinesterase inhibitors. These Alzheimer's disease medications, such as rivastigmine (Exelon), donepezil (Aricept) and galantamine (Razadyne), work by increasing the levels of chemical messengers in the brain (neurotransmitters) believed to be important for memory, thought and judgment. This can help improve alertness and cognition and might reduce hallucinations and other behavioral problems.
Possible side effects include gastrointestinal upset, muscle cramps and frequent urination. It can also increase the risk of certain cardiac arrhythmias.
In some people with moderate or severe dementia, an N-methyl-d-aspartate (NMDA) receptor antagonist called memantine (Namenda) might be added to the cholinesterase inhibitor.
- Parkinson's disease medications. These medications, such as carbidopa-levodopa (Sinemet, Rytary, Duopa) can help reduce parkinsonian signs and symptoms, such as rigid muscles and slow movement. However, these medications can also increase confusion, hallucinations and delusions.
- Medications to treat other symptoms. Your doctor might prescribe medications to treat other signs and symptoms associated with Lewy body dementia, such as sleep or movement problems.
Certain medications can worsen memory. Try to avoid over-the-counter sleep aids that contain diphenhydramine (Advil PM, Aleve PM) and medications used to treat urinary urgency such as oxybutynin (Ditropan XL).
Also limit sedatives and sleeping tablets, and talk to your doctor about whether any of the drugs you take might make your memory worse.
Antipsychotic drugs can cause severe confusion, severe parkinsonism, sedation and sometimes death. Very rarely, certain second-generation antipsychotics, such as quetiapine (Seroquel) or clozapine (Clozaril, Versacloz) might be prescribed for a short time at a low dose but only if the benefits outweigh the risks.
Therapies
Because antipsychotic drugs can worsen Lewy body dementia symptoms, it might be helpful to first try nondrug approaches, such as:
- Tolerating the behavior. Some people with Lewy body dementia aren't distressed by the hallucinations. In these cases, the side effects of medication might be worse than the hallucinations themselves.
- Modifying the environment. Reducing clutter and noise can make it easier for someone with dementia to function. Caregivers' responses sometimes worsen behavior. Avoid correcting and quizzing a person with dementia. Offer reassurance and validation of his or her concerns.
- Creating daily routines and keeping tasks simple. Break tasks into easier steps and focus on successes, not failures. Structure and routine during the day can be less confusing.