Lewy body dementia is the second most common type of dementia after Alzheimer's disease. Protein deposits called Lewy bodies develop in nerve cells in the brain. The protein deposits affect brain regions involved in thinking, memory and movement. This condition is also known as dementia with Lewy bodies.

Lewy body dementia causes a decline in mental abilities that gradually gets worse over time. People with Lewy body dementia might see things that aren't there. This is known as visual hallucinations. They also may have changes in alertness and attention.

People with Lewy body dementia might experience Parkinson's disease symptoms. These symptoms may include rigid muscles, slow movement, trouble walking and tremors.

Lewy body dementia symptoms can include:

• Visual hallucinations. Seeing things that aren't there, known as hallucinations, might be one of the first symptoms of Lewy body dementia. This symptom often occurs regularly. People with Lewy body dementia might see shapes, animals or people that aren't there. Hallucinations involving sounds, smells or touch are possible.
• Movement disorders. Signs of Parkinson's disease, known as parkinsonian signs, may occur. These symptoms include slowed movement, rigid muscles, tremor or a shuffling walk. This can cause the person to fall.
• Poor regulation of body functions. The part of the nervous system that controls automatic functions is called the autonomic nervous system. Lewy body dementia can affect how well the autonomic nervous system controls blood pressure, heart rate, sweating and digestion. This can result in sudden drops in blood pressure upon standing, dizziness, falls, loss of bladder control and bowel issues such as constipation.
• Cognitive problems. People with Lewy body dementia might have thinking problems similar to those of Alzheimer's disease. They may include confusion, poor attention, visual-spatial problems and memory loss.
• Trouble with sleep. People with Lewy body dementia can have rapid eye movement (REM) sleep behavior disorder. This disorder causes people to physically act out their dreams while asleep. People with REM sleep behavior disorder may punch, kick, yell or scream while sleeping.
• Varying attention. Episodes of drowsiness, long periods of staring into space, long naps during the day or disorganized speech are possible.
• Depression. People with Lewy body dementia might develop depression.
• Apathy. Loss of motivation may occur.

Lewy body dementia is characterized by the buildup of proteins into masses known as Lewy bodies. This protein also is associated with Parkinson's disease. People who have Lewy bodies in their brains also have the plaques and tangles associated with Alzheimer's disease.

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.

Lewy body dementia is progressive. This means it gradually gets worse over time. As symptoms get worse, Lewy body dementia can lead to:

• Severe dementia.
• Aggressive behavior.
• Depression.
• Increased risk of falling and injury.
• Worsening of parkinsonian symptoms, such as tremors.
• Death, on average about 7 to 8 years after symptoms start.

People who are diagnosed with Lewy body dementia have a gradual decline in the ability to think. They also have at least two of the following:

• Varying alertness and thinking function.
• Repeated visual hallucinations.
• Parkinsonian symptoms.
• REM sleep behavior disorder, in which people act out their dreams during sleep.

Other symptoms support a Lewy body dementia diagnosis. This includes problems with the autonomic nervous system. When this happens, the body isn't able to regulate blood pressure, heart rate, body temperature and sweating.

Sensitivity to medicines that treat psychosis also supports a diagnosis. This is particularly true for medicines such as haloperidol (Haldol). Antipsychotic medicines aren't used for people with Lewy body dementia because they can make symptoms worse.

No single test can diagnose Lewy body dementia. The diagnosis is based on your symptoms and by ruling out other conditions. Tests might include:

Neurological and physical exam

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 exam tests:

• Reflexes.
• Strength.
• Walking.
• Muscle tone.
• Eye movements.
• Balance.
• Sense of touch.

Assessment of mental abilities

A short form of this test, which assesses memory and thinking skills, can be done in less than 10 minutes. The test doesn't usually distinguish between Lewy body dementia and Alzheimer's disease. But the test can determine whether you have cognitive impairment. 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. Dementias are diagnosed based on the medical history and physical examination. But 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 symptoms aren't typical, you may need other imaging tests. These imaging tests may support a diagnosis of Lewy body dementia:

• Fluorodeoxyglucose PET brain scans, which assess brain function.
• Single-photon emission computerized tomography (SPECT) or PET imaging. These tests can show reduced dopamine transporter uptake in the brain. This can help diagnose Lewy body dementia.

Sleep evaluation

You may need a sleep evaluation called a polysomnogram to check for REM sleep behavior disorder. You also may need an autonomic function test to look for signs of heart rate and blood pressure instability.

Heart test

In some countries, health care professionals also might order a heart test called myocardial scintigraphy. This checks 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.

There's no cure for Lewy body dementia, but many of the symptoms can improve with targeted treatments.

Medications

• Cholinesterase inhibitors. These Alzheimer's disease medicines work by increasing the levels of chemical messengers in the brain, known as neurotransmitters. These chemical messengers are believed to be important for memory, thought and judgment. They include rivastigmine (Exelon), donepezil (Aricept, Adlarity) and galantamine (Razadyne ER). The medicines may help improve alertness and thinking. They also may reduce hallucinations and other behavioral symptoms.

  Possible side effects include stomach upset, muscle cramps and urinating more often. It also can 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 medicines. Medicines such as carbidopa-levodopa (Sinemet, Duopa, others) can help reduce rigid muscles and slow movement. However, these medicines also can increase confusion, hallucinations and delusions.
• Medicines to treat other symptoms. Your doctor might prescribe medicines to treat other symptoms, such as sleep problems or movement problems.

Certain medicines can worsen memory. Don't take sleep aids that contain diphenhydramine (Advil PM, Aleve PM). Also don't take medicines used to treat urinary urgency such as oxybutynin (Ditropan XL. Gelnique, Oxytrol).

Limit sedatives and sleeping medicines. Talk to a health care professional about whether any of the medicines you take might make your memory worse.

Antipsychotic medicines 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 they're offered only if the benefits outweigh the risks.

Therapies

Antipsychotic medicines can worsen Lewy body dementia symptoms. It might be helpful to first try other approaches, such as:

• Tolerating the behavior. Some people with Lewy body dementia aren't distressed by the hallucinations. If this is true, the side effects of the medicine 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.

Symptoms and progression are different for everyone with Lewy body dementia. Caregivers and care partners may need to adapt the following tips to individual situations:

• Speak clearly and simply. Maintain eye contact and speak slowly, in simple sentences, and don't rush the response. Present only one idea or instruction at a time. Use gestures and cues, such as pointing to objects.
• Encourage exercise. Benefits of exercise include improvements in physical function, behavior and depression. Some research shows exercise might slow cognitive decline in people with dementia.
• Provide mind stimulation. Participating in games, crossword puzzles and other activities that involve thinking skills might help slow mental decline in people with dementia. Encourage artistic and creative activities, such as painting, singing or making music.
• Create opportunities for social activity. Talk to friends. Participate in religious services.
• Establish bedtime rituals. Behavior issues can worsen at night. Create calming bedtime rituals without the distraction of television, meal cleanup and active family members. Leave night lights on to prevent disorientation.

Limit caffeine during the day. Discourage daytime napping and offer activities for daytime exercise. This might help prevent nighttime restlessness.

Frustration and anxiety can worsen dementia symptoms. To promote relaxation, consider:

• Music therapy, which involves listening to soothing music.
• Pet therapy, which involves the use of animals to improve moods and behaviors in people with dementia.
• Aromatherapy, which uses fragrant plant oils.
• Massage therapy.

People with Lewy body dementia often have a mixture of emotions. The person may feel confused, frustrated, angry or afraid. They may not be certain about the future and may feel grief and depression. Offer support by listening. Provide assurance that the person can still enjoy life. Be positive and do your best to help the person retain dignity and self-respect.

If you're a caregiver or care partner for someone with Lewy body dementia, watch the person closely. Make sure the person doesn't fall, lose consciousness or have a bad reaction to medicines. Provide reassurance during times of confusion, delusions or hallucinations.

Looking after yourself

Caring for a person with Lewy body dementia can be exhausting physically and emotionally. You may have anger, guilt, frustration, discouragement, worry, grief or social isolation. Help prevent caregiver burnout by:

• Asking friends or other family members for help when you need it. Consider in-home health services to help you care for the person with Lewy body dementia.
• Exercising regularly and eating a healthy diet.
• Learning about the disease. Ask questions of doctors, social workers and others on the care team.
• Joining a support group.

Many people with Lewy body dementia and their families can benefit from counseling or local support groups. Contact your local agencies on health or aging. Local agencies can help you connect with support groups, health care professionals, resources, referrals, home care agencies, supervised living facilities, a phone help line and educational seminars.

You might first discuss your symptoms with a health care professional. This person may refer you to a doctor trained in dementia. This is usually a doctor trained in brain and nervous system conditions, called a neurologist, or a doctor trained in mental health conditions, called a psychiatrist.

Ask a friend or family member to come to the appointment, if possible. This person can help you remember the information you're given and give your doctor information about you. Here's some information to help you get ready for your appointment.

What you can do

Make a list of:

• Your symptoms and when they began.
• All medicines, vitamins or other supplements you take, including doses.
• Questions to ask.

What to expect from your doctor

You, your spouse, partner or close friend are likely to be asked a number of questions about:

• Changes in your memory, personality and behavior.
• Visual hallucinations.
• Your history of stroke, depression, alcohol use disorder, head trauma or other neurological disorders.