Lewy body dementia shares characteristics with both Alzheimer's disease and Parkinson's disease. Like Alzheimer's, it causes confusion. Like Parkinson's, it can result in rigid muscles, slowed movement and tremors.

But the most striking symptom of Lewy body dementia may be its visual hallucinations, which can be one of the first signs of the disorder. Hallucinations may range from abstract shapes or colors to conversations with deceased loved ones.

In Lewy body dementia, abnormal round structures — called Lewy bodies — develop in regions of your brain involved in thinking and movement. While risk increases with age, Lewy body dementia is estimated to affect less than 1 percent of the population over the age of 65.

Lewy body dementia signs and symptoms may include:

• Visual hallucinations. Seeing colors, shapes, animals or people may be one of the first symptoms of Lewy body dementia.
• Movement disorders. Parkinson's-like signs may include slowed movement, rigid muscles, tremors or a shuffling walk.
• Delusions. These may consist of false ideas about another person or situation.
• Cognitive problems. Alzheimer's-like problems may include confusion, memory loss and reduced attention spans.
• Sleep difficulties. A sleep disorder can cause you to physically act out your dreams while you're asleep.

The cause of Lewy body dementia isn't known, but the disorder may be related to Alzheimer's or Parkinson's disease because:

• Lewy bodies contain a protein associated with Parkinson's disease.
• Lewy bodies often are found in the brains of people who have Parkinson's and other rare dementias.
• People who have Lewy bodies in their brains also often have the plaques and tangles associated with Alzheimer's disease.

Some scientists have suggested that there is a Lewy body variant of Alzheimer's disease. Conversely, Lewy body dementia and Alzheimer's may just coexist in some people.

Although the cause of Lewy body dementia isn't clear, several factors appear to increase the risk of developing the disease:

• Age. Most cases of Lewy body dementia occur in adults older than 60.
• Sex. Lewy body dementia appears to be more common in men.
• Heredity. If you have a family member with Lewy body dementia, you may be at increased risk of the disease.

After onset, Lewy body dementia typically causes severe dementia. The Parkinson's-like features and visual hallucinations tend to worsen with time. Average survival is about eight years after symptoms begin.

You'll probably first bring your symptoms to the attention of your family doctor, who may refer you to a dementia specialist — usually a neurologist or a psychiatrist.

What you can do
Appointments can be brief. To make the best use of the limited time, plan ahead and write lists of important information, including:

• Detailed descriptions of all your symptoms
• A list of all your medications and dosages, including nonprescription drugs and supplements
• Questions for the doctor, such as what tests or treatments he or she may recommend

You might also want to bring a family member or close friend who can tell the doctor about symptoms you might not have noticed.

What to expect from your doctor
You and your spouse, partner or someone else who knows you well may be asked:

• About any changes in your memory, personality and behavior
• What medications you're taking
• If you have a history of stroke, depression, alcohol abuse, head trauma or other neurological disorders

For the doctor to make a diagnosis of Lewy body dementia, you must have experienced a progressive decline in your ability to think, as well as two of the following:

• Fluctuating alertness and cognition
• Repeated visual hallucinations
• Parkinson's-like symptoms

No single test can diagnose Lewy body dementia. Instead, doctors diagnose the disease through a process of elimination — ruling out other diseases and conditions that may cause similar signs and symptoms. Tests may include:

Neurological exam
As part of your physical exam, your doctor may also check for signs of Parkinson's disease, strokes, tumors or other medical conditions that can impair brain function as well as physical function. The neurological exam may test:

• Reflexes
• Eye movements
• Balance
• Sense of touch

Mental status exam
A short form of this type of test, which assesses your memory and thinking skills, can be done in less than 10 minutes in your doctor's office. Longer forms of neuropsychological testing can take several hours. Your results are then compared with those of people from a similar age and education level. This can help distinguish normal from abnormal cognitive aging, and may help identify patterns in cognitive functions that provide clues to the underlying condition.

Lab tests
Simple blood tests can rule out physical problems that can affect brain function, such as vitamin B-12 deficiency or an underactive thyroid gland.

Electroencephalogram (EEG)
If your confusion comes and goes, your doctor may suggest an EEG. This test can help determine if your symptoms are better explained by seizures or Creutzfeldt-Jakob disease, a very rare degenerative brain disorder more commonly known as mad-cow disease. This painless test records the electrical activity in your brain via wires attached to your scalp.

Brain scans
Your doctor may order an MRI or CT scan to check for evidence of stroke or bleeding, and to rule out the possibility of a tumor.

Treatment can be challenging, and there's no cure for Lewy body dementia. Instead, doctors treat the individual symptoms.

Medications

• Cholinesterase inhibitors. These Alzheimer's disease medications work by increasing the levels of neurotransmitters — chemical messengers believed to be important for memory, thought and judgment — in the brain. This can help improve alertness and cognition, and may help reduce hallucinations and other behavioral problems.
• Parkinson's disease medications. These medications can help reduce Parkinson's-like muscular symptoms in some people with Lewy body dementia, but they can also cause increased confusion, hallucinations and delusions.
• Antipsychotic medications. These medications may somewhat improve delusions and hallucinations. However, at least a third of the people who have Lewy body dementia have a dangerous sensitivity to some of these types of drugs. Reactions, which are sometimes irreversible, can include severe Parkinson's-like symptoms and a worsening of confusion.

Therapies
Because antipsychotic drugs can worsen the symptoms of Lewy body dementia, it might be better to initially try nondrug approaches, such as:

• Modify the environment. Reducing clutter and distracting noise can make it easier for someone with dementia to focus and function.
• Modify the response. A caregiver's response to a behavior can make the behavior worse. It's best to avoid correcting and quizzing a person with dementia. Reassuring the person and validating his or her concerns can defuse most situations.
• Modify tasks. Break tasks into easier steps and focus on success, not failure. Structure and routine also help people with dementia feel safe.

Each person with dementia experiences symptoms and progression differently. Consequently, the techniques to care for each person should vary. Caregivers may need to adapt the following tips to individual situations:

• Enhance communication. When talking with your loved one, stand where you can be seen and touch his or her arm or shoulder to focus attention. 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. Exercise carries many benefits. The fact that these benefits often are the same for people without dementia doesn't lessen their importance. In fact, it just makes exercise a more important activity for caregivers and people with dementia to engage in together. The main benefits of exercise include improved strength and cardiovascular health. Exercise can also lessen symptoms of depression, help retain motor skills and create a calming effect. It can also help sustain strength, flexibility and balance — which may lessen the risk of serious injury from a fall.
• Establish a nighttime ritual. Behavior is often worse at night. Try to establish going-to-bed rituals that are calming and away from the noise of television, meal cleanup and active family members. Leave night lights on to prevent disorientation. Limiting caffeine during the day, discouraging daytime napping and offering opportunities for exercise during the day may help prevent nighttime restlessness.

People with dementia often experience a worsening of their symptoms when they are frustrated or anxious. The following techniques may help promote relaxation.

• Music therapy, which involves listening to soothing music
• Aromatherapy, which uses fragrant plant oils
• Massage therapy

People with Lewy body dementia often experience a mixture of emotions — confusion, frustration, anger, fear, uncertainty, grief and depression.

You can help a person cope with the disease by being there to listen, reassuring the person that life can still be enjoyed, providing unconditional love and doing your best to help the person retain dignity and self-respect.

Caregivers must watch closely to make sure the person with Lewy body dementia doesn't fall or lose consciousness or react badly to medications and must reassure that person during times of delusions or hallucinations.

Looking after yourself
The physical and emotional demands of caregiving can be exhausting. Feelings of anger and guilt, frustration and discouragement, worry and grief, and social isolation are common. If you're a caregiver for someone with this disease, you can help yourself and help prevent caregiver burnout by doing the following:

• Ask friends or other family members for help when you need it.
• Take care of your health.
• Learn as much about the disease as you can. Ask questions of doctors, social workers and others involved in the care of your loved one.
• Join 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 to get connected with support groups, doctors, resources and referrals, home-care agencies, supervised living facilities, a telephone help line and educational seminars.