When You See Things That Are Not There

A child in the hallway. A dog under the table. If you have Lewy body dementia, this is a known part of it, and simple checking strategies can make it easier.

Why am I seeing things that are not there?

In Lewy body dementia, the disease affects the parts of the brain that interpret what your eyes take in. Your eyes are usually working. The interpretation is what goes wrong.

Recurrent, detailed visual hallucinations are one of the core features doctors use to diagnose dementia with Lewy bodies. The UK's Lewy Body Society estimates that about 70% of people with Lewy body dementia have them at some point.

They are usually visual and often specific: people, children, animals, insects, sometimes figures that are small or partly hidden. Many people describe them as calm rather than frightening, at least at first. They tend to come in the evening or at night, when the light is dimmer and you are tired.

Some people also see an ordinary object as something else, a coat on a hook as a person, a pattern on a rug as something moving. That is a misperception rather than a full hallucination, and better lighting often fixes it.

Does it mean I am going mad?

No. It is a symptom of a specific brain disease, the same way a tremor is a symptom of Parkinson's. It says nothing about your sanity or your judgment.

People with Lewy body dementia often keep a good deal of insight early on. Many know, at least some of the time, that what they are seeing is not there. Insight varies from person to person and from day to day, and a hallucination can still feel completely real while it is happening.

If you have been keeping this to yourself because you were afraid of how it sounds, tell your doctor and the people close to you. It is expected, it is in the textbooks, and it changes some important decisions about your care.

What helps when it happens?

Check it against something else: another sense, another person, or a change of scene. Most people find one or two strategies that work for them.

These come from the Lewy Body Society's guidance for people living with the condition:

• Remind yourself it is a symptom. Some people say a short sentence to themselves, such as "that is the Lewy body."
• Close your eyes and open them again. Many hallucinations change or go when you look again.
• Go and touch it. Or speak to it. A figure that does not answer, or a dog your hand passes through, settles the question.
• Ask someone you trust whether they can see it too.
• Change the scene. Move to another room, make a drink, turn on a light, put on music.
• Turn up the lights in the evening. Shadows and dim rooms make misperceptions more likely.

You may also want to agree on a signal with the people you live with, a word or a question that lets you check without a long conversation. "Is the dog real?" is easier to ask when everyone knows what it means.

What should every doctor know about me?

That you have Lewy body dementia, and that many antipsychotic drugs can cause severe reactions in people with it. This matters most in emergencies.

Antipsychotics are the drugs most often reached for when someone is seeing things or is agitated, especially in an emergency room. In Lewy body dementia, they can cause serious harm.

A 1992 study in the BMJ, which helped establish this, found that among people with Lewy body dementia who had an adverse reaction to these drugs, 54% had a severe one, and severe reactions were linked to higher death rates over the following year. The Lewy Body Dementia Association estimates severe sensitivity reactions in 25 to 50% of people with Lewy body dementia given antipsychotics at usual doses. Reactions include sudden worsening of confusion, severe stiffness, sedation and, rarely, a life-threatening reaction.

The LBDA advises that older "typical" antipsychotics such as haloperidol (Haldol) should be avoided, and that several newer ones carry similar risks. The FDA also requires a boxed warning on all antipsychotics about increased risk of death in older people with dementia-related psychosis.

What to do now, while it is easy:

• Put it in writing. A card in your wallet and a note on your phone listing your diagnosis and "sensitive to antipsychotics."
• Tell every new doctor, including dentists and surgeons, and any hospital on admission.
• Make sure the people who would go to the ER with you know to say it out loud.

Is there a medicine that helps with the hallucinations?

Sometimes. The medicines used for memory in dementia, cholinesterase inhibitors, have trial evidence for reducing hallucinations in Lewy body dementia.

In a 2000 trial in The Lancet, 120 people with Lewy body dementia were given rivastigmine (Exelon) or a placebo for 20 weeks. People on rivastigmine had fewer hallucinations and delusions and were less apathetic and anxious. By the trial's measure, 63% on rivastigmine improved by at least 30%, compared with 30% on placebo. Side effects were common: nausea, vomiting, loss of appetite and sleepiness, and people lost weight.

If hallucinations are not bothering you, you may not need treatment for them at all. Many people live with calm, familiar hallucinations and choose not to. That decision is yours.

When should a new hallucination worry me?

When it is new, sudden or different from your usual pattern. That can mean something else is going on.

Call your doctor if:

• Hallucinations start suddenly or become much worse over a day or two. Infection, especially a urinary tract infection, and dehydration can cause this.
• You recently started or changed a medication. Some Parkinson's medicines, sleep aids, bladder medicines and pain medicines can trigger hallucinations.
• Your vision has changed. Eye disease can cause hallucinations of its own, and an eye exam is a simple thing to rule out.
• The hallucinations have become frightening, or you have started to act on them.