What are hallucinations?

They can be. During a hallucination, a person sees, hears, smells, tastes or feels something that is not there. The National Institute on Aging says people with Alzheimer's may have hallucinations, such as seeing their late mother in the room, along with delusions and paranoia. It advises telling the doctor, because an illness or medicine can sometimes be the cause.

In Alzheimer's, hallucinations usually appear in the later stages. The Alzheimer's Association says they are caused by brain changes from the disease, and a person may see a former friend's face in a curtain, see insects on their hand, or talk with someone who is not there. New hallucinations still call for a medical check, since infections and medicines can cause them.

Yes. The National Institute on Aging says visual hallucinations occur in most people with Lewy body dementia, often early in the disease. They are typically realistic and detailed, such as images of children or animals. Hallucinations that are not disruptive may not need treatment, but if they are frightening or lead to dangerous behavior, a doctor may prescribe medication.

Dementia is one cause, but not the only one. The Alzheimer's Association lists kidney or bladder infections, dehydration, intense pain, alcohol or drug use, eyesight or hearing problems, medications and schizophrenia. If someone starts hallucinating, get a medical evaluation to rule out these causes and have their eyesight and hearing checked. Sudden hallucinations with confusion need prompt medical attention.

Non-drug approaches come first. The Alzheimer's Association suggests responding calmly, not arguing about what the person sees, offering reassurance and a comforting touch, moving to a well-lit room, and removing shadows, mirrors or noises that may be misread. If symptoms are severe, medication may be considered, but antipsychotics carry an increased risk of stroke and death in older adults with dementia.