People with Alzheimer's disease may see, hear, smell, taste, or feel things that are not really there. The most common hallucinations are those that involve sight or hearing. Some people with Alzheimer's disease develop strange ideas about what is actually happening and may come to believe that other people want to harm them. This kind of belief is called a delusion.

These symptoms are usually thought of as being caused by mental illness, but they are actually fairly common in Alzheimer's disease, especially in the middle stage, although they can occur at other stages. There may be many causes mostly having to do with the parts of the brain affected by the disease. In any case, it is important not to be frightened by what are irrational thoughts and experiences and to know how to respond to them.

It is essential that you do not tell the person who is seeing or hearing things that you know what he sees is not real because the things are real to the person. Reassure the person that you will keep him safe and try to understand the emotion behind the hallucination or delusion. This may be enough to enable the person to let go of these concerns, at least for the moment. If the hallucination is pleasant and the person is planning a birthday party, try to connect to her by joining in the fantasy. You do not need to say that you see or hear the same things but you can accept that the person does.

People with Alzheimer's disease may also become suspicious and may accuse someone of stealing from them when they cannot find something. When the person with dementia does not remember where he put something, the idea that it has been taken by someone may appear to be a reasonable explanation for its being missing. Tell him you will help him look for it, and try not to mention the fact that he is the one who misplaced it. He may feel relieved when the object is found.

Paranoia in people with Alzheimer's disease appears as unrealistic beliefs, usually of someone seeking to do them harm. They may hoard or hide things because they believe someone is trying to take their possessions. These symptoms can be very distressing both for the person with AD and for you. Remember, what the person is experiencing is very real to him. It is best not to argue or disagree. Try not to take it personally. In this situation it is best to offer to help the person to find the missing item. It will not be helpful to try to convince him that his explanation is wrong or based on his poor memory.

When these behaviors do not respond to supportive caregiving techniques it may be necessary to consider medication, especially if the person is very upset or puts himself or others in danger because of his symptoms. These symptoms are sometimes caused by depression, which often accompanies Alzheimer's disease. Consult with your physician, who may recommend an antidepressant medication. Other medications, called anti-psychotics, are frequently prescribed. They should be used with caution and sensitivity.