It is estimated that between 20 to 40 percent of people with Alzheimer's disease experience hallucinations.
This feature of the disease usually occurs in the middle stages. Hallucinations are most frequently associated with psychoses. The term psychotic, or psychosis, simply describes someone who has lost contact with reality.
Most people think of hallucinations as a visual experience, but they can actually involve any one or more of the senses. Someone with Alzheimer's disease may hear, see, taste, touch or even smell things that are not really there.
Hallucinations offer the person an alternative reality. For the observer, it can be uncomfortable and distressing to witness someone hallucinating and difficult to know how best to help. It can however help to know a little more about the nature of hallucinations.
When someone hears voices or noises that are not there, we term this an auditory hallucination.
People with Alzheimer's do hear voices and noises that are not real. Most commonly it will be the voice of someone they recognise, such as a family member. Sometimes it can be the voice of a stranger or a number of different voices.
The voices may say ordinary mundane things, but sometimes, and usually more upsettingly, they may be threatening and abusive. It is the extent of intrusion and the frequency they are experienced that often dictates how distressed a person becomes.
People hear voices in different ways. In people with Alzheimer's, it is my experience, that the voice is usually external, i.e. someone calling to them or holding a conversation with them.
A person with Alzheimer's in the middle stages may not be able to describe their experience in detail, so their explanation has to be coupled by their response to the auditory hallucination to gain greater understanding.
People with psychotic illnesses (such as schizophrenia) describe hearing voices in the head, from outside the head, or even in the body. They can also experience voices, not only through the ears but as if they are thoughts entering the mind from somewhere outside themselves.
Seeing things that aren't there is the most common type of hallucination. Again, they are not always disturbing or troublesome.
Visual hallucinations can involve seeing family, friends and animals (some long dead), to the more bizarre, such as seeing people floating through walls or wearing masks. Hallucinations can be complex scenes, which might explain why the person seems to be concentrating or staring as they attempt to interpret what is happening. Visual hallucinations may happen at certain times of day or night. This could indicate that the person is misinterpreting something due to poor or different types of lighting. If this is the case the problem may be more of an illusion (a distortion of the senses) which can be corrected by modifying the environment.
Feeling and touching things that are not there, is not uncommon. I have seen someone with Alzheimer's disease stroke a cat. They not only see the cat but can feel their fur, and seem to feel the shape of it too.
Smelling things that aren't there is quite common in both younger and older people. It rarely causes distress.
People with Alzheimer's may believe they are eating something that either does not exist or it may be they are confused about what it is they are eating. Gustatory hallucinations (taste) may be experienced in combination with delusional thoughts, such as thinking someone is trying to poison them, or tricking them into eating something disgusting.
Hallucinations may be the result of diseases other than Alzheimer's. Epilepsy, infections or tumors are examples. It is important that your doctor investigates the possible alternatives.
Unless hallucinations appear to cause distress there may be a case for not intervening with medication. Use of antipsychotic medications may help with symptoms but they have costs as well as benefits and need to be considered in the overall context of the wellbeing of the patient.
Causes of Hallucinations in Alzheimer's Disease