What is visual hallucination?
Visual hallucination is the most common type of hallucination in dementia. The person may see people, animals or other objects. Sometimes the hallucinations involve quite complicated scenes or bizarre situations. Visual hallucinations can start with misinterpretations. The person may think they see faces or objects in swirling patterns on fabrics or in the
shadows in a room, for instance. Many people with dementia who experience visual hallucinations only experience them occasionally. Moreover they often only last a few seconds. However, sometimes they are more persistent and troublesome.
Visual hallucinations may occur both as formed objects like stars or other recognizable objects or may be unformed as in flashes and spots. The formed images may represent misunderstanding of information in the brain or background "noise" from the disruption of brain tissue that is needed to process the information. People who have persistent visual hallucinations together with stiffness and slowing of movement, or marked fluctuations in their abilities, are likely to have Lewy body dementia. If this is the case, anti-psychotic medication, which is sometimes given for troublesome hallucinations, can make any stiffness worse. It should therefore only be prescribed in low doses, if at all, and regularly reviewed.
Visual hallucinations are one of the hallmarks of dementia with Lewy bodies disease, or DLB, a degenerative neurological illness that, like the better-known and more common Alzheimer's disease, robs its victims of their minds - and eventually their lives. In this type of dementia the person usually has a mixture of the symptoms found in Alzheimer's and Parkinson's disease. In some people it shares symptoms with Alzheimer's and Parkinson's disease, but DLB tends to progress more rapidly. For all three, there is no known cure, just treatment for some of the symptoms.
A separate but related cause of visual hallucinations is called Charles Bonnet Syndrome. It occurs in patients with significant loss of vision. The hallucinations from Charles Bonnet Syndrome are often very detailed such as a group of people, a truck or an animal. These are not psychotic in nature but simply represent the brains attempt to interpret the impaired information and find a mental image to match the incoming message.