Hallucination, Illusion or Misinterpretation?


Most people viewing this pattern feel visually uncomfortable and disorientated because it’s designed to make you feel that way. Now imagine feeling like that all the time, as though every surface has that pattern on it. To a person with dementia changes in colour, or shadows on a path,  or the pattern on wallpaper can produce the same effect. The world can be a visually terrifying and uncomfortable place for them.

Often in my work with elderly patients, a son or daughter reports to me in a low whisper that they think their mother or father might be hallucinating. Sometimes the elderly person is aware that they are ‘…seeing things that aren’t there,’ and sometimes they report that their family ‘…think I’m going doolally…’

These reports of hallucinations are particularly prevalent among those dealing with a parent with dementia. But are these patients really hallucinating? It might be helpful if we discussed what an hallucination actually is.

An hallucination is an experience of something that isn’t really there. The most common type of hallucination is visual and these are the type flagged up to me, but it’s perfectly possible to have auditory hallucinations as well as those for smell, taste and touch. Hallucinations may be simple flashes of light, or they may be rich and complex featuring people, animals and scenery.

In my experience most of my elderly dementia patients are not experiencing visual hallucinations; rather their damaged brain is misinterpreting visual information, in other words they are mistaken about what they see. There are lots of reasons for this and sometimes not a single cause.

Many elderly patients already have some visual problems such as developing cataracts, glaucoma or macula degeneration (AMD). These can disturb and distort the vision. Cataract causes a reduction in the ability to detect contrast; glaucoma causes a restriction to the peripheral vision meaning that the person can’t see around the edges of their vision, and AMD causes a reduction in the central vision leading to difficulties reading and recognising faces.

To complicate the issue dementia can also cause or exacerbate all of these problems, depending on the part of the brain affected. It can also cause a reduced ability to detect movement, colour differences, and perception of depth. In addition the affected person may have difficulty changing their direction of gaze or putting a name to an object.

Then there are orientation difficulties. Judgement of distance is often impaired and an affected person may begin to bump their car as they park, flinch as someone walks past them thinking they are closer than they are, or swerve to avoid obstacles which are not actually in close proximity. They may miss when attempting to pick up a cup or a knife and fork or when aiming for a chair. They might misinterpret reflections in mirrors and windows as real people, and visually ‘busy’ environments (loud wallpaper, patterned carpet, lots of clutter) might cause them distress.

In our practice we have a beautiful original restored mosaic floor in the entrance. It’s extremely attractive and most patients express delight when they first see it, but I’ve noticed that many of my dementia patients make a distasteful expression and avert their gaze upwards. The pattern is too busy and they find it disorientating. Fortunately the consulting rooms are decorated in calm, plain colours which is a much more comfortable environment for them.

As dementia is a brain disorder it helps to know a little about how the brain works. The brain is divided into four regions or lobes:

The occipital lobe – This is situated at the back of the brain and is responsible for dealing with visual information.

The parietal lobe – Situated just above and in front of the occipital lobe, it is responsible for information about shape, size and space. Damage to this area can lead to a person struggling to dress themselves, feed themselves and find their way around, a well as make it more likely they’ll bump their car, or misjudge object distances. These are the patients most often brought to see me with concerns about possible cataracts or vision loss.

The temporal lobes – Situated either side of the brain these areas are responsible for speech, language, naming of objects, meanings of words and memory.

The frontal lobes – Situated at the front of the brain these act as a sort of management centre  for the brain. They allow us to plan, set goals and complete complex tasks.

To help dementia patients I recommend:

Using high contrast to help them – so plain dark crockery on a white table or light crockery on a dark table; light-coloured furniture against a dark floor or vice versa. In the bathroom using a dark toilet seat against a white bowl can help orientation. Stair edges can be marked clearly with contrasting tape.

Keep environments visually calm – no loud wallpaper, keep clutter to a minimum, remove rugs which might cause them to doubt their footing – dark rugs on a pale carpet can be perceived as holes in the floor.

Check that mirrors are not causing problems – If they are remove them.

Draw curtains and blinds at night so window reflections don’t cause issues.

Make lighting levels as even as possible throughout the home. Many people with dementia avoid shadowy areas as they are perceived as threatening.

Finally, many well-meaning relatives avoid taking their relatives with dementia for regular eye examinations so as not to distress them, and this is perfectly understandable. But if handled sensitively it can be a worthwhile exercise. Clear vision makes people feel more secure, helps them to orientate better, and simply improves the quality of their life, even if that’s only improving the clarity of the television picture.