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Dementia

Audio version of this page. Read by Professor Gordon DuttonVideo Link: https://vimeo.com/611778088

Dementia is a medical condition where certain areas of the brain are not functioning typically, particularly around memory and understanding, broadly covered by the term cognition or cognitive abilities.

The word cognition comes from the Latin word cognoscere meaning 'get to know'.  With dementia, getting to know things becomes more difficult.The word cognition comes from the Latin word cognoscere meaning 'get to know'. With dementia, getting to know things becomes more difficult.

With dementia, some things are more difficult to 'get to know', remember and therefore understand. Dementia is progressive, so cognitive abilities can change.

There are many different types of dementia with different causes, including:

  • Alzheimer's Disease, estimated accounting for 60-80% of all cases
  • Posterior Cortical Atrophy
  • Vascular Disease (causing Vascular Dementia)
  • Lewy Body Disease (causing Lewy Body Dementia)
  • Creutzfeldt-Jacob Disease
  • Frontotemporal lobe degeneration
  • Stroke
  • Parkinson's' Disease (causing Parkinson's Disease Dementia)
  • Huntington's Disease (causing Huntington's Disease Dementia)
  • HIV (causing HIV Associated Dementia)
  • Alcohol Related Dementia
  • Dementia after Traumatic Head Injuries
  • Dementia due to Malnutrition

Not all of these conditions affecting the brain will lead to dementia, but they can and in some they will.

It seems pretty much anything that can alter the brain can possibly also lead to dementia in some.

There is nothing new about dementia, it was described in Ancient Greece by the philosophers Pythagoras, Plato and Aristotle, and by the Roman writer Cicero and Shakespeare.

The treatment for dementia involves managing the condition.

The best way to most effectively target any difficulties is when you know the cause. With cognition, the cause of the difficulties is not always obvious, and can be multiple.

Brain Networks

Think of a city lit up at night, with all the electric lights shining and showing the roads with traffic moving in every direction.

Imagine you are looking down on a busy city at night and can see the roads and traffic moving and lights and lit up buildings.Imagine you are looking down on a busy city at night and can see the roads and traffic moving and lights and lit up buildings.

Imagine that city like your neighbourhood or town has different things you need in different places. The grocery store is in one area and you get to it by a certain road, and the library is somewhere else etc.

  • But what happens if a part of the city is cut off, or not working so well, so the routes to get to places take longer or may be completely blocked?
  • How do you get to the grocery store or library if the route is no longer there?
  • What if the grocery store or library have closed down, or are just not as good as they once were?

Thinking of our city...

  • There might be another way to get to the library or grocery store, or...
  • There might be a slightly different library or grocery store somewhere else.

Now think of the brain as the city.

The roads are the pathways in the brain. The traffic is all the messages or signals your brain is sending all the time, including right now so that you can read or listen to these words, and the illuminated buildings are the many stations in your mind where you keep all your memories and you are able to make sense of where you are and what you are doing...your cognition.

With dementia, some of those roads may not be as easy to navigate as they once were, and some of the lights and buildings may not be open, meaning things that were once simple and took a moment, like recognising someone well known, can take longer or may not seem possible.

Why Vision?

Many think of vision as to do with the eyes, but vision is processed, and is effectively created in the brain. Eye health and tests are important, and everyone should regularly get their eyesight tested. Here, on this website we are looking specifically at the brain part of vision, called visual processing.

As we have shown with the multiple possible causes of dementia (in the list at the top of this page), almost anything that slowly and progressively affects the brain can lead to dementia.

Vision is a major part of brain processing, and it is estimated that 40% of the brain is dedicated to visual processing. It is further estimated that up to 80% of how we learn, so our cognitive abilities, are linked to vision.

So where the brain is causing cognitive challenges, difficulties with visual processing should be considered as a possible factor.

Visual processing is not just about creating the picture you see. There are multiple networks of processes, enabling you to recognise what is seen, move about safely, understand the world as you interact with it, and relate to others.

Disorders of visual processing will not always be the cause of difficulties, but sometimes it can be almost impossible to work out what specifically the causes of the cognitive difficulties are.

Our suggestions may help and no harm can come from trying them. Many involve finding different ways to do things, so with our city example, offering an alternative route or slightly different store. If they do not work, then vision may not be the cause of the difficulties.

Visual processing is not just about creating the picture you see.  There are networks or processes, so you can recognise what is seen, move about safely, understand the world as you interact with it, and relate to others.Visual processing is not just about creating the picture you see. There are networks or processes, so you can recognise what is seen, move about safely, understand the world as you interact with it, and relate to others.

Alzheimer's Disease & Posterior Cortical Atrophy

It is estimated that between 60-80% of people with dementia have Alzheimer's Disease.

Is it also estimated that between 5-15% of people diagnosed with Alzheimer's Disease may have been incorrectly diagnosed and have posterior cortical atrophy. Posterior cortical atrophy is another form of dementia. One of the earliest symptoms of posterior cortical atrophy is visual difficulties, so the person may think their eyesight needs testing and see an optometrist (eye specialist) or ophthalmologist (eye doctor). As the visual difficulties are likely to be from an area in the brain with visual functions not tested in standard sight tests, these are often not picked up. As symptoms progress, posterior cortical atrophy can easily be mistaken for Alzheimer's Disease. If the estimates are correct (source, Alzheimer's Association, USA), rather than extremely rare, posterior cortical atrophy may be the cause of 10% of all cases of dementia. These figures require further research. See sections below for more information.

Sections:

For more information on Dementia:
UK NHS
World Health Organisation

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At CVI Scotland we are devoted to helping people understand cerebral visual impairments, and together working towards developing the understanding of this complex condition.