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All about dementia

Updated: Feb 10

Dementia is one of the leading causes of death and disability in the world. Most people have heard of it but it remains poorly understood. For instance, many people believe that Alzheimer's disease and dementia are interchangeable terms, but this is not accurate.

Dementia refers to a condition characterised by certain symptoms and signs where cognitive impairment - problems with thinking - is a core problem. It is not, in of itself, a diagnosis - in the same way that cancer itself is not a diagnosis. Like cancer, there are a number of causes. Here are the most common:

  • Alzheimer's disease is the most common cause of dementia, causing approximately 2/3rds of cases in older adults. Although we are not entirely sure what causes this disease, it is associated with the accumulation of toxic proteins in and between nerve cells in the brain. These proteins damage the cells and interfere with their function, causing the characteristic features of early difficulty remembering new things, problems with other areas of thinking, and a number of psychological and physical changes.

  • Vascular Disease can also cause dementia. Vascular refers to our blood supply, including to the brain. When this is compromised, the affected areas of the brain don't work as well, leading to a number of cognitive, physical and psychological symptoms. This is probably the second most common cause of dementia.

  • Frontotemporal dementia is another type of dementia. This is a complicated disease which can present with a number of symptoms that, initially at least, are quite different to that seen in Alzheimer's disease. As the name suggests, it is caused by damage to the frontal and the temporal lobes of the brain. Often there are specific problems with language, or there may be changes in behaviour and personality that precede other cognitive problems

  • Lewy body disease can also cause dementia. Lewy bodies are proteins that accumulate within nerve cells and can cause a number of symptoms depending on which nerve cells are affected. If they affect the deeper parts of the brain, they can cause problems with movement such as that seen in Parkinson's disease. They can also cause cognitive symptoms including memory loss and other problems with thinking. Parkinson's disease dementia is closely associated with Lewy Body dementia, though in the former, problems with movement and muscle tone come first, and in Lewy body dementia, cognitive problems usually come first.

  • Excessive alcohol consumed over a long period can also cause memory problems, including dementia. This often preferentially affects the front part of our brain - the frontal lobe. This is responsible for various cognitive skills including those that allow us to behave in a socially appropriate way, to plan and organise ourselves, and to inhibit unhealthy impulses. These skills are often affected along with memory.

There are in fact over one hundred potential causes of dementia, though those above account for the vast majority.

Here are the aspects that are common to all different types of dementia:

  • The problems experienced represent a change from a previous state. That means to say that things have to be different to how they used to be. If I had always had a terrible memory and that is the only problem I have (and it is no worse), then that wouldn't make me worried I have dementia. On the flip side, if someone has always been good with remembering things, and they start to forget everyday things, that would be a concern.

  • The problems are bad enough to interfere with everyday function. As we age, there are changes in our thinking and memory - more 'tip of the tongue moments', mild forgetfulness and a general slowing of our thinking abilities. Despite these changes we are able on the whole to do what we usually do day to day - wash ourselves, get dressed, remember appointments and medications, cook for ourselves (assuming this is something we have done before!) and manage our finances. It is only when these so called activities of daily living (ADLs) are unable to be adequately performed that dementia becomes likely. There are sometimes more subtle changes that may herald a dementia, especially in those who have been highly educated or possess superior intelligence, though this is the exception rather than the rule.

  • The problems over time will get worse. Dementia is caused by degenerative conditions, and as further damage is effected to the brain, the symptoms of memory loss or other cognitive skills will worsen. There are again some exceptions - notably, the symptoms of alcohol-related dementia may improve if no further alcohol is drunk - but a decline with time is generally expected.

  • Other causes of cognitive impairment need to be excluded. Numerous health conditions, both physical and psychological, can cause a deterioration in thinking, as can the use of certain prescribed and illicit drugs

Beyond this, the symptoms of dementia will vary depending on the cause, at least early on:

Dementia due to Alzheimer's Disease classically causes early problems with forming new memories. Someone with this condition may struggle to remember what they have done recently, and may appear forgetful and repetitive. They may frequently misplace objects and can have periods of disorientation (forgetting where they are and what day it is). Their long term memory - events from many years ago - tends to be more robust, especially early on, in large part because they are more solidly stored in various parts of the brain.

The symptoms and signs of vascular dementia depend on which part or parts of the brain do not receive adequate blood, either because of a blood clot in the blood vessels or due to a haemorrhage - leakage of blood out of the vessel and into the brain tissue.

Frontotemporal dementia classically presents with early language problems or with changes in personality or behaviour. Conversational ability, including the ability to name things, may be affected. Speech may become broken or halted or may remain fluent but make little sense. Apathy, obsessional thinking and rigid behaviours may develop, as may an apparent lack of concern for others. There may also be a preference for sweet foods, leading to weight changes.

Alcohol-related dementia may cause problems with memory - both short term and long term - and problems with executive function - abilities that allow us to plan and manage more complex cognitive tasks, especially those that involve multiple steps e.g. cooking, managing finances etc.

Lewy body disease often presents with executive problems, visuospatial issues and a markedly fluctuating picture of alertness and attention. Those with this condition may appear relatively alert and lucid one moment to then become drowsy and confused the next. It has a number of other characteristics features including signs of Parkinsonism and neuropsychiatric symptoms such as visual hallucinations.

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