What is the difference between Alzheimer’s disease and dementia, must be the most common question that I get asked at public events. So, it is about time to write an article on this topic to make clear what the difference is. By the end of the article we will know the difference between dementia and Alzheimer’s disease is and, hopefully, not confuse them anymore in the future.

Let’s get started.

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Dementia

Let’s start with dementia. What is dementia?

Dementia is what is often referred to as an ‘umbrella term’, meaning it describes a whole range of diseases or in this case different dementias. We can compare it to the term ‘cancer’, which is another umbrella term for any kind of cancer. All cancers have something in common (uncontrolled cell growth) but are also quite different in terms which cells in the body they are affect and the exact mechanisms for the uncontrolled cell growth.

It is similar for dementia. All dementias have in common that they are caused by proteins clumping together (the only exception is vascular dementia) and those proteins when clumping together become toxic to the nerve/brain cells (so-called proteinopathies – literally translated ‘diseases caused by proteins’). In the end this toxicity leads to nerve/brain cells to die, which in turn results in symptoms, such as memory problems, as the nerve cells responsible for those brain functions have died. So, that all dementia are caused by proteins clumping together is the thing they have in common, what about their differences?

One key difference between different dementias is that they are caused by different proteins clumping together. For example, the proteins causing Alzheimer’s disease are different from the proteins causing Dementia with Lewy Bodies or the proteins causing Frontotemporal dementia. This also explains why different dementias have often different symptoms since the different proteins start clumping together in different brain areas, causing different symptoms. As I mentioned before the only exception is vascular demenita which is not caused by proteins clumping together but blood vessels in the brain getting blocked or leaky. But often these blocked or leaky blood vessels can also cause proteins to clump together, hence vascular dementia is considered under the umbrella of dementia. If you want to find out more about the differences between Alzheimer’s disease and vascular dementia, I recommend my article on this here.

So, all we have to remember is that dementia is an umbrella term describing all kinds of dementia.

But what about the difference to Alzheimer’s disease then?

Difference between dementia and Alzheimer’s disease

For that, let’s have a look at the dementia ‘umbrella’ below.

We can see that there are four different types of dementia under the dementia umbrella. These are the our most common forms of dementia, which I have ranked according to how common they are (if you are interested in how many types of dementia there are in total, I recommend reading my specfic article on this here). From the figure we can see that Alzheimer’s disease is the most common form of dementia, followed by Vascular dementia, then Dementia with Lewy Bodies and finally Frontotemporal dementia.

Never heard of Dementia with Lewy Bodies or Frontotemporal dementia? This is not a surprise as they are already classed as ‘rare dementias’ and many health professionals will not be familiar with them either.

The more important point is that Alzheimer’s disease and Vascular dementia are by far the most common forms of dementia, with Alzheimer’s disease accounting for ~60-70% of all dementias alone. Vascular dementia accounts for another ~20-30% of dementias, meaning that Alzheimer’s disease and vascular dementia account for ~80-90% of all dementias – the rest are considered rare dementias. The pie chart below really brings home the point that the vast majority of people with dementia will have Alzheimer’s disease or Vascular dementia.

Since Alzheimer’s disease account for nearly three-quarters of all dementias, it should become clear why we often confuse dementia with Alzheimer’s disease, since the vast majority of people with dementia will have Alzheimer’s disease. However, we should remember that Alzheimer’s disease is only one type of dementia, albeit the most common one. Hence, if someone has a diagnosis of dementia we will -rightly- assume that they have Alzheimer’s disease, since the likelihood of having another dementia is much lower. But we can see also that this creates now a problem since Alzheimer’s disease now ‘dominates’ any discussing of dementia, since many people equate dementia with Alzheimer’s disease – to the frustration of the people with other types of dementia and their families.

It is, therefore, important to understand that dementia does not mean/equate to Alzheimer’s disease but describes more generally all types of dementia. So, when using the term dementia we should always carefully consider that it describes all people with all different types of dementia and not only Alzheimer’s disease.

Right, that’s that then – but hang on while we are discussing this topic we might as well have a look at the terminology of dementia which is by itself problematic.

Dementia terminology

Over the last few years the language used in the context of dementia has become increasingly scrutinised. For example, many people with dementia and their carers reject the term ‘patient’ to refer to them and hence the preferred terminology is now ‘people with dementia’. The exact reason why people object to term ‘patient’ is actually not clear but it seems to stem from the etymology of the word ‘patient’, which orginates from the Latin word ‘pati’ meaning ‘to suffer’. Patient as a term was, therefore, adopted in the Middle Ages by doctors to describes people ‘suffering from a disease’. If I understand the reason behind objecting to the term ‘patient’ correctly, then it is that ‘suffering’ that implies that the person is seen as more passive than active with the disease. This is clearly debatable and many healthcare professionals would argue that a person with a disease is clearly an active participant in their disease management, treatment, healing and not just someone passive . But in the end, we should respect that people with dementia and their carers do not want to be referred to as ‘pateints’ and I am fine with that.

However, the irony with the discussion about dementia terminology is that many healthcare professionals are far more uneasy with the term ‘dementia’ itself, as it has quite a negative connotation. Dementia comes from the latin words ‘de’ – about, of, from and ‘mentis’ – mind. Now, the ‘de’ often refers in medical condtions to a ‘loss of something’, so dementia literally translates to a ‘loss of mind’, which can be seen as far more upsetting than the term ‘patient’. I guess it raises the question whether we need to have a new terminology for ‘dementia’ in general. Not only is it confusing that dementia and Alzheimer’s disease are equated with each other but also that the term dementia is itself highly problematic and has a significant negative connotation. So, when using ther term ‘dementia’ we might also want to be careful that the actual term has a very negative connotation, in addition to the stigma it carries. Based on that, it will be interesting to see how the dementia terminology will develop in the future.

Summary

Taken together, dementia is an umbrella term describing all types of dementia, including Alzheimer’s disease. Alzheimer’s disease is the most common type of dementia with ~60-70% of people with dementia having Alzheimer’s disease. Because Alzheimer’s disease is so common for dementia, it explains why people assume that dementia equates Alzheimer’s disease. But we should remember that Alzheimer’s disease is only one type of dementia, even though it is the most common one.

Finally, the actual dementeia terminology is problematic, since dementia litertally translated means ‘ to lose one’s mind’, which is righlty upsetting or even offensive to many people with dementia. It raises the question whether there needs be a better dementia terminology in the future which not only avoids the confusion between dementia and Alzheimer’s disease but also offers a more positive or less offensive terminology.

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Links

• https://www.alz.org/alzheimers-dementia/difference-between-dementia-and-alzheimer-s
• https://www.alzheimers.org.uk/blog/difference-between-dementia-alzheimers-disease