Diseases that cause Dementia

There are many diseases and medical conditions that cause dementia.These are the causes of dementia, but are also often referred to as the types of dementia, or sometimes, simply, dementias. So, a patient showing the group of symptoms called “dementia” could be suffering from one or more of the diseases that cause dementia, such as Alzheimer’s Disease, vascular dementia, fronto-temporal dementia, or mixed dementia. There are said to be around a hundred causes of dementia.

A common confusion

Fact: Dementia is a group of symptoms. Alzheimer's Disease is the most common cause of dementia, but there could be other causes, too.

Unfortunately, there are many misunderstandings about dementia and its causes. For example, many people assume Alzheimer’s Disease and dementia are the same. Others assume that they are different. The fact is, though Alzheimer’s Disease is the most common cause for dementia, it is not the only cause.

Confusions like this make it difficult to understand available information on dementia. Caregivers and non-medical laypersons often get confused because much of the information available does not make it clear that dementia symptoms can have many causes. Sometimes, for convenience, the word “dementia” is used as if it refers to a disease.

Another confusion occurs because many documents talk of how dementia gets worse over time and that there is no treatment for it. Yet other articles insist that diagnosis is needed so that treatment can start.

Here are some salient facts are:

Simple, easy to remember videos in English and Hindi for: What is the Difference between Dementia and Alzheimer’s?

• Dementia symptoms can be caused by one or more of several medical conditions.
• Some medical conditions that cause dementia can be reversed with treatment. A patient exhibiting dementia symptoms because of these medical problems can, after treatment, revert to normal.
• Irreversible causes of dementia will progress with time, ultimately resulting in the patient being totally dependent and bed-ridden. There is no cure currently available for them Some treatments are available for some of these diseases–these treatments may help reduce the symptoms, but do not change the underlying disease and do not slow down the progress of dementia (new research may change the situation)
• The progression of dementia depends on the progression of the underlying disease. Knowing which disease is causing dementia helps us know which type of problems are more likely, and how fast the dementia will worsen.
• Family members may be concerned that they will get dementia; to assess this probability, it is necessary to know which disease is causing the patient’s dementia. They can also stay in touch with relevant research advances and studies.
• Most discussions on caregiving and dementia assume an irreversible dementia. That is, most discussions assume that reversible causes have been diagnosed and eliminated, and that the persons concerned about dementia are facing an irreversible form of dementia.

Reversible causes

Reversible causes of dementia include depression, hypothyroidism, infections,  and vitamin B12 deficiency. Once doctors investigate the dementia and find that it is has a reversible cause, they treat the underlying cause, and the dementia symptoms reverse.

Irreversible causes

In most dementia cases, the underlying disease(s) cannot be cured. The disease progresses and the patient’s brain function declines till the patient is bed-ridden and fully dependent.  That is, the dementia is irreversible and progressive.

Alzheimer’s Disease, the most common cause of dementia, cannot currently be cured, and is therefore an irreversible, progressive form of dementia. Other disorders that cause dementia include strokes, Pick’s Disease, and Parkinson’s Disease.

“At least one in three people with Parkinson’s will develop some form of dementia”, according to this project document from Prof David Burn, Newcastle University.

While Alzheimer’s Disease explains 60 to 80 % of the dementia cases, we must also remember that 20 to 40% cases of dementia are not caused by Alzheimer’s Disease. Often, literature is not as easily available for non-Alzheimer’s dementia, and caregivers must extrapolate from what is available for Alzheimer’s Disease patients to understand what can be done. Caregiving concerns remain similar across various types of dementia, but some types of symptoms are more typical in certain types of dementias.

According to The Dementia India Report 2010:

The common causes accounting for 90% of all cases are Alzheimer’s disease, Vascular dementia, Dementia with Lewy bodies and Frontotemporal dementia.

The report gives the proportion of common subtypes of irreversible dementia as (from Table 1 of the report)

Very often, patients have mixed dementias.

It matters which disease has caused dementia, because diseases differ in which areas of the brain they affect. This means, the patients differ in which functions deteriorate faster.

Take Alzheimer’s Disease. Here, initially, only the memory impairment may be visible, and the patient may face problems learning new things or making decisions. Other impairments, such as speech, may occur later. Front-temporal dementias are characterized by a more rapid onset, and here, initial symptoms are changes in personality, such as making rude or sexual comments to people around. Patients have poor judgment and make unwise financial decisions. In vascular (multi-infarct) dementia, the brain gets damaged due to a series of strokes, and the functions affected depend on which area of the brain was damaged in the stroke.

Research is ongoing to understand the impact of the various diseases underlying dementia. For example, in this video on youtube, Dr Olivier Piguet talks about overeating in frontotemporal dementia (the abstract of the paper is here:  Eating and hypothalamus changes in behavioral-variant frontotemporal dementia.)

The progression of dementia also depends on the underlying cause. In Alzheimer’s Disease, the progression is gradual; it is usually more rapid in fronto-temporal dementias. In multi-infarct dementia, which is caused by strokes, a patient may remain steady at a level for a while if subsequent strokes are prevented. When the patient suffers another set of strokes, we will see a visible decline occur over a short period of time.

Learn more about the types of dementia at these links: Related dementias (alz.org) and What is dementia (ADEAR). An informative presentation is also available at medicinenet.com at: Dementia Pictures Slideshow: Disorders of the Brain.

As caregivers, we need to understand enough of the underlying disease so as to know what to expect. However, as the group of symptoms is the same, and as the behavioural aspect of all dementias is similar, tools and tips that are required are common, and we can benefit from a wide range of material available. Even if our patient’s dementia is not caused by Alzheimer’s, caregiving resources on Alzheimer’s Disease sites are likely to be useful for us.