Diseases that cause dementia

A common confusion

Dementia is a group of symptoms. Alzheimers disease is one possible cause
Fact: Dementia is a group of symptoms. Alzheimer's Disease is the most common cause of dementia. But the symptoms could be caused by other diseases, too.

There are many diseases that can cause dementia symptoms. These are the causes of dementia. They are also called the types of dementia, or simply dementias. A person with dementia could have one or more diseases that cause dementia. The most common dementia-causing disease is Alzheimer’s Disease. Others include vascular dementia, Fronto-Temporal Dementia (FTD), Lewy Body Dementia (LBD), and mixed dementia. There are said to be around a hundred causes of dementia.

Unfortunately, there are many confusions around dementia. Articles on dementia do not explain that the dementia symptoms can be caused by many diseases. The word “dementia” is often used in place of the name of the disease causing it. Many articles use “dementia” and “Alzheimer’s” interchangeably; this confuses readers about the relationship between dementia and Alzheimer’s.

Some basic information on dementia and diseases that cause it

  • Dementia symptoms can be caused by one or more medical conditions.
  • Dementia is the name of a group of symptoms. A person may have some of these symptoms and not the others. The doctor checks the person and decides whether to diagnose the person with dementia.
  • Some medical causes of dementia can be treated. In these cases, medicines reverse the symptoms. The person can become normal. This is called reversible dementia.
  • In many dementia-causing diseases, the damage done to the brain by the disease cannot be reversed. Such dementia is called “irreversible dementia”.
  • In most irreversible dementias, the brain keeps getting more damaged over time. This is called progressive dementia. The person with dementia finally becomes fully dependent and bed-ridden. There is no cure.
  • In some irreversible dementias, the brain damage stays at the same level. This is called a plateau. Or the damage gets worse in steps. It stays at the same level for some time, then gets worse over a short period of time, and stays at this new level for some time. This is called step-wise progression of dementia.
  • Medicines for irreversible dementias try to reduce the symptoms. They cannot change the underlying disease. They cannot repair the damage already done. The symptom relief may improve the person’s quality of life, especially in early stages, for some patients. But medicines do not slow down the progress of the disease.There are no “disease-modifying” medicines so far. Researchers are trying to find better medicines.
  • Dementia symptoms get worse when the brain gets more damaged because the disease has progressed. Existing symptoms get worse. More symptoms may also appear. Which symptoms are seen, and how they get worse, depends on which disease is causing dementia.
  • Family members of persons with dementia often worry that they will get dementia. Their risk of dementia depends on many factors. Family members can ask the doctor and stay informed about research in this area.

Note that most material on dementia care assumes that the person has an irreversible dementia. It is assumed that all reversible causes have been diagnosed and cured. All care advice is given assuming that existing symptoms are being caused by an irreversible dementia disease.

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Reversible causes of dementia

There are several reversible causes of dementia. Here the disease causing the symptoms can be treated. Treatment will reverse the dementia symptoms.

One common reversible cause of dementia is depression. Such dementia is called depressive pseudodementia or depressive dementia. Another common cause is medications. Here, symptoms are seen because of a reaction to some medicine. They could be a side-effect of some medicine. Or they happen due to a toxic buildup in the body. Some medicines affect the brain’s neurotransmitters and cause dementia symptoms.

Well-known reversible dementias include hypothyroidism, infections, and vitamin B12 deficiency. Electrolyte imbalance, a common problem in elders, may also be confused with dementia. Dehydration and poor nutrition are other possible causes. Ups and downs in blood sugar may be confused with dementia. A person with hearing loss or poor vision may not respond well to others. This may be mistaken as dementia.

Some causes are less common. One is normal pressure hydrocephalus (NPH). Here excess fluid is built up in the brain. A person with NPH may get relief if a shunt can remove this excess fluid. Some other uncommon causes may seem unrelated to the brain. For example, some studies show that celiac disease can cause dementia-like symptoms. Diseases with symptoms similar to neurodegenerative diseases may also get mistaken for dementia. One example is Lyme’s disease.

A medical checkup is needed to know which disease is causing the dementia symptoms. Doctors have to look at the medical history and current medicines. Investigations are done. Based on these the doctor will decide if the person has dementia. The doctor will try to find out which disease is causing the symptoms. A person showing dementia symptoms may have more than one dementia-causing disease.

If you have dementia symptoms, or are worried about someone who has symptoms: Getting a proper diagnosis is a must for anyone who has symptoms. Contact doctors and get a check up done. Remember that a person can have more than one medical problem causing dementia symptoms. Also remember that someone with dementia can also develop other diseases which can worsen the dementia symptoms. So you must remain alert about all medical problems. Get checkups done regularly to detect any new problems.

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Irreversible causes of dementia

Most dementia cases are irreversible. The disease causing the symptoms cannot be cured. In some such cases the person’s symptoms stay at the same level for a long time. This may happen for someone who has vascular dementia. But most irreversible dementias are “progressive”. The symptoms get worse with time. The person’s abilities keep declining till the person is fully dependent.

Alzheimer’s Disease is the most common cause of dementia. It is an irreversible and progressive disease. 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 below (from Table 1 of the report):

Dementia subtype Early characteristic of dementia Proportion of dementia cases
Alzheimer’s Disease (AD) Impaired memory, apathy and depression, gradual onset 50-75%
Vascular Dementia Similar to AD but memory less affected and mood fluctuations more prominent. Physical frailty. Stepwise progression 20-30%
Dementia with Lewy Bodies Marked fluctuation in cognitive ability. Visual hallucinations. Parkinsonism (tremor and rigidity) <5%
Frontotemporal dementia Personality changes. Mood changes. Disinhibition. Language difficulties 5-10%

Alzheimer’s Disease explains 50 to 75% of the dementia cases. The remaining cases (25 to 50%) are not caused by Alzheimer’s Disease alone. They may be caused by some other disease. Or they may be a “mixed” dementia where the dementia is a result of Alzheimer’s Disease along with some other disease.

Let’s look at some types of dementia and their typical symptoms. Take Alzheimer’s Disease (AD). The probability of AD increases with age. The disease often starts at an older age. In most cases, in the beginning the person faces memory problems or has problems learning new things or making decisions. Problems in speech and other problems appear later. But consider another type of dementia, Fronto-Temporal Dementias (FTD). FTD often starts at a younger age. FTD’s initial symptoms are usually language difficulties, mood changes, personality changes, and inappropriate social behavior. Persons with FTD may make rude or sexual comments. They may not care about people around them, They may show poor judgment and make unwise financial decisions. Some show overeating. They may not show memory loss, a symptom usually seen in persons with Alzheimer’s.

One common cause of dementia in India is vascular dementia. This dementia occurs because blood flow to the brain is reduced or blocked. This means the brain cells do not get enough oxygen and nutrients. This may happen because of a series of strokes. This is also called vascular cognitive impairment (VCI) or multi-infarct dementia. Symptoms depend on which parts of the brain were damaged because of vascular problems. Vascular dementia can exist along with Alzheimer’s Disease. This is called mixed dementia. It has its own typical symptoms.

Dementia symptoms get worse when the underlying disease progresses. In Alzheimer’s Disease, this could be gradual or rapid. It could range from a few years to even a couple of decades. However, in vascular dementia, symptoms may remain at the same level if the person gets no more strokes. When the person suffers more strokes, there is a rapid decline because another part of the brain has been damaged.

Most caregiving material is written for Alzheimer’s Disease, or for dementia in general. This material can be helpful even if the person has a non-Alzheimer’s dementia because many problems are similar. But some aspects of care may be different because they depend on the disease. Caregivers should get information from the appropriate communities to learn how the particular disease will affect someone.

Caregivers must make sure that all the person’s doctors (not just the specialists) know the diagnosis.They must ask about medicine side-effects. Some medicines help in one form of dementia but not in other forms of dementia. They may even cause harm. For example, some drugs help in hallucinations in AD patients but can harm LBD patients. Unfortunately, LBD is often mistaken for AD. Support forums for specific diseases can help caregivers learn about such problems.

On a related note, many persons who have Parkinson’s Disease will also develop dementia (called Parkinsonian dementia, and part of the overall “Lewy Body Dementia” umbrella ). The nature of correlation between Parkinson’s Disease and dementia is still a matter of active research. As laypersons concerned about our loved ones, however, what is important to remember is that persons with Parkinson’s Disease also have some cognitive problems. Many persons with Parkinson’s Disease will go on to develop dementia at later stages.

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See Also (References for detailed reading)

Resources/ references from Dementia Care Notes and related sites

To understand the relation between dementia and Alzheimer’s, see videos in English and Hindi for: What is the Difference between Dementia and Alzheimer’s?

External Resources/ references

Data from India on dementia, causes, status of care, and current and estimated prevalence: The Dementia India Report 2010 (PDF file)Opens in new window.

Below there are many links to sites containing information on various causes of dementia. You may also be looking for information on these by searching the Internet, reading books and manuals, talking to experts, etc. Note that the names and groups of various dementia-causing diseases are modified very often. They are not standard across websites, documents and books. Some terms earlier used for a single disease are now “umbrella terms” that include many related dementias. As an example, consider FTD. Some sites call FTD frontotemporal degeneration, some call it frontotemporal dementia or frontotemporal disorders, and some sites use the term “Pick’s Disease.” Terminology can confuse and mislead. Please be alert about these different terms. Ask your doctor if you get confused.

Links to understand more about various diseases that cause dementia symptoms (reversible and irreversible):

Important sites to learn about specific diseases that cause dementia

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Page/ post last updated on: August 31, 2018

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