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Introduction to Dementia


Dementia is not a specific disease. It's an umbrella term that describes a wide range of symptoms associated with the progressive decline in the function of the brain. Progressive meaning it gets worse over a period of time. Dementia is caused by a variety of diseases affecting the brain which can cause loss of memory beyond what might be expected from normal ageing, difficulties with thinking, problem-solving or language, orientation, comprehension, learning capacity, and judgement. The impairment in cognitive function is commonly accompanied by deterioration in behaviour such as agitation, delusions, and hallucinations or motivation. The progression depends greatly on the underlying cause of the dementia.

The brain communicates by sending messages to nerve cells (neurons). A nerve is made up of hundreds or even thousands of microscopic nerve fibers often all individually wrapped in myelin. Nerves conduct messages to and from the brain by way of electrical impulses. With dementia the communication between the neurons are interrupted. The deterioration in cognitive function depends on the physical changes in the brain caused by a variety of conditions and the part of the brain affected. The physical changes can be caused by a buildup of abnormal protein on the outside of the neurons interfering with the communication between the neurons, or abnormal deposits of protein forming clumps or masses inside the neurons, interrupting the brain's messages. Dementia can also be caused by the breakdown of the myelin covering the nerves, a brain injury or many other conditions.

Dementia can progress rapidly, or may take many years to reach an advanced stage. While a person with dementia will experience the stages differently, most people can have similar and overlapping symptoms. Every person is different. How the illness affects a person depends on which areas of the brain are most damaged.

Common types of dementia

There are many conditions which cause different forms of dementia. The common factor in all these diseases is that they damage and kill brain cells, so that the brain cannot work as well as it should.

Some of the diseases that can cause symptoms of dementia are:

Alzheimer's disease:

The most common form of dementia caused by the buildup of abnormal protein on the outside of the neurons. Alzheimer’s disease gradually destroys brain cells and their connections. This affects how the person copes with everyday tasks.

More information on Alzheimer's disease

Vascular dementia:

Is caused by problems with the blood supply to brain cells. It can involve tiny strokes which damage small areas of the brain.

More information on Vascular Dementia

Mixed cell dementia:

It is possible to have more than one type of dementia at the same time. Alzheimer’s disease and vascular dementia are the two most common types of Mixed Cell dementia.

More information on Mixed Cell Dementia

Lewy Body dementia:

Characterized by cellular inclusions called Lewy bodies found in the neurons. It isn’t as easy to identify as some other types of dementia, so it can be hard to diagnose. Lewy body can include hallucinations and symptoms that are similar to Parkinson’s disease.

More information on Lewy Body Dementia (LBD)

Frontotemporal dementia:

Affects the parts of the brain responsible for decision-making, control of behaviour and emotion and language are affected.

More information on Frontotemporal Dementia

Parkinson's disease (PD):

Part of a group of conditions known as motor systems. It devastates the nervous system, causing tremors and making it hard to move, walk and balance. It is the most common movement disorder and the second most common neurodegenerative disorder, the most common being Alzheimer's disease.

More information on Parkinson's Disease

Huntington’s disease (HD):

Caused by an inherited defect in a single gene which is referred to as the HD gene. The defect causes the HD protein to proliferation abnormally quickly, producing a protein ball called “huntingtin". The formation of protein balls leads to cell death.

More information on Huntington's Disease

Creutzfeldt-Jakob disease (CJD)

Is a rare, degenerative fatal brain disorder causing rapid progressive dementia. This condition might be due to an abnormal form of a protein. CJD belongs to a family of human and animal diseases known as the transmissible spongiform encephalopathies (TSEs). In cows it is referred to as BSE or "mad cow" disease.

More information on Creutzfeldt-Jakob Disease

Other conditions that can cause dementia or dementia-like symptoms include: Reactions to medications, metabolic problems and endocrine abnormalities, nutritional deficiencies, infections, poisoning, brain tumors, anoxia or hypoxia (conditions in which the brain’s oxygen supply is either reduced or cut off entirely), heart and lung problems, and depression.

Dementia has physical, psychological, social and economic impact on caregivers, families and social abilities these are some of the most common.


Symptoms of dementia affect each person in a different way, depending upon the impact of the disease, the person’s personality prior to the disease and the areas of the brain most damaged.

• Memory loss beyond what might be expected for normal aging is one of the most common symptoms of dementia. A person with dementia may forget the names of family members or repeat the same question numerous times without even realizing it.

• A person with dementia may lose track of the time and day or be confused.

• The ability to think and work things out can be affected. Decisions may seem strange to another person.

• Handling money may become difficult as well as solving problems.

• Dementia can also change the person’s personality and behaviour. A person who was active and energetic may become listless. A person who was pleasant and polite may become rude and aggressive.

• Over several years, most functions of the brain will gradually be affected. Eventually, a person with dementia will probably need help with simple activities like dressing, eating or going to the toilet.


It is very important not to jump to conclusions. While memory loss is a common symptom of dementia, memory loss or confusion by itself does not mean that a person has dementia, nor is dementia a normal part of growing older. It is important to have a full medical assessment to help rule out other possible causes of the symptoms. Many other conditions, such as infections, depression or the side effects of medicines can cause similar problems. If the Doctor cannot find an explanation for the symptoms, the person will be referred to a specialist for further testing.

Doctors diagnose dementia only if two or more brain functions such as memory and language skills are significantly impaired without loss of consciousness.

Being diagnosed with dementia early, means there is more time to come to terms with the illness. This will make it easier to plan for the future and find help and support. In some cases there are treatments that may help with some of the symptoms of dementia.


There is no treatment currently available to cure dementia or to alter its progressive course. Drugs to specifically treat Alzheimer’s disease and some other progressive dementias are now available. Although these drugs do no reverse existing brain damage, they can improve symptoms and slow the progression of the disease. This may improve the person with dementia's quality of life, ease the burden on caregivers, or delay admission to a nursing home.

Dementia is overwhelming not only for the person who has it, but also for the caregivers and families. There is often a lack of awareness and understanding of dementia, resulting in misconceptions. The impact of dementia on caregivers, family and societies can be physical, psychological, social and economic. Research the disease as much as possible. Some communities offer support to help improve the lives of a person with dementia and the caregivers and families.


Dementia care at Mayo Clinic
World Health Organization

Prepared by:Jody McCoppen October 2016