Types of Dementia
The term ‘dementia’ is used to describe a set of symptoms that occur when the brain is damaged by specific diseases. These diseases include Alzheimer’s disease, vascular dementia, dementia with Lewy Bodies, Parkinson’s, Korsakoff’s syndrome and others.
Someone with dementia may also experience loss of memory, mood changes, and problems with language, reasoning and decision making.
There are many types of dementia, the most common is Alzheimer’s disease however most of the problems seen in Alzheimer’s disease are also prevalent in other dementias. What happens in the other dementias is that they are seen ‘out of order’ in comparison to what we see with Alzheimer’s disease. For example, many people with Alzheimer’s disease eventually have trouble walking, but this is a late sign. When someone with dementia is seen to have a problem with walking early in the course of their illness, that suggests another cause, such as vascular dementia, dementia with Lewy bodies, Parkinson’s disease dementia, or some types of frontotemporal dementia.
Alzheimer’s disease, the most common cause of dementia, was first identified in 1906 by a German neurologist named Alois Alzheimer. Occurring most often in the elderly population, the likelihood of developing Alzheimer’s disease doubles every five years after the age of 65.
Currently, there is no known, single cause of Alzheimer’s disease. However, research has found certain genes that are thought to play a role. Previous head injuries have also been linked to Alzheimer’s disease in some cases. As well, studies have shown that Alzheimer’s disease occurs more often in women than in men.
Alzheimer’s disease slowly and progressively destroys portions of the brain. In the early stages of this disease, it may be difficult to decide whether a person’s forgetfulness is a sign of Alzheimer’s disease or a sign of normal aging. As the disease progresses and simple activities become more and more difficult, it becomes apparent that Alzheimer’s disease is not part of the normal aging process. Alzheimer’s disease typically decreases a person’s life span. After diagnosis, a person is generally expected to live an average 8-11 years with the disease.
Vascular dementia is the second most common form of dementia after Alzheimer’s disease.
A complication resulting from stroke is loss of cognitive function, or intellectual abilities, called vascular dementia. It is estimated that nearly a fifth of people who suffer a stroke will develop problems involving their mental abilities.
A stroke occurs when a person has a sudden interruption of the blood supply to a part of the brain and the brain tissue being supplied by that blood dies. This may leave the person unable to move one or more limbs, unable to understand or formulate speech and/or unable to see one side of the visual field.
Dementia with Lewy Bodies
Dementia with Lewy Bodies is one of the more common forms of dementia and can affect as many as one in ten people with dementia.
Lewy Bodies appear in neurons which are breaking down. When these Lewy bodies are in deep regions of the brain that affect control of movement, they cause Parkinson’s disease. Dementia with Lewy bodies occurs when Lewy bodies are in other areas of the brain such as the thinking parts of the brain in the cortex. Lewy body dementia can occur together with Alzheimer’s disease and, therefore, shares many symptoms with Alzheimer’s disease.
Parkinson’s disease is a common disorder of deep brain structures that help control movement. Over time, many people with Parkinson’s disease develop Parkinson’s disease dementia. The majority of Parkinson’s disease service users over the age of 65 develop dementia within a few years.
In Parkinson’s disease, an abnormal protein accumulates inside neurons in deep brain structures. This abnormal accumulation was first described by a Professor Lewy and still bears the name of being a “Lewy body”. Lewy bodies are also seen outside the deep brain structures, in the “thinking” parts of the brain in Parkinson’s disease dementia and in Lewy body dementia.
Frontotemporal dementia is a type of dementia that tends to occur at a younger age than does Alzheimer’s disease. Typically the onset occurs between the ages of 40 and 70. Frontotemporal dementia has less to do with memory loss in the early stages and more to do with changes in personality and behaviour because of the part of the brain that it affects.
What is Korsakoff’s syndrome?
Korsakoff’s syndrome is a brain disorder usually associated with heavy alcohol consumption over a long period.