There are more than 100 different types of dementia that have been discovered, however six forms of dementia account for the majority of cases. These are:
Rare forms of dementia account for only a small percentage of cases. Some of these rare dementias include:
Creutzfeldt-Jakob disease is a rare degenerative brain disorder in which an abnormally shaped protein called a prion causes rapid loss of memory and muscle control. The most common form of Creutzfeldt-Jakob disease is sporadic CJD, which usually affects people over 40.
Initial symptoms include:
Before a diagnosis of Creutzfeldt-Jakob disease is given, a range of other causes may be considered including Alzheimer's disease and vascular dementia as there is no known cure for Creutzfeldt-Jakob disease and it is usually fatal within six to twelve months of onset.
Huntington's disease is a neurological condition that is passed down in families, and is characterised by problems with movement and a lack of coordination.
Symptoms of Huntington’s disease include:
While Huntington’s disease is commonly thought of as a motor disorder, cognitive symptoms can occur and dementia can appear at any time through the disease’s progression.
Dementia symptoms include:
There is no cure for Huntington's disease, however treatment is available to help slow the symptoms and assist with function for as long as possible.
Very similar to Lewy body dementia, Parkinson's disease dementia is caused by microscopic deposits gathering in the nerve cells in the brain stem, which then transfer to other parts of the brain. Parkinson's disease dementia is diagnosed when someone has already been diagnosed with Parkinson’s disease and then develops dementia symptoms.
People with Parkinson's disease have a higher risk of developing dementia, although around two thirds of people remain unaffected. When dementia symptoms occur, it is typically not until late in the course of the illness.
Everyone with Parkinson’s disease experiences different symptoms, however some of the most common are:
Dementia related symptoms include:
The side-effects of certain drugs for Parkinson's disease may make symptoms of dementia worse, so adjusting a person's medication accordingly can sometimes be of benefit.
Posterior cortical atrophy, also known as Benson's syndrome, is a rare form of dementia which is usually considered to be caused by having Alzheimer’s disease.
The disease causes gradual but progressive degeneration of the outer layer of the brain, known as the cortex, in the part of the brain located in the back of the head (posterior). It causes people to lose the ability to interpret what they are looking at.
The first symptoms of posterior cortical atrophy tend to occur when people are in their mid-50s or early 60s. However, the first signs are often subtle and it may be some time before a formal diagnosis is made.
Symptoms of posterior cortical atrophy include:
As damage in the brain spreads and the disease progresses, people develop the more typical symptoms of Alzheimer's disease, such as memory loss and confusion.
With corticobasal degeneration, multiple areas of the brain including the cerebral cortex and basal ganglia shrink, causing the nerve cells to degenerate and eventually die. Corticobasal degeneration progresses gradually and affects movement on one or both sides of the body. Symptoms typically appear in people from 50 to 70 years of age.
Symptoms usually begin in one limb and include:
As corticobasal degeneration progresses, dementia symptoms may start to appear, including:
There is no cure or treatment available for corticobasal degeneration, but medication can alleviate some symptoms and allied health therapies such as physiotherapy or occupational therapy can also be beneficial for movement based symptoms.
Unlike most other dementias, Niemann-Pick disease type C is an inherited condition that mainly affects children. It should not be confused with Pick’s disease, which is another name for frontotemporal dementia. People with this rare disease are unable to process cholesterol and other fats. As a result they accumulate in cells, including brain cells, affecting movement.
The onset of the disease in the teenage years or early adulthood means that people are more likely to experience dementia as part of the disease.
Dementia symptoms include:
There no treatment for the disease, and life expectancy varies. However, researchers have identified the responsible gene and there is continuing research into this area.
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