Related Dementias

Vascular Dementia

Vascular Dementia occurs when the cells in the brain are deprived of oxygen.  A network of blood vessels called the vascular system supplies the brain with oxygen.  If there is a blockage in the vascular system, or if it is diseased, blood is prevented from reaching the brain.  As a result, cells in the brain die, leading to the symptoms of dementia. 

A number of conditions can cause or increase damage to the vascular system.  These include high blood pressure, heart problems, high cholesterol and diabetes.

Vascular Dementia is the second most common form of dementia (after Alzheimer’s disease), accounting for up to 20% of all cases.

When Alzheimer’s disease and Vascular Dementia occur at the same time, the condition is called mixed dementia.

Frontotemporal Dementia

Unlike Alzheimer’s disease, which generally affects most areas of the brain, Frontotemporal Dementia is an umbrella term for a group of rare disorders that primarily affect the frontal and temporal lobes of the brain – the areas generally associated with personality and behaviour.  In some cases, brain cells in these areas shrink or die.  In other cases, the brain cells get larger, containing round, silver “Pick’s bodies”.  Pick’s Disease refers to a subtype of Frontotemporal Dementia that has these specific abnormalities.  In Frontotemporal Dementia, the changes in the brain affect the person’s ability to function.  Researchers estimate that approximately 2 to 5% of all dementia cases are Frontotemporal Dementia.

Other names often used for Frontotemporal Dementia, in addition to Pick’s Disease, include: Semantic Dementia, Frontal Lobe Dementia, Primary Progressive Aphasia, Corticobasal Degeneration and Pick’s Complex.

Lewy body Dementia

Lewy body Dementia is a form of dementia characterized by abnormal deposits of a protein called alpha-synuclein that form inside the brain’s nerve cells.  These deposits are called “Lewy bodies” after the scientist who first described them.  The process that leads to the formation of Lewy bodies in unknown.  Areas of the brain involved in thinking and movement are most affected in Lewy body Dementia.

Lewy body Dementia can occur by itself, or together with Alzheimer’s or Parkinson’s disease.  It accounts for 5 to 15% of all dementias.

Other names for Lewy body Dementia include: Diffuse Lewy body Disease, Cortical Lewy body Disease, Lewy body Disease, Senile Dementia of Lewy Type, Dementia with Lewy bodies and Lewy body variant of Alzheimer’s disease.

Creutzfeldt-Jakob Disease

Creutzfeldt-Jakob Disease is a rare, rapidly developing and fatal form of dementia caused by infectious proteins called prions.  Prions are proteins that occur naturally in the brain and are normally harmless.  When they are misshapen, however, they can have devastating effects, attacking the brain, killing cells and creating gaps in tissue.

Prion diseases affect both human and animals.  Prion disease started to attract public attention during the mid 1980’s with the bovine spongiform encephalopathy epidemic, a prion disease of cattle.  The best known prion disease in humans is Creutzfeldt-Jakob Disease.  It affects about one to two persons in a million worldwide each year, with about 35 new cases being diagnosed in Canada every year.

For more information about Related Dementias, visit http://www.alzheimer.ca/english/disease/dementias-intro.htm.

 

Reference:  Alzheimer Society of Canada, 2009