Everybody has heard about Alzheimer’s disease. Some people think that dementia is Alzheimer’s disease, whereas others think that dementia and Alzheimer’s are two different things. In fact, there are several types of dementia, and Alzheimer’s Disease is the most common. Dementia is a general term used to describe a condition in which brain cells are gradually destroyed, leading to a progressive decline in mental function. Physicians rely mostly on their experience and on behavioral assessment to dissociate between the different types of dementia.
Alzheimer’s disease (AD)
AD is the most common type of dementia. Plaques (deposits of beta-
amyloid protein) and tangles (twisted fibers of tau protein) tend to
start forming in the temporal region of the brain (in the hippocampus),
triggering memory problems. In the later stages of the disease, symptoms include language, spatial, reasoning, comprehension and orientation problems.
Vascular dementia is the second most common dementia. One major stroke can cause vascular dementia. In another form of the disease, a series of small strokes block small blood vessels. In that case, individual damages are not noticeable but their combined effect over time becomes noticeable. Symptoms vary depending on which brain areas are damaged.
Dementia with Lewy Bodies
This type of dementia is characterized by the development of abnormal deposits of a protein (i.e., Lewy bodies) inside the brain cells. Patients show memory problems and other cognitive symptoms such as in Alzheimer’s disease. They also exhibit movement symptoms (stiffness, shakiness, etc.) such as in
Parkinson’s disease. Symptoms may also include visual hallucinations and Rapid Eye Movement (REM) sleep disorders (i.e., acting out dreams).
This is a relatively rare dementia that follows damage to the front (frontal) and sides (temporal) parts of the brain. Several abnormalities have been identified as the cause of this dementia (e.g., Pick’s disease). Symptoms include changes in personality, planning, social functioning, as well as a lack of judgment and inhibition and repetitive compulsive behaviors.
Wernicke-Korsakoof syndrome is a 2 steps brain disease caused by the lack of thiamine (vitamin B1) in the brain. Since thiamin helps produce the energy that brain cells need to function normally, insufficient levels of thiamin can cause damage to the neurons or event their death. The vitamin deficiency can be caused by chronic alcoholism and severe malnutrition. Wernicke encephalopathy is the first step of the syndrome and Korsakoff psychosis the second one. Symptoms include amnesia or severe memory loss, confabulations and unsteadiness. In the early stages, treatment with high-doses of thiamin may reverse some of the damage.
This is a very rare disease in which a specific type of protein (prion protein) becomes abnormal and damages brain cells. Death typically occurs within a year. The first symptom is a rapidly progressing dementia including memory loss, personality change and hallucinations. Problems with movements may also be present.
Parkinson disease impairs motor skills and speech. It is a movement disorder caused by the loss of dopaminergic cells. In the later stages, some patients develop dementia (difficulty with abstract thought, memory, etc.).