An Overview of Different Types of Dementia

Alzheimer's Disease
Alzheimer's Disease, which constitutes 50% - 60% of all forms of dementia, is a brain disorder that was named after German physician Alois Alzheimer who first illustrated it in 1906. It is a fatal brain disorder that is progressive and currently affects about 5.3 million people across America. Alzheimer's is an irreversible disease that destroys brain cells, causing symptoms such as memory loss, impairment of thinking skills and judgment, difficulty with language, loss of intellectual abilities, and behavioral problems that can interfere with day-to-day living. It can also affect one's work and social life. Alzheimer's is a progressive disease meaning that it gets worse over time. Although the cause of this disease is not yet completely known, scientists do believe that it develops because of a multifaceted sequence of events that occur in the brain over a long period of time. There is the likelihood that genetics and the environment play a role in its cause. It has been shown that a healthy diet, exercise, and stimulating the brain in a positive way can help one in reducing the risk of cognitive decline. Alzheimer's is a fatal disease and is now the seventh leading cause of death in the United States.

Vascular Dementia
Vascular Dementia, the second most common form of dementia, is also known as Multi-Infarct Dementia. In Vascular Dementia there is an impairment of blood flow to the brain, which leads to damage in the tissues of the brain. The origin is usually a narrowing of the blood vessels, and sometimes a blockage, that causes a stroke. Disorders such as diabetes and hypertension can also lead to a narrowing of the vessels in the brain. The brain is then deprived of oxygen and other nutrients that it needs in order to operate. Some of the symptoms of Vascular Dementia include short-term memory loss, wandering away or getting lost in places that are familiar, losing control of the bladder or bowel, problems with following directions, walking quickly, and emotional outbursts such as laughing out loud or crying when it is inappropriate. Because this type of dementia is caused by "mini-strokes" there is no treatment to reverse the damage. Treatment generally focuses on preventing future strokes from occurring.

Dementia with Lewy Bodies
Other names for this type of dementia include Lewy Body Dementia, Diffuse Lewy Body Disease, Senile Dementia of Lewy Type, and Cortical Lewy Body Disease. About 10% - 20% of all dementia cases are of the Lewy Body type. A prominent neurologist from Berlin, named Frederick Lewy, first discovered it in 1914. In the 1960's, scientists found Lewy Bodies in the outer layer of gray matter in the cortex region of the brain. Lewy Bodies are abnormal masses of protein that build up inside of nerve cells. These bodies that are found in the cortex are known as Cortical Lewy Bodies, hence the name Cortical Lewy Body Disease. The most important attribute is a decline in cognition with three defining features:

1. Variation In Attention and Alertness: this includes confusion in speech patterns, long periods of time spent staring into outer space, drowsiness, and lethargy.

2. Recurrent Visual Hallucinations: these types of strong psychotic symptoms usually happen in the earlier stages of the disease.

3. Parkinsonian Motor Symptoms: this includes muscular rigidity, tremors, and impaired motor control.

Those who suffer from Dementia with Lewy Bodies also experience syncope (fainting), temporary loss of consciousness, sleep disorders with rapid eye movement, delusions, non-visual hallucinations, depression, and hypersensitivity (excessively sensitive or allergic) to neuroleptic or anti-psychotic medications. This type of dementia is incurable and worsens over time. The goal of treatment is to control cognitive and motor symptoms of the disease.

Parkinson's Disease
Parkinson's Disease, also known as Paralysis Agitans or Shaking Palsy, was first described by an English physician named James Parkinson in 1817. It affects the neurons (nerve cells) in the part of the brain that controls the muscular system. With Parkinson's Disease it is believed that there is a deterioration of the brain cells that produce a neurotransmitter called dopamine. This neurotransmitter sends signals to your brain that aid in the coordination of muscle movement. It is not known what causes damage to these cells. The most prominent feature of this disease is a trembling of the fingers and hands, arms, legs, jaws, and face. Tremors usually occur while a person is awake and sitting or standing still. This is known as a resting tremor. Resting tremors diminish when the affected body part is moved. Other symptoms include muscle rigidity (stiffness), aching muscles, slow movement (especially when in a resting position), difficulty with walking and equilibrium (balance), weakness in the muscles of the face and throat (making it difficult to chew, swallow and speak), and poor coordination. There is no known cure for Parkinson's Disease but there are several medications that are now available to help alleviate or reduce the symptoms of this disorder.

Normal Pressure Hydrocephalus
Normal Pressure Hydrocephalus is a chronic condition in which there is a buildup of cerebrospinal fluid (CSF), causing an increase in intracranial pressure. The cause of this disease is unknown but it can occur in cases where there is bleeding around the brain (following a head injury), after someone has suffered a stroke, in cases of brain tumors, if someone develops meningitis (an infection in the protective layer of tissue around the brain), or after brain surgery. The symptoms of this disease are usually unremarkable at first and worsen gradually. Symptoms of Normal Pressure Hydrocephalus include problems with cognition, memory, and reasoning, lack of interest and lethargy, difficulty with speech and language, trouble with walking and equilibrium (balance), urinary incontinence, and occasionally, bowel incontinence. Unlike most forms of dementia, Normal Pressure Hydrocephalus can be treated and reversed if it is diagnosed properly and in a timely manner.

Sources

Taylor, Richard. Alzheimer's from the Inside Out. Baltimore, Maryland: Health Professions P; 1st Edition, 2006.

Meyer, John, Gaiane Rauch, and Helmut Lechner. Vascular Dementia. Hoboken, NJ: Wiley-Blackwell; 1st Edition, 2001.

O'Brien, John, David Ames, and Ian McKeith. Dementia with Lewy Bodies: And Parkinson's Disease Dementia. London, England, United Kingdom: Informa Healthcare; 1st Edition, 2005.

Larner, Andrew J. A Dictionary of Neurological Signs. New York, NY: Springer; 2nd Edition, 2005.