Definition of Dementia

"Frank Talk About Dementias..."

...It's not easy to pin down a definition of dementia.  Dementia is not a specific disease. It is a descriptive term for a collection of symptoms that can be caused by a number of disorders that affect the brain.  Azheimer's is a type of dementia.

People with dementia have significantly impaired intellectual functioning that interferes with normal activities and relationships.

They also lose their ability to solve problems and maintain emotional control, and they may experience personality changes and behavioral problems such as agitation, delusions, and hallucinations.

While memory loss is a common symptom of dementia, memory loss by itself does not mean that a person has dementia.

Doctors diagnose dementia only if two or more brain functions - such as memory, language skills, perception, or cognitive skills including reasoning and judgment - are significantly impaired without loss of consciousness.

Definition of Dementia

There are many disorders that can cause dementia. Some, such as AD, lead to a progressive loss of mental functions. But other types of dementia can be halted or reversed with appropriate treatment.

With AD and many other types of dementia, disease processes cause many nerve cells to stop functioning, lose connections with other neurons, and die. In contrast, normal aging does not result in the loss of large numbers of neurons in the brain.

Types of Dementia

Dementing disorders can be classified many different ways. These classification schemes attempt to group disorders that have particular features in common, such as whether they are progressive or what parts of the brain are affected. Some frequently used classifications include the following:

--  Cortical dementia - dementia where the brain damage primarily affects the brain's cortex, or outer layer. Cortical dementias tend to cause problems with memory, language, thinking, and social behavior.

--  Subcortical dementia - dementia that affects parts of the brain below the cortex. Subcortical dementia tends to cause changes in emotions and movement in addition to problems with memory.

--  Progressive dementia - dementia that gets worse over time, gradually interfering with more and more cognitive abilities.

--  Primary dementia - dementia such as AD that does not result from any other disease.

--  Secondary dementia - dementia that occurs as a result of a physical disease or injury.

There is even something called vascular dementia.

Some types of dementia fit into more than one of these classifications. For example, AD is considered both a progressive and a cortical dementia.

Alzheimer's disease is the most common cause of dementia in people aged 65 and older. Experts believe that up to 4 million people in the United States are currently living with the disease: one in ten people over the age of 65 and nearly half of those over 85 have Alzheimer's disease . At least 360,000 Americans are diagnosed with Alzheimer's disease  each year and about 50,000 are reported to die from it.

In most people, symptoms of Alzheimer's disease  appear after age 60. However, there are some early-onset forms of the disease, usually linked to a specific gene defect, which may appear as early as age 30. Alzheimer's disease  usually causes a gradual decline in cognitive abilities, usually during a span of 7 to 10 years. Nearly all brain functions, including memory, movement, language, judgment, behavior, and abstract thinking, are eventually affected.

Abnormalities in the Brain

Alzheimer's disease  is characterized by two abnormalities in the brain: amyloid plaques and neurofibrillary tangles. Amyloid plaques, which are found in the tissue between the nerve cells, are unusual clumps of a protein called beta amyloid along with degenerating bits of neurons and other cells.

Neurofibrillary tangles are bundles of twisted filaments found within neurons. These tangles are largely made up of a protein called tau. In healthy neurons, the tau protein helps the functioning of microtubules, which are part of the cell's structural support and deliver substances throughout the nerve cell.

However, in Alzheimer's disease , tau is changed in a way that causes it to twist into pairs of helical filaments that collect into tangles. When this happens, the microtubules cannot function correctly and they disintegrate. This collapse of the neuron's transport system may impair communication between nerve cells and cause them to die.

Researchers do not know if amyloid plaques and neurofibrillary tangles are harmful or if they are merely side effects of the disease process that damages neurons and leads to the symptoms of Alzheimer's disease . They do know that plaques and tangles usually increase in the brain as Alzheimer's disease  progresses.

In the early stages of Alzheimer's disease , patients may experience memory impairment, lapses of judgment, and subtle changes in personality. As the disorder progresses, memory and language problems worsen and patients begin to have difficulty performing activities of daily living, such as balancing a checkbook or remembering to take medications.

Visuospatial Problems

They also may have visuospatial problems, such as difficulty navigating an unfamiliar route. They may become disoriented about places and times, may suffer delusions (such as the idea that someone is stealing from them or that their spouse is being unfaithful), and may become short-tempered and hostile.

During the late stages of the disease, patients begin to lose the ability to control motor functions. They may have difficulty swallowing and lose bowel and bladder control. They eventually lose the ability to recognize family members and to speak. As Alzheimer's disease  progresses, it begins to affect the person's emotions and behavior. Most people with Alzheimer's disease  eventually develop symptoms such as aggression, agitation, depression, sleeplessness, or delusions.

On average, patients with Alzheimer's disease  live for 8 to 10 years after they are diagnosed. However, some people live as long as 20 years. Patients with Alzheimer's disease  often die of aspiration pneumonia because they lose the ability to swallow late in the course of the disease.

Definition of Dementia