Your brain is nourished by one of your body's richest networks of blood vessels.
With each heartbeat, arteries carry about 20 to 25 percent of your blood to your brain, where billions of cells use about 20 percent of the oxygen and fuel your blood carries.
When you are thinking hard, your brain may use up to 50 percent of the fuel and oxygen.
The whole vessel network includes veins and capillaries in addition to arteries.
Alzheimer's changes the whole brain
Alzheimer’s disease leads to nerve cell death and tissue loss throughout the brain. Over time, the brain shrinks dramatically, affecting nearly all its functions.
The picture above is another view of how massive cell loss changes the whole brain in advanced Alzheimer's disease. This slide shows a crosswise "slice" through the middle of the brain between the ears.
In the Alzheimer brain:
* The cortex shrivels up, damaging areas involved in thinking, planning and remembering.
* Shrinkage is especially severe in the hippocampus, an area of the cortex that plays a key role in formation of new memories.
* Ventricles (fluid-filled spaces within the brain) grow larger.
Under the microscope:
* Alzheimer tissue has many fewer nerve cells and synapses than a healthy brain.
* Plaques, abnormal clusters of protein fragments, build up between nerve cells.
* Dead and dying nerve cells contain tangles, which are made up of twisted strands of another protein.
Scientists are not absolutely sure what causes cell death and tissue loss in the Alzheimer brain, but plaques and tangles are prime suspects.
In areas where tangles are forming:
* The tracks can no longer stay straight. They fall apart and disintegrate.
* Nutrients and other essential supplies can no longer move through the cells, which eventually die.
Progression of the disease.
Plaques and tangles (shown in the blue-shaded areas) tend to spread through the cortex in a predictable pattern as Alzheimer’s disease progresses.
The rate of progression varies greatly. People with Alzheimer’s live an average of eight years, but some people may survive up to 20 years. The course of the disease depends in part on age at diagnosis and whether a person has other health conditions.
[Clockwise from top left]
* Earliest Alzheimer's – changes may begin 20 years or more before diagnosis.
* Mild to moderate Alzheimer stages – generally last from 2 - 10 years.
* Severe Alzheimer’s – may last from 1 - 5 years.
Shown in the blue highlighted area above, studies prove that tangles and plague build-up begins to form here before a person is diagnosed with the disease.
Mild to Moderate Alzheimer's (above)
*blue areas represent areas of the brain over-taken by tangles and plaques*
Plaques and tangles also spread to areas involved in:
* Speaking and understanding speech
* Your sense of where your body is in relation to objects around you
As Alzheimer’s progresses, individuals may experience changes in personality and behavior and have trouble recognizing friends and family members.
Severe Alzheimer's Disease (above)
*blue areas represent areas of the brain over-taken by tangles and plaques*
*Note: the difference between this picture and the one above it
In advanced Alzheimer’s disease, most of the cortex is seriously damaged. The brain shrinks dramatically due to widespread cell death. Individuals lose their ability to communicate, to recognize family and loved ones and to care for themselves.
Take an interactive virtual tour of a brain with Alzheimer's disease: at....
http://www.alz.org/brain/08.asp
Heroes:
Alzhiemer's Association
