What Happens in the Brain in Alzheimer's Disease
One of the primary functions of neurons in the brain is to communicate with each other. One to two decades before symptoms of AD appear, communication begins to be disrupted. In a small region of the hippocampal formation, deep within the brain (called the entorhinal cortex), neurons begin to work less efficiently probably because abnormal proteins begin to accumulate, forming tangles. Neurons begin to lose their ability to communicate. The damage then spreads to adjacent regions of the hippocampal formation, where, in addition to neurofibrillary tangles, plaques are also formed. This brain region plays a major role in learning and is thought to be the brain's memory center, responsible for converting short-term memories into long-term memories. Long-term memories are then stored in other parts of the brain. Consider this conversion process as similar to clicking SAVE on a computer to store a paragraph in your computer's long-term memory. The brain absorbs information, holds it in short-term memory, and then converts short-term to long-term memory. This complex process depends on the ability of neurons to communicate with each other, and is disrupted by the onset and progression of Alzheimer's disease.
As tangles accumulate on the inside of neurons, and plaques accumulate on the outside of neurons, an increasing number of neurons become sick and die. Brain tissue in that area begins to shrink. Gradually, cell sickness and death spreads beyond the hippocampal formation. Over the course of years, this process overtakes much of the cerebral cortex—the gray matter, or outer shell of the brain—and it, too, degenerates. Nerve cells no longer communicate with each other and die. Fluid-filled spaces in the brain, called ventricles, enlarge as these other regions shrink, and the brain slowly loses its ability to create thoughts, experience emotion, or plan actions. Because the hippocampal formation is disrupted early, memory changes are among the first symptoms. As the disease progresses and other regions of the brain fall victim, more cognitive skills are affected and other symptoms appear. Eventually, people with AD are unable to carry out even simple tasks.
Excerpted from THE ALZHEIMER'S PROJECT: MOMENTUM IN SCIENCE, published by Public Affairs, www.publicaffairsbooks.com.
In This Section
Momentum in Science: The Supplementary Series
- Understanding and Attacking Alzheimer's 12 min
- How Far We Have Come in Alzheimer's Research 15 min
- Identifying Mild Cognitive Impairment 20 min
- The Role of Genetics in Alzheimer's 12 min
- Advances in Brain Imaging 11 min
- Looking Into the Future of Alzheimer's 6 min
- The Connection Between Insulin and Alzheimer's 21 min
- Inflammation, the Immune System, and Alzheimer's 29 min
- The Benefit of Diet and Exercise in Alzheimer's 16 min
- Cognitive Reserve: What the Religious Orders Study is Revealing about Alzheimer's 20 min
- Searching for an Alzheimer's Cure: The Story of Flurizan 30 min
- The Pulse of Drug Development 15 min
- The DeMoe Family: Early-Onset Alzheimer's Genetics 25 min
- The Nanney/Felts Family: Late-Onset Alzheimer's Genetics 20 min
- The Quest for Biomarkers 17 min
Video: Inside the Brain: Unraveling the Mystery of Alzheimer's Disease
This 4-minute captioned video shows the progression of Alzheimer's disease in the brain.
Inside the Brain: An Interactive Tour
The Brain Tour explains how the brain works and how Alzheimer's affects it.
Alzheimer's Disease: Unraveling the Mystery
This book explains what AD is, describes the main areas in which researchers are working, and highlights new approaches for helping families and friends care for people with AD.
- About The Scientists
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- Rapid advances in our knowledge about AD have led to the development of promising new drugs and treatment strategies. However, before these new strategies can be used in clinical practice, they must be shown to work in people. Advances in prevention and treatment are only possible thanks to volunteers who participate in clinical trials.
- Among those touched by Alzheimer's (excluding self), nearly one-third provide support as a friend or relative, another 3% provide support as a healthcare professional, and the remaining two-thirds provide no support to the person suffering from Alzheimer's. When support is provided, it most often entails emotional support, followed by care-giving support. While small in comparison, more than one person in ten is providing financial support. Read more.