Brain Changes During Alzheimer's Disease

July 2, 2015
To learn more about Alzheimer's disease, we're turning our focus to the brain itself to better understand this condition. According to the Alzheimer’s Association, Alzheimer’s leads to nerve cell death and tissue loss throughout the brain. Over time, the brain shrinks dramatically, affecting nearly all functionality. Massive brain cell loss literally forms holes in the brain, whereas a healthy brain is connected and thick with cells. In the Alzheimer’s 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. The damage gets even more significant when doctors look at the brain under a microscope. Tissue has many fewer nerve cells and synapses than in 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’s brain, but plaques and tangles are prime suspects.

More about plaques and tangles

The most damaging form of betamyloid (the protein pieces that form plaques) may be groups of a few pieces rather than the plaques themselves. The small clumps may block cell-to-cell signaling at synapses. They may also activate immune system cells that trigger inflammation and devour disabled cells. Tangles destroy a vital cell transport system made of proteins. In areas of the brain where tangles are forming, nutrients and other essential supplies can no longer move through the cells, which eventually die. The rate of progression of plaques and tangles 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.

The brain during different phases

In mild and moderate stages of Alzheimer’s, brain regions important in memory and thinking and planning develop more plaques and tangles than were present in early stages. As a result, individuals develop problems with memory or thinking serious enough to interfere with work or social life. They may also get confused and trouble handling money, expressing themselves and organizing their thoughts. As the disease progresses, individuals may experience changes in personality and behavior and have trouble recognizing friends and family members. In severe cases of Alzheimer’s, 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.

Learn more about Alzheimer's and dementia. Or, contact your local BrightStar Care to learn more about how we can help.