Feb 8, 2018

Unraveling the Mystery of Alzheimer's Disease

This fascinating video explains how Alzheimer's affects the brain, and the three abnormalities that are most common in the brains of those with Alzheimer's who have been autopsied after death.

This fascinating video explains how Alzheimer's affects the brain, and the three abnormalities that are most common in the brains of those with Alzheimer's who have been autopsied after death.
by Alzheimer's Reading Room

Amyloid plaques, neurofibrillary tangles, synaptic loss, and cell death are the most striking features of the Alzheimer’s brain when it is viewed under the microscope after death.

At first, the Alzheimer's disease typically destroys neurons and their connections in parts of the brain involved in memory, including the entorhinal cortex and the hippocampus.

Later on, Alzheimer's affects areas in the cerebral cortex responsible for language, reasoning, and social behavior.

Eventually, other areas of the brain are damaged, and a person with Alzheimer's can become helpless and unresponsive to the outside world.

Subscribe to the Alzheimer's Reading Room

What Are the Main Characteristics of the Brain with Alzheimer’s Disease?

Many changes take place in the brain of a person with Alzheimer’s disease. Some of these changes can be observed in brain tissue under the microscope after death.

The three abnormalities most evident in the brains of people who have died with the disorder are:
  • Amyloid plaques. Found in the spaces between neurons, plaques consist predominantly of abnormal deposits of a protein fragment called beta-amyloid. Beta-amyloid is formed from the breakdown of a larger protein called amyloid precursor protein (APP). Beta-amyloid comes in several different molecular forms. One of these, beta-amyloid 42, has a strong tendency to clump together. When produced in excess, beta-amyloid 42 accumulates into plaques. Scientists used to think that amyloid plaques were the primary cause of the damage to neurons seen in Alzheimer’s. Now, however, many think that unclumped forms of beta-amyloid, seen earlier in the plaque formation process, may be the major culprits. Scientists have not yet determined if plaques are a cause or a byproduct of Alzheimer’s disease.

  • Neurofibrillary tangles. Found inside neurons, neurofibrillary tangles are abnormal clumps of a protein called tau. Healthy neurons are internally supported in part by structures called microtubules, which help guide nutrients and molecules from the cell body to the axon and dendrites. Researchers believe that tau normally binds to and stabilizes microtubules. In Alzheimer’s disease, however, tau undergoes abnormal chemical changes that cause it to detach from microtubules and stick to other tau molecules, forming threads that eventually clump together to form tangles. The tangles disrupt the microtubule network and create blocks in the neuron’s transport system. Abnormal tau may also cause blocks in synaptic signaling. As with beta-amyloid, some scientists think that other, smaller forms of abnormal tau may cause the most damage to neurons.

  • Loss of neuronal connections and cell death. In Alzheimer’s disease, the synaptic connections between certain groups of neurons stop functioning and begin to degenerate. This degeneration may be due to the abnormal deposits of beta-amyloid and tau. When neurons lose their connections, they cannot function properly and eventually die. As neuronal injury and death spread through the brain, connections between networks of neurons break down, and affected regions begin to shrink in a process called brain atrophy. By the final stage of Alzheimer’s, damage is widespread, and brain tissue has shrunk significantly.

Source: National Institutes of Health

Related Content

6 Ways to Reduce Alzheimer's Risk and Keep Your Brain Healthy As You Age

How Alzheimer's Destroys the Brain -- Video

Dementia Patients are People Too

Why People with Dementia Switch Back to the Past

How I Stopped My Mother from Being Mean to Me

Bill Gates Reveals His Father is Living with Alzheimer's Disease

Repetitive Questions and Learning How to Communicate Effectively with a Person Living with Dementia

Why Do People Living with Alzheimer's Want to Go Home?

Original content the Alzheimer's Reading Room

We help Alzheimer’s patients to live a better life. We accomplish this by providing excellent advice and practical solutions to the problems that caregivers face each day. Our solutions work and have been tested over time by millions of caregivers.

The Alzheimer's Reading Room is the number one source of high quality expert information for Alzheimer's care, dementia care, memory care, and for caregivers and dementia professionals. The goal of the Alzheimer's Reading Room is to Educate and Empower Alzheimer's caregivers, their families, and the entire Alzheimer's and dementia community worldwide.

The Alzheimer's Reading Room operates for the benefit of society. The Alzheimer’s Reading Room Knowledge Base is considered to be the highest quality, deepest collection, of information on Alzheimer’s and dementia in the world. The Knowledge Base is easy to use and easy to search. It is ideal for caregivers, educators, and dementia care professionals.

Need Help? Search Our Award Winning Knowledge Base for Answers to Your Questions About Alzheimer's and Dementia

What They Say About the Alzheimer’s Reading Room

"The Alzheimer’s Reading Room is what it claims to be – and more. This comprehensive site is run by full-time caregiver and gifted advocate Bob DeMarco. Filled with wonderful contributions from a variety of talented writers, this site offers everything you need to know about the challenge of caregiving, learning about your loved one’s condition, and taking care of yourself as well. Thanks to the tireless efforts of everyone at the Alzheimer’s Reading Room, you have a go-to place for advice, education, and an occasional laugh. Stop by, and start feeling empowered to handle life as a caregiver." - Healthline
"The Alzheimer's Reading Room and Bob DeMarco are true treasures to Alzheimer's patients and their loved ones, especially their caregivers". - Rudy Tanzi, Harvard, Time Magazine's 100 most influential people in the world
"All of us in the Alzheimer’s community are fortunate that Bob has taken on this important work. At Cure Alzheimer’s Fund, we encourage people to follow the Alzheimer's Reading Room; and, we rely on it ourselves to stay up to date and in touch." - Tim Armour, President of Cure Alzheimer’s Fund
"Without a doubt, you were the most sensational, inspirational speaker ever! "Caregivers can relate to your message because it truly comes from your heart and your personal experience; and caregivers need to know that others have done it and survived." - Janet Steiner, Director, Brevard Alzheimer's Foundation
Bob you are really remarkable. The articles in the Alzheimer's Reading Room are allowing me and my husband to live our lives again. - Susan Lay