Alzheimer's disease is irreversible and destroys brain cells, causing thinking ability and memory to deteriorate. Alzheimer's disease is not a normal part of aging.
What is Alzheimer’s disease?
Dr. Alois Alzheimer first identified the disease in 1906. He described the two hallmarks of the disease: "plaques," which are numerous tiny, dense deposits scattered throughout the brain that become toxic to brain cells at excessive levels, and "tangles," which interfere with vital processes, eventually choking off the living cells. When brain cells degenerate and die, the brain markedly shrinks in some regions.
“Plaques” are deposits of a protein called “beta amyloid,” or A-beta. When A-beta molecules clump together in the brain, they form plaques which prevent signals from being transferred between nerve cells in the brain, ultimately causing the cells to die.
“Tangles” are fiber clumps of a protein called Tau. Tau proteins can be seen as parallel railroad tracks within the brain. Nutrients and other important material are transported along those tracks, keeping brain cells alive.
In healthy brain areas, tau proteins make sure that nutrients can reach their destination.
In unhealthy brain areas, the tau protein collapses and twists, forming tangles which prevent nutrients from reaching brain cells, resulting in cell death.
The image below shows that a person with Alzheimer's disease has less brain tissue (right) than a person who does not have the disease (left). This shrinkage will continue over time, affecting how the brain functions.
MRI images courtesy of Sunnybrook and Women's College Health Sciences Centre
What is the difference between Alzheimer’s disease and dementia?
If you have been confused by these terms in the past, or mistakenly thought that they were the same thing, watch the video:
The material was created by Dr. Sabina Brennan of Trinity College Dublin and Trinity Brain Health with financial support from GENIO.
© 2018 Trinity Brain Health. Permission to use this material was granted by Trinity Brain Health (trinitybrainhealth.com) which reserves all rights in the material.
The effects of Alzheimer’s disease
Alzheimer’s disease is a fatal disease that eventually affects all aspects of a person’s life: how they think, feel, and act. Each person is affected differently. It is difficult to predict symptoms, the order in which they will appear, or the speed of their progression.
The following are some of the changes you may expect as the disease progresses.
Cognitive and functional abilities: a person’s ability to understand, think, remember and communicate will be affected. This could impact a person’s ability to make decisions, perform simple tasks, or follow a conversation. Sometimes people lose their way, or experience confusion and memory loss, initially for recent events and eventually for long-term events.
Emotions and moods: a person may appear apathetic and lose interest in favourite hobbies. Some people become less expressive and withdrawn.
Behaviour: a person may have reactions that seem out of character. Some common reactions include repeating the same action or words, hiding possessions, physical outbursts and restlessness.
Physical abilities: the disease can affect a person’s coordination and mobility, to the point of affecting their ability to perform day-to-day tasks such as eating, bathing and getting dressed.
TreatmentThere are several medications that can help with symptoms such as memory decline, changes in language, thinking abilities and motor skills. Although there is still no cure for Alzheimer's disease, those who respond to these treatments can experience improvements in their quality of life for several years.
- Risk factors - how can we reduce the risk?
- 10 warning signs - know the signs and symptoms
- What is Alzheimer's disease? (print-friendly version) - brochure by the Alzheimer Society of Canada
- Stages of Alzheimer's disease - learn about the progression of the disease
- Shared experiences - advice from people living with Alzheimer's disease