Conditions

Alzheimer's Disease


About Alzheimer's Disease

Alzheimer's disease is a progressive disorder that causes brain cells to waste away (degenerate) and die. Alzheimer's disease is the most common cause of dementia — a continuous decline in thinking, behavioural and social skills that disrupts a person's ability to function independently.

The early signs of the disease may be forgetting recent events or conversations, but as the disease progresses, the person will develop severe memory impairment and lose the ability to carry out everyday tasks.

Current Medications may temporarily improve symptoms or slow the rate of decline. These treatments can sometimes help the person maximize function and maintain independence for a little bit more time.

There is no treatment that cures or alters the disease process in the brain. In advanced stages of the disease, complications from severe loss of brain function, such as dehydration, malnutrition or infection, result in death.

Symptoms

Memory loss is the key symptom of Alzheimer's disease.

Brain changes associated with Alzheimer's disease lead to growing trouble with:
  • Memory -
    • Repeat statements and questions over and over
    • Forget conversations, appointments or events, and not remember them later
    • Routinely misplace possessions, often putting them in illogical locations
    • Get lost in familiar places
    • Eventually forget the names of family members and everyday objects
    • Have trouble finding the right words to identify objects, express thoughts or take part in conversations
  • Thinking and Reasoning
  • Making Judgements and Decisions
  • Planning and Performing Familiar Tasks
  • Changes in Personality and Behaviour -
    • Depression
    • Apathy
    • Social withdrawal
    • Mood swings
    • Distrust in others
    • Irritability and aggressiveness
    • Changes in sleeping habits
    • Wandering
    • Loss of inhibitions
    • Delusions, such as believing something has been stolen
  • Preserved skills - Preserved skills may include reading or listening to books, telling stories, singing, listening to music, dancing, drawing, or doing crafts. These skills may be preserved longer because they are controlled by parts of the brain affected later in the course of the disease.

Causes

Scientists believe that for most people, the disease is caused by a combination of genetic, lifestyle and environmental factors that affect the brain over time. Less than 1 percent of the time, the disease is caused by specific genetic changes that virtually guarantee a person will develop the disease. These rare occurrences usually result in disease onset in middle age.

The exact causes are not fully understood, but at its core are problems with brain proteins that fail to function normally, thus disrupting the work of brain cells (neurons) and unleashes a series of toxic events. Neurons are damaged which then causes them lose connection to each other and eventually die.

The damage most often starts in the region of the brain that controls memory, but the process begins years before the first symptoms. The loss of neurons spreads in a somewhat predictable pattern to other regions of the brain. By the late stage of the disease, the brain has already shrunken significantly.

Researchers are focused on the role of two proteins:

Plaques: Beta-amyloid is a leftover fragment of a larger protein. When these fragments cluster together, they appear to have a toxic effect on neurons and disrupt cell-to-cell communication. These clusters form larger deposits called amyloid plaques, which also include other cellular debris.

Tangles: Tau proteins play a part in a neuron's internal support and transport system to carry nutrients and other essential materials. In Alzheimer's disease, tau proteins change shape and organize themselves into structures called neurofibrillary tangles. The tangles disrupt the transport system and are toxic to cells.

Risk Factors

Age - Increasing age is the greatest known risk factor for Alzheimer's disease even though it is not part of normal aging, but as you grow older the likelihood of developing Alzheimer's disease increases.

Family History and Genetics - Your risk of developing Alzheimer's is somewhat higher if a first-degree relative, your parent or sibling, has the disease. Most genetic mechanisms of Alzheimer's among families remain largely unexplained, and the genetic factors are likely complex.

Down syndrome - Many people with Down syndrome develop Alzheimer's disease. This is likely related to having three copies of chromosome 21, and subsequently three copies of the gene for the protein that leads to the creation of beta-amyloid. Signs and symptoms of Alzheimer's tend to appear 10 to 20 years earlier in people with Down syndrome than they do for the general population.

Sex - There appears to be little difference in risk between men and women, but overall, there are more women with the disease because they generally live longer than men.

Mild Cognitive Impairment - Mild cognitive impairment (MCI) is a decline in memory or other thinking skills that is greater than what would be expected for a person's age, but the decline doesn't prevent a person from functioning in social or work environments.

Past Head Trauma - People who've had a severe head trauma have a greater risk of Alzheimer's disease.

Poor Sleep Patterns - Research has shown that poor sleep patterns, such as difficulty falling asleep or staying asleep, are associated with an increased risk of Alzheimer's disease.

Lifestyle and Heart Health - Research has shown that the same risk factors associated with heart disease may also increase the risk of Alzheimer's disease. These include:
  • Lack of exercise
  • Obesity
  • Smoking or exposure to secondhand smoke
  • High blood pressure
  • High cholesterol
  • Poorly controlled type 2 diabetes