Definition: Dementia is a loss of brain function that occurs with certain diseases. Alzheimer disease (AD) is the most common form of dementia. It affects memory, thinking, and behaviour.
The exact cause of Alzheimer disease is not known. Research shows that certain changes in the brain lead to Alzheimer disease.
You are more likely to develop Alzheimer disease if you:
- Are older — Developing Alzheimer disease is not a part of normal aging.
- Have a close relative, such as a brother, sister, or parent with Alzheimer disease.
- Have certain genes linked to Alzheimer disease.
The following may also increase the risk:
- Being female
- Having heart and blood vessel problems due to high cholesterol
- History of head trauma
There are two types of Alzheimer disease:
- Early onset Alzheimer disease — Symptoms appear before age 60. This type is much less common than late onset. It tends to get worse quickly. Early onset disease can run in families. Several genes have been identified.
- Late onset Alzheimer disease — This is the most common type. It occurs in people age 60 and older. It may run in some families, but the role of genes is less clear.
Alzheimer disease symptoms include difficulty with many areas of mental function, including:
- Emotional behaviour or personality
- Thinking and judgment (cognitive skills)
Alzheimer disease usually first appears as forgetfulness.
Mild cognitive impairment (MCI) is the stage between normal forgetfulness due to aging, and the development of Alzheimer disease. People with MCI have mild problems with thinking and memory that do not interfere with daily activities. They are often aware of the forgetfulness. Not everyone with MCI develops Alzheimer disease.
Symptoms of MCI include:
- Difficulty performing more than one task at a time
- Difficulty solving problems
- Forgetting recent events or conversations
- Taking longer to perform more difficult activities
Early symptoms of Alzheimer disease can include:
- Difficulty performing tasks that take some thought, but used to come easily, such as balancing a checkbook, playing complex games (bridge), and learning new information or routines
- Getting lost on familiar routes
- Language problems, such as trouble remembering the names of familiar objects
- Losing interest in things previously enjoyed and being in a flat mood
- Misplacing items
- Personality changes and loss of social skills
As Alzheimer disease becomes worse, symptoms are more obvious and interfere with the ability to take care of oneself. Symptoms may include:
- Change in sleep patterns, often waking up at night
- Delusions, depression, and agitation
- Difficulty doing basic tasks, such as preparing meals, choosing proper clothing, and driving
- Difficulty reading or writing
- Forgetting details about current events
- Forgetting events in one’s life history and losing self-awareness
- Hallucinations, arguments, striking out, and violent behavior
- Poor judgment and loss of ability to recognize danger
- Using the wrong word, mispronouncing words, or speaking in confusing sentences
- Withdrawing from social contact
People with severe Alzheimer disease can no longer:
- Recognize family members
- Perform basic activities of daily living, such as eating, dressing, and bathing
- Understand language
Other symptoms that may occur with Alzheimer disease:
- Problems controlling bowel movements or urine
- Swallowing problems
A skilled health care provider can often diagnose Alzheimer disease with the following steps:
- Performing a complete physical exam, including a nervous system exam
- Asking about the person’s medical history and symptoms
- Mental function tests (mental status examination)
A diagnosis of Alzheimer disease is made when certain symptoms are present, and by making sure other causes of dementia are not present.
Tests may be done to rule out other possible causes of dementia, including:
- Brain tumour
- Long-term (chronic) infection
- Intoxication from medicines
- Severe depression
- Increased fluid on the brain (normal pressure hydrocephalus)
- Thyroid disease
- Vitamin deficiency
The only way to know for certain that someone has Alzheimer disease is to examine a sample of their brain tissue after death.
There is no cure for Alzheimer disease. The goals of treatment are:
- Slow the progression of the disease (although this is difficult to do)
- Manage symptoms, such as behavior problems, confusion, and sleep problems
- Change the home environment to make daily activities easier
- Support family members and other caregivers
Medicines are used to:
- Slow the rate at which symptoms worsen, though the benefit from using these drugs may be small
- Control problems with behaviour, such as loss of judgment or confusion
Before using these medicines, ask the provider:
- What are the side effects? Is the medicine worth the risk?
- When is the best time, if any, to use these medicines?
- Do medicines for other health problems need to be changed or stopped?
Someone with Alzheimer disease will need support in the home as the disease gets worse. Family members or other caregivers can help by helping the person cope with memory loss and behaviour and sleep problems. It is important to make sure the home of a person who has Alzheimer disease is safe for them.
Having Alzheimer disease or caring for a person with the condition may be a challenge. You can ease the stress of illness by seeking support through Alzheimer disease resources. Sharing with others who have common experiences and problems can help you not feel alone.
How quickly Alzheimer disease gets worse is different for each person. If Alzheimer disease develops quickly, it is more likely to worsen quickly.
People with Alzheimer disease often die earlier than normal, although a person may live anywhere from 3 to 20 years after diagnosis.
Families will likely need to plan for their loved one’s future care.
The final phase of the disease may last from a few months to several years. During that time, the person becomes totally disabled. Death usually occurs from an infection or organ failure.
Call the provider if:
- Alzheimer disease symptoms develop or a person has a sudden change in mental status
- The condition of a person with Alzheimer disease gets worse
- You are unable to care for a person with Alzheimer disease at home
Although there is no proven way to prevent Alzheimer disease, there are some measures that may help prevent or slow the onset of Alzheimer disease:
- Stay on a low-fat diet and eat foods high in omega-3 fatty acids.
- Get plenty of exercise.
- Stay mentally and socially active.
- Wear a helmet during risky activities to prevent brain injury.
Knopman DS. Cognitive impairment and dementia. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 374.
Peterson R, Graff-Radford J. Alzheimer disease and other dementias. In: Daroff RB, Jankovic J, Mazziotta JC, Pomeroy SL, eds. Bradley’s Neurology in Clinical Practice. 7th ed. Philadelphia, PA: Elsevier; 2016:chap 95.