Alzheimer’s disease

What is Alzheimer’s disease?

Alzheimer’s disease is a neurodegenerative disease that results in the progressive and irreversible loss of higher brain functions, including memory, thinking, reason, judgment, orientation, language, behavior and emotion. It is characterized by the formation of abnormal structures in the brain called neuritic plaques and neurofibrillary tangles. As these structures accumulate, nerve cell connections are reduced. During the course of Alzheimer’s disease, neurons in several areas of the brain become damaged and die, leading to decreased levels of neurotransmitters, signaling problems and subsequent loss of brain function.

How many people get Alzheimer’s disease?

Alzheimer’s disease is a major public health concern, affecting millions of patients and their families. It is the most common form of dementia, with approximately one in 10 people over the age of 65—and nearly half over the age of 85—affected. It is currently estimated that more than 4 million elderly individuals in the United States have Alzheimer’s disease—a number that is expected to increase as the population ages. If no cure or preventative treatment is discovered, approximately 14 million people in the United States will develop Alzheimer’s disease by the year 2050. Furthermore, it is estimated that 22 million individuals worldwide will develop the disease by the year 2025.

The risk of developing Alzheimer’s disease increases with age, usually occurring around the age of 65, although onset may occur as early as age 40. The average life expectancy after diagnosis is eight years; however, individuals with Alzheimer’s disease may live for as many as 20 years or more from the onset of symptoms. Because there are various causes of dementia, some of which are treatable or reversible, early and comprehensive evaluation using physical, neurological and mental testing is important for the diagnosis of Alzheimer’s disease.

What causes Alzheimer’s disease?

So far no one single factor has been identified as a cause for Alzheimer’s disease. It is likely that a combination of factors, including age, genetic inheritance, environmental factors, diet and overall general health, are responsible.

Age

Age is the greatest risk factor for dementia. Although Alzheimer’s disease is not restricted to elderly people, dementia affects one in 20 over the age of 65 and one in five over the age of 80.

Genetics

In the vast majority of cases, the effect of genetic inheritance seems to be small. However, in some families, there is a very clear inheritance of the disease from one generation to the next, especially when the disease appears relatively early in life.

Other Factors

Because of the difference in their chromosomal make-up, people with Down’s syndrome who live into their 50s and 60s may be more likely to develop Alzheimer’s disease.

People who have had severe head or whiplash injuries appear to be at increased risk of developing dementia. Boxers who receive continual blows to the head are also at risk.

Research has shown that people who smoke and those who have high blood pressure or high cholesterol levels increase their risk of developing Alzheimer’s disease.

How is Alzheimer’s disease diagnosed?

Because there is no straightforward test, identifying mild cases of Alzheimer’s disease can be very difficult. Testing usually involves a blood test and a full physical examination. Memory is assessed through questions about recent events and past memories, and a psychologist may provide a detailed assessment of memory and thinking skills. An imaging study such as a CT scan or MRI may also be carried out to provide clues about the changes taking place in the brain.

The classic sign of early Alzheimer’s disease is gradual loss of short-term memory. Other signs include:

• Problems finding or speaking the right word
• Inability to recognize objects
• Forgetting how to use simple ordinary things such as a pencil
• Forgetting to turn off the stove, close windows or lock doors
• Mood and personality changes such as agitation, problems with memory, and poor judgment, which may cause unusual behavior

Symptoms appear gradually in persons with Alzheimer’s disease but may progress more slowly in some persons than in others. In other forms of dementia, symptoms may appear suddenly or may come and go.

Is Alzheimer’s disease fatal?

The prognosis of patients with Alzheimer’s disease is difficult to predict because the type, severity, sequence and progression of mental changes vary from individual to individual. Some people have the disease only for the last five years of life, whereas others may have it for as many as 20 years. The most common cause of death in individuals with Alzheimer’s disease is a secondary illness such as an infection.

How is Alzheimer’s disease treated?

Despite the fact that there is currently no cure and no way to stop or reverse disease progression, medical and social management of Alzheimer’s disease can improve the quality of life of the patient and ease the burden on families and caregivers.

People with Alzheimer’s disease have been shown to have a shortage of the chemical acetylcholine in their brains. New drugs such as Aricept, Exelon and Reminyl work by maintaining existing supplies of acetylcholine. Although these drugs are not a cure, they may stabilize some of the symptoms of Alzheimer’s disease for a limited period of time. Also, some medications may help control behavioral symptoms such as sleeplessness, agitation, wandering, anxiety and depression. Current research efforts are focused on investigating the cause of Alzheimer’s disease, with the goal of prevention and improved diagnosis and treatment.

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