The most common form of dementia among older people, Alzheimer’s disease (AD) is an irreversible, progressive brain disease that slowly destroys memory, thinking, and reasoning skills. Eventually, the affected person’s ability to carry out even the simplest daily activities is severely compromised.
The cause or causes of AD remain unknown. Named after Alois Alzheimer, a German physician who first noticed brain tissue changes indicative of the disease—amyloid plaques and neurofibrillary tangles—AD begins damaging brain cells’ ability to function and communicate long before problems are evident, as many as 10 to 20 years before outward signs are manifested, according to the National Institute on Aging.
While the course of AD differs for each individual, in general, the disease develops gradually, following a recognized three-step progression, according to the National Institutes of Health (NIH):
Mild. Simple forgetfulness may be the only symptom. People with mild Alzheimer's may be unable to remember recent events, ask the same question over and over, and become lost in familiar places. A person may seem healthy, but is actually having increasing trouble making sense of his or her immediate world. Such difficulties can also be due to other conditions.
Moderate. As the disease progresses, memory worsens. People may have problems recognizing family and friends and may experience difficulty learning new things. In this stage, people may behave differently, too. For example, they might be restless, agitated, or angry, or they may wander.
Severe. As Alzheimer's disease becomes more severe, people lose the ability to communicate. They may sleep more, lose weight, and have trouble swallowing. Often they cannot control their bladder and bowel. Eventually, they need total care.
The length of this terminal illness—from diagnosis until end of life—also varies. According to the NIH, it can be as little as three years if the person is more than 80 years old or as long as 10 years or more if the person is younger.
Currently, a definitive AD diagnosis can occur only after death with an autopsy. However, physicians now can determine a fairly accurate diagnosis with the help of several methods and tools, including a physical exam and patient history; cognitive function assessments such as memory and problem-solving tests; blood, urine, spinal fluid or other medical tests; and brain scans.
While AD is not a normal part of aging, the greatest risk factor for the disease is advancing age. According to the Alzheimer’s Association’s 2010 Alzheimer’s Disease Facts and Figures report, of the estimated 5.3 million Americans suffering from the disease, 5.1 million are age 65 and older—one in eight or 13 percent of the 65-and-older population. When recognized in persons under age 65, Alzheimer’s or other forms of dementia are referred to as “young-onset” or “early-onset.” While the rate of AD among women aged 71 and older is higher than for men, the difference is not gender-related, but can be explained by the fact that women live longer on average than men, according to the Alzheimer’s Association report.
Most experts believe the majority of Alzheimer’s disease occurs as a result of complex interactions among genes and other risk factors. Aging, family history, and heredity are risk factors that cannot be changed. However, research suggests lifestyle factors, such as physical, mental, and social activities, may be helpful in reducing the risk of cognitive decline and of Alzheimer’s disease. In addition, scientists are investigating the associations between cognitive decline and such cardiovascular risk factors as heart disease, diabetes, stroke, high blood pressure, and obesity.
There is no known cure for Alzheimer’s disease. Critical elements of disease management include timely diagnosis and effective therapies to manage cognitive and behavioral symptoms. Drugs approved by the U.S. Food and Drug Administration primarily aid in temporarily curbing disease symptoms. Researchers are, however, investigating additional therapies aimed at slowing or stopping the progression of the disease.