Alzheimer's disease occurs when the progressive destruction of brain cells strips away command of memory, reason and learning, eventually leading to dementia and death. It is a devastating problem among the elderly, striking nearly half of those 85 and older. Already a major public health issue, Alzheimer's disease seems destined to escalate rather than ease any time soon. There are currently about four million people in the United States with this disease, but it is estimated that by the year 2025, 22 million people throughout the world will suffer from Alzheimer's disease.

While even healthy people have occasional age-related lapses in memory – so-called "senior moments" – Alzheimer's disease causes far more severe and debilitating symptoms. A patient's early days are marked by forgetfulness, difficulty in talking and an unsettling inability to carry out familiar tasks. As the disease advances, sometimes quite rapidly, agitation, confusion, depression, sleep disruption, and hallucinations often add increasing hardship. In its final stages, Alzheimer's disease destroys the capacity to recognize or communicate with others and entirely erases the patient's ability to take care of even the most basic personal needs.

Diagnosis

Unlike many diseases, which can be identified with simple laboratory tests, there is no single method for diagnosing Alzheimer's disease. Although a definitive diagnosis can only be made at the time of autopsy, new diagnostic tools allow physicians trained in neurodegenerative disorders to make a determination of Alzheimer's disease with about 90 percent accuracy. Diagnosis usually requires:

• a thorough review of personal and family medical history
• a complete physical and neurological exam
• a wide range of laboratory tests, which can include X-ray, CT and MRI diagnostic imaging, as well as blood analysis and testing for thyroid problems.

This thorough evaluation helps to eliminate the possibility of any other major cause of dementia, such as Parkinson's disease, thyroid problems, depression, brain trauma and stroke, some of which may be treatable.

Treatment

Today, treatments for Alzheimer's disease can produce short-term help in reducing and delaying lapses in memory, reasoning, and learning. Though these improvements may be slight, achieving some headway against symptoms of the disease is still significant. Inspired by this early progress, researchers are forging ahead to test a variety of new drugs and natural agents that show promise in preventing the onset of Alzheimer's disease and slowing its course.

Genes & Alzheimer's Disease

With the rapid pace of human genetic research, the understanding of the genetics of Alzheimer's disease and other dementias is changing everyday. Several genes have been identified that are associated with Alzheimer's disease and other neurodegenerative diseases. Individuals who have a family history of Alzheimer's disease or other related diseases may have questions about what effect these genetic advances mean for families.

Four genes have been identified that influence the risk of developing Alzheimer's-one is associated with late-onset disease (ages 65 and older) and three with early-onset, familial Alzheimer's disease (many individuals with Alzheimer's disease who have onset of disease younger than age 60). The late-onset Alzheimer gene, apolipoprotein E (ApoE), is a susceptibility gene that occurs in three forms-ApoE-e4, ApoE-e3, and ApoE-e2. Studies have shown that people with one copy of ApoE-e4 have an increased chance of developing AD. People who inherit two copies are at an even higher risk. However, not everyone with two copies develops AD, and many people with the disease have no ApoE-e4 gene at all. Experts believe that there are several other unidentified genes that also influence the likelihood to develop AD. Environmental factors may also be involved.

The three genes associated with early-onset, familial Alzheimer's are called presenilin 1, presenilin 2, and amyloid precursor protein. A mutation (or change) in one of these genes results in Alzheimer's disease. Each child of a parent who has a mutation in one of these genes has a 50 percent chance-or 1 chance in 2-of inheriting the mutation that causes Alzheimer's disease.

Tests are available that can determine whether a person carries copies of ApoE-e4 or one of the early-onset, familial Alzheimer's disease genes. Many people with affected relatives wonder if they should be tested. Most experts do not recommend testing for ApoE-e4 because ApoE status is not predictive. This means that having one or two copies of ApoE-e4 suggests an increased risk-but not a certainty-of developing Alzheimer's, and lacking ApoE-e4 does not protect against it.

Genetic testing may also be indicated for diseases such as CADASIL, frontotemporal dementia, prion diseases (Creutzfeldt-Jakob Disease) and others.

Genetic counseling and testing may make more sense for people with a strong family history of dementia, for example a history of early-onset, familial Alzheimer's disease.

The Columbia University Memory Center's Genetic Counseling provides the genetic counseling for those individuals who want to learn more about their family history and their options for genetic testing. The genetic counseling process allows people explore emotional and legal implications as well as scientific and technical issues before testing proceeds. After testing is completed, the neurologist and genetic counselor explain and interpret the results.