New Methods Reported for Safely and Accurately Disclosing Alzheimer’s Disease Risk based on Newly Approved Tests

With FDA approval of a brain amyloid imaging compound in early 2012 and the expected start in 2012 and 2013 of three clinical trials in people with pre-symptomatic Alzheimer’s disease, issues around disclosure of dementia risk status are becoming more urgent. Several research efforts reported today at the Alzheimer’s Association International Conference® 2012 (AAIC® 2012) describe the creation and evaluation of new risk disclosure methods, and the examination of related ethical issues.

Alzheimer’s is a devastating, progressive, and fatal illness. There is a movement in the Alzheimer’s research field to detect and treat the disease earlier – even before there are outward symptoms – so that people do not have to suffer from the debilitating memory and thinking problems that lead to loss of normal daily activities and independence, and eventually death.

A number of Alzheimer’s prevention trials are in the planning stages. They will be conducted in people without memory or thinking symptoms who are considered at-risk for Alzheimer’s on the basis of genetic and/or biomarker positivity.

A biomarker is something in the body that can be measured as an indicator of normal biological processes, disease processes, or changes in response to therapy. For example, cholesterol levels are a biomarker for heart disease. A variety of imaging and fluid biomarkers are under investigation in Alzheimer’s disease. Biomarkers allow investigators and clinicians to detect Alzheimer’s-related changes in the brain and other body systems prior to the onset of dementia symptoms due to Alzheimer’s.

“Biomarkers are being increasingly used in clinical practice and research trials to provide risk information for Alzheimer’s. The goal is to develop evidence-based methods for communicating this risk in effective and supportive ways,” said J. Scott Roberts, PhD, of the University of Michigan, School of Public Health. Dr. Roberts is chair of an AAIC 2012 featured research session where new research on disclosing risk information will be reported and discussed.

One of the most promising biomarkers is brain imaging using positron emission tomography (PET) scans that can show whether a person has deposits of an abnormal protein called beta amyloid, which is one of the hallmarks of Alzheimer’s disease. There also are well-established genetic risk factors, such as the APOE Alzheimer’s risk gene.**

Based on current knowledge, APOE-e4 is the gene with strongest impact on Alzheimer’s risk. APOE-e4 is one of three forms of the APOE gene; the others are APOE-e2 and APOE-e3. Everyone inherits a copy of APOE from each parent. Those who inherit one copy of APOE-e4 have an increased risk of developing Alzheimer’s. Those who inherit two copies have an even higher risk, but not a certainty. Scientists estimate that APOE-e4 is implicated in about 20 to 25 percent of Alzheimer’s cases. APOE-e2 may provide some protection against Alzheimer’s.

Until recently, the presence of brain amyloid could only be confirmed by autopsy. Now it is possible to look for the protein in living brains using a special type of dye during a PET scan. These PET scans may help determine whether or not a person who is experiencing memory loss has Alzheimer’s disease.

“People with memory loss who test negative on a PET scan using the newly-approved dye do not have Alzheimer’s disease,” said William Thies, PhD, Alzheimer’s Association® Chief Medical and Scientific Officer. “Their symptoms are caused by something else. If they test positive, the cause is likely Alzheimer’s, but that is not 100% certain because the presence of amyloid can be detected in other diseases besides Alzheimer’s. We do not yet know what the test means in people without symptoms. The predictive value of the test is uncertain.”

“The disclosure of test results to cognitively normal older people raises some important ethical issues because researchers and clinicians do not yet know how to interpret them. How will this biomarker information be gathered? When, how, and to whom will it be disclosed? How do we disclose it accurately while minimizing any potential negative impact? These are issues that must be addressed by the research and healthcare communities, with crucial input from Alzheimer’s families and other stakeholders,” Thies added.

The Alzheimer’s Association currently is working with the Society of Nuclear Medicine to develop guidelines for when an amyloid PET scan is appropriate and how it should be interpreted.

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