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November 01, 2017

As the Alzheimer's field moves closer to new and earlier tests for the disease, innovative global research initiatives are taking the first important steps to confirm and standardize Alzheimer's biomarkers. A biomarker is something that can be objectively measured as an indicator of disease processes or the body's response to therapy. For example, blood pressure is a biomarker for heart disease. Two studies presented at AAIC 2011 show the importance of global standardization of biomarkers for Alzheimer's and sharing international data.

Data from three multi-center studies of Alzheimer's compared, for the first time, results of brain amyloid imaging and the impact of genetics and ethnicity on those results across countries on three different continents. The three studies are: the Alzheimer's Disease Neuroimaging Initiative (US-ADNI), Australian Imaging Biomarker and Lifestyle Flagship Study of Aging (AIBL), and Japanese Alzheimer's Disease Neuroimaging Initiative (J-ADNI). They found that the effect of age and APOE-e4 on amyloid deposition in the Japanese population is similar to Caucasians, despite a lower e4 allele frequency in the Japanese. Most importantly for the Alzheimer's research field, the results suggest that the three multi-national ADNI data sets are feasible for combined analysis. Combined analysis increases the power of the results, decreases ethnicity effects and makes the findings more broadly applicable. This is one of the first demonstrations of the value of open data sharing in the worldwide ADNI initiative, spearheaded by the Alzheimer's Association.

The earliest Alzheimer's related brain changes are usually seen in the hippocampus, the "control center" of memory-related activity in the brain ?? which often is one of the first brain areas affected by Alzheimer's. A variety of published protocols now exist for assessing hippocampal volume. As a first phase of the standardization process, researchers surveyed the various available protocols to identify underlying reasons why they result in different volume estimates. This work was funded by the Alzheimer's Association. The next step will be to create, test and verify a single protocol for MRI-based evaluation of Alzheimer's disease-related hippocampal shrinkage.A person with mild cognitive impairment (MCI) has problems with memory, language, or another mental function that are severe enough to be noticeable to themselves or to other people and to show up on tests, but not serious enough to interfere with daily life. Not everyone diagnosed with MCI goes on to develop Alzheimer's disease. However, research has shown that individuals with MCI have an increased risk of developing Alzheimer's over the next few years, especially when their main problem is memory. Identification of factors that predict progression from MCI to Alzheimer's dementia has emerged as an important Alzheimer's research priority.  A global perspective on MCI including data from six countries (Australia, France, Germany, Sweden, United Kingdom,  and the United States), presented for the first time at AAIC 2011, found that a number of common factors emerge as indicators of the progression from MCI to Alzheimer's, including: depression, apathy, anxiety, age, loss of ability in activities of daily living, cardiovascular factors (including stroke and diabetes), and low levels of education. The studies also call for doctors to pay more attention to subjective memory complaints in otherwise healthy individuals as possible indicators of Alzheimer's.It is believed that build-up of a toxic molecule known as beta amyloid in the brains of people with Alzheimer's occurs prior to cognitive decline. An accurate measurement or indicator of increased amyloid deposits in the brain could possibly provide an earlier diagnosis compared to current methods of cognitive testing, and also possibly indicate the progression or severity of the disease. Two studies reported at AAIC 2011 investigated new methods for possible use in early detection of Alzheimer's, tracking progression of the disease, identifying participants for research trials and measuring the impact of therapies. One study uses blood measurements for estimating the amount of a toxic substance known as beta amyloid deposited in the brain. The other study suggests that abnormal levels of certain proteins in cerebrospinal fluid (including beta amyloid) in people with mild cognitive impairment may indicate who will develop Alzheimer's within the next 10 years.A small pilot study presented at AAIC 2011, researchers explored whether characteristics of blood vessels in the back of the eye might serve as possible biomarkers for Alzheimer's disease. The researchers found that the width of certain blood vessels in the back of the eye were significantly different for people with Alzheimer's compared with healthy people, and that this correlated with brain imaging that is indicative of Alzheimer's. While most Alzheimer's-related pathology occurs in the brain, the disease has also been reported to create changes in the eye, which is closely connected to the brain and more easily accessible for examination in a doctor's office. The study is very preliminary, but encouraging.Results of a survey of people in France, Germany, Poland, Spain and the U.S. reported that while people fear Alzheimer's second only to cancer, the overwhelming majority say they would go to the doctor if they saw symptoms of memory loss and confusion. The poll was supported by a grant to Alzheimer Europe from Bayer, and was conducted by the Harvard School of Public Health. However, many of the respondents believe there is now an effective medical treatment to slow the progression of Alzheimer's; and many also said there is a reliable test currently available to determine if a person is in the early stages of Alzheimer's. Neither of these statements is true. The scientists say better public education about Alzheimer's is needed.

SOURCE Alzheimer's Association