Two new genetic studies, both involving the recently identified TOMM40 gene, provide data supporting that Alzheimer’s disease could be diagnosed as early as 20 years prior to developing symptoms.

One of the studies, led by Dr. Mark Sager, director of the Wisconsin Alzheimer’s Institute and professor of medicine at the University of Wisconsin School of Medicine and Public Health, included 726 middle-aged and healthy individuals carrying the TOMM40 gene and with a family history of Alzheimer’s disease. According to the university’s website, “Researchers discovered that the 229 people with the high-risk version of TOMM40 did significantly worse on tests of learning and memory than study participants with the low-risk version.”

The second study was led by University of Wisconsin School of Medicine professor and Madison VA Hospital Geriatric Research of Education and Clinical Center researcher, Dr. Sterling Johnson. The data Johnson analyzed concluded “that healthy, middle-aged adults who have the high-risk version of TOMM40 had a significantly lower volume of gray matter in two brain regions affected in early Alzheimer’s disease.”

“This is the first study to associate TOMM40 to brain imaging in people at risk for Alzheimer’s,” said Johnson. “The research suggests that the group with the high-risk version of TOMM40 may be having early signs of cognitive and brain changes related to Alzheimer’s.”

This discovery in genetics and its connection with Alzheimer’s disease comes to the scientific and medical community on the heels of such revelatory studies as Boston University School of Medicine’s Risk Evaluation and Education for Alzheimer’s disease (REVEAL) study. The 2009 study concluded that, in general, there are not significant long-term risks, such as anxiety or depression, associated with receiving genetic test results. Researchers found that asymptomatic first-degree relatives of Alzheimer’s patients who received genetic testing results regarding a possible propensity for Alzheimer’s disease (the presence of an APOE ε4 allele) did not have a change in the levels of anxiety, depression or overall general distress. According to the study, “The disclosure of APOE genotyping results to adult children of patients with Alzheimer’s disease did not result in significant short-term psychological risks.”

Click here to read more about the studies led by Dr. Mark Sager and Dr. Sterling Johnson.

Click here to download the full text of Boston University School of Medicine’s REVEAL study (PDF).

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