You might have heard of the Alzheimer’s gene, or ApoE4. Individuals carrying two copies, one inherited from each parent, are thought to have a 91 percent chance of developing Alzheimer’s in their lifetime. Those carrying one copy have about a 47 percent chance. Those who don’t have the ApoE4 gene at all have a 20 percent chance.
Finding out your ApoE4 status is information that some people change their whole lives around. But now, scientists have found evidence that another gene, TOMM40, may have an even greater impact on increasing the risk of Alzheimer’s. TOMM40 and ApoE4 are genetic neighbors, and previously TOMM40 was thought to slightly heighten the risk. This study, conducted by the University of Southern California and The University of Manchester, found that TOMM40 was more influential than ApoE4 in memory loss, especially when ApoE3 was present.
Scientists found that those with a TOMM40 gene had greater decline in immediate memory loss—for example, repeating direction back to someone—than their ApoE4-carrying counterparts. Researchers looked at verbal memory scores of over 20,000 participants over the age of 50. Participants were asked to repeat back a list of 10 nouns immediately after hearing them, and then again five minutes later. After examining 1.2 million gene variations for a link between a decline in recall, only TOMM40 had a strong association.
“The results from this study provide more evidence that the causes of memory decline are even more complicated than we thought before, and they raise the question of how many findings in other studies have been attributed to ApoE4 that may be due to TOMM40 or a combination of TOMM40 and ApoE4,” said Carol A. Prescott, the study’s lead author and professor of psychology and gerontology at University of Southern California.
Read the full write-up here.