A lot of research has been done on possible causes of Alzheimer’s disease — a terrible degenerative condition that affects the central nervous system. One of the most commonly recognized — and most dreaded — effects of Alzheimer’s is continuous mental decline.
Â Now, a new study, published in February’s Archives of General Psychiatry, has confirmed the strong genetic link for the disease by looking at twins. Until now, studies done on twins have focused on smaller groups of participants. The study, performed at the University of Southern California, is the largest twin study conducted yet, thus making it an important milestone in Alzheimer’s research.
Â Starting in 1998, the researchers have been analyzing data taken from the Swedish Twin Registry. Specifically, they looked at 11,884 twins (identical and fraternal) who were 65 years old or older. Of this group, at least one twin in 392 pairs had Alzheimer’s. The backgrounds of the twins were examined for shared and non-shared environmental risks and genetic factors.
Â Put simply, the study found that genetics seemed to be the cause of approximately 79% of the Alzheimer’s cases. The remaining 21% of the cases were found to be due to environmental causes that were not shared by twins, such as childhood environment and lifestyle factors. Compared to the fraternal twins (who share 50% of their genetic material), the identical twins were more likely to both develop Alzheimer’s, thus confirming a genetic factor in the disease.
Â However, the study does more than just substantiate a long- suspected genetic link. It also throws a wrench into the popular theory that there are two separate forms of Alzheimer’s disease: one based on genes (“familial”); and one based on environmental factors (“sporadic”). Rather, this research shows that it’s more likely that the disease is more complicated, with both genetic and environmental triggers present within a single case.
Â For example, the study showed that for 55% of identical male twins, where one has Alzheimer’s, the other one would either never get the disease or wouldn’t develop it until a later point in life.
Â This large-scale study adds to the growing amount of information we have on Alzheimer’s disease. What’s important to take away from these findings is that your genetic background — while a major factor in your susceptibility — is only one piece of the puzzle.
Â Environment and lifestyle factors — such as diet, high blood pressure, and education — are all being studied for their connection to this form of dementia. So, don’t waste your time blaming your family tree; instead, get fit, eat well, and look into the many ways you can reduce the risks for developing Alzheimer’s.