A study has found that black Americans are twice as likely to develop Alzheimer's disease as black Nigerians, suggesting that environment and lifestyle play a role in the neurological disorder.
The 10-year study, which was conducted in Indianapolis and Ibadan, Nigeria, also concluded that American blacks are more likely to develop high blood pressure, diabetes and other illnesses than blacks in Nigeria.
Hugh Hendrie, a professor of psychiatry at Indiana University School of Medicine, is the principal author of the study, which appears in today's issue of the Journal of the American Medical Association.
He said his IU team and their counterparts at the University of Ibadan now hope to determine why the Americans developed Alzheimer's and other forms of dementia more frequently than their African counterparts.
Link to Lifestyle?
Bill Thies, a vice president of the Chicago-based Alzheimer's Association, said the findings strongly suggest that lifestyle and environment play a role in causing the mind-robbing disease.
"It's not only where you live but how you live that may increase your likelihood of developing Alzheimer's disease," he said.
More than 4 million Americans, most of them elderly, suffer from Alzheimer's, which causes gradual memory loss, disorientation and personality changes.
The Indianapolis-Nigeria study enlisted 2,147 Indianapolis residents and 2,459 Nigerians. About two-thirds of both groups were women.
Although the two groups were not a perfect match, it is believed that many African-Americans descended from people brought from West Africa to the United States as slaves. Nigeria is in West Africa.
The Ibadan residents in the study are unable to afford much more than vegetables to eat, Hendrie said, with a diet including yams, cassava and palm oil with an occasional sprinkling of fish.
The study participants in Indianapolis ate the typical American diet.
Moving Toward Prevention
All participants were 65 or older and were determined to have no signs of dementia or Alzheimer's at the beginning of the study.
At the end of the study, 2.52 percent of the Americans had developed Alzheimer's, and a total of 3.24 percent showed signs of dementia. By contrast, 1.15 percent of the Nigerians had developed Alzheimer's, and 1.35 percent had dementia.
For the study's second phase, an additional 2,000 Indianapolis residents age 70 or older will be recruited, said Hendrie, who is also a researcher at the Center for Aging at the Regenstrief Institute.
No volunteers will be accepted for the five-year study. Instead, participants will be sought out to ensure a representative sample.
The results of the initial part of the study are significant, Hendrie said, because it marks the first time that the same group of scientists has investigated and compared the rate of an illness in a developing and a non-developing country.
Often, researchers study different groups at different times using a variety of criteria, making analysis difficult. With this study, researchers hope to move Alzheimer's research further toward prevention.
Hendrie said that the second part of the study will likely show that Alzheimer's is rooted in a combination of genetic and environmental causes.