African-Americans in Indianapolis are twice as likely to develop Alzheimer'sdisease as Africans in a Nigerian city, suggesting that environmental factors such as diet play a role in the neurological disorder, according to a study releases on Wednesday, USA reports. Researchers from the Indiana University School of Medicinein Indianapolis and the University of Ibadan in Nigeria collaborated on the 10-year study. To investigate whether the Americans actually were at a greater risk, the researchers followed 2,147 people in Indianapolis and 2,459 in Ibadan for five years during the study. All of them were at least 65 years old and hadn't suffered from dementia when the study began. After accounting for age differences, the scientists found that 3.24% of those in Indianapolis developed dementia during the study, compared with 1.35% of the Nigerians. A similar difference was found in the proportion of subjects who developed Alzheimer's: 2.52% in Indianapolis and 1.15% in Ibadan. The Indianapolis residents also had higher incidences of hypertension, high cholesterol and diabetes than those in Ibadan, leading the authors to speculate that Alzheimer's and vascular disease may share some risk factors. Co-author Adesola Ogunniyi, of the Ibadan school, stated that Nigerians typically eat less protein and fat and fewer total calories than Americans. Unidentified genetic differences also may play a role, commented lead author Hugh Hendrie of Indiana. Full findings are published in the February 14 issue of the Journal of American Medical Association: 2001;285:739-747.
