Incidence of Dementia and Alzheimer Disease in Nigeria and the United States

To the Editor: Dr Hendrie and colleagues¹ suggest that the lower incidence of dementia and Alzheimer disease in Nigeria compared with African Americans in Indianapolis could be due to dietary factors. Farrer² has suggested that environmental factors, such as diet and exercise, may mediate this relationship. While not ruling out involvement of diet and exercise, there is reason to believe that another factor is also important, namely differing levels of exposure to data input, especially from television.