Residents of the so-called U.S. Stroke Belt have a greater incident cognitive impairment than those who do not live in the south, researchers say. A study of U.S. adults age 45 and older, part of the Reasons for Geographic and Racial Differences in Stroke study from 2003 to 2007, assessed cognitive status annually by telephone and every two years with fluency and recall tasks. The study sample included 30,239 residents, with 16,934 from Stroke Belt states -- Alabama, Arkansas, Georgia, Louisiana, Mississippi, North Carolina, South Carolina and Tennessee -- and 13,305 from the remaining 40 contiguous states and the District of Columbia. The Stroke Belt gets its name from its concentration of high stroke death rates in southern states. Although the causes have not been determined, possible contributing factors include: hypertension, low socioeconomic status, diet, cultural lifestyle, quality of healthcare, smoking and infections. Study participants answered demographic and medical history questions during a computer-assisted telephone interview conducted by the Survey Research Unit at the University of Alabama at Birmingham. During a home visit, anthropometric measurements, blood and urine, and an electrocardiogram were obtained. Participants were tracked by telephone twice per year to gather information on hospitalized events. If a stroke was suspected during follow-up calls, medical records were obtained and adjudicated by study physicians. The study, published online in the Annals of Neurology, found 1,090 in eight stroke-belt states showed signs of cognitive decline after four years, compared with 847 people the other states. The memory issues may be related to the same underlying risk factors that contribute to high blood pressure, high cholesterol, diabetes and obesity, the researchers say.