New Study Suggests Sickle Cell Disease May Affect Brain Function
Adults who have mild sickle cell disease scored lower on brain function tests when compared to healthy participants, suggesting the blood disease may impact the brain more than previously realized, according to new research published in the May 12 issue of the Journal of the American Medical Association. This is the first study to examine cognitive functioning in adults with sickle cell disease.
The study was conducted by 12 sites within the Comprehensive Sickle Cell Centers funded by the National Heart, Lung, and Blood Institute (NHLBI), part of the National Institutes of Health. Elliott P. Vichinsky, M.D., of the Children’s Hospital and Research Center in Oakland, Calif., is the lead author of “Neuropsychological Dysfunction and Neuroimaging Abnormalities in Neurologically Intact Adults with Sickle Cell Anemia.” An editorial accompanies the article.
Researchers tested cognitive functioning, including nonverbal function, of 149 adult sickle cell disease patients (average age 32) as compared to 47 healthy study participants of similar age and education levels from the same communities. The sickle cell disease patients in the study were considered low risk for complications from the disease because they did not have a history of frequent pain episodes or hospitalizations, stroke, high blood pressure, or other conditions that might otherwise affect brain function.
More sickle cell disease patients scored lower on measures such as intellectual ability, working memory, processing speed, and attention, than participants in the healthy group. Older sickle cell disease patients scored lower on the tests, and severity of anemia was also linked to lower scores.
The study shows that many adults with sickle cell disease may develop a dysfunctional lower ability to organize and learn than those without sickle cell disease ““ even if they do not have other complications of the blood disorder. Cognitive functioning may become an important factor in effectively managing sickle cell disease in patients. The study also reveals the need to learn whether treatments can preserve or possibly reverse cognitive function.
Sickle cell disease affects about 70,000 Americans, and at one time most children died from the disease. Over the years, new therapies have enabled sickle cell disease patients to live into middle age. As more people with sickle cell disease are living into adulthood, health care providers are uncovering previously unrecognized complications.
Sickle cell disease involves an altered gene that produces abnormally-shaped hemoglobin, a protein found in red blood cells and carries oxygen throughout the body. Red blood cells that have too little oxygen become C-shaped in addition to becoming stiff and sticky. These crescent-shaped cells can clump to block blood flow, causing severe pain and potential organ damage. In the United States, the disease mainly affects those of African descent, but it is also found in patients of Hispanic descent.
Susan B. Shurin, M.D., NHLBI acting director, and W. Keith Hoots, M.D., director of the NHLBI Division of Blood Diseases and Resources, are available to comment on the significance of the study and the need for more research on cognitive impairments in patients with sickle cell disease and whether available treatments can reverse or prevent these complications. Researchers are recruiting patients with sickle cell disease into a clinical trial to determine whether blood transfusions may help preserve cognitive function (NCT00850018).
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