Medical Overview and Epidemiology

Sickle cell disease (SCD) is a group of inherited autosomal recessive disorders, including sickle cell anemia, sickle beta-thalassemia, and other hemo-globinopathies, which are characterized by the production of abnormal hemoglobin. SCD affects approximately 1 in every 400-500 African American newborns annually in the United States (Tarnowski and Brown 2000). Although most common in people of African descent, SCD also affects other ethnic groups, including persons of Mediterranean, Caribbean, South and Central American, Arabian, and East Indian descent.

In persons with SCD, abnormal genes for hemoglobin produce a change in the shape of red blood cells from their normal disk shape to a sickle shape. The abnormally shaped cells can obstruct normal blood flow and production of new red blood cells, resulting in chronic anemia and pain. Persons with SCD are susceptible to pneumococcal and other infections, stroke, and multiple organ dysfunctions. The most common type of SCD is the homozygous condition, sickle cell anemia, which is caused by two abnormal genes for hemoglobin S (Hb SS) and is associated with earlier and more frequent and severe symptoms than are other types of SCD (Charache et al. 1989).

Although SCD continues to be associated with a reduced life expectancy (Charache 1994; O.S. Platt et al. 1994), treatment for the disease has improved significantly (Cohen 1998; Ris and Grueneich 2000). Treatment advances reflect findings from clinical, molecular, and genetic studies (Hagar and Vinchinsky 2000) and the use of new tools, including transcranial Doppler ultrasonography, to evaluate patients for stroke risk (Abboud et al. 2004; Adams 2000).

In addition, new therapies are under investigation, including hydroxyurea, a drug that stimulates production of fetal hemoglobin, a determinant in the clinical severity of SCD. Although hydroxyurea was initially established as safe and efficacious in adults (Charache et al. 1995), studies in children have demonstrated encouraging findings. Specifically, a Phase I/II trial of hydroxyurea in children ages 5-15 with SCD demonstrated similar safety and efficacy as in adults (Kinney et al. 1999). Moreover, clinical efficacy of hydroxyurea has been reported in small groups of children (Ferster et al. 1996, 2001; J.P. Scott et al. 1996). In a Phase I/II pilot study, the feasibility and safety of hydroxyurea were demonstrated in very young children (ages 524 months), with no negative effects on growth and development (Hankins et al. 2005; Wang et al. 2001b). A recent pilot study also revealed that hydroxyurea may prevent chronic organ damage (Thornburg et al. 2009). Finally, use of bone marrow transplantation holds promise for some patients with SCD (Hoppe and Walters 2001; Locatelli et al. 2003; Nietert et al. 2000; Walters et al. 2000).

Because SCD is a genetic condition present from birth, the disease is likely to interact with developmental factors in infancy or early childhood and therefore to have implications for cognitive and psychosocial functioning (Berkelhammer et al. 2007; Gustafson et al. 2006; Schatz and Puffer 2006). In this chapter, we summarize current knowledge about the brain bases of the psychological effects of SCD and psychological factors associated with adjustment and quality of life. Additionally, we review available evidence-based interventions for treatment adherence, pain coping and psychosocial adjustment, and cognitive and academic difficulties.

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