The purpose of this study is to assess whether methylphenidate is effective in enhancing the cognitive performance of children with the HbSS or HbSC genotype of SCD who have sustained neurological complications on laboratory-based measures of sustained attention, reaction time, and executive functions, and indirectly, verbal short-term and long-term memory.

Sickle cell disease (SCD) is a group of autosomal recessive disorders, affecting an estimated 1 in 400 African American newborns annually. The pathophysiology of this group of disorders involves the production of abnormal hemoglobin (HbS), which causes red blood cells to assume a rigid, sickled shape upon release of oxygen, thereby reducing their viability in circulation. Consequently, chronic anemia and system-wide ischemia result in acute painful episodes, organ system failure, and neurological complications. Among the most debilitating effects of SCD are neurological complications. Despite the mounting evidence for structural and functional involvement of the frontal systems in pediatric SCD, there have been no clinical trials designed to manage the cognitive and behavioral sequelae associated with pediatric SCD.

Inclusion Criteria:

• Informed Consent can be obtained from parent or care-giver and Assent can be obtained from the child
• Children with sickle cell disease (HbSS or HbSC)
• Age range from 6 to 16 years inclusive
• English is the child's primary language
• T-score greater than or equal to 63 on either the Conners' Parent Rating Scale - Revised or the Conners' Teacher Rating

Exclusion Criteria:

• History of glaucoma for which methylphenidate is contraindicated
• Child or immediate family member has a history of a tic disorder or Tourette's syndrome
• Child is currently receiving antidepressant, anxiolytic, antipsychotic, or stimulant drug therapy
• Family history of substance abuse disorder due to potential for abuse of stimulants by caregivers or other family members
• Recent history of uncontrolled seizures (may be on anticonvulsants, provided seizures are under "reasonable" control and that the patient and family understand the risk of altered seizure control and potential interference with maintaining therapeutic levels of anticonvulsants)
• Hypothyroidism
• Symptoms of affective and mood disorders
• Previously diagnosed with ADHD prior to the onset of neurological complications (e.g., stroke or silent infarct) as documented in the medical record or caregiver report.
• Mental retardation (FSIQ < 70 on WASI)