Clinical Research Directory

Inclusion Criteria: * Diagnosed with SCD of any genotype * Enrolled on the institutional protocol: Sickle Cell Clinical Research Intervention Program (SCCRIP) * Between the ages of 8.0 and 17.9 years \*Included if performance measure, rating scale or diagnostic criteria met (within the past 2 years): * \*Score at or below the 16th percentile on any 2 out of 4 performance measures: * NIH Toolbox Flanker * NIH Toolbox List Sorting * NIH Toolbox Dimensional Change Card Sort Test (DCST) * Wechsler Intelligence Scale for Children (WISC) -5/ Wechsler Adult Intelligence Scale (WAIS)-4 Digit Span Forward (DSF) * \*Score at or above the 84th percentile on any 1 out of 2 parent rating scales: * BRIEF-2 Global Executive * BASC-3 Attention * \*Have a documented diagnosis of attention deficit / hyperactivity disorder (any subtype) * English as the primary language * Research participant and one parent willing to participate and provide consent/assent according to institutional guidelines * Negative pregnancy test Exclusion Criteria: * Primary language other than English * Score below the 2nd percentile on the Wechsler Abbreviated Scale of Intelligence (WASI)-2 intelligence quotient (IQ) test * Uncontrolled seizures (seizure within the past 6 months) * Cardiomyopathy or known congenital structural cardiac defects * Stenotic valvular disease, left coronary artery stenosis, or history of myocarditis or pericarditis * History of heart arrhythmia including ventricular tachycardia, ventricular fibrillation, supraventricular tachycardia, QT prolongation or concomitant use of medications associated with QT prolongation * Two or more prior episodes of priapism * Blood pressure \>95th percentile at the three most recent visits consecutively (i.e., \>95th percentile reading at all three of the most recent hospital visits to St. Jude). * If blood pressure is \> 95th %ile compared to age-norms on the day of the baseline visit, a repeat blood-pressure reading will be performed both electronically and manually to confirm findings. * Stimulant medication within the past two weeks * Severe sensory loss * Previous adverse reaction to methylphenidate * Inability or unwillingness of research participant or legal guardian/representative to give written informed consent. * Currently prescribed another investigational medication. * Currently prescribed any of the following: * Phenobarbital (anticonvulsant) * Phenytoin (anticonvulsant) * Primidone (anticonvulsant) * Warfarin (anticoagulant) * Antipsychotic medications * Selective Serotonin Reuptake Inhibitor (SSRI) medications * Tricyclic antidepressant (TCA) medications * Vasopressor medications