[Show abstract][Hide abstract] ABSTRACT: This study was conducted to determine the relationship of frontal lobe cortical thickness and basal ganglia volumes to measures of cognition in adults with sickle cell anemia (SCA).
Participants included 120 adults with SCA with no history of neurologic dysfunction and 33 healthy controls (HCs). Participants were enrolled at 12 medical center sites, and raters were blinded to diagnostic group. We hypothesized that individuals with SCA would exhibit reductions in frontal lobe cortex thickness and reduced basal ganglia and thalamus volumes compared with HCs and that these structural brain abnormalities would be associated with measures of cognitive functioning (Wechsler Adult Intelligence Scale, 3rd edition).
After adjusting for age, sex, education level, and intracranial volume, participants with SCA exhibited thinner frontal lobe cortex (t = -2.99, p = 0.003) and reduced basal ganglia and thalamus volumes compared with HCs (t = -3.95, p < 0.001). Reduced volume of the basal ganglia and thalamus was significantly associated with lower Performance IQ (model estimate = 3.75, p = 0.004) as well as lower Perceptual Organization (model estimate = 1.44, p = 0.007) and Working Memory scores (model estimate = 1.37, p = 0.015). Frontal lobe cortex thickness was not significantly associated with any cognitive measures.
Our findings suggest that basal ganglia and thalamus abnormalities may represent a particularly salient contributor to cognitive dysfunction in adults with SCA.
[Show abstract][Hide abstract] ABSTRACT: Silent cerebral infarct (SCI) is the most common form of neurologic disease in children with sickle cell anemia (SCA). SCI is defined as abnormal magnetic resonance imaging (MRI) of the brain in the setting of a normal neurologic examination without a history or physical findings associated with an overt stroke. SCI occurs in 27% of this population before their sixth, and 37% by their 14th birthdays. In adults with SCA, the clinical history of SCI is poorly defined, although recent evidence suggests that they too may have ongoing risk of progressive injury. Risk factors for SCI include male sex, lower baseline hemoglobin concentration, higher baseline systolic blood pressure, and previous seizures. Specific morbidity associated with SCI includes a decrement in general intellectual abilities, poor academic achievement, progression to overt stroke, and progressive SCI. In addition, children with previous stroke continue to have both overt strokes and new SCI despite receiving regular blood transfusion therapy for secondary stroke prevention. Studies that only include overt stroke as a measure of CNS injury significantly underestimate the total cerebral injury burden in this population. In this review, we describe the epidemiology, natural history, morbidity, medical management, and potential therapeutic options for SCI in SCA.
[Show abstract][Hide abstract] ABSTRACT: Senicapoc, a novel Gardos channel inhibitor, limits solute and water loss, thereby preserving sickle red blood cell (RBC) hydration. Because hemoglobin S polymerization is profoundly influenced by intracellular hemoglobin concentration, senicapoc could improve sickle RBC survival. In a 12-week, multicenter, phase 2, randomized, double-blind, dose-finding study, we evaluated senicapoc's safety and its effect on hemoglobin level and markers of RBC hemolysis in sickle cell anemia patients. The patients were randomized into 3 treatment arms: placebo; low-dose (6 mg/day) senicapoc; and high-dose (10 mg/day) senicapoc. For the primary efficacy end point (change in hemoglobin level from baseline), the mean response to high-dose senicapoc treatment exceeded placebo (6.8 g/L [0.68 g/dL] vs 0.1 g/L [0.01 g/dL], P < .001). Treatment with high-dose senicapoc also produced significant decreases in such secondary end points as percentage of dense RBCs (-2.41 vs -0.08, P < .001); reticulocytes (-4.12 vs -0.46, P < .001); lactate dehydrogenase (-121 U/L vs -15 U/L, P = .002); and indirect bilirubin (-1.18 mg/dL vs 0.12 mg/dL, P < .001). Finally, senicapoc was safe and well tolerated. The increased hemoglobin concentration and concomitant decrease in the total number of reticulocytes and various markers of RBC destruction following senicapoc administration suggests a possible increase in the survival of sickle RBCs. This study is registered at http://clinicaltrials.gov as NCT00040677.