Steady-State Cognitive Function and Pain Severity in Youth with Sickle Cell Disease

Introduction : In youth with sickle cell disease (SCD), vaso-occlusive crises are a major cause of morbidity and episodes of acute pain are among the most common manifestations of the disease. Previous studies in other chronic pain populations suggest that pain, as well as treatment for pain, impairs cognitive and neuropsychological functioning. In SCD, there have been studies examining the role of disease-related factors and disease severity, psychosocial and demographic factors, coping strategies and personality factors, and environmental factors on pain severity, but we are not aware of research investigating whether pain in SCD is related to baseline cognitive function. The goal of this study is to examine whether steady-state intellectual function, attention, and/or executive function differs in youth with SCD based on pain severity.

Methods : Adolescents and young adults with SCD (N = 47) aged 17-24 years (M = 15.9, SD = 2.4); 57% male; 64% HbSS disease, completed a brief neuropsychological evaluation as part of their participation in one of several research studies, which included measures of intellectual function (WASI-II), attention (CPT-II), and executive function (D-KEFS Trail Making Test, Color Word Interference Test, Tower; WISC-IV Processing Speed Index and Working Memory Index). Those measures were collected at steady-state, when subjects were not experiencing pain or fever and were not taking medication for pain. Medical chart review was used to collect information about genotype and steady-state hemoglobin, as well as self-reported pain at each outpatient clinic visit (coded 1-5 at each) and number and length of hospitalizations for pain in the year prior to and the year following neuropsychological evaluation.

Results :Chi square and linear correlation analyses found no significant relationships between number of admissions or mean pain report and age, gender, genotype, or mother's education. Two pain variables with 4 levels each were also constructed for analysis: Admissions for pain (ADM) and subjective Pain Report. Analysis of Variance (ANOVA) with each of 9 neuropsychological (NP) variables as outcomes found significant associations of ADM with cognitive inhibition (DKEFS Color Word Interference: Inhibition; p = .015) and PR with sustained attention/vigilance (CPT-II Hit RT Standard Error; p = .031). Linear correlations of actual number of admissions and mean pain score over all reports showed a significant negative correlation between admissions and cognitive inhibition. (r = -.428, p = .007).

Conclusion :Results of this study suggest that poorer attention and executive functioning (inhibition) at baseline are associated with pain report or health utilization for pain in youth with SCD. There was no association with general intellectual function and these relationships were not accounted for by disease severity or demographic factors. These findings support the possibility that neuropsychological weaknesses unrelated to disease severity may place youth with SCD at risk for more severe subjective pain or for increased hospitalizations. This could be related to coping styles. Further study of neuropsychological risk factors associated with pain experience and health utilization in youth with SCD is warranted.