Cognitive Outcome After Pediatric Stem-Cell Transplantation: Impact of Age and Total-Body Irradiation

Abstract

To examine the influence of age and conditioning with total-body irradiation (TBI) on the trajectory of cognitive functioning after treatment with pediatric hematopoietic stem-cell transplantation (SCT). Pediatric patients who were scheduled to undergo a SCT were eligible for the study, with 315 patients completing a baseline assessment. Of these, 183 patients (58.1%) were alive at 1 year after SCT and completed additional assessments at 1, 3, and 5 years after SCT. Half of the long-term sample (52.1%) received TBI during conditioning. Cognitive functioning was assessed via age-appropriate standardized measures. At baseline, there were no differences in intelligence quotient (IQ) based on age. At 5 years after SCT, the youngest patients (< 3 years old at baseline) who received TBI demonstrated a significantly lower IQ than those who did not receive TBI (P = .05). Longitudinal analyses (piecewise linear mixed-effects models with a knot at 1 year after SCT) revealed a significant impact of age and TBI over time. The youngest patients evidenced declines in cognitive functioning during the first year; however, patients who did not receive TBI largely recovered their functioning in subsequent years. In contrast, young patients who received TBI failed to recover the losses experienced during the first year after SCT, demonstrating stability in their functioning, but at a lower level. Our findings clarify the relationship between TBI and age on cognitive outcomes in pediatric SCT survivors. Young patients who receive TBI may benefit from early intervention efforts to minimize cognitive losses during the first year after SCT and to maximize potential recovery.