Cognitive and behavioral abnormalities in adenosine deaminase deficient severe combined immunodeficiency

Objective: The objective was to evaluate the cognitive, behavioral, and neurodevelopmental function in patients with adenosine deaminase deficient severe combined immunodeficiency (ADA-SCID) and to compare the findings with those of a case control group of patients without ADA-SCID. Study design: Case-matched pairs of patients with ADA-SCID (n = 11) and patients without ADA-SCID who had undergone bone marrow trans plantation were recruited. Subjects were assessed by age-appropriate standard tests of intelligence, behavior, and neurodevelopment. Results: Cognitive ability was not significantly different between the 2 groups, but patients with ADA-SCID showed a significant inverse correlation between deoxyadenosinetrisphosphate levels at diagnosis and IQ (P =.048). Behavioral assessment showed that patients with ADA-SCID functioned in the pathologic range on all domains, whereas mean scores for the control group were within normal limits. Behavioral impairment in patients with ADX-SCID also showed a significant positive correlation with age (P =.026). Conclusions: Cognitive function in ADA deficiency is adversely affected by the severity of metabolic derangement at the lime of diagnosis. In addition, patients with ADA-SCID have significant behavioral abnormalities after transplantation. These defects are not due to the transplant procedure but reflect the systemic nature of ADA deficiency. These findings have important implications for future medical and nonmedical management strategies.