Learning Disabilities in Children With Congenital Adrenal Hyperplasia

Abstract

Early exposure to androgens may be a cause of the higher incidence of learning disabilities among males. To test this hypothesis, we determined the frequency of learning disabilities, as measured by extent of Wechsler Verbal-Performance IQ discrepancy, among female patients with congenital adrenal hyperplasia, who are exposed in utero to excess androgens for their sex. A significantly larger Verbal-Performance IQ discrepancy (10.1 vs 7.7) was found for the 18 female patients than for 27 unaffected female siblings (P = .045, one-tailed). The Verbal-Performance IQ discrepancy of the females with congenital adrenal hyperplasia is in the male range (10.4 to 13.4), similar to males with congenital adrenal hyperplasia (n = 20) and unaffected male siblings (n = 31). In addition to the sex effect, there is an effect of the type of congenital adrenal hyperplasia on the frequency of learning disabilities. Simple virilizers are more likely to be learning disabled than salt-wasters ( P = .04, one-tailed). However, salt-waster patients have a lower IQ (104 vs 117) than simple virilizer patients ( P = .005, one-tailed). Presumably, this is because some salt-waster patients suffer brain injury from episodes of hypotension and hyponatremia. The diffuse insult to the central nervous system may overide the androgen effect and result in a general cognitive impairment. Because of this confounding effect on IQ in the salt-waster form of congenital adrenal hyperplasia, the simple virilizer female versus unaffected female siblings represents the best test of the hypothesis. Simple virilizer females have a significantly larger, male range, Verbal-Performance IQ discrepancy (13.5 vs 7.4) than unaffected female siblings ( P = .03, one-tailed). Early androgen exposure may, as reported in the "normal" male, increase the incidence of learning disabilities in females with congenital adrenal hyperplasia by causing abnormalities of neuronal migration and/or connectivity. (J Child Neurol 1991;6:306-312).