Declines in IQ scores and cognitive dysfunctions in children with acute lymphocytic leukaemia treated with cranial irradiation.

Intellectual and other neuropsychological dysfunctions have been observed in survivors of childhood acute lymphocytic leukaemia (ALL). The possible relationship of therapy to these dysfunctions was investigated in a prospective study of children with newly diagnosed ALL seen at the Children's Hospital of Philadelphia. They were evaluated with standardised intelligence tests during the first month of treatment and periodically thereafter. There were two therapy schedules--one using standard drugs for induction and maintenance, the other a more intensive schedule. Central-nervous-system prophylaxis (2400 rad cranial radiation and six doses of intrathecal methotrexate) was given to all. Significant reductions were found in overall IQ score for the majority of children, younger patients being most affected. More extensive testing of surviving children, with and without decline in IQ, all of whom were normal on the first test, revealed patterns of functional deficits and residual strengths that could not be characterised with IQ testing alone. These deficits, which could affect learning and academic performance, were not seen in six children studied years after receiving similar chemotherapy that included intrathecal and oral methotrexate but not cranial irradiation.