Mental function following scalp irradiation during childhood.

Between 1950 and 1960 about 20,000 israeli children were treated for tinea capitis by x-ray therapy as part of a large public health campaign to eradicate the disease. Dosimetric studies determined that these children were subjected to a mean brain dose of 130 rads. Almost 20 years later, possible radiation effects on the central nervous system were evaluated by comparing several measures of mental and brain function in approximately 11,000 of the irradiated children and in two nonirradiated, tinea-free comparison groups: (a) ethnic, sex- and age-matched individuals from the general population, and (b) siblings. While not all comparisons were statistically significant, there was a consistent trend for the irradiated subjects to exhibit signs of central nervous system inpairment more often than either comparison group. The irradiated children had lower examination scores on scholastic aptitude, intelligence quotient (IQ) and psychologic tests, completed fewer school grades, and had an increased risk for mental hospital admissions for certain disease categories. A slightly higher frequency of mental retardation was also suggested. These-long-lasting scholastic and mental health effects lead the authors to conclude that radiation to the immature brain may cause damage to the central nervous system.