COGNITIVE DEFICITS IN LONG-TERM SURVIVORS OF CHILDHOOD MEDULLOBLASTOMA AND OTHER NONCORTICAL TUMORS - AGE-DEPENDENT EFFECTS OF WHOLE-BRAIN RADIATION

Twenty-four children, aged 1.5-20 yr at diagnosis, with noncortical br ain tumors, primarily medulloblastoma, have been followed for 3-4 yr f or intellectual status. All the children received craniospinal irradia tion, and 19 of 24 received chemotherapy as well. For the group as a w hole, Full Scale IQ fell from 104 at baseline to 91 at final follow-up . Children younger than 7 yr at diagnosis showed a significant decreas e in IQ as early as year 1, and all changes from baseline to years 3 a nd 4 were significant. In contrast, children older than 7 yr at diagno sis did not show a significant IQ change from baseline to year 3 or 4. The Spearman correlation coefficient between IQ change and age at dia gnosis from baseline to year 4 was 0.57 (P=0.003). This study supports the hypothesis that children treated with whole brain radiation at a younger age have more severe cognitive impairment than those treated a t a later age. Limitations in sample size and duration of observations do not permit us to identify whether a true plateau occurs 24 yr afte r irradiation versus a continued progressive decline in intellectual p erformance. Moreover, we cannot at this time distinguish between a tru e dementing process versus failure to acquire new cognitive skills at a rate comparable to age-matched peers.