A prospective longitudinal study of early cognitive development in tuberous sclerosis - a clinic based study.

We report a prospective longitudinal study of cognitive development in a series of 20 clinic-referred infants with Tuberous Sclerosis. The infants were seen between the ages of 11 and 37 months and were assessed regularly at 6-month periods using a within-subjects repeated measures design. Assessment using the Mullen Scales of Early Learning, a measure of cognitive and motor showed that with the exception of one child, all children had composite developmental quotients that fell into the mentally retarded range of intellectual functioning. In general, the infants' developmental quotients changed little between 12 and 36 months of age. Developmental progress was evident; however, with small incremental changes in raw scores for subjects over the course of the study. In three children, the developmental quotient changed by more than 20 points during the course of the study. The findings are considered in relation to the neurobiological risk factors for cognitive development in Tuberous Sclerosis.