Neurophysiological and neuropsychological differences related to performance and verbal abilities in subjects with mild intellectual disability.
The present study compared two group of subjects with intellectual disability. The 44 subjects in group 1 had equivalent verbal and performance IQs (67 and 64, respectively), while the 12 subjects in group 2 had an intellectual performance IQ which was > or = 10 points above their verbal performance IQ (80 and 65, respectively). The second group showed an alpha peak at a higher frequency and an evoked potential closer to normality. The decrease in the voltage of the P300 wave in group 1 was especially significant. The cognitive evoked potentials were also different between the two groups.