Non-Gaussian behavior of the EEG in Down's syndrome suggests decreased neuronal connections.

Computer analyses of the electroencephalograms of normal children, and children with Down's syndrome who were mentally retarded, revealed differences in the distribution of amplitude between the two groups. Normal children, in the early postnatal period, generate EEG's which have a non-Gaussian distribution of amplitude that becomes increasingly Gaussian before one year of age and remains so throughout subsequent development. Conversely, the EEG's of children with Down's syndrome exhibit highly non-Gaussian properties at all ages studied. The EEG's of two mentally retarded autistic children did not show this property, so it is not merely a concomitant of mental retardation. The first-order Gaussian distribution may reflect the degree of inteneuronal coupling; since an increased number of connections on any neuron implies decreased functional dependence of that neuron on any other particular single neuron, the present evidence, which indicates stronger interneuronal coupling in mongoloids, suggests that Down's syndrome may be associated with incomplete postnatal development of interconnections between cortical neurons.