Pathophysiology of Rett syndrome from the standpoint of early catecholamine disturbance.

The polysomnography of Rett syndrome (RS) revealed early disturbance, hypofunctioning, of the noradrenaline, serotonin, and dopamine neurons. Neuropathologically, early lesions of the dopamine neurons in the pars compacta of the substantia nigra and the ventrotegmental areas were observed. These aminergic neurons have roles in the functional maturation of their targets in the brain and for synaptogenesis of the cortex at critical ages. Early hypofunctioning of the dopamine neurons results in receptor supersensitivity of the receptors, which could cause the characteristic clinical features of RS in which particular signs and symptoms appear age dependently. The correlating lesions of the cholinergic neurons in the Meynert basal nucleus might relate to the deterioration of higher cortical function which becomes apparent from early childhood.