Intermittently occurring right-posterior slow waves (IRP) in psychiatric patients. An electroencephalographic indicator of cerebral dysfunction.

Intermittent right-posterior accentuated slow waves (irregular theta and/or delta waves: IRP phenomenon) in the EEG showed an incidence of about 5% in the total in-patients of a psychiatric university hospital. The IRP phenomenon was found in 7.5% of patients with schizophrenic psychoses, 2% of patients with affective psychoses and in 2.4% of patients with neurotic and personality disorders. The IRP groups differed from control groups in a number of sociobiographical and clinical characteristics. Having repeatedly confirmed these relationships with different samples, we regard IRP patients, irrespective of the diagnosis given, as having a maturational deficit of brain function.