Quantitative electroencephalography in late-onset schizophrenia

Background and Objectives: A variety of electroencephalogram (EEG) abnormalities may occur in schizophrenics who had a typical onset of the disorder in early adulthood. The purpose of this study was to investigate EEG findings in patients with late-onset schizophrenia (onset of illness between ages 40 and 60). Methods: Ten patients (one male, nine female, average age 52.8 years old) with late-onset schizophrenia underwent magnetic resonance imaging (MRI) of the brain and recording of quantitative EEG. Results: MRI results for seven of the subjects were within normal limits and the other three showed nonspecific changes. Quantitative analysis of EEG variables revealed that for eight of the subjects, absolute power and relative power for the four EEG frequency bands, overall mean frequency, mean frequency for each of the EEG frequency bands, and interhemispheric coherence values did not vary significantly from a normative database of age-matched normal subjects. Conclusions: Results obtained to some degree replicate the single previous EEG study of late-onset schizophrenia. These findings suggest that the neurophysiological etiology and mechanism of late-onset schizophrenia may differ from that of schizophrenia with a typical age of onset, and that brain abnormalities are not an inevitable accompaniment to late onset of schizophrenia.