Is EEG a useful test in adult psychiatry?

We present a brief overview of the use of EEG in psychiatry, with particular emphasis on differential diagnosis examination in case of acute psychiatric conditions.

The article is based on a literature search in PubMed and the authors' own collections of articles and personal experience.

Onset of epilepsy, encephalitis or other cerebral diseases may be accompanied by psychiatric or cognitive symptoms. Slow EEG activity may be an unspecific sign of cerebral disease. Psychiatric patients are also at an increased risk of epilepsy. In case of seizure symptoms such as convulsions or conditions with rapid changes in affective states, epileptiform activity during EEG is a specific sign of epileptic aetiology or comorbidity. Quantitative frequency analysis (QEEG) is useful for research purposes and in exceptional cases also in a clinical context. No QEEG method has as yet become accepted as providing reliable, independent markers for psychiatric disease or treatment response.

EEG should be undertaken in case of newly occurring psychoses and for conditions with a fluctuating or progradiating loss of cognitive function. Adult psychiatric patients with seizure symptoms or rapid changes in affective states should also be referred to EEG.