Objectives: EEG abnormalities and neurocognitive deficits have been reported in patients with bipolar affective disorder. The aim of this study was to ascertain whether brain function remains impaired in young bipolar patients who have become euthymic in response to treatment.
Methods: Brain function was assessed by quantitative electroencephalographic (EEG) power-spectral mapping and by a battery of neuropsychological tests. The subjects were 29 euthymic bipolar patients aged 18-40 years and 26 healthy volunteers of similar age, IQ and socioeconomic status.
Results: Grand means of spectral power of the resting EEG showed significantly (from p < 0.01 to p < 0.0001) greater power in all wave bands (delta, theta, alpha and beta) in patients compared with controls. The most marked increases were in right temporal theta and left occipital beta power (with eyes open) encompassing brain areas concerned in visuospatial processing. Neurocognitive performance was significantly impaired in the patients compared with controls in a range of visuospatial tasks.
Conclusions: The findings show significant disturbance of EEG activity and deficits in visuospatial processing in young bipolar patients despite clinical euthymia. The abnormalities were not related to age of onset or duration of illness and do not appear to be attributable to medication. The cognitive impairments were associated with the number of previous affective episodes.