A Comparison of the Effects on Depression and Memory of Bilateral E.C.T. and Unilateral E.C.T. to the Dominant and Non-Dominant Hemispheres

¹ Consultant in Clinical Neurophysiology, National Hospital, Queen Square, London. Member of the External Staff of the Medical Research Council
² Consultant Psychiatrist, Department of Psychological Medicine, Newcastle upon Tyne. Psychiatric Registrar, National Hospital, Queen Square, London
³ Consultant Psychiatrist, Brookwood Hospital, Woking, Surrey. Assistant Psychiatrist, Netherne Hospital
⁴ Consultant Psychotherapist, Halliwick Hospital, London. Senior Registar in Psychiatry to Westminster and Netherne Hospitals

Fifty-two depressed patients, for whom E.C.T. had been prescribed, were randomly assigned to one of three treatment groups, receiving a standardized course of four E.C.T. at half-weekly intervals, given unilaterally to the right or left hemisphere, or bilaterally with conventional bifrontal electrodes. All patients were under 65, right-handed, without sinistrality in the family, and without any evidence of organic brain damage.

Depression was rated in a double-blind situation, both by a psychiatrist and by the patients themselves, before and after the treatments and again three months later following a variable amount of further treatment. There was no significant difference in the effect on depression of the three types of E.C.T. However, the speed of immediate recovery after E.C.T. was very significantly faster with unilateral E.C.T., and more so with unilateral E.C.T. to the right hemisphere than to the left. The fit produced by unilateral E.C.T. was preponderantly or wholly contralateral in about a third of the cases so treated.

A non-significant trend to a more immediate response to bilateral E.C.T. at 2 weeks was not confirmed at the three months' assessment, when the trend was for the best response to be obtained with unilateral treatment to the right hemisphere. Unilateral E.C.T. to the dominant left hemisphere appeared more unfavourable than the other two treatments, a significantly greater number of patients relapsing and dropping out of the trial while on this treatment.

Half a week after the four treatments verbal learning was selectively impaired by E.C.T. to the dominant hemisphere, and non-verbal learning by E.C.T. to the non-dominant hemisphere. Bilateral E.C.T. produced an intermediate pattern of impairment except on the verbal tests, which were less severely impaired than for either of the other two types of E.C.T. After three months the verbal memory impairment was still present in the patients who had received dominant hemisphere E.C.T., but the impairment of non-verbal memory appeared to be more persistent after bilateral E.C.T. than after unilateral E.C.T. to the non-dominant hemisphere.

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