Change in barbiturate anaesthetic sensitivity as a prognostic indicator of electroconvulsive therapy outcome

Barbiturate anaesthesia is modulated by brain noradrenergic (NA) function. As derangement of NA pathways is postulated to occur in depression, changes in anaesthetic sensitivity measured as producing loss of eyelash reflex were monitored in 29 depressed patients throughout a course of electroconvulsive therapy (ECT). Patients thus monitored were followed for 12 months after completing treatment. An increase in barbiturate induction dose over a course of ECT, indicating a decrease in anaesthetic sensitivity, was a powerful predictor of maintained wellbeing. All patients who increased their sensitivity to the anaesthetic either failed to respond to the course of ECT or relapsed within 12 months. The possible mechanism for this is discussed.