Cognitive change and assessment during electroconvulsive therapy : a thesis presented in partial fulfillment of the requirements for the degree of Doctor of Clinical Psychology at Massey University, Wellington, New Zealand

Abstract

Electroconvulsive therapy (ECT) is the most effective treatment available for depression; however, cognitive side effects limit its use. If detected early in treatment, cognitive decline can be reduced by modifying the way the treatment is administered. Currently, no gold standard measures exist to assess ECT related cognitive change. The studies within this thesis aimed to improve the standard in which cognition is assessed during a course of ECT. Study One surveyed health professionals across New Zealand on their current practice of cognitive assessment during ECT. Study Two collected normative data for a neuropsychological measure of motor speed which had potential to be included in a cognitive screening measure for use with people receiving ECT. Study Three prospectively investigated objective cognitive changes in 13 people receiving electroconvulsive therapy for a mood disorder. Study Four investigated the subjective cognitive changes by qualitatively analysing patients’ reports of cognitive function throughout treatment. Finally, a brief but comprehensive cognitive screening measure was proposed for repeated use with patients receiving ECT. This measure was largely informed by findings from the aforementioned studies. Time, resources and a lack of sensitive tests restricted professionals from conducting more frequent and thorough cognitive assessments. ECT resulted in both cognitive decline and improvement across a range of cognitive domains. Alleviation in depression was associated with improvement in cognitive function from baseline. Six weeks post ECT, cognitive decline most often resolved back to or was superior to the baseline functioning. Domains sensitive to decline during a course of treatment included retrograde memory, anterograde memory, verbal and visual learning, attention, verbal fluency and information processing speed. Retrograde amnesia was more likely for memories formed closer in time to ECT treatment. Subjective reports of cognitive change were broad, and varied as a function of treatment phase and severity of depression. It is proposed that future research determine the psychometric properties of the suggested screening measure.