A Longitudinal Pilot Investigation of Neuropsychological Performance Associated with Electroconvulsive Therapy in Late Life Depression

Introduction: Previous investigations have assessed global cognitive scores or a single cognitive domain in the context of electroconvulsive therapy (ECT) in the elderly, but the specific cognitive domains that affected by electroconvulsive therapy are poorly understood. The present investigation used neuropsychological assessment to delineate the specific cognitive domains that are affected by treatment with ECT in late-life major depressive disorder (MDD). We hypothesized that ECT response would result in improvement in specific domains of cognitive functioning. Methods: Thirteen subjects (5 males and 8 females, average age 67.15 (+/8.93) years) with MDD met the following inclusion criteria: 1) DSM-IV TR diagnosis ofMDD; 2) the clinical indications for ECT including treatment resistance and a need for a rapid and definitive response; and 3) a Hamilton Depression Rating Scale-24 item (HDRS 24) > 21. The pre-ECT assessment was administered less than two days before the ECT series, and the post-ECT assessment was administered greater than five days after completing the ECT series. A Thymatron System IV delivered a right unilateral (n 1⁄4 11) or bitemporal ECT (n 1⁄4 2) stimulus delivery with a constant-current, brief pulse (0.50milliseconds (ms)). Seizure threshold obtained during the first sessionwith a dose titrationmethod guided subsequent stimulus dosage (6 threshold for right unilateral, 2 threshold for bitemporal). Treatments occurred thrice weekly until adequate clinical response or clinical decision to stop treatment in the context of non-response (11.17 +/3.33 sessions in the series). Depression was assessed with the Hamilton Depression Rating Scale 24-item (HDRS-24). The neuropsychological assessment included and the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS; Randolf, 1998) and the Trails Making Test, Parts A and B (Trails A, B; Reitan, 1958). The RBANS measures several cognitive domains including immediatememory, visuospatial/construction, language, delayedmemory, and a total cognitive score. Trails A measures attention and processing speed, and Trails Bmeasures executive functioning.We used paired t-tests to test the hypothesis that longitudinal improvement in specific cognitive domains would occur with ECT response. Results: Subjects had a reduction in symptom severity as measured by the HDRS-24 (t121⁄4 8.52, p 0.05). Furthermore, subtracting the Trails B raw data (seconds) from Trails A did not show any change pre-/post-ECT. Pairwise correlations between changes in the pre-/post HDRS-24 and RBANS IM and the four learning trials of the RBANS verbal declarative memory task were not significant (p > 0.05). Conclusions: Subjects with MDD whose mood symptoms were reduced with ECT had a non-significant improvement in RBANS immediate memory. The pattern of larger differences in the first learning trial relative to the latter trials suggests an improvement in attention with ECT response. As depression episodes resolved, subjects did not experience global or specific cognitive impairments. We attribute this pattern of results to the following factors: 1) the reduction in depression symptomatology and 2) the time period between completion of the ECT series and the post-ECT neuropsychological assessment (> 5 days). The delay in the post-ECT assessment minimized the immediate effect of the seizure from sustained cognitive changes. Future work will include a larger sample size and a mixture of ECT responders and non-responders to test the hypothesis that resolution of a depressed episode is associated with cognitive improvement in the context of ECT response.