A dissociation between anterograde and retrograde amnesia after treatment with electroconvulsive therapy: a naturalistic investigation.

OBJECTIVE: The aim of the present study is to investigate the cumulative effects of a clinically determined course of electroconvulsive therapy (ECT) on anterograde and retrograde amnesia. In this study, mood and memory were examined in the context of a protocol driven by therapeutic response, rather than by preordained research criteria. METHODS: Twenty-two patients with major depressive disorder and 18 nondepressed controls were taught a series of faces and names before the initiation of ECT, and their retention of this information was examined after the end of treatment. Anterograde (ie, new learning) and retrograde memory (ie, recall of information learned before ECT) were assessed. Eleven ECT patients underwent unilateral (UL) stimulation, and 11 had a combination of UL and bilateral stimulation. Major depressive disorder patients and nondepressed controls participants were matched according to baseline memory abilities. Unilateral and unilateral/bilateral (UB) ECT patients were matched according to baseline depression and memory abilities. RESULTS: Treatment with ECT resulted in a dissociation between anterograde and retrograde memory; after treatment, major depressive disorder patients demonstrated significant retrograde amnesia, whereas there was no change in their anterograde memory. Unilateral and UB ECT patients performed equally well on tasks of anterograde memory. Contrary to our expectation, UB ECT was not associated with greater retrograde memory loss than was UL ECT treatment. However, a trend toward a group difference was present on 1 memory measure. CONCLUSIONS: Results of the study suggest that a clinical course of ECT is associated with isolated impairment for information learned before treatment (ie, retrograde memory), whereas there was no effect of ECT on posttreatment learning abilities (ie, anterograde memory).

An open-label, prospective study of repetitive transcranial magnetic stimulation (rTMS) in the long-term treatment of refractory depression: reproducibility and duration of the antidepressant effect in medication-free patients.

OBJECTIVE: Several studies have assessed the acute antidepressant effects of repetitive transcranial magnetic stimulation (rTMS), and many have revealed positive results. However, the impact of rTMS throughout the long course of major depressive disorder (MDD) and the efficacy of rTMS in the treatment of depressive relapses still remain to be elucidated. METHOD: Sixteen medication-free patients with refractory MDD (diagnosed according to DSM-IV) who initially had clinically significant antidepressant responses to a 10-day course of 10-Hz rTMS were consecutively admitted to the protocol from 1997 to 2001 and were followed for 4 years. The cohort was studied during a total of 64 episodes of depressive relapse. Severity of depression was evaluated with the Hamilton Rating Scale for Depression (HAM-D) and the Beck Depression Inventory (BDI) prior to and after completion of each rTMS treatment course. Clinically significant response was defined as a reduction in HAM-D score of at least 50%. Safety was assessed by serial neurologic examinations and neuropsychological evaluations. RESULTS: Approximately one half of the patients individually sustained a clinically significant response to the repeated courses of rTMS; the mean +/- SD decrease in HAM-D scores was 64.8% +/- 12.6% (p < .0001), and, in BDI scores, 60.4% +/- 20.6% (p < .0001). Despite the lack of adjuvant antidepressant medication, the mean interval between treatment courses was approximately 5 months, and the medication-free period ranged from 26 to 43 months. Transcranial magnetic stimulation was well tolerated, and evaluations regarding the safety of the repeated applications of rTMS revealed no findings of concern. CONCLUSIONS: Repeated rTMS applications have demonstrated a reproducible antidepressant effect in patients with refractory depression who initially showed a clinically significant benefit. The duration of effect varied across patients, but benefits were sustained for a mean of nearly 5 months. Further studies with larger cohorts will be useful in determining the long-term effectiveness of rTMS maintenance therapy.

Relative effects of repetitive transcranial magnetic stimulation and electroconvulsive therapy on mood and memory: a neurocognitive risk-benefit analysis.

OBJECTIVE: Two procedures for treating major depressive disorder were compared with regard to their respective effects on mood and cognition. BACKGROUND: Fourteen patients underwent treatment with electroconvulsive therapy and 14 underwent treatment with repetitive transcranial magnetic stimulation. Patients were tested on three occasions: before initiation of treatment, at the end of treatment, and 2 weeks after the end of treatment. METHODS: Electroconvulsive therapy was applied unilaterally approximately three times per week for 2 to 4 weeks. Repetitive transcranial magnetic stimulation was applied in sessions of 1600 stimuli at 10 Hertz and 90% of motor threshold intensity to the left dorsolateral prefrontal cortex daily (Monday through Friday) for 2 consecutive weeks. RESULTS: Results indicate that electroconvulsive therapy had a more positive effect on mood than did a 2-week trial of repetitive transcranial magnetic stimulation. With regard to cognitive outcome measures, electroconvulsive therapy exerted a deleterious but transient effect on various components of memory that were no longer detected 2 weeks after the end of treatment; however, there was evidence of persistent retrograde amnesia after treatment with electroconvulsive therapy. As a group, repetitive transcranial magnetic stimulation patients experienced only a modest reduction in depression severity but there was no evidence of anterograde or retrograde memory deficits in the aftermath of treatment with repetitive transcranial magnetic stimulation. CONCLUSIONS: Findings suggest that electroconvulsive therapy is associated with transient negative cognitive side effects, most of which dissipate in the days after treatment. Deficits of this sort are not apparent after treatment with a 2-week course of repetitive transcranial magnetic stimulation.

Correlation of cerebral blood flow and treatment effects of repetitive transcranial magnetic stimulation in depressed patients.

The aims of this study were to: (1) assess the effects of repetitive transcranial magnetic stimulation (rTMS) on brain activity in depressed patients as measured by single photon emission tomography (SPECT); (2) evaluate the predictive value of brain SPECT on the antidepressant efficacy of rTMS. Patients (n=17) received 1600 rTMS stimuli at a rate of 10 Hz, 5 days per week for 2 weeks to the left dorsolateral prefrontal cortex. Whole brain SPECT data were acquired using Tc99m-Bicisate. Regional cerebral blood flow (rCBF) was correlated with the % change in the 28-item Hamilton Depression Rating Scale Score (Delta-HDRS) and a semiquantitative region of interest (ROI) analysis was conducted. Prior to rTMS there was a significant left-right asymmetry favoring the right, whereas 2 weeks after the rTMS treatment this asymmetry was reversed. The rCBF in limbic structures was negatively correlated with the outcome and rCBF in several neocortical areas was positively correlated. Brain SPECT can provide information about mechanisms of action of rTMS and may have predictive value for the antidepressant efficacy of rTMS.

Inter- and intra-individual variability of paired-pulse curves with transcranial magnetic stimulation (TMS).

OBJECTIVES: Previous studies have evaluated the variability of motor thresholds (MTs) and amplitude of motor-evoked potentials (MEPs) to transcranial magnetic stimulation (TMS) within and across individuals. Here we evaluate the reproducibility and inter-hemispheric variability of measures of cortical excitability using the 'conventional' paired-pulse (PP) TMS technique. METHODS: We studied PP curves of the left and right hemisphere in 10 healthy subjects on two separate days 2 weeks apart. The inter-stimulus intervals studied were 1, 3, 6, 8, 10 and 12 ms with the conditioning stimulus being 80% of the resting MT, and a single test stimulus producing MEPs of approximately 0.8 mV peak-to-peak amplitude. RESULTS: As a group, the PP curves of the left and right hemispheres, and of Day 1 and Day 2 were not significantly different. The intracortical inhibition (ICI), but not the intracortical facilitation, showed a good correlation across days within the individuals. CONCLUSIONS: Cortical excitability, particularly ICI, measured by PP TMS shows no inter-hemispheric asymmetry and is reproducible within individuals.