Electroconvulsive therapy as an anticonvulsant. Implications for its mechanism of action in affective illness

Differential plastic changes in synthesis and binding in the mouse somatostatin system after electroconvulsive stimulation

OBJECTIVE

Electroconvulsive therapy (ECT) is regularly used to treat patients with severe major depression, but the mechanisms underlying the beneficial effects remain uncertain. Electroconvulsive stimulation (ECS) regulates diverse neurotransmitter systems and induces anticonvulsant effects, properties implicated in mediating therapeutic effects of ECT. Somatostatin (SST) is a candidate for mediating these effects because it is upregulated by ECS and exerts seizure-suppressant effects. However, little is known about how ECS might affect the SST receptor system. The present study examined effects of single and repeated ECS on the synthesis of SST receptors (SSTR1-4) and SST, and SST receptor binding ([125I]LTT-SST28) in mouse hippocampal regions and piriform/parietal cortices.

RESULTS

A complex pattern of plastic changes was observed. In the dentate gyrus, SST and SSTR1 expression and the number of hilar SST immunoreactive cells were significantly increased at 1 week after repeated ECS while SSTR2 expression was downregulated by single ECS, and SSTR3 mRNA and SST binding were elevated 24 h after repeated ECS. In hippocampal CA1 and parietal/piriform cortices, we found elevated SST mRNA levels 1 week after repeated ECS and elevated SST binding after single ECS and 24 h after repeated ECS. In hippocampal CA3, repeated ECS increased SST expression 1 week after and SST binding 24 h after. In the parietal cortex, SSTR2 mRNA expression was downregulated after single ECS while SSTR4 mRNA expression was upregulated 24 h after repeated ECS.

CONCLUSION

Considering the known anticonvulsant effects of SST, it is likely that these ECS-induced neuroplastic changes in the SST system could participate in modulating neuronal excitability and potentially contribute to therapeutic effects of ECT.

Polymorphism of the brain-derived neurotrophic factor and dynamics of the seizure threshold of electroconvulsive therapy

During a course of electroconvulsive therapy (ECT), the level of currency necessary to induce an epileptic seizure in a patient may either remain relatively stable or-more often-may require repeated upward adjustment over time due to a constantly increasing seizure threshold. We aimed to determine whether a common polymorphism of the brain-derived neurotrophic factor (BDNF), which constitutes an important and ubiquitously expressed neurotrophine in the brain, affects the stimulation threshold of ECTs required to induce an epileptic seizure over time. Twenty-seven adult patients who underwent at least 12 consecutive ECT sessions were analyzed for the stimulation intensities required during the course of the stimulation as well as their BDNF gene status. We could not find a relation between the Val/Met polymorphism of the BDNF and the development of the seizure threshold during the course of the ECT sessions. Mechanisms and predispositions other than the BDNF polymorphism investigated in this study are responsible for the change in seizure thresholds over the course of ECT.

Propofol ameliorates electroconvulsive shock-induced learning and memory impairment by regulation of synaptic metaplasticity via autophosphorylation of CaMKIIa at Thr 305 in stressed rats

Electroconvulsive therapy (ECT) is an effective treatment for depression, but it can induce learning and memory impairment. Our previous study found propofol (γ-aminobutyric acid (GABA) receptor agonist) could ameliorate electroconvulsive shock (ECS, an analog of ECT to animals)-induced cognitive impairment, however, the underlying molecular mechanisms remain unclear. This study aimed to investigate the effects of propofol on metaplasticity and autophosphorylation of CaMKIIa in stressed rats receiving ECS. Depressive-like behavior and learning and memory function were assessed by sucrose preference test and Morris water test respectively. LTP were tested by electrophysiological experiment, the expression of CaMKIIa, p-T305-CaMKII in hippocampus and CaMKIIα in hippocampal PSD fraction were evaluated by western blot. Results suggested ECS raised the baseline fEPSP and impaired the subsequent LTP, increased the expression of p-T305-CaMKII and decreased the expression of CaMKIIα in hippocampal PSD fraction, leading to cognitive dysfunction in stressed rats. Propofol could down-regulate the baseline fEPSP and reversed the impairment of LTP partly, decreased the expression of p-T305-CaMKII and increased the expression of CaMKIIα in hippocampal PSD fraction and alleviated ECS-induced learning and memory impairment. In conclusion, propofol ameliorates ECS-induced learning and memory impairment, possibly by regulation of synaptic metaplasticity via p-T305-CaMKII.

Electroconvulsive therapy in catatonic patients: Efficacy and predictors of response

Recent evidence favors the view of catatonia as an autonomous syndrome, frequently associated with mood disorders, but also observed in neurological, neurodevelopmental, physical and toxic conditions. From our systematic literature review, electroconvulsive therapy (ECT) results effective in all forms of catatonia, even after pharmacotherapy with benzodiazepines has failed. Response rate ranges from 80% to 100% and results superior to those of any other therapy in psychiatry. ECT should be considered first-line treatment in patients with malignant catatonia, neuroleptic malignant syndrome, delirious mania or severe catatonic excitement, and in general in all catatonic patients that are refractory or partially responsive to benzodiazepines. Early intervention with ECT is encouraged to avoid undue deterioration of the patient's medical condition. Little is known about the long-term treatment outcomes following administration of ECT for catatonia. The presence of a concomitant chronic neurologic disease or extrapyramidal deficit seems to be related to ECT non-response. On the contrary, the presence of acute, severe and psychotic mood disorder is associated with good response. Severe psychotic features in responders may be related with a prominent GABAergic mediated deficit in orbitofrontal cortex, whereas non-responders may be characterized by a prevalent dopaminergic mediated extrapyramidal deficit. These observations are consistent with the hypothesis that ECT is more effective in "top-down" variant of catatonia, in which the psychomotor syndrome may be sustained by a dysregulation of the orbitofrontal cortex, than in "bottom-up" variant, in which an extrapyramidal dysregulation may be prevalent. Future research should focus on ECT response in different subtype of catatonia and on efficacy of maintenance ECT in long-term prevention of recurrent catatonia. Further research on mechanism of action of ECT in catatonia may also contribute to the development of other brain stimulation techniques.

Psychotropic management of seizure duration during electroconvulsive therapy: trazodone, a case report

The authors summarize a case wherein trazodone was utilized to maintain therapeutic seizure duration during electroconvulsive therapy (ECT) and review the literature in detail (36 references).

Frequency of and rationales for the combined use of electroconvulsive therapy and antiepileptic drugs in Austria and the literature

Our aim was to observe the frequency of combination therapy using antiepileptic drugs (AEDs) and electroconvulsive therapy (ECT) in Austria and the literature, and to provide rationales and recommendations based on clinical and molecular properties. The responsible ECT leaders of eight Austrian departments were contacted for information about combination therapy. A computerized PubMed database search was performed and supplemented by cross-referencing from papers, review articles and psychiatric manuals. The frequency of combination therapy in Austrian departments ranges between 0 and 85.7%. In 17 studies enrolling a total of 189 patients, 87 (46.0%) patients received combination therapy. Of these 87 patients, nine (10.3%) reported adverse effects. ECT and AEDs show overlapping clinical and molecular properties. Combination therapy is an observed reality and, according to the currently available literature, feasible. A comparison of clinical and molecular properties indicates possible augmentative effects, making combination therapy a promising alternative in treatment-resistant cases. But there is still a clear need for prospective case controlled data concerning side effects, safety profiles and effectiveness until it can be recommended.

Anticonvulsants during electroconvulsive therapy: review and recommendations

OBJECTIVES

To review the literature on the concurrent use of electroconvulsive therapy (ECT) and anticonvulsant drugs (AC) and to provide recommendations to guide clinical practice.

METHODS

A MEDLINE search (1985-2006) was performed, using the terms "electroconvulsive therapy," "anticonvulsants," "epilepsy," "carbamazepine," "gabapentin," "lamotrigine," "topiramate," and "valproate," supplemented by manual searches of guidelines and textbooks on ECT.

RESULTS

To date, no prospective, randomized and controlled trials examining outcome and safety of the AC-ECT combination have been published. Existing data are from case reports on the use of ECT for psychiatric conditions that are simultaneously treated with AC, and from case reports of patients treated with ECT and AC for epilepsy or for psychiatric conditions with comorbid epilepsy. Apart from an occasional difficulty in eliciting seizures, no severe adverse effects or complications are reported.

CONCLUSIONS

The literature that is currently available indicates that ECT can be safely and effectively administered to patients treated with various AC. There is, however, no evidence to combine the 2 treatment modalities to augment therapeutic efficacy.

Unaltered neuropeptide Y (NPY)-stimulated [35S]GTPgammaS binding suggests a net increase in NPY signalling after repeated electroconvulsive seizures in mice

Although electroconvulsive seizures (ECS) are widely used as a treatment for severe depression, the working mechanism of ECS remains unclear. Repeated ECS causes anticonvulsant effects that have been proposed to underlie the therapeutic effect of ECS, and neuropeptide Y (NPY) is a potential candidate for mediating this anticonvulsant effect. Repeated ECS results in prominent increases in NPY synthesis. In contrast, NPY-sensitive receptor binding is decreased, so it is unclear whether ECS causes a net increase in NPY signalling. Agonist-stimulated [35S]GTPgammaS binding is a method for detecting functional activation of G-protein-coupled receptors. The present study in mice examined the effects of daily ECS for 14 days on NPY-stimulated [35S]GTPgammaS functional binding and compared this with gene expression of NPY and NPY receptors as well as [125I]peptide YY (PYY) binding in hippocampus of the same animals. Significant increases in NPY mRNA and concomitant reductions in NPY-sensitive binding were found in the dentate gyrus, hippocampal CA1, and neocortex of ECS treated mice, which is consistent with previous rat data. These changes remained significant 1 week after repeated ECS. Significant increases in NPY Y1, Y2, and Y5 mRNA were found in the dentate gyrus after ECS. Surprisingly, unaltered levels of functional NPY receptor binding accompanied the decreased NPY-sensitive binding. This suggests that mechanisms coupling NPY receptor stimulation to G-protein activation could be augmented after repeated ECS. Thus increased synthesis of NPY after repeated ECS should result in a net increase in NPY signalling in spite of reduced levels of NPY-sensitive binding.

Evidências da eficácia da eletroconvulsoterapia na prática psiquiátrica

A eletroconvulsoterapia (ECT) consiste em tratamento biológico ainda não amplamente utilizado na prática psiquiátrica, devido aos inúmeros fatores que contribuem para uma resistência acerca do método. Objetivando sustentar, com embasamento científico, o emprego da ECT, agregamos evidências de sua eficácia, indicações, contra-indicações e efeitos adversos, advindas dos principais ensaios clínicos randomizados e meta-análises disponíveis na literatura médica atual sobre o tema (PubMed/MEDLINE, Cochrane).

Effects of psychotropic drugs on seizure threshold

Psychotropic drugs, especially antidepressants and antipsychotics, may give rise to some concern in clinical practice because of their known ability to reduce seizure threshold and to provoke epileptic seizures. Although the phenomenon has been described with almost all the available compounds, neither its real magnitude nor the seizurogenic potential of individual drugs have been clearly established so far. In large investigations, seizure incidence rates have been reported to range from approximately 0.1 to approximately 1.5% in patients treated with therapeutic doses of most commonly used antidepressants and antipsychotics (incidence of the first unprovoked seizure in the general population is 0.07 to 0.09%). In patients who have taken an overdose, the seizure risk rises markedly, achieving values of approximately 4 to approximately 30%. This large variability, probably due to methodological differences among studies, makes data confusing and difficult to interpret. Agreement, however, converges on the following: seizures triggered by psychotropic drugs are a dose-dependent adverse effect; maprotiline and clomipramine among antidepressants and chlorpromazine and clozapine among antipsychotics that have a relatively high seizurogenic potential; phenelzine, tranylcypromine, fluoxetine, paroxetine, sertraline, venlafaxine and trazodone among antidepressants and fluphenazine, haloperidol, pimozide and risperidone among antipsychotics that exhibit a relatively low risk. Apart from drug-related factors, seizure precipitation during psychotropic drug medication is greatly influenced by the individual's inherited seizure threshold and, particularly, by the presence of seizurogenic conditions (such as history of epilepsy, brain damage, etc.). Pending identification of compounds with less or no effect on seizure threshold and formulation of definite therapeutic guidelines especially for patients at risk for seizures, the problem may be minimised through careful evaluation of the possible presence of seizurogenic conditions and simplification of the therapeutic scheme (low starting doses/slow dose escalation, maintenance of the minimal effective dose, avoidance of complex drug combinations, etc.). Although there is sufficient evidence that psychotropic drugs may lower seizure threshold, published literature data have also suggested that an appropriate psychotropic therapy may not only improve the mental state in patients with epilepsy, but also exert antiepileptic effects through a specific action. Further scientific research is warranted to clarify all aspects characterising the complex link between seizure threshold and psychotropic drugs.

The ketogenic diet may have mood-stabilizing properties

The ketogenic diet, originally introduced in the 1920s, has been undergoing a recent resurgence as an adjunctive treatment for refractory epilepsy, particularly in children. In this difficult-to-treat population, the diet exhibits remarkable efficacy with two-thirds showing significant reduction in seizure frequency and one-third becoming nearly seizure-free. There are several reasons to suspect that the ketogenic diet may also have utility as a mood stabilizer in bipolar illness. These include the observation that several anticonvulsant interventions may improve outcome in mood disorders. Furthermore, beneficial changes in brain-energy profile are noted in subjects on the ketogenic diet. This is important since global cerebral hypometabolism is a characteristic of the brains of depressed or manic individuals. Finally, the extracellular changes that occur in ketosis would be expected to decrease intracellular sodium concentrations, a common property of all effective mood stabilizers. Trials of the ketogenic diet in relapse prevention of bipolar mood episodes are warranted.

Antiepileptic drugs: affective use in autism spectrum disorders

Antiepileptic drugs are widely administered to individuals with autistic spectrum disorders. There are several reasons for the use of antiepileptic drugs in autistic spectrum disorders, including the high incidence of epilepsy in these individuals, the anecdotal reports suggesting an improvement of communication and behavior in autistic subjects with epileptic discharges, and the increased awareness that some disruptive behaviors may be manifestations of an associated affective disorder. In this study, data on the current use of antiepileptic drugs in the treatment of autism, and on the association of affective disorders with epilepsy and autism, are reviewed. The evidence supporting the hypothesis that there may be a subgroup of autistic children with epilepsy and affective disorders that preferentially respond to antiepileptic drugs is still very preliminary, and further investigations with double-blind controlled studies are needed. Although the role of antiepileptic drugs at the present time is not established, there is evidence that autism, epilepsy, and affective disorders commonly co-occur, and that they may share a common neurochemical substrate, which is the common target of the psychotropic mechanism of action of different antiepileptic drugs.

ECT in bipolar and unipolar depression: differences in speed of response

OBJECTIVES

There is sparse evidence for differences in response to electroconvulsive therapy (ECT) between patients with bipolar or unipolar major depression, with virtually no information on speed of response. We contrasted a large sample of bipolar (BP) and unipolar (UP) depressed patients in likelihood and rapidity of clinical improvement with ECT.

METHODS

Over three double-blind treatment protocols, 228 patients met Research Diagnostic Criteria for UP (n = 162) or BP depression (n = 66). Other than lorazepam PRN (3 mg/day), patients were withdrawn from psychotropics prior to the ECT course and until after post-ECT assessments. Patients were randomized to ECT conditions that differed in electrode placement and stimulus intensity. Symptomatic change was evaluated at least twice weekly by a blinded evaluation team, which also determined treatment length.

RESULTS

Patients with BP and UP depression did not differ in rates of response or remission following the ECT course, or in response to unilateral or bilateral ECT. Degree of improvement in Hamilton Rating Scale for Depression scores following completion of ECT was also comparable. However, BP patients received significantly fewer ECT treatments than UP patients, and this effect was especially marked among bipolar ECT responders. Both BP I and BP II patients showed especially rapid response to ECT.

CONCLUSIONS

The BP/UP distinction had no predictive value in determining ECT outcome. In contrast, there was a large effect for BP patients to show more rapid clinical improvement and require fewer treatments than unipolar patients. The reasons for this difference are unknown, but could reflect a more rapid build up of anticonvulsant effects in BP patients.

EEG effects of ECT: implications for rTMS

Electroconvulsive therapy (ECT) involves the use of electrical stimulation to elicit a series of generalized tonic-clonic seizures for therapeutic purposes and is the most effective treatment known for major depression. These treatments have significant neurophysiologic effects, many of which are manifest in the electroencephalogram (EEG). The relationship between EEG data and the response to ECT has been studied since the 1940s, but for many years no consistent correlates were found. Recent studies indicate that a number of specific EEG features recorded during the induced seizures (ictal EEG) as well as before and after a course of treatment (interictal EEG) are related to both the therapeutic efficacy and cognitive side effects. Similar to ECT, repetitive transcranial magnetic stimulation (rTMS), which involves focal electromagnetic stimulation of cortical neurons, has also been studied as an antidepressant therapy and also appears to have neurophysiologic effects, although these have not been as fully investigated as is the case with ECT. Given the similarity of these treatments, it is natural to consider whether advances in understanding the electrophysiologic correlates of the ECT response might have implications for rTMS. The present article reviews the literature on the EEG effects of ECT and discusses the implications in terms of the likely efficacy and side effects associated with rTMS in specific anatomic locations, the potential for producing an antidepressant response with rTMS without eliciting seizure activity, eliciting focal seizures with rTMS, and the possibility of using rTMS to focally modulate seizure induction and spread with ECT to optimize treatment.

Electroconvulsive therapy in the treatment of neuropsychiatric conditions and transcranial magnetic stimulation as a pathophysiological probe in neuropsychiatry

It is a challenging task to review transcranial magnetic stimulation (TMS) studies in neuropsychiatric disorders alongside assessments of longstanding clinical applications of ECT as an empirical treatment. The task is challenging because TMS was developed as a probe of neural mechanisms, whereas, in marked contrast, ECT has been a clinical technique from its inception. Since the onset of modern psychopharmacology, the understanding of the potential applications of ECT to neuropsychiatric disorders is generally restricted to case reports of patients with intractable disease that have had at least a partial response to ECT. Studies of the possible efficacy of TMS in neuropsychiatric conditions have a significant advantage over ECT as the treatments are associated with less morbidity. The only serious known complication in TMS is a risk of seizures that may increase in patients with neuropsychiatric conditions such as course brain disease. Only cortical structures are themselves accessible to TMS using current technology. Present TMS techniques, however, seem capable of affecting activity in deeper brain structures that are functionally linked to cortical brain regions. TMS permits novel explorations of relationships between regional brain activity and symptoms of a number of neuropsychiatric disorders, as well as in research relating activity in functionally related brain regions to modulation of cognition and affective states in healthy individuals. This is particularly true at present because TMS and powerful neuroimaging and neuropsychological tools are all making rapid advances simultaneously.

Electroshocks delay seizures and subsequent epileptogenesis but do not prevent neuronal damage in the lithium-pilocarpine model of epilepsy

Electroconvulsive therapy, which is used to treat refractory major depression in humans increases seizure threshold and decreases seizure duration. Moreover, the expression of brain derived neurotrophic factor induced by electroshocks (ECS) might protect hippocampal cells from death in patients suffering from depression. As temporal lobe epilepsy is linked to neuronal damage in the hippocampus, we tested the effect of repeated ECS on subsequent status epilepticus (SE) induced by lithium-pilocarpine and leading to cell death and temporal epilepsy in the rat. Eleven maximal ECS were applied via ear-clips to adult rats. The last one was applied 2 days before the induction of SE by lithium-pilocarpine. The rats were electroencephalographically recorded to study the SE characteristics. The rats treated with ECS before pilocarpine (ECS-pilo) developed partial limbic (score 2) and propagated seizures (score 5) with a longer latency than the rats that underwent SE alone (sham-pilo). Despite this delay in the initiation and propagation of the seizures, the same number of ECS- and sham-pilo rats developed SE with a similar characteristic pattern. The expression of c-Fos protein was down-regulated by repeated ECS in the amygdala and the cortex. In ECS-pilo rats, c-Fos expression was decreased in the piriform and entorhinal cortex and increased in the hilus of the dentate gyrus. Neuronal damage was identical in the forebrain areas of both groups, while it was worsened by ECS treatment in the substantia nigra pars reticulata, entorhinal and perirhinal cortices compared to sham-pilo rats. Finally, while 11 out of the 12 sham-pilo rats developed spontaneous recurrent seizures after a silent period of 40+/-27 days, only two out of the 10 ECS-pilo rats became epileptic, but after a prolonged latency of 106 and 151 days. One ECS-pilo rat developed electrographic infraclinical seizures and seven did not exhibit any seizures. Thus, the extensive neuronal damage occurring in the entorhinal and perirhinal cortices of the ECS-pilo rats seems to prevent the establishment of the hyperexcitable epileptic circuit.

Seizure threshold rise during electroconvulsive therapy in schizophrenic patients

A rise in seizure threshold during a course of electroconvulsive therapy (ECT) has been demonstrated in patients with depression and mania, but no information has been available as to whether the same result occurs in schizophrenia. Ninety-three patients with schizophrenia underwent estimation of the seizure threshold by the dose-titration method, at the first and second, seventh, fourteenth, and twentieth treatments over an index ECT course. The 3-week stabilization period was used as a response criterion. Eighty-six patients (92%) showed a rise in threshold. The magnitude of increment was 269+/-244%. The rise in seizure threshold could be predicted by the number of treatments, initial seizure threshold and EEG seizure duration, and these factors explained 42% of the variance.

Synergism of lorazepam and electroconvulsive therapy in the treatment of catatonia

Electroconvulsive therapy (ECT) and lorazepam are effective treatments for catatonia. ECT combined with benzodiazepines has been associated with reduced efficacy and efficiency and therefore is not recommended in the routine practice of ECT. We report 5 prospectively identified cases of catatonia treated either sequentially or concurrently with lorazepam and ECT. In each case, the combination of lorazepam with ECT was superior to monotherapy. This apparent synergism, its possible mechanisms, and its implications for treating catatonia are discussed.

A speculative model of affective illness cyclicity based on patterns of drug tolerance observed in amygdala-kindled seizures

In this article, we discuss molecular mechanisms involved in the evolution of amygdala kindling and the episodic loss of response to pharmacological treatments during tolerance development. These phenomena allow us to consider how similar principles (in different neurochemical systems) could account for illness progression, cyclicity, and drug tolerance in affective disorders. We describe the phenomenon of amygdala-kindled seizures episodically breaking through effective daily pharmacotherapy with carbamazepine and valproate, suggesting that these observations could reflect the balance of pathological vs compensatory illness-induced changes in gene expression. Under certain circumstances, amygdala-kindled animals that were initially drug responsive can develop highly individualized patterns of seizure breakthroughs progressing toward a complete loss of drug efficacy. This initial drug efficacy may reflect the combination of drug-related exogenous neurochemical mechanisms and illness-induced endogenous compensatory mechanisms. However, we postulate that when seizures are inhibited, the endogenous illness-induced adaptations dissipate (the "time-off seizure" effect), leading to the re-emergence of seizures, a re-induction of a new, but diminished, set of endogenous compensatory mechanisms, and a temporary period of renewed drug efficacy. As this pattern repeats, an intermittent or cyclic response to the anticonvulsant treatment emerges, leading toward complete drug tolerance. We also postulate that the cyclic pattern accelerates over time because of both the failure of robust illness-induced endogenous adaptations to emerge and the progression in pathophysiological mechanisms (mediated by long-lasting changes in gene expression and their downstream consequences) as a result of repeated occurrences of seizures. In this seizure model, this pattern can be inhibited and drug responsivity can be temporarily reinstated by several manipulations, including lowering illness drive (decreasing the stimulation current), increasing drug dosage, switching to a new drug that does not show crosstolerance to the original medication, or temporarily discontinuing treatment, allowing the illness to re-emerge in an unmedicated animal. Each of these variables is discussed in relation to the potential relevance to the emergence, progression, and suppression of individual patterns of episodic cyclicity in the recurrent affective disorders. A variety of clinical studies are outlined that specifically test the hypotheses derived from this formulation. Data from animal studies suggest that illness cyclicity can develop from the relative ratio between primary pathological processes and secondary endogenous adaptations (assisted by exogenous medications). If this proposition is verified, it further suggests that illness cyclicity is inherent to the neurobiological processes of episode emergence and amelioration, and one does not need to postulate a separate defect in the biological clock. The formulation predicts that early and aggressive long-term interventions may be optimal in order to prevent illness emergence and progression and its associated accumulating neurobiological vulnerability factors.

The current status of seizure duration in the practice of electroconvulsive therapy

OBJECTIVE

To critically review data relating the seizure duration in electroconvulsive therapy (ECT) to its therapeutic effect in the treatment of depressive illness.

METHOD

The authors used MEDLINE, PSYCHINFO on CDROM, and their own knowledge of the literature to find studies or reviews concerning the role of seizure duration in ECT efficacy.

RESULTS

Rigorous studies cast doubt on the usefulness of seizure duration as a clinical marker. Some medications that decrease seizure time have deleterious treatment effects but also affect other seizure dynamics. Several medications dramatically shorten seizures but have no influence on treatment efficacy.

CONCLUSION

The guidelines of ECT seizure length are arbitrary, suggesting exaggerated durations for ECT treatment.

Prolonged induction of c-fos in neuropeptide Y- and somatostatin-immunoreactive neurons of the rat dentate gyrus after electroconvulsive stimulation

Induction of c-fos mRNA and Fos was studied in the hilus and granular layer of the dentate gyrus at various times up to 24 h after single electroconvulsive stimulation (ECS) using in situ hybridization and immunocytochemistry. In both areas of the dentate gyrus, a prominent induction of c-fos mRNA and Fos was observed. Compared to the granular layer, however, c-fos mRNA and Fos in hilar cells reached maximum later and remained elevated considerably longer. Several neurochemically distinct populations of hilar neurons have been described, some of which contain neuropeptide Y (NPY) and/or somatostatin (SS). Using double-labelling immunocytochemistry, we examined to what extent Fos was induced in these hilar neurons after ECS. Although a minor population of non-NPY non-SS cells displayed Fos induction early after ECS, prolonged induction of Fos almost exclusively occurred in NPY or SS neurons. The Fos-immunoreactive NPY or SS neurons only amounted to about 50% of the total hilar population of NPY or SS neurons. The present observations suggest that a subpopulation of hilar NPY and SS neurons may be central to the actions of electroconvulsive seizures in the dentate gyrus.

Seizure threshold in electroconvulsive therapy (ECT) II. The anticonvulsant effect of ECT

To measure the anticonvulsant effects of a course of electroconvulsive therapy (ECT), we used a flexible stimulus dosage titration procedure to estimate seizure threshold at the first and sixth ECT treatments in 62 patients with depression who were undergoing a course of brief pulse, constant current ECT given at moderately suprathreshold stimulus intensity. Seizure threshold increased by approximately 47% on average, but only 35 (56%) of the 62 patients showed a rise in seizure threshold. The rise in seizure threshold was associated with increasing age, but not with gender, stimulus electrode placement, or initial seizure threshold. Dynamic impedance decreased by approximately 5% from the first to the sixth ECT treatment, but there was no correlation between the change in dynamic impedance and the rise in seizure threshold. No relation was found between the rise in seizure threshold and either therapeutic response status or speed of response to the ECT treatment course. These findings confirm the anticonvulsant effect of ECT but suggest that such effects are not tightly coupled to the therapeutic efficacy of moderately suprathreshold ECT.

Kindling induces transient changes in neuronal expression of somatostatin, neuropeptide Y, and calbindin in adult rat hippocampus and fascia dentata

Fully hippocampus-kindled rats were examined 1 day and 1 month after the last stimulation for changes in somatostatin (SS)-, neuropeptide Y (NPY)-, and calbindin (CaBP)-immunoreactivity (ir) and SS- and NPY-mRNA in situ hybridization (ISH). One day after the last stimulation, there was marked, bilateral increase in SS- and NPY-ir in the outer part of the dentate molecular layer. The cell bodies of dentate hilar SS- and NPY-containing neurons, known to project to this area, also appeared to display increased immunoreactivity as well as an increased ISH signal for SS and NPY mRNA. Bilateral de novo expression of NPY-ir in dentate mossy fiber projection to dentate hilus and CA3 was also evident, but we noted no corresponding NPY-mRNA signal in the parent cell bodies, the dentate granule cells. After 1 month, the levels of NPY-ir and ISH signal appeared essentially normal. In contrast, the levels of SS apparently were decreased, although not yet normal. CaBP-ir was markedly and selectively reduced in dentate granule cell bodies, dendrites, and mossy fibers 1 day after the last stimulation, but after 1 month CaBP-ir appeared essentially normal. Because kindling, once established, is a permanent phenomenon, the observed transient changes in SS, NPY, and CaBP in specific hippocampal terminal fields and neuronal populations cannot be associated specifically with kindling. Rather, they relate to the repeated high-frequency stimulations and may serve as protective measures against deleterious effects of such stimulations.

TRH gene products are implicated in the antidepressant mechanisms of seizures

1. After a series of electroconvulsive seizures, levels of TRH-Gly (the immediate precursor of TRH) in four limbic regions correlate significantly and highly with increased swimming in the forced-swim test model of antidepressant efficacy. Only in hippocampus did TRH itself correlate with swimming. 2. After ECS, limbic forebrain regions differ in the relationship of TRH to its precursor peptides. This probably results from differences in the coordination of induction of TRH-processing enzymes, as well as differences in the level of prepro-TRH following seizures. 3. Sprague-Dawley rats that are partially kindled with corneal stimulation swim less in the forced-swim test, opposite to the effect seen with antidepressant agents. 4. Pyriform cortex is unique among the four limbic regions examined in showing decreased amounts of the TRH precursor following swim/stress. 5. Combining ECS with the forced-swim test of antidepressant effects creates a useful model for studying the involvement of TRH and its precursor peptides in both the antidepressant and anticonvulsant effects of controlled therapeutic seizures in the treatment of major depressive disorders. Regional differences between the effects of pinnate and corneal ECS on peptides and behavior support the idea that corneal ECS is a better model than pinnate ECS for human bitemporal ECT. 6. Together with recent results in other laboratories, our results suggest that a series of generalized seizures results in prolonged and increased release and action of TRH in limbic forebrain.

Transient decrease in calbindin immunoreactivity of the rat fascia dentata granule cells after repeated electroconvulsive shocks

Changes in hippocampal calbindin immunoreactivity were investigated after repeated electroconvulsive shocks. Adult rats were subjected to 10, 20, or 36 electroconvulsive shocks (50 mA, 0.5 seconds), given as on shock per day, 5 days a week. The rats were sacrificed and processed for calbindin immunohistochemistry 1, 2, and 30 days after the last electroconvulsive shock. In the rats receiving 10 or 20 electroconvulsive shocks, a selective reduction of the calbindin immunoreactivity of the dentate granule cell bodies, dendrites, and mossy fibers was noted 1 and 2 days after the last electroconvulsive shock. After 36 electroconvulsive shocks there was an almost complete loss of calbindin immunoreactivity from the granule cell bodies and dendrites, and the calbindin immunoreactivity of the mossy fibers was markedly reduced. Thirty days after the last of 36 electroconvulsive shocks, the calbindin immunoreactivity was back to normal. Besides demonstrating pronounced changes associated with repeated electroconvulsive shocks, the results confirm the transient nature of these changes.

Electroconvulsive shock (ECS) does not facilitate the development of kindling

1. For many years it has been discussed whether repeated electroconvulsive shock (ECS) may induce a lasting epileptogenic effect on the brain (i.e. a kindling effect). In the present study the authors investigated whether weekly ECS do exert such an effect. 2. Bipolar electrodes were implanted in amygdala of 32 rats. Following a two to three week recovery period the rats were randomly allocated to two groups. One group received 12 weekly ECS, the other 12 weekly sham-ECS. 3. Three months after the last ECS/sham-ECS, kindling was initiated. Daily stimulation, eliciting an EEG-afterdischarge was given to all the rats. The animals received a total of 15 stimulations. 4. ECS-pretreated animals did not kindle faster than the sham-group. The two groups reached stage 4 (clonic rearing) after 5.8 (ECS-group) and 5.7 (sham-group) stimulations, respectively. 5. The authors did not find a facilitated development of kindling following ECS, instead they observed a slight, yet statistically significant inhibition of the development of the maximally generalized kindling-seizure--the stage 5 seizure--in the ECS-group. 6.

IN CONCLUSION

The present study did not show a kindling effect of weekly ECS suggesting that kindling requires more than repeated elicitation of after-discharge.

EEG manifestations during ECT: effects of electrode placement and stimulus intensity

This study examined the ictal electroencephalographic (EEG) characteristics of four forms of electroconvulsive therapy (ECT) known to differ in efficacy. Previously, we demonstrated that titrated, low-dose right unilateral ECT reliably produces generalized seizures of adequate duration, but is remarkably weak in antidepressant effects. Using a new rating scale, we found that specific features of the ictal and immediate postictal EEG varied significantly with ECT stimulus intensity and electrode placement. The low-dose right unilateral condition differed from more effective forms of ECT in having the longest polyspike phase duration, averaging twice that of the other conditions; it was also the condition least likely to manifest bioelectric suppression immediately following seizure termination. In contrast, high-dose bilateral ECT--a treatment with particularly rapid antidepressant effects--resulted in the greatest peak slow-wave amplitude in both hemispheres. Total seizure duration did not differ among the four treatment conditions. These findings indicate that seizure duration is not a useful marker of therapeutic efficacy, and instead provide preliminary evidence that other features of the EEG may be more useful markers of treatment adequacy.

Electroconvulsive shock and lidocaine-induced seizures in the rat activate astrocytes as measured by glial fibrillary acidic protein

The effects of repeated electroconvulsive shock (ECS) and/or lidocaine treatment in the rat were studied by means of biochemical markers: GFAP (glial fibrillary acidic protein), NCAM (neural cell adhesion molecule), NSE (neuron specific enolase) and D3-protein. In adult rats given daily either ECS alone or in combination with lidocaine (experiment 1) we found that ECS significantly increased the concentration of the glial marker GFAP in limbic areas: hippocampus, amygdala, and piriform cortex. The maximal increase in GFAP was found in the piriform cortex (77%). In both piriform cortex and amygdala ECS also induced a significant decrease in D3-protein (a marker of mature synapses), but no change in NCAM (especially enriched in newly formed synapses). In piriform cortex the ratio between NCAM and D3-protein was significantly increased (4%) by ECS. The lidocaine treatment, which induced seizures in some of the animals, was without significant effect on the biochemical markers. However, multiple lidocaine-induced seizures (experiment 2) were found to be associated with a significant increase in GFAP in amygdala and piriform cortex. The study shows that seizures, whether electrically or pharmacologically induced, activate astrocytes in certain brain regions. This activation is especially pronounced in the piriform cortex and may be caused by a particularly marked synaptic vulnerability and remodeling in this area, as demonstrated by the increased NCAM/D3-ratio. Synaptic remodeling and activation of astrocytes may well influence brain function and could play a role in the chain of neurobiological events underlying the clinical effects of electroconvulsive therapy (ECT).

Does ECT permanently alter seizure threshold?

Recent research has raised the possibility that electroconvulsive therapy (ECT) results in a persistent elevation of seizure threshold among males. In this study, seizure threshold, quantified by the method of limits procedure, was assessed at the first and last treatments of 148 consecutive depressed patients. Patients with and without a prior history of ECT did not differ in seizure threshold at the first treatment, seizure duration at the first treatment or averaged across all treatments, or in the magnitude of the seizure threshold increase over the ECT course. No evidence was obtained that history of ECT was associated with alterations of seizure threshold or seizure duration.

Long-term effects of repeated electroconvulsive shock on exploratory behaviour and seizure susceptibility to lidocaine in rats

Electroconvulsive shock (ECS) has anticonvulsant properties while a proconvulsant effect has not, so far, been documented. In the present experiments, we determine whether repeated ECSs lead to an increased seizure susceptibility to lidocaine (lignocaine) in rats. Furthermore, we investigated whether ECS will cause prolonged changes in the locomotion and exploratory activity of the animals. Two groups of rats received 18 ECSs: the first group (ECS-WEEKLY) was given ECS once a week, the second (ECS-DAILY) once a day. A third group (ECS-SHAM) received only sham ECS. Five, as well as 10 weeks after the last ECS, the ECS-WEEKLY group made significantly fewer "hole visits" in an eight hole box than did the ECS-SHAM group. The ECS-DAILY group also made fewer hole visits than the ECS-SHAM group, but the difference was only significant ten weeks after the last ECS. No significant difference in locomotor activity was found. Twelve weeks after the last ECS, all rats received an injection of a high dose of lidocaine (65 mg/kg i.p.). ECS was observed to have a significant effect on the number of animals convulsing in response to the lidocaine challenge. Sixty percent (6/10) of the animals in the ECS-WEEKLY group and 20% (2/10) of those in the ECS-DAILY group convulsed, whereas none of the animals (0/12) in the ECS-SHAM group had convulsions. Thus, the present study shows that ECS may induce prolonged changes in the exploratory behaviour of rats and in their sensitivity to the convulsant effects of lidocaine.

Seizure threshold to lidocaine is decreased following repeated ECS (electroconvulsive shock)

Seizure susceptibility to lidocaine was investigated in rats which had received repeated ECS (electroconvulsive shock). In the first experiment three groups of rats received an ECS daily for 18 days, an ECS weekly for 18 weeks, and 18 sham treatments, respectively. Twelve weeks after the last ECS all rats received a lidocaine challenge (LC) in the form of an intraperitoneal (IP) injection of lidocaine (65 mg/kg). After the injection the animals were observed for occurrence of motor seizures. A total of 67% (10/15), 47% (7/15), and 0% (0/18) of the daily, weekly, and sham groups, respectively, had motor seizures in response to the LC. In the second experiment five groups of rats received an ECS daily for 0, 1, 6, 18, and 36 days, respectively. Eighteen weeks after the last ECS all rats received an LC and 0% (0/15), 13% (2/15), 20% (3/15), 53% (8/15), and 58% (7/12), respectively, developed seizures in response to the LC. In the third experiment two groups of rats received daily ECS and sham-ECS, respectively. Twenty-four hours after the last ECS all rats received an LC. A total of 60% (9/15) of the ECS group and 0% (0/10) of the sham-ECS group had seizures in response to the LC.(ABSTRACT TRUNCATED AT 250 WORDS)

Electroconvulsive therapy

The following position paper was approved by the Board of Directors of the Canadian Psychiatric Association on September 15,1992.

Elevated TRH levels in pyriform cortex after partial and fully generalized kindled seizures

In a previous study we reported significant elevations of TRH in neocortex, hippocampus and combined amygdala/pyriform cortex in rats 48 h after the last of a series of stage 5 kindled seizures. In the present study, to determine whether the increases in TRH were proportional to the intensity of the convulsions, and the degree of development of the kindling process, we compared the effects of partially kindled (stage 2) vs fully kindled (stage 5) seizures. As a further refinement, we examined separately the TRH responses in the pyriform, cingulate and frontal cortices. The responses were especially marked in the pyriform cortex, where TRH increased 7-fold after stage 5 kindled convulsions, compared with 2-fold increases after stage 2-3 seizures. Increases were seen in other cortical regions, as well, but only after stage 5 seizures. These findings are consistent with reports suggesting that the increases in brain TRH occurring after convulsions are aftereffects of the seizures, possibly representing homeostatic anticonvulsant responses, and that the pyriform cortex is a site that is uniquely activated by convulsions.

Effect of repeated versus single electroconvulsive seizures on adrenergic-mediated phosphatidylinositol hydrolysis in rat neocortex

Adrenergic-stimulated phosphatidylinositol (PI) hydrolysis was measured in cortical slices obtained from adult rats following electroconvulsive seizures (ECS). One group of animals received ECS daily for 15 days and a second group received a single ECS. Rats were then sacrificed at intervals of 15 min, 60 min, 4 h, and 24 h after the last ECS. Inositol 1-monophosphate (IP1) accumulation was transiently reduced (20%, P less than 0.01), at 15 min, in repeatedly shocked versus sham-shocked control animals. No changes were observed at later intervals nor at any time in rats submitted to a single ECS. These findings suggest that repeated but not single convulsive seizures transiently desensitize adrenergic-mediated PI metabolism. Although repeated ECS significantly increased the density (Bmax) of alpha 1 recognition sites in cortical slices at 15 min, 4 h, and 24 h, this upregulation was not coupled to a functional change in PI hydrolysis.

Are disturbances in lipid-protein interactions by phospholipase-A2 a predisposing factor in affective illness?

Current theories of affective disorders do not account for many of the biological markers replicated in patient studies. We link many biological findings in a reasonable physiological relationship, compatible with mechanisms of action of pharmacological and electroshock therapies for depression. We propose that excessive phospholipase-A2 (PLA2) activity disrupts membrane fluidity, composition, and therefore, the activity, of membrane-dependent proteins. Similar disruptions in these proteins are documented in depressed patients and can be accounted for by excessive PLA2 activity. This paradigm accounts for disturbances in the activity of Na-K-ATPase, beta2- and alpha2-adrenergic receptors, MAO, norepinephrine and serotonin uptake, and imipramine binding. Disturbances in other membrane-dependent proteins, tyrosine and tryptophan hydroxylase, can explain the biogenic amine hypothesis. Inhibition of glucocorticoid receptor and TRH receptor binding to their respective ligands by PLA2 may explain patient nonsuppression in the Dexamethasone Suppression Test and poor response in the TRH stimulation test. Physiological regulators of PLA2 activity; calcium, cortisol, estrogen, progesterone, and PGE2 are documented abnormalities in some patients with affective disorders and consistent with excessive PLA2 activity. Thus, postpartum depression and premenstrual tension syndrome may be described in the paradigm. The mechanisms of action of tricyclic antidepressants, lithium, electroconvulsive shock, and some novel antimanic agents can be described in terms of alterations of PLA2 activity. Interestingly, ethanol perturbs membrane fluidity and membrane-bound enzymes in a manner similar to excessive PLA2 activity. A hereditary factor predisposing patients to affective disorders may be a gene defect at either PLA2 or in its regulation.

Electroconvulsive shock (ECS) and the adenosine neuromodulatory system: effect of single and repeated ECS on the adenosine A1 and A2 receptors, adenylate cyclase, and the adenosine uptake site

The effect of a single electroconvulsive shock (ECS) (30 min and 24 h after treatment) and repeated ECS (10 once-daily) on the adenosine neuromodulatory system was investigated in rat cerebral cortex, cerebellum, hippocampus, and striatum. The present study examined the adenosine A1 receptor using N6-[3H]cyclohexyladenosine ([3H]CHA), the A2 receptor using 5'-N-[3H]ethylcarboxyamidoadenosine ([ 3H]NECA), adenylate cyclase using [3H]forskolin, and the adenosine uptake site using [3H]nitrobenzylthioinosine ([3H]NBI). At 30 min after a single ECS, the Bmax of the [3H]NBI binding in striatum was increased by 20%, which is in good agreement with the well-known postictal adenosine release. The Bmax of [3H]forskolin binding in striatum and cerebellum was increased by 60 and 20%, respectively. In contrast to earlier reported changes following chemically induced seizures, [3H]CHA binding was not altered postictally. At 24 h after a single ECS, there were no changes for any ligand in any brain region. Following repeated ECS, there was a 20% increase of [3H]CHA binding sites in cerebral cortex, which lasted for at least 14 days after the last ECS. [3H]Forskolin binding in hippocampus and striatum was 20% lowered 24 h after 10 once-daily ECS but had already returned to control levels 48 h after the last treatment. Evidence is provided that the upregulated adenosine A1 receptors are coupled to guanine nucleotide binding proteins and, furthermore, that this upregulation is not paralleled by an increase in adenylate cyclase activity as labeled by [3H]forskolin.

Chronic electroconvulsive shock and neurotransmitter receptors--an update

Electroconvulsive shock (ECS) produces many neurochemical alterations which may be related to its efficacy in the treatment of different psychiatric disorders. This review focuses particularly on experimental findings of CNS receptor changes in animals following chronic ECS and relates them to neurotransmitter and behavioral changes. Also, the pharmacological effect of other antidepressant treatment are compared. Possible mechanisms of action are discussed.

Transient changes in cortical alpha 1 adrenoceptors and seizure threshold following electroconvulsive seizures in rats

Alpha 1 adrenoceptor density (Bmax) is consistently decreased in actively spiking human cortical epileptic foci. Interpretation of these unique human data is limited because all surgical excisions are completed shortly after a period of active seizure discharge. To determine the temporal profile of seizure-induced changes in cortical alpha 1 adrenoceptors we examined rats primed by 15 daily electroconvulsive seizures (ECS). Since the noradrenergic system has an inhibitory effect on epileptic activity, we also measured the postictal rise in minimal ECS seizure threshold. Animals were sacrificed immediately before or at intervals after the last scheduled seizure. Cortical membranes were assayed using [3H]prazosin as specific radioligand. Repeated ECS produced an increase in the number of cortical alpha 1 sites from 4 to 24 h postictally, but following the last seizure there was a transient 'normalization' of alpha 1 receptor density which persisted for 3 h. The postictal ECS seizure threshold also remained elevated for a 2 h period. Both these transient postictal changes may in part result from activation of the central NA system. Decreased alpha 1 adrenoceptors in surgical specimens of spiking cerebral cortex may also be a secondary response to focal seizure activity.

Studies of dosage, seizure threshold, and seizure duration in ECT

Seizure threshold, defined as the minimal electrical dosage necessary to elicit adequate generalized seizure, was determined throughout the course of electroconvulsive therapy (ECT) in depressed patients randomly assigned to bilateral and right unilateral treatment, with brief pulse, constant current stimulation. In Study 1, it was found that seizure threshold may be more accurately measured using the unit of charge compared to the traditional unit of watt-second. In Study 2, it was found that seizure threshold was associated with seizure duration. Patients with high thresholds had shorter seizure durations. This indicated that the seizure threshold measure assesses in part functional neural activity. In Study 3, it was found that failure for seizure threshold to increase substantially over the course of ECT was associated with poor clinical outcome. In Study 4, it was found that electrical dosage at threshold was not related to magnitude of acute cognitive impairments. This suggested that the degree to which dosage exceeds threshold may be more strongly tied to adverse effects than the absolute dosage administered to patients. Implications of the data are discussed, particularly in relation to a hypothesized link between the anticonvulsant properties of ECT and its mechanism of therapeutic action.