The authors thank J.H.A.M. Tuerlings, MD, PhD, for critically reviewing the manuscript.
References
(1) Malitz S, Sackeim HA, Decina P. ECT in the treatment of major affective disorders: clinical and basic research issues. Psychiatr J Univ Ottawa 1982;7.
(2) Abrams R. Electroconvulsive Therapy. Fourth edition. New York, NY: Oxford University Press; 2002. (3) Coffey CE. The Clinical Science of Electroconvulsive Therapy. Washington DC: American Psychiatric
Press Inc; 1993.
(4) Abrams R. Stimulus titration and ECT dosing. J ECT. 2002;18:3-9.
(5) Sackeim HA, Prudic J, Devanand DP et al. Effects of stimulus intensity and electrode placement on the efficacy and cognitive effects of electroconvulsive therapy. N Engl J Med 1993;328:839-846. (6) Welch CA, Drop LJ. Cardiovascular effects of ECT. Convuls Ther 1989;5:35-43.
(7) Lisanby SH, Devanand DP, Nobler MS, et al. Exceptionally high seizure threshold: ECT device limitations. Convuls Ther 1996;12:156-164.
(8) Bush G, Fink M, Petrides G, et al. Catatonia. I. Rating scale and standardized examination. Acta Psychiatr Scand 1996;93:129-136.
(9) American Psychiatric Association. The Practice of Electroconvulsive Therapy. Second Edition. Washington DC: American Psychiatric Association; 2001.
(10) Lurie SN, Coffey CE. Caffeine-modified electroconvulsive therapy in depressed patients with medical illness. J Clin Psychiatry 1990;51:154-157.
(11) Sackeim HA. Are ECT devices underpowered? Convuls Ther 1991;7:233-236.
(12) Boylan LS, Haskett RF, Mulsant BH et al. Determinants of seizure threshold in ECT: benzodiazepine use, anesthetic dosage, and other factors. J ECT 2000;16:3-18.
(13) Shapira B, Lidsky D, Gorfine M, et al. Electroconvulsive therapy and resistant depression: clinical implications of seizure threshold. J Clin Psychiatry 1996;57:32-38.
(14) Lisanby SH, Bazil CW, Resor SR, et al. ECT in the treatment of status epilepticus. J ECT 2001;17:210- 215.
(15) Khalid N, Atkins M, Kirov G. The effects of etomidate on seizure duration and electrical stimulus dose in seizure-resistant patients during electroconvulsive therapy. J ECT 2006;22:184-188. (16) Luchowska E, Luchowski P, Wielosz M, et al. Propranolol and metoprolol enhance the anticonvulsant
action of valproate and diazepam against maximal electroshock. Pharmacol Biochem Behav 2002;71:223-231.
(17) Girish K, Gangadhar BN, Janakiramaiah N, et al. Seizure threshold in ECT: effect of stimulus pulse frequency. J ECT 2003;19:133-135.
(18) Kotresh S, Girish K, Janakiramaiah N, et al. Effect of ECT stimulus parameters on seizure physiology and outcome. J ECT 2004;20:10-12.
(19) Datto C, Rai AK, Ilivicky HJ, et al. Augmentation of seizure induction in electroconvulsive therapy: a clinical reappraisal. J ECT 2002;18:118-125.
(20) Krystal AD, Watts BV, Weiner RD, et al. The use of flumazenil in the anxious and benzodiazepine- dependent ECT patient. J ECT 1998;14:5-14.
(21) Pisani F, Oteri G, Costa C, et al. Effects of psychotropic drugs on seizure threshold. Drug Saf 2002;25:91-110.
(22) Gilabert E, Rojo E, Vallejo J. Augmentation of electroconvulsive therapy seizures with sleep deprivation. J ECT 2004;20:242-247.
(23) Hillbom M, Pieninkeroinen I, Leone M. Seizures in alcohol-dependent patients: epidemiology, pathophysiology and management. CNS Drugs 2003;17:1013-1030.
(24) Chung KF. Determinants of seizure threshold of electroconvulsive therapy in Chinese. J ECT 2006;22:100-102.
(25) Swartz CM. Stimulus dosing in electroconvulsive therapy and the threshold multiple method. J ECT 2001;17:87-90.
(26) Bough KJ, Valiyil R, Han FT, et al. Seizure resistance is dependent upon age and calorie restriction in rats fed a ketogenic diet. Epilepsy Res 1999;35:21-28.
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(27) Sackeim HA, Decina P, Portnoy S, et al. Studies of dosage, seizure threshold, and seizure duration in ECT. Biol Psychiatry 1987;22:249-268.
(28) Mueller PS, Barnes RD, Varghese R, et al. The safety of electroconvulsive therapy in patients with severe aortic stenosis. Mayo Clin Proc 2007;82:1360-1363.
4
Jeroen A. van Waarde Rose C. van der Mast
Current Psychiatry Reviews 2010;6:184-190
ELDERLY
PATIENTS
TREATED
WITH
ELECTROCONVULSIVE
THERAPY
FOR
MAJOR
Abstract
Background: Electroconvulsive therapy (ECT) is effective and generally safe in depression. Its effectiveness and side effects are suggested to be related to the electrical stimulus administered relative to the seizure threshold. Since aging seems to raise the seizure threshold in ECT, we reviewed the literature for evidence correlating advanced age and seizure threshold, and for hypotheses explaining why seizure thresholds might raise with age.
Methods: Pubmed, PsychINFO, three standard works on ECT, and cross-references were searched for studies investigating seizure thresholds and/or associated factors in elderly depressed patients.
Results: A total of 406 possibly relevant articles were found, of which 27 studies
could be included. One very recently published study was included afterwards because of its significance. Aging was moderately associated with a raised initial seizure threshold with correlation coefficients ranging from 0.30 to 0.64 (P<0.05). Also, seizure thresholds in elderly patients were more likely to raise during the ECT course. Reported hypotheses for these clinical phenomena include a decrease of neuroexcitability, changes in morphologic and functional characteristics of the brain, somatic comorbidity, and concomitant medication use.
Conclusions: To optimize ECT in elderly patients, hypotheses and suggestions for further research are proposed regarding the moderate correlation between advanced age and initial seizure threshold and the rise in seizure threshold during the ECT course.
4
Introduction
Electroconvulsive therapy (ECT) is an effective treatment for late life depression.1
Also in other severe psychiatric conditions (e.g., catatonia, malignant neuroleptic syndrome, intractable psychosis, mania and delirium) ECT can be worthwhile and even lifesaving in elderly patients.2 In old age, treatment of depression is often
complicated by somatic comorbidity and polypharmacy, whereas transient post-ictal confusion, cardiovascular problems and falls are the most serious side-effects of ECT.3,4 Even in patients aged >75 years, ECT is generally safe when
carefully monitored and when its side-effects are balanced against the risks of untreated depression and complications of psycho-pharmacotherapy.3
Effectiveness and side-effects of ECT seem to be related to the administered electrical stimulus dose and electrode placement.2 The electrical stimulus must
exceed the seizure threshold to elicit a sufficient seizure,5 whereas subconvulsive
stimulation may cause bradycardia and asystole.6 Seizure threshold has been
defined as the smallest electrical stimulus dose that is necessary to produce a generalized seizure of at least a 25-30 seconds on EEG.2 In addition, the extent of
the electrical dose above the individual seizure threshold, rather than the absolute electrical dose, was suggested to be associated with short-term cognitive side-effects.7 For example, patients aged > 50 years who fail to respond to moder-
ate-charge right unilateral ECT, may benefit from high-charge right unilateral stimulation rather than from bilateral ECT, with less cognitive side-effects.8
Although not studied extensively, it is established that seizure thresholds vary substantially between patients. Several factors are known to increase seizure threshold and in clinical practice higher seizure thresholds seem to occur more often in elderly patients, especially in elderly men.9-11
To decide on the proper electrical dose for a patient, the empirical dose-titration method that determines the actual initial seizure threshold may be used to calculate individualized ‘moderate’ or ‘high above’ seizure threshold stimulation. In clinical practice, an ‘age-based’ method is often used to estimate the electrical dose that sufficiently exceeds the seizure threshold, based on the assumption that increasing age raises the seizure threshold.12 However, the precise relationship
between age and age-associated factors on the one hand and seizure threshold on the other hand is unknown. Therefore, we reviewed the literature for evidence correlating advanced age and seizure threshold in depressed patients, and for hypotheses explaining why seizure thresholds might raise with age.
Method
Medline (Pubmed, National Library of Medicine, http://www.ncbi.nlm.nih.gov) and PsychINFO (American Psychological Association, 2007) were searched for articles that were published from 1966 through March 2008 (see Figure 1 for the search strategy). All retrieved titles and abstracts (n=406) were investigated. Studies exploring seizure thresholds and/or associated factors in elderly patients were included in this review. In addition, one important, more recently published study was included afterwards,13 three standard works on ECT were consulted 2,12,14 and
their references were cross-checked to reveal relevant additional articles.
Results
For the present review, 27 studies appeared to be relevant. Of these, 13 studies presented data on correlations between seizure threshold and age, 3 studies compared younger and older age groups (of which 1 also calculated correlations), 1 study examined changes in seizure thresholds during the ECT course, 3 studies indirectly showed an increase of seizure threshold in elderly patients, and 8 studies presented hypotheses for an increased seizure threshold in elderly patients.