|October 2001||The Use of Electroconvulsive Therapy in Special Patient Populations|
A recent review of studies conducted since 1990 found that the response rate to ECT among adolescents with mood disorders was about 65% (10). Based on this, the Texas Children’s Medication Algorithm Project has developed a treatment algorithm for major depressive disorder (MDD) in this age group (20). These practice parameters delineate indications for ECT in adolescents, including persistent treatment-resistant depression that is severe enough to be life-threatening by causing suicidality or catatonia. The algorithm may form the basis for developing controlled clinical trials in adolescents and perhaps extend to preadolescent children. The ethical and moral dilemma of treating children with ECT, as well as getting informed consent for such procedures, is not to be underestimated. At present, psychiatrists caring for children with life-threatening and disabling depression face a difficult choice: they may offer ineffective therapy or no treatment, or they may offer ECT—a treatment that many still oppose and for which clinical certainty in children has not been well established. Currently, ECT in children would fall under the category of research that involves greater-than-minimum risk but presents the prospect of direct benefit to the individual subject (19–21).
ECT Use in the Elderly
ECT is most frequently used in the elderly to treat depression (22,23). Medication resistance is suspected to be age-related (23,24), especially in cases of late-onset depression (25). ECT has been shown to be effective in 70% to 80% of patients who have failed drug therapy (26). Most controlled studies indicate that a history of prior nonresponse to medication trials is associated with a 20% to 30% lower rate of antidepressant response to ECT (27). Overall, approximately 50% of medication-resistant patients subsequently respond to ECT (28). Many elderly patients with severe depression, who are medication-resistant or medication-intolerant respond more reliably and quickly to a course of ECT (29–31). ECT is increasingly used as first-line therapy for severely ill patients who are refusing to eat or drink, are psychotic, or are at high risk for suicide (27). Coexisting medical conditions that frequently occur in the elderly may make ECT the treatment of choice in some patients, due to its speed of action and safety profile. ECT should be considered a first-line treatment for those elderly patients whose hepatic, renal, or cardiac functions prevent the use of pharmacotherapy for depression (27,32).
In general, the short-term outcome of ECT treatment in the elderly with depression appears to be more favourable compared with younger adults (33,34). Due to medication intolerance, medical complications, or psychotic depression, they often receive ECT earlier in the course of illness than do younger adults. These factors, in essence, probably reduce the duration of the index episode and medication resistance, both of which are positive predictors of response to ECT (34). The elderly, however, may not respond as well to unilateral ECT as do younger patients, more often requiring bilateral ECT (35,36) and a longer treatment course to achieve remission (37). Seizure threshold rises with increasing age—particularly with bilateral ECT—sometimes creating difficulty when it exceeds maximum outputs of available ECT machines (38–40). Reducing or withholding the dosage of sedatives, hypnotics, benzodiazepines, or anticonvulsants prior to ECT, as well as using lower dosages of barbiturate anesthesia and adequate ventilation during ECT, may be helpful (7). Although the use of intravenous caffeine pre-ECT does lengthen seizure duration, it does not appear to reduce seizure threshold (41,42). Since the ECT’s efficacy is not directly related to seizure duration (43,39) and potential cardiac and other complications of caffeine use are known, this augmenting strategy is not generally recommended.
Older patients and those with medical illnesses are at greater risk for ECT-related confusion and greater memory deficits (44,45). They tend to have more persistent amnesia for autobiographic information, in addition to anterograde and retrograde amnesia. Baseline pre-ECT cognitive scores and postictal disorientation have been shown to predict the degree of long-term retrograde amnesia in patients who are not neurologically impaired (46). Cognitive impairment associated with depression may actually improve with ECT, even when associated with underlying cerebral vascular disease (47,48). ECT is known to cause hypoprofusion in frontal areas (48); this may contribute to the dementia process in patients with compromised cerebral vascular systems, but there are no controlled studies to help with this clinical question. Therefore, the risk of not treating an older person with severe depression must be weighed against the potential risk of exacerbating cognitive impairment (54).