Chapter 2: 2.1. - Indications for Use of ECT - Indications for Use of ECT

Written by Juli Lawrence

Prediction of response. ECT is an effective antidepressant in all subtypes of major depressive disorder. Nonetheless, there have been many attempts to determine whether particular subgroups of depressed patients or particular clinical features of depressive illness have prognostic value with respect to ECT's therapeutic effects.

In the 1950's and 1960's, a series of studies showed impressive power to predict clinical outcome in depressed patients on the basis of pre-ECT symptomatology and history (Hobson 1953; Hamilton and White 1960; Rose 1963; Carney et al. 1965; Mendels 1967; see Nobler & Sackeim 1996 and Abrams 1997a for reviews). This work is now largely of historical interest (Hamilton 1986). While the early research emphasized the importance of vegetative or melancholic features as prognostic of positive ECT outcome, recent studies restricted to patients with major depression suggest that subtyping as endogenous or melancholic has little predictive value (Abrams et al. 1973; Coryell and Zimmerman 1984; Zimmerman et al. 1985, 1986; Prudic et al. 1989; Abrams and Vedak 1991; Black et al. 1986; Sackeim and Rush 1996). It is likely that the early positive associations were due to the inclusion of patients with "neurotic depression" or dysthymia in the sampling. Similarly, the distinction between unipolar and bipolar depressive illness has generally been found to be unrelated to therapeutic outcome (Abrams and Taylor 1974; Perris and d'Elia 1966; Black et al. 1986, 1993; Zorumski et al. 1986; Aronson et al. 1988).

In recent research a few clinical features have been related to ECT therapeutic outcome. The majority of studies that have examined the distinction between psychotic and nonpsychotic depression found superior response rates among the psychotic subtype (Hobson 1953: Mendels 1965a, 1965b: Hamilton and White 1960; Mandel et al. 1977; Avery and Lubrano 1979: Clinical Research Centre 1984; Kroessler 1985; Lykouras et al. 1986; Pande et al. 1990; Buchan et al. 1992; see also Parker et al. 1992: Sobin et al. 1996). This is of particular note given the established inferior response rate in psychotic or delusional depression to monotherapy with an antidepressant or antipsychotic medication (Spiker et al. 1985; Chan et al. 1987; Parker et al. 1992). To be effective, a pharmacological trial in psychotic depression should involve combination treatment with an antidepressant and an antipsychotic medication (Nelson et al. 1986; Parker et al. 1992; Rothschild et al. 1993; Wolfersdorf et al. 1995). However, relatively few patients referred for ECT with psychotic depression are administered such combination treatment in sufficient dosage and duration to be considered adequate (Mulsant et al. 1997). Multiple factors may be contributory. Many patients cannot tolerate the dosage of antipsychotic medications generally viewed as necessary for an adequate medication trial in this subtype (Spiker et al. 1985 Nelson et al. 1986). Patients with psychotic depression commonly have severe symptomatology, and are at increased risk for suicide (Roose et al. 1983). The rapid onset and high probability of improvement with ECT makes this treatment of particular value for these patients.

Several studies have also noted that, as with pharmacological treatment, patients with long duration of current episode are less likely to respond to ECT (Hobson 195 Hamilton and White 1960; Kukopulos et al. 1977; Dunn and Quinlan 1978; Magni et al. 1988; Black et al. 1989b. 1993; Kindler et al. 1991; Prudic et al. 1996). As already discussed, the treatment history of patients may provide a useful predictor of ECT outcome, with patients who have failed one or more adequate medication trials showing a substantial, but diminished, rate of ECT response (Prudic et al. 1990, 1996). In the majority of relevant studies patient age has been associated with ECT outcome (Gold and Chiarello 1944; Roberts 1959a, 1959b; Greenblatt et al. 1962; Nystrom 1964; Mendels 1965a, 1965b; Folstein et al. 1973; Stromgren 1973; Coryell and Zimmerman 1984: Black et al. 1993). Older patients are more likely to show marked benefit compared to younger patients (see Sackeim 1993, 1998 for reviews). Gender, race and socioeconomic status do not predict ECT outcome.

The presence of catatonia or catatonic symptoms may be a particularly favorable prognostic sign. Catatonia occurs in patients with severe affective disorders (Abrams and Taylor 1976; Taylor and Abrams 1977), and is now recognized in the DSM-IV as a specifier of a major depressive or manic episode (APA 1994). Catatonia may also present as a consequence of some severe medical illnesses (Breakey and Kala 1977; O'Toole and Dyck 1977; Hafeiz 1987), as well as among patients with schizophrenia. The clinical literature suggests that regardless of diagnosis, ECT is effective in treating catatonic symptoms, including the more malignant form of "lethal catatonia" (Mann et al. 1986, 1990; Geretsegger and Rochawanski 1987; Rohland et al. 1993; Bush et al. 1996).

Major depression which occurs in individuals with preexisting psychiatric or medical disorders is termed "secondary depression." Uncontrolled studies suggest that patients with secondary depression respond less well to somatic treatments, including ECT, than those with primary depressions (Bibb and Guze 1972; Coryell et al. 1985; Zorumski et al. 1986; Black et al. 1988, 1993). Patients with major depression and a co-morbid personality disorder may have a reduced probability of ECT response (Zimmerman et al. 1986; Black et al. 1988). However, there is sufficient variability in outcome with ECT that each case of secondary depression must be considered on its own merits. For example, patients with post-stroke depression (Murray et al. 1986; House 1987; Allman and Hawton 1987; deQuardo and Tandon 1988, Gustafson et al. 1995) are believed to have a relatively good prognosis with ECT. Patients with major depression superimposed on a personality disorder (e.g. Borderline Personality Disorder) should not be denied ECT out of hand.

Dysthymia as the sole clinical diagnosis has been rarely treated with ECT. However, a history of dysthymia preceding a major depressive episode is common and does not appear to have predictive value with regard to ECT outcome. Indeed, recent evidence suggests that the degree of residual svmptomatology following ECT is equivalent in patients with major depression superimposed on a dysthymic baseline, i.e., "double depression", and in patients with major depression without a history of dysthymia (Prudic et al. 1993).

Patient features, such as psychosis, medication resistance, and episode duration, only have statistical associations with ECT outcome. This information may be considered in the overall risk/benefit analysis of ECT. For example, a patient with a nonpsychotic, chronic major depression, who has failed to respond to multiple robust medication trials may be less likely to respond to ECT than other patients. Nonetheless, the probability of response with alternative treatments may be still lower, and the use of ECT justified.