T H E EFFECTS OF UNILATERAL AND BILATERAL ECT ON VERBAL AND VISUAL SPATIAL MEMORY’

BASIL JACKS ON^ Lutheran Hospital and Jackson Psychiatric Center

Milwaukee, Wisconsin

Investigated the effects of unilateral left (UL), unilateral right (UR), and bilateral (B) ECT on the performance of right-handed male patients on. the Wechsler Memory Scale and two tests of the Williams battery, whch provided eight independent measures of verbal memory and two of visual-spatial mem- ory. Patients were tested three times: ( I ) within 1 week prior to ECT; (2) within 30 minutes after the sixth ECT; (3) 10 days after the sixth ECT. Double blind procedures were maintained carefully. Results showed a signi- ficant loss on second testing followed by a significant im rovement 10 days later for all ECT groups compared with matched controg. There was some tendency for the UR group to show the least impairment on verbal measures and the UL grou to show the least impairment on visual-s atial memory test of the WMS, g u t most of the differences between UL and 8 R groups and between each of these and the B group were not significant. The most sensitive test in differentiating among the ECT groups was the brief Verbal Learning subtest of the Williams battery.

I n the effort to minimize the memory loss that attends the use of electrocon- vulsive therapy (ECT), one of the most widely recommended procedures is the placement of both electrodes on the same side of the head (Cannicott & Waggoner, 1967; Impastato I% Karliner, 1956; Impastato & Pacella, 1952). Despite the sub- stantial number of investigations into the effectiveness of this unilateral ECT, no study has been found in which the minimum of four groups necessary to assure adequate control is employed. There are few studies, indeed, in which the effects on memory of ECT were assessed immediately after the treatment, even though it is known that the effects are greatest then; and few studies in which nonverbal as well as verbal memory was assessed, though ECT to the non-dominant hemisphere could be expected to affect visual-spatial memory (Wilcox, 1954).

METHOD On these accounts the present study was designed to measure the influence on

both verbal and nonverbal memory of unilateral left (UL) , unilateral right (UR), and bilateral (B) ECT relative to each other and to a “no ECT” control group (CG), with measurements made immediately after the final ECT as well as 10 days later. The ECT was administered on a Monday-Wednesday-Friday schedule for a total of six treatments. All patients were tested for the first time in the week prior to the ECT administration, and the second testing was started within a half-hour after the sixth treatment.

Subjects All patients were male veterans a t the Wood Veterans Administration Center

in Wisconsin, who were referred by their ward psychiatrist for ECT. Each patient was subjected to detailed physical (including neurological) examination and psy- chiatric evaluation. To be included in this study a patient had to: (1) be under 60 years of age; (2) show no evidence of brain damage; (3) have received no ECT

‘This stud was completed some 10 years ago, and plans to revise (and reduce) for publication were postponei indefinite1 becauee of administrative considerations. Recent resurgence of interest in the effects of ECT and t i e fact that an adequately cmtrolled study of its special effects on memory is still wanting have led me to the conclusion that the results of this long-ago-completed invwti- gation should still be cf value to psychiatrists and psychologists, particularly to those who care to replicate it under contemporary conditions.

*The author thanks all of his colleagues who helped in a variety of ways to make this research possible. Special thanks and appreciation go to Drs. R. McCall, S. Simon, T. Leitschuh and to Mr. E. May.

4

The Effects of ECT 5

within the past year; (4) show no medical contraindications for ECT; (5) be pre- dominantly- right-handed.

Initial Ss were assigned randomly to the four groups, UL, UR, B, CG. Later Ss were rouehlv matched with earlier Ss on age, education. and WAIS I&, and then assigned raido"m1y to the remaining groups.-The N s of the groups were: UL, 12; UR, 11; B, 11; CG, 12. Average age was roughly 45, average WAIS I& 106, average education eleventh grade, with no significant differences among any of the groups on these measures. Medication was not modified during the study in order to main- tain comparability with the control group, who were without ECT and often re- quired medication. Assessment of Memory Disturbance

The instruments employed were the Wechsler Memory Scale (WMS) and one verbal and one nonverbal learning test utilized by Williams (1968). A separate score was recorded for the Visual Reproduction subtest of the WMS, with the other subtests scored separately, but also totaled as a measure of verbal memory in general. The verbal portion of the Williams test required the learning of five unfami- liar words, the visual-spatial portion required the identification of a fixed peg on four Rey Davis boards. Two matched forms of the WMS and three of the Williams tests were employed in random order. Treatment Procedures

Identical pretreatment medication (atropine, .8 mg and succinyl choline chlo- ride, 10-15 mg, I.V.) and standard ECT procedure with sufficiently heavy dosage to insure full seizure (160 volts for .75 seconds, using a "glissando" technique) were employed for all Ss who received ECT. All treatments were administered by a senior staff psychiatrist who did not have clinical responsibility for the patient and who was not aware of the specific hypotheses that were being tested. All tests were administered by a specially trained technician who had not been apprised of any expected relationship between ECT procedures and test results and who was unaware of the various treatment groups to which the patients belonged. (The identity of the control group patients could not be disguised, to be sure, because they did not show the postictal confusion manifested by the treated patients.) The ECT patients were kept unaware that different kinds of ECT procedures were being used with different patients, while the individual responsible for the random- ization of Ss according to age, education, and I& knew nothing about the patients beyond these measures. Finally, the principal investigator played no part in the assignment of patients to the various groups and therefore could not have influenced the composition of these groups on the basis of his clinical impressions of the patients.

RESULTS The means and standard deviations of the verbal and nonverbal portions of the

WMS, and the Verbal and Spatial portions of the Williams battery for each of the four groups and each of the three testings are presented in Table 1. Table 1 also notes that in a one-way analysis of variance of the preliminary or pretreatment testing of the four groups on the 10 variables that may be regarded as relatively independent of each other (df = 3, 39), one of these measures (New Word Learning from the Williams battery) reached an alpha level of .05. In itself, this cannot be taken to indicate any significant differences among the four groups in the prelimi- nary testing because with this many measures it is well within chance expectation that a single variable apparently will differentiate a t the .05 level. Thus no one (or the total) of the 8 verbal subtests of the WMS differentiates any of the groups from the others, so that we may be reasonably sure that none of the groups differed significantly from the others a t the outset in either verbal or visual-spatial memory function.

6 Journal of Clinical Psychology, January , 1978, Vol. 34, No. 1

TABLE 1 MEANS AND STANDARD DEVIATIONS OF VARIOUS MEASURI~S USED I N PRE- AND POST- ECT TESTING

Left Right Bilateral Control Differ- ential

Test testing" X SD x SD x SD SD

Visual - 1 9.8 3.2 9 . 5 2 .4 8.9 2 . 7 10.7 2.8 Reproduction 2 7.3 3.4 6.2 2.8 5.3 3.0 10.4 2.4

3 9.9 2.3 10.2 2.6 10.1 2.5 11.6 2.6

WMS Minus 1 47.5 7.2 48.9 11.6 47.3 9.4 49.8 8 .4 Visual 2 31.8 9 . 1 37.7 15.8 32.2 6.8 50.7 7 .5 Reproduction 3 51.8 7 .3 52.2 12.8 50.3 4.8 53.7 6.7

Williamsb 1 22.6 10.8 29.9 7.6 22.1 7.4 19.4 8 . 4 Verbal 2 34.2 5 .5 32.8 9 .1 36.6 3.4 22.0 10.2 Learning 3 21.8 12.1 29.8 7.8 26.3 6 . 5 23.6 8.9 ReY 1 7 .6 11.3 7.6 6.9 5 .9 7.9 6 .3 10.2 Davis 2 22.1 11.6 18.6 12.1 20.5 10.2 5.6 8.0

3 7.8 10.4 11.4 11.7 10.4 9.4 9.3 11.7

The basic analyses were made on the difference scores (D) between the pre- liminary and first post-ECT testing (D-1), the preliminary and third testing (D-2), and the second and third testing (D-3) ; the score of the test mentioned second in each of the three pairs was subtracted from the score of the first. The means and standard deviations of the differential testings of the four groups are given in Table 2.

TABLE 2

APPLICATIONS OF ECT MEANS AND STANDARD DEVIATIONS O F MEMORY DIFFERENCE SCORES FOR VARIOUS

Left Right Bilateral Control Differ- ential

Test testinga x SD x SD x SD SD

Visual - 1 2.5 4.9 3 . 3 4 .2 3 .6 2 .5 .3 3.0 Reproduction 2 - .1 2.9 - .7 2.3 -1.2 3.4 .9 1.2

3 -2.6 3.5 -4.0 3 .6 -4.8 4.0 -1.2 2.5

WMS Minus 1 15.7 13.3 11.1 10.9 15.1 9 .1 -.9 5.2 Visual 2 -4.3 9.2 -3.4 5.7 -3.0 8.9 -3.9 4.3 Reproduction 3 -20.0 7.8 14.5 9 .4 -18.1 7.0 -3.0 3.7

Williams 1 -11.6 11.8 -2.9 8 .7 -14.6 8.7 -2.6 8.7 Verbal 2 .8 15.2 . I 5.4 -4.2 10.4 -4.2 7.2 Learning 3 12.3 10.6 3.0 7.3 10.4 6.8 -1.6 5.0 ReY 1 -14.5 16.6 -11.0 10.8 -14.6 15.6 .7 3.4 Davis 2 - .3 15.5 -3.7 12.9 -4.5 13.4 -3.0 7.7

3 14.3 12.4 7.3 14.1 10.1 11.0 -3.7 6.0

SThe differential testings are as follows: 1 = Pre-ECT-ECT; 2 = Pre-ECT-Post-ECT; 3 = ECT-Post-ECT.

The Effects of ECT 7

50 - 10 w 0

Lo 4 5 -

t- 4 0 -

3 5 -

To obtain a synoptic picture of the effects of ECT on the various measures of memory, performance scores for the 44 Ss were converted to T-scores in such a way that the higher T-score always represented an improved performance (upper por- tion of Figures 1 and 2). The significance levels of the differences in memory scores among all combinations of Ss and tests that emerged from the statistical analysis (ANOVA and t-tests) also are presented (lower portion of Figures 1 and 2.)

It is noteworthy that between preliminary (Pre-ECT) and final (Post-ECT) memory scores, only 1 of 70 possible differences reached an alpha level of .05. That six applications of ECT in any form produce any permanent loss of memory function thus is unsupported by this investigation.

-4

A Left 0 R i g h t 0 Bi la t e ra l

5 5 -Control 6o i

I I I I I 1 I I 8 I I

A L L , 0 0 3 .001 .02L) - - - - . O O E . 0 0 1 ,002 .O1 .033 w Z L / C f . n i ,001 .OI - - - . 0 2 - . n i . o o i ,001 . o5 -01

R / C 5 .01 .01 . 0 2 - .05 - .05 - - -01 .02 - .oS al

u 5 B/C .01 . 01 - - - . 0 5 - .05 . 0 0 1 .001 ,001 -01 .02

- .05 - ._(

?: L/R f - - - - - - - - - . . L - - - - - - - - - _ _ _ _ .i co L/B I

R / R f - . 0 5 - - .01 - - - - - - . . . .

FIG. 1. Mean changes in memory scores between Pre ECT and ECT testings and significance

On the second testing, by contrast, all groups subjected to ECT show some decrement in memory function on all of the nine measures employed except one (Logical Memory), while the control group gives no evidence of decrement. These differences are summarized graphically in the Pre-ECT to ECT slope in Figures 3, 4, and 5 and are specified in greater detail in Figure 1. Significant F-ratios were obtained for all but the Digits Forward, Digits Backward, Logical Memory, and Visual Reproduction subtests. Many of the differences noted are significant a t the .01 level and beyond. Of 30 comparisons on independent measures, 18 are significant and 12 a t the .01 level or better.

With regard to differential effects of electrode placement, Figure 1 shows that the bilateral group (B) has an apparently larger decrement than the other two ECT groups on 8/13 measures (or 8/10 if we exclude nonindependent measures). Only two of these differences are significant, however, and both are between the bilateral (B) and the unilateral right (UR) group: one on Digits Backward (.05), the other

levels of t and F-ratios obtained.

8 Journal of Clinical Psychology, January , 1978, Vol. 34, No . 1.

on Williams Verbal Learning (.Ol). It is perhaps especially noteworthy that between the bilateral and unilateral left hemisphere ECT there is not a single significant difference in memory test performance.

Both the Digits Backward and the Williams Verbal Learning require novel verbal memorization, and the results with these subtests support the expectation

c

4 s

40 i ALL 1 .004 .001 - .03 - .006 .022 - .002 .001 ,601 .001 .OOC

el L / C t .Ol .OOl - .01 - .01 .05 - .001 .001 .001 .001 .001

R/C t .02 .01 - - .05 - - - .05 .001 ,001 - .05 01

f B/C 5 .01 .001 - .05 - .01 -01 .05 .01 .001 .001 .01 .01 m

- .O1 - .2 L/R 5 - - - _ _ - _ _ _ v. ._I

- .05 - - - - - . 0 5 - - - - - R/B I.

FIG. 2. Mean changes in scores between ECT and Post ECT testings and their levels of significance.

that the UR group would be least affected in such learning. This expectation is supported further by the finding that on these two subtests the UR group is the only ECT group that does not differ significantly from the control group (CG).

Though the differences between the UR and UL groups are in the expected direction on five of eight independent measures, these differences reach the .05 level of significance with only one measure, the Williams Verbal Learning subtest, which makes i t the subtest that showed the greatest number of significant differences between the Pre-ECT and immediate Post-ECT testing, and between immediate Post-ECT and longer-range Post-ECT testing. We may recall that the Williams Verbal Learning subtest also yielded a significant F-ratio in the Pre-ECT testing, the only subtest to do so. As is evident from Figure 1, this was associated with initially high error scores for those destined to receive unilateral right hemisphere ECT. I n spite of this, the predicted difference between the UL and UR groups occurred on the second testing, in which the UR group obtained the lowest error score of any of the E C T groups.

The graphs in Figures 3, 4, and 5 show that all measures of the groups that received E C T return to Pre-ECT levels on the third testing (10 days Post-ECT). At the same time, the control group has shown no significant change over the three

The Effects of ECT 9

60 651 I

// \ Left 0 Right u Bilateral e- Control

35 1 PRE-ECT ECT POST-ECT

FIQ. 3. Mean total scores on Wechsler Memory Scales for three testings.

testings, though a trend toward slight improvement on the WMS is suggested. Should the latter change prove reliable, it probably could be classed as a practice effect. No practice effect can be ascribed to the ECT groups, however. As indicated on Table 3, no reliable differences in memory scores between the Pre-ECT and the 10-days-post ECT groups can be found. Only 1 of 70 t- and F-ratios reached an alpha level of .05, far fewer than would be expected by chance. As far as the tests employed in this research are concerned, ECT effected no irreversible change in memory ability.

LEGEND

A Left 0 Right 0 B i l a t e r a l 0 Control

60 1 PRE-ECT ECT POST-ECT

FIG. 4. Mean positive scores on William Verbal Learning Test for three test,ings.

10 Journal of Clinical Psychology, January, 1978, Vol. 34, No. 1,

LEGEND

A Left 0 R i g h t U Bilateral 0 Control

PRE-ECT ECT POST-ECT

FIG. 5 . Mean positive scores on Rey-Davis for three testings.

The recovery of function for all ECT groups from the second to third testings is evident from Figures 3, 4, and 5. The significance levels of these differences are summarized in Figure 2, from which i t is evident that the vast majority of the differences noted between ECT and control cases are significant. Of the subtests involved, only three (Mental Control, Digits Forward, and Visual Reproduction) failed to show numerous reliable differences between the ECT and control cases from the second to the third testing.

With regard to differential effects of electrode placement on recovery of memory function 10 days after ECT, the t- and F- ratios in Figure 2 show that the UR group has changed least on all the verbal learning measures except Digits Forward. The UL group, predictably, shows the least change on Visual Reproduction but, con- trary to expectation, the UR group shows the least change on the Rey Davis. The tendency for the UR group to show less change on measures of verbal learning, however, is highlighted by the finding that in the four instances in which only one ECT group was not significantly different from the control group (CG), in every case it was the UR group. When we compare unilateral left with unilateral right and with bilateral ECT administration, we find only two significant differences from immediate Post-ECT to later testing, and both of these are on the Williams Verbal Learning subtest. The changes in the UR group are significantly less than those with the UL Group (.01 level), and also significantly less than with theBgroup (.05 level).

DISCUSSION The findings of the D-1 and D-3 analyses are very similar. Both show a signi-

ficant general effect of E C T on most measures of memory function. Both indicate a tendency for the UR group to show less change on verbal measures and for the UL group to show less change on only one of the two measures of visual-spatial memory (Visual Reproduction). I n both analyses only one test shows a significant difference between the UL and the UR groups, the Williams Verbal Learning test,

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12 Journal of Clinical Psychology, January , 197’8, Vol. 34, N o . 1.

and this same test alone shows the UR group significantly different from the B group in both the D-1 and D-3 testing. In both analyses, too, only the UR group is not significantly different from the CG. Findings at variance with these results, such as those of Halliday, Davison, Browne, and Kreeger (1968), may be connected with their having delayed the “immediate” post-ECT testing for 2 t o 4 days.

Martin, Ford, McDonald and Towler (1965) used the WMS total score and tested 1 day after the 10th ECT; they found improvement in the unilateral right group and impairment in the bilateral group. Zamora and Kaelbling (1965) used the WMS score with the Visual Reproduction score excluded and also found im- provement in the UR group and a loss in the UL group. Like Halliday et al., how- ever, they did not test until sometime after the fifth ECT (in this case 30 to 36 hours), so that their study was not designed to detect the maximum effect of ECT or, thereby, the full extent of later recovery.

The present findings are generally consistent with those of Levy (1968), who used the WMS and a Paired Associates learning task. Levy retested his unilateral and bilateral ECT groups 6 hours after the sixth ECT and found a significant loss for both groups on both measures and no significant differences between groups on either.

It is very likely that differences in the time elapsed after ECT before retesting are very important in this regard. The results of many studies suggest that the postictal confusion in the first few hours after ECT is almost sure to impair the process of registering and retaining information, which is likely then to be reflected in measures of anterograde amnesia. In this postictal state, moreover, differences associated with placement of electrodes and content of the tests (e.g., verbal vs. visual-spatial) are unlikely to be demarcated clearly. This would offer some explana- tion of the immediate general impairment revealed in this and the Levy study and account for the greater probability that the longer time interval before retesting in other studies would allow some of the global confusion to dissipate and specific strengths and weaknesses t o appear once more.

How long a time period is necessary for optimal differentiation of the ECT groups is not clear, but it may be at least a partial function of the measures em- ployed. Several studies, particularly those of Strain, Brunschwig, Duffy, Agle, Rosenbaum, and Bidder (1968), Cohen, Noblin, Silverman, and Penick (1968), Gottlieb and Wilson (1965), and Wilson and Gottlieb (1967), together with this study, suggest that the period between 6 and 8 hours after the final ECT in a brief series may reveal differences on particular tests, such as the Paired Associates learning tests and certain visual-spatial tests, that are not evident immediately after ECT and that may be weakened several days later.

It is also possible that the decision to use in this study a level of ECT dosage sufficient t o assure a generalized seizure even in unilateral administration (160 volts for .75 seconds, which is greater than that which ordinarily is used with bilateral administration) may have resulted in an obscuring of differences between unilateral and bilateral administration. Thus a generalized seizure implies bilateral involve- ment, even though the electrode placement may be unilateral. It is possible that the differences between groups would have been revealed more clearly if we had reduced the ECT dosage to a level sufficient to provide generalized seizure for the bilateral group while increasing the probability of a principally unilateral effect for the UR and UL groups.

Separate analyses of the WMS subtests seemed justified in view of the wide variation among these subtests in sensitivity to the procedures employed. For example, the Logical Memory subtest showed no significant decrement as a result of ECT for any of the groups, but did differentiate the bilateral and UL groups from the control cases and from the UR group from second to third testing. The Associate Learning subtest, on the other hand, showed a fairly consistent sensi- tivity to the UL and B procedures, but not to the UR procedure, though it was sensitive t o changes in all three on the second post-ECT testing. The Current Infor-

The Eflects of ECT 13

mation and Orientation subtests showed the most consistent and reliable differences of any subtests from Pre-ECT to immediate Post-ECT and from the latter to the third testing. This underscores the likelihood that the immediate Post-ECT testing is most likely to pick up the disorientation and confusion of the postictal state, which are rectified pretty thoroughly on later testing.

One unexpected finding is the tendency for Digits Forward and Digits Back- ward to differ in their sensitivity to the several ECT procedures. In Figure 1 i t may be noted that the UR group is the only ECT group to differ significantly from the CG on Digits Forward, though it does not differ significantly on Digits Back- ward. In the D-3 analysis shown in Figure 2, the UR group is the only group to differ significantly from the CG on Digits Forward, and i t is the only ECT group not to differ significantly from the CG on Digits Backward. Yet the UL does not differ significantly from the UR on these measures, and neither differs significantly from the bilateral (B) group, so the suggested possibility that more intensive testing with more sensitive instruments would reveal more remains only a possibility. Such possibilities ought to be explored, nevertheless, if we are to escape the error, nicely described by McAndrew, Berkey, and Matthews (1967), of supposing that the average of a group of different tests is a fair reflection of the whole battery.

One last point that this study highlights is the great individual variation between Xs in response to different ECT procedures. The large standard deviations listed in Tables 1 and 2 make i t difficult for the apparent trends of the data to reach statistical significance, which bespeaks the need for more refined and sensitive methods of psychometric analysis-perhaps principally multivariate and non-para- metric-than customarily are employed in clinical research.

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