Memory training and multiple sclerosis: A case study - Springer Link

International Journal of Rehabilitation and Health, Vol. L No. 3, 1995

Memory Training and Multiple Sclerosis: A Case Study Daniel N. Allen, 1,3 Susan Longmore, 2 and Gerald Goldstein 2

Multiple sclerosis (MS) is a progressive neurological disorder often accompanied by significant cognitive deficits. Some research suggests that recent memory is the most commonly affected cognitive ability in MS. However, there is only one empirical investigation examining the efficacy of cognitive rehabilitation in individuals with MS. We report the application of a memory training program to remediate memory deficits in a patient with MS. The program focused on teaching mnemonic strategies to increase list learning ability and ability to recall names of faces. Results suggested that memory training improved visual and verbal memory abilities. The most marked improvement was present on tests assessing verbal memory abilities. These results contribute to a growing body of literature indicating that teaching mnemonic strategies is one method of improving memory functioning in individuals with mild to moderate memory impairment. KEY WORDS: multiple sclerosis; cognitive rehabilitation; neuropsychology; memory; mnemonic strategies.

INTRODUCTION Multiple sclerosis (MS) affects between 250,000 and 500,000 individuals living in the United States (Anderson et al., 1992; National Institutes of Health, 1984). The majority of individuals with MS are between 15 and 50 years of age and typically experience initial symptoms of the disorder between 20 and 40 years of age. Because MS attacks CNS white matter, plaques caused by the disease's attack can form anywhere in the CNS. Gray matter can also become affected when plaques that form in the white matter at the tips of gyri expand into adjacent gray matter (see Raine, 1990). MRI studies suggest that lesions develop at a rate of between 3 and 6 per year (Koopmans et al., 1989; Willoughby et al., 1989), although exacerbations accompanied by clinical symptoms occur only between 0.5 and 1.0 time per year (Sibley, 1990). 1Psychology Service (116B), Highland Drive VA Medical Center, 7180 Highland Drive, Pittsburgh, Pennsylvania 15206. 2Medical Research Service, Highland Drive VA Medical Center, Pittsburgh, Pennsylvania. 3To whom correspondence should be addressed. 189

1068-9591/95/0700-0189507.50/0O 1995PlenumPublishingCorporation

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Allen, Longmore, and Goldstein

Plaque development throughout the CNS causes a wide array of symptoms, including cognitive deficits. In fact, cognitive deficits caused by MS plaques are quite prevalent. Prevalence rates of cognitive impairment range anywhere from 43 to 72% (Beatty et aL, 1988, 1989; Heaton et al., 1985; Kessler et aL, 1992; Klonoff et aL, 1991; Mclntosh-Michaelis et al., 1991; Rao et al., 1984; van den Burg et al., 1987), depending on the type of patients under investigation, disease duration, and course of MS in the patient groups studied. In a recent report examining performance of a general MS population on a battery of neuropsychological tests, Rao et al. (1991a) found that individuals with MS failed significantly more neuropsychological tests than a control group similar in age, education, premorbid occupational status, and estimated premorbid intelligence. Testing classified 43% of individuals with MS as cognitively impaired. Tasks most often failed required recent memory (31% failure rate), followed by tests of sustained attention and verbal fluency (approximately 25%) and visual-spatial perception and conceptual reasoning (approximately 20%). The relationships among physical disability, duration of illness, disease course, and cognitive dysfunction in MS patients remain poorly understood. However, there is some evidence indicating that physical disability does not highly correlate with degree of cognitive impairment (Peyser et al., 1980; Rao et al., 1984, 1991a; Ron et al., 1991; van den Burg et al., 1987). For example, Rao et al. (1991a) indicated that the number of cognitive tests failed correlates significantly but weakly with tests of disability, accounting for only 6% of the variance. This is not surprising given that there are only weak correlations between neurological signs and findings from cerebral MRIs (Baumhefner et al., 1990). With regard to duration of illness, some investigators report no significant relationship between duration of disease and cognitive dysfunction (Rao et al., 1991a). Although duration of illness and level of physical disability do not appear to correlate strongly with cognitive impairment, functional status does relate to cognitive impairment. Compared to cognitively unimpaired patients with MS, cognitively impaired MS patients are significantly less likely to have gainful employment, are less likely to participate in social activities, require greater physical assistance, exhibit more problems maintaining personal hygiene and ADLs, and are less able to follow simple recipes when cooking (Rao et aL, 1991b). These differences are present despite similar levels of physical disability and illness duration between the cognitively impaired and unimpaired patients (Rao et al., 1991). Also, patients with MS and cognitive impairment have higher rates of depression than do MS patients who are cognitively intact (Gilchrist and Creed, 1994). Finally, Kessler et al. (1992) reported that individuals with MS who exhibit high levels of functional impairment perform significantly worse on tests requiring memory and motor ability and tend to receive lower scores on tests of cognitive abilities when compared to less functionally impaired patients with MS. This research suggests that individuals with relatively short illness duration who do not have significant physical disabilities may nevertheless experience significant and disabling cognitive deficits. Due to the prevalence of cognitive deficits and the apparent impact these deficits can have on social, psychological, and vocational functioning, some authors have suggested that patients with MS may benefit significantly from cognitive rehabili-

Memory Training and MS

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tation techniques found to be effective in treating individuals with other types of brain injuries (DeLuca and Johnson, 1993; JCnsson et al., 1993; LaRocca, 1990; Schapiro, 1990). Because memory abilities appear to be the most commonly impaired cognitive ability, memory training programs would be particularly helpful for patients with MS. Comprehensive reviews of memory training studies with braindamaged individuals are available elsewhere (Franzen and Haut, 1991; Leng and Copello, 1990; Lewinsohn et al., 1977; Wilson, 1986; Wilson and Moffat, 1984) so we do not provide a lengthy review of this literature. However, in the ensuing discussion we briefly note several important points drawn from these reviews. Memory training research borrows heavily from experimental psychology of memory, behavioral neurology of memory disorders, and writings of mnemonists. Clinical applications of memory training techniques began to emerge as individuals working with brain-damaged patients became concerned whether memory difficulties were remediable to any extent. By the late 1970s, a confluence appeared to develop among basic science, popular strategies to increase memory abilities, and computer application approaches, perhaps best represented in a paper in which the investigators applied sophisticated experimental design and computer technology to memory training (Gianutsos and Gianutsos, 1979). Since that time, the general thrust of the literature from both laboratory and clinical settings has suggested that a modest degree of memory improvement is possible (Lewinsohn et al., 1977; Richardson, 1992). In our view (Davis and Goldstein, 1993), restoration of memory is a continuum. In cases of mild. impairment, individuals can utilize existing or spared internalized memory systems to compensate for existing or acquired deficits. As memory impairment becomes more severe, more external supports (prosthetics) are necessary for adaptive functioning. Thus, individuals with mild-moderate memory deficits might achieve restoration of function based solely on improvement in their own biological memory mechanisms. Most of the reports advocating the possible efficacy of cognitive rehabilitation with patients who have MS have done little more than (a) suggest that cognitive rehabilitation is a relevant treatment for patients with MS and (b) provide general suggestions for application of available techniques (DeLuca and Johnson, 1993; LaRocca, 1990; Schapiro, 1990). Although these types of reports highlight the relevance of cognitive rehabilitation for patients with MS, they do little to validate empirically the efficacy of such treatments. At this time, there is only one empirical investigation reporting the use of cognitive rehabilitation techniques with patients who have MS (Jr et al., 1993). This may be due to the fact that, because MS is a progressive and chronic disorder, many clinicians and researchers prematurely conclude that patients will quickly lose any gains made in treatment. However, most individuals with MS experience periods of remission between exacerbations, and some experience very few exacerbations over the course of their lifetimes. As such, clinicians must distinguish MS from other progressive disorders characterized by a progressive, steady deterioration (such as Alzheimer's dementia) when considering treatment of patients with MS and, more specifically, when considering treatment of cognitive deficits in these patients. In their study, Jcnsson and colleagues (1993) examined the effects of a cognitive rehabilitation program designed to remediate concentration, memory, and visuospa-


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tial abilities in patients with MS. In addition, patients participated in psychotherapy developed specifically to help them understand, accept, and adapt to their current cognitive and behavioral limitations. As a control condition, patients in an attention placebo control group participated in a variety of activities, including fdm viewing, game playing, and discussion of newspaper articles. The authors assessed effects of treatment using pretreatment, posttreatment, and 6-month follow-up neuropsychological evaluations. In contrast to the control group, the treatment group exhibited significant improvement in visuospatial memory abilities and significant decreases in depression at posttest and at 6-month follow-up. The authors concluded that, although their results do not convincingly demonstrate the efficacy of cognitive rehabilitation when used with individuals who have MS, cognitive rehabilitation is worthwhile and deserves consideration when treating individuals who have MS and concomitant cognitive and/or behavioral deficits. However, this conclusion seems premature because it is not clear from their results which component of treatment impacted the cognitive functioning of the treatment group. Improved neuropsychological test performance may have been due to decreased levels of depression and anxiety noted in the treatment group, and these decreased levels of affective disturbances may have resulted from the psychotherapy rather than the cognitive rehabilitation per se. Additional research is necessary to determine whether traditional psychotherapies designed to treat affective disturbances (e.g., cognitive behavioral therapy) or cognitive rehabilitation strategies designed to ameliorate specific cognitive deficits are more effective in improving cognitive functioning. The current case study reports the use of a computer assisted memory training program to treat memory deficits noted in a 47-year-old male with MS. This memory training program has been successful when used to treat other individuals with memory deficits secondary to brain injuries (Goldstein et aL, 1988). We believe that memory training had particular relevance for this patient because of self-reported difficulties with recent memory abilities as well as psychometric data indicating the presence of memory deficits. However, memory training has broader applications for individuals with MS than this one case presents for at least two reasons. First, research indicates that recent memory ability is the most often impaired cognitive ability in the general MS population (Rao et al., 1991a). Second, memory abilities, along with motor ability, appear to relate to functional impairment so that functionally impaired patients with MS score lower on tests that assess memory and motor abilities (Kessler et al., 1992).

METHODS Subject The subject was a 47-year-old Caucasian re,l,, u,lth 19 9. . . . . . r , a . . . . , ; , ~ , , u ~ had received the diagnosis of MS approximately 18 years prior to his participation in the cognitive rehabilitation program. Since the time of his initial diagnosis oi probable MS, clinical tests including MRI supported the diagnosis of MS. He con-


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tinued to maintain employment as a maintenance administrator for a telephone company. However, his difficulties with memory first became apparent when he began having work-related problems evinced by an inability to master skills needed to learn a new computing system and information presented during total quality management training. Throughout cognitive rehabilitation, the subject continued to take fluoxetine and trazodone. The dosages of fluoxetine and trazodone were stable for at least 6 months prior to initiating the cognitive rehabilitation program, and they remained stable throughout memory training. Approximately 2 weeks before pretesting, he began a regime of interferon-13 lb, which may have interfered with his cognitive functioning; he reported periods of confusion and decreased concentration. He reported these symptoms consistently throughout the memory training program. He eventually discontinued use of interferon-I] lb after completing all of the memory training study procedures, including follow-up evaluations. Procedures

Screening and Pre- and Posttraining Evaluation The procedure for screening subjects for the memory training appears in detail in the original publication (Goldstein et al., 1988). We repeated the psychometric and neuropsychological assessments from this previous study. Results of the screening tests appear in Table I. The MS subject in our research, as in the previous study, had no evidence of aphasia, as assessed by the Responsive Naming, Animal Fluency, and Visual Confrontation Naming subtests of the Boston Diagnostic Aphasia Examination (within 1 SD of age and education corrected norms), and had no physical disabilities that prevented him from using a computer. Although one symptom of the MS included blurred vision, the subject was able to read a computer screen with the aid of a small portable magnifying glass. Other screening test results, as shown in Table I, indicated an average range Full Scale IQ of 95 on the Wechsler Adult Intelligence Scale--Revised (WAIS-R; Wechsler, 1981) and a low averagerange delayed recall score of 85 on the Wechsler Memory Scale--Revised (WMS-R; Wechsler, 1987). Scores on the Mattis Dementia Rating Scale fell well within the normal range. Although the patient did not exhibit the severe memory impairment exhibited by patients in our previous studies, we believed that his WMS-R Delayed Recall Index (DRI) of 85 was sufficiently different from his WAIS-R Full Scale IQ (FSIO) and from his overall level of functioning to warrant memory training. Following initial neuropsychological screening, a technician administered a pretest evaluation consisting of a brief series of memory tests. Pretesting and posttesting (at 1 week and 1 month) included the following: (a) a face-name learning task that required the subject to learn 8 names of black-and-white photos of people within 10 trials; (b) the Buschke Selective Reminding Task (BSRT; Buschke, 1973), which attempted to teach a list of 20 words, selectively reminding the subject of missed words for 5 trials and having a free recall sixth trial; (c) a recall of practical items, consisting of 20 nouns, composed by the subject and recalled after a 3-min

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Allen, Longmore, and Goldstein Table I. Screening Scores

Variables

Scores

IO~ Full Scale Verbal Performance

95 97 92

WMS-Rb Verbal Memory Index Visual Memory Index General Memory Index Attention/ConcentrationIndex Delayed Recall Index

94 92 92 95 85

Mattis Dementia Rating Scale Total Score

140

BDAE c

Repeating Phrases (N = 16) Responsive Naming Articulation Response lag (N = 30) Animal Fluency Visual ConfrontationNaming Articulation Response lag (N = 114)

15 Normal 30 15 Normal 114

aWechsler Adult IntelligenceScale--Revised. bWechsler Memory Scale--Revised. CBoston Diagnostic Aphasia Examination.

learning period; and (d) a delayed face-name, 1-trial free recall. The subject also completed the Beck Depression Inventory (BDI; Beck et al., 1961) and the Beck Anxiety Inventory (BAI; Beck and Steer, 1990). Because we had an interest in determining the generalization of memory training to other visual and verbal memory tasks, we administered the WMS-R again 1 month after completion of treatment. Of particular interest were the immediate and delayed recall components of the Logical Memory and Visual Reproduction subtests of the WMS-R because these provided indices of verbal and visual memory that were substantially different from the memory training strategies taught to the subject during memory training. In addition to these tests, we were able to obtain California Verbal Learning Test (CVLT; Delis et al., 1987) scores conducted approximately 1 year prior to the current memory training program. In order to judge generalization of learning strategy to a significantly different list of words, we also administered the CVLT 1 month following the completion of memory training. We administered the same forms of the CVLT and WMS-R at pretest and posttest because these are standardized measures of memory abilities. However, in order to control for practice effects, we used all new material for the BSRT and the list of 20 practical items. Also, we generated a new set of face-name associations for the eight black-and-white photos. Records indicated that the subject was not experiencing an exacerbation when he completed the initial CVLT, although he was experiencing significant depressive


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symptomatology as indicated by clinician rating and self-report (BDI = 30). There was also no evidence of exacerbations of the disorder during the memory training or during follow-up.

Memory Training Computer-assisted memory training consisted of techniques designed to remediate both verbal and visual memory deficits. Visual memory training used a facename association task, while verbal memory training utilized a list learning task based on a modified version of Kovner and co-workers' (1983, 1985) Ridiculously Imaged Stories technique (RIS). There were a total of 10 face-name association sessions and 15 list learning sessions scheduled two or three times each week. Each memory training session began with the face-name association training. Face-Name Association. Face-name association training occurred as an automated procedure in which the subject viewed a picture of an individual presented on a computer screen along with an audiotaped presentation of the individual giving his/her name (e.g., "My name is Harry"). This training technique provided the subject with a realistic audiovisual presentation of the face-name pairs. We used 10 new faces and names for each training session. The trainer encouraged the subject to learn the face-name pairs using one of three techniques, including (a) associating the name with a familiar or famous person (e.g., "Lauren looks like Lauren Bacall"), (b) relating the name with some physical characteristic of the picture (e.g., "Harry has a hairy face"--for someone named Harry who has a beard and mustache), or (c) relying on some other cueing method (e.g., rhyming or word associations: "Angela looks like an angel"). Following completion of list learning, the trainer again presented the pictures and asked the patient to give the names. We used a cueing procedure when the subject was unable to recall a name. This procedure consisted of providing the associations previously assigned to the face-name pair by the patient when he was unable to remember the correct name. We subsequently provided the correct name when cueing was not successful. The number of correct names recalled after cueing constituted the score for each session. We used a different set of pictures at each session in order to promote generalization. List Learning. RIS list learning training, also computer assisted, consisted of two components: direct training and generalization. During the first eight sessions, the trainer presented two stories to stimulate imagery-based learning and provide time for the patient to learn the technique. The subject read a story in which we embedded 20 words for him to recall later. The trainer then encouraged the subject to use visual imagery to imagine the story and the designated words within it. Following direct training, we changed the lists and stories at intervals to encourage generalization of the technique. Finally, we faded out trainer-generated materials, beginning with session 9, and the subject received new word lists, with which he was to write his own subject-generated stories. The last two sessions challenged him to use personally relevant lists and stories composed of difficult to remember social and/or occupational information. We used the number of words

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Allen,

Longmore,

and

Goldstein

freely recalled at the end of each session to evaluate his progress during training. We also used 40 words in the recognition task, and the patient attempted to identify the 20 key words used in each session.

RESULTS

Pretraining and posttraining performance on neuropsychological measures appears in Table II. The subject evidenced relative improvements during the facename association memory training. Although the within-training learning curve remained somewhat fiat, with the subject recalling 9 faces at the end of Session 1 to 10 faces at the end of Session 10, the number of trials to learn all 8 faces decreased from three trials to one trial, which may suggest the ability to learn at a faster pace. Improvements were also present on the face-name learning task. This task required the subject to learn names associated with black-and-white photographs. Before training, he was able to recall five of eight face-name pairs at the end of the first trial. At 1 week and 1 month posttesting, the number of face-name

Table IL List Learning and Face-Name Association Pretest and Posttest Results Test index

Pretest 1 (3/23/93)

Buschke Selective Reminding Test (N = 20) Recall of practical items (N = 20) Face-name association Trial 1 (N = 8 faces) Delayed recall (N = 8) Trials to learn (N = 10 trials) WMS-R Logical Memory I Logical Memory II Visual Reproduction I Visual Reproduction II

i

m

m

m

Pretest 2 (5/10/94)

Posttest I (8/29/94)

Posttest 2 (9/15/94)

9

18

17

5

20

18

5 8 3

8 8 1

8 8 2

41st %ile 3rd %ile 63rd %ile 30th %ile

-----

42 (-1 SD) 6 (-1 SD)

---

---

8

--

--

9 11 8 (-3 SD) 5 (-1 SO)

--

--

--

--

---

---

65 (+1 SD) 10 (+1 SD) 11 15 14 15 ( + 2 SD) 10 ( + 2 SO)

Short Delay Free/Cued Recall

4/6 (--3/-3 SO)

--

--

12/12 (+1/0 SO)

Long Delay Free/Cued Recall

7/7 (-2/-2 SD)

--

--

16/14 ( + 2 / + 1 SD)

Beck Depression Inventory

30

24

--

47

Beck Anxiety Inventory

--

14

--

14

CVLT Total for trials 1-5 1 2 3 4 5 List B

m

83rd 89th 41st 53rd

%ile %ile %ile %ile


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pairs recalled on the first trial was eight (100%). Visual Reproduction percentile scores were less impressive. On Visual Reproduction I, the 63rd percentile score before training decreased slightly, to the 41st percentile, after training [standard scores (ss) = 105 and 97, respectively]. Visual Reproduction II scores improved from the 30th percentile before training to the 53rd percentile after training (ss = 92 and 101, respectively). The results of the RIS list learning memory training appear in Fig. 1. The MS subject was clearly able to learn the new word lists during direct memory training and sustained this learning curve through generalization. New word lists and subject-generated words and stories had little effect on his ability to learn. The most significant improvements were evident when comparing pre- and posttest scores as shown in Table II. The comparison of verbal memory pretraining scores with both the 1-week (posttest 1) and 1-month follow-up (posttest 2) scores reveals significant effectiveness of the cognitive rehabilitation program with this subject. The Buschke Selective Reminding Test's sixth list comparisons for before training (N = 9/20) and the same list recall for 1 week after training (N = 18/20) show a 100% increase in recall output. As shown in Table II, the recall of personally relevant words yielded a 300% increase between pre- and 1-week posttests. Recall for Buschke items and personally relevant items decreased slightly at 1-month follow-up. However, scores obtained at 1-month follow-up still remained significantly improved compared to pretesting. Memory training appeared to affect positively neuropsychological test performance as well. Reviewing several subtests from the Wechsler Memory Scale--Revised also shows a significant improvement. Percentile ranking increased from the 41st percentile before training to the 83rd percentile after training for Logical Memory

20

U L) ,~ 18

9

d~

List I List 2

.t Generalization

z

14

I I

I 2

I

I

I

I

I

I

I

I

I

I

I

I

I

3

4

5

6

7

8

9

I0

II

12

13

14

15

List Learning Practice Sessions

Fig. 1. List learning practice sessions.

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I (ss = 97 and 114, respectively) and from the 3rd to the 89th percentile (ss = 72 and 118, respectively) for Logical Memory II. California Verbal Learning Test results also suggested positive effects from memory training. On the CVLT administered 1 year prior to training, the subject recalled 52.5% of the words on List A and 43.7% of the words on the Long Delay Free Recall. One month after training he recalled 81.2% of the words on List A and 100% of the words on the Long Delay Free Recall. Interestingly, the decrease in overall recall errors may also suggest improved memory efficiency. Comparing pretesting to posttesting, the number of free and cued recall intrusions decreased from 12 to 3, respectively.

DISCUSSION The conclusions of the current investigation are similar to those in our previous investigation (Goldstein et al., 1988). First, the RIS list learning technique enhanced the subject's list learning ability. Second, some evidence for generalization was present as improvements were present not only for the training task list but also for different lists memorized during generalization sessions, on the CVLT, and on the BSRT. We also noted an improvement on the WMS-R Logical Memory II subtest, which is a story recall task rather than a list learning task. Anecdotally, the patient reported that it was, in fact, the memory strategies taught during the training sessions that he utilized to improve his performance on the list learning tasks. Learning mnemonic strategies appears to have had the effect of increasing his performance immediately, which is in contrast to some patients from our other studies, who have seemed to progress slowly but incrementally from trial to trial. As in our previous report, the results of the face-name association training suggest improvement but are more equivocal than the RIS list learning training. Our subject was able to recall 9 face-name pairs in the first training session and consistently correctly recalled 9 or 10 face-name pairs in 8 of the 10 remaining training sessions. It appears, then, that a ceiling effect limited our ability to determine the magnitude of effectiveness. However, although the ability to form meaningful and relevant associations does not appear to have increased significantly, the efficiency with which the subject accomplished this task appears to have improved. It initially took the subject three trials to learn all 10 face-name pairs at pretest, in contrast to one trial at the 1-week follow-up and two trials at the 2-week follow-up. Although one could argue that this decrease in the number of trials is the result of chance, we have noted a similar pattern of improvement in other subjects undergoing memory training, which lends support to the improved memory efficiency explanation (Goldstein et al., 1988). In the absence of an adequate control group, it is not possible to conclude unequivocally that improvement in memory test performance was not simply the result of practice effects. However, several points argue against this explanation. First, the lapse of time between pre- and posttesting on the CVLT and WMS-R (17 and 4 months, respectively) decreased the influence of practice effects. Second, the subject exhibited marked improvement at posttesting on instruments for which we


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administered alternate forms (e.g., BSRT, recall of practical items, and face-name associations). If practice effects alone accounted for the current results, one would not expect improvement on all of the measures of verbal memory ability. Rather, the generalization suggested by his improved performance on alternate forms is consistent with an improvement in the ability to form meaningful associations. Third, our experience suggests that cognitively impaired patients often have more difficulty with the list learning tasks, such as the CVLT, relative to story recall tests, such as those used in the WMS-R. This may be because list learning tasks, in which patients hear unrelated words presented serially, require patients to develop organizational strategies in order to memorize efficiently and recall the maximum number of words. In contrast, story recall tasks already provide structure by the logical organization of the story around several temporally and semantically related major concepts. The vast improvement in scores on the CVLT and other list learning tasks suggests that an improvement in performance is due to strategy application rather than practice effects. As with all single-case designs, the issue of generalizability of results is of concern. Hersen (1990) identified three sources that could affect generalizability, including the subject, the behavior change agent, and the setting. Put a different way, one could ask, "Will the memory training treatment we report work if a different therapist applied.it to a different subject in a different setting?" With regard to subject generalizability, we reported similar positive results in patients undergoing memory training who had memory deficits resulting from different neuropathology (head injury) (Goldstein et al., 1988). Also, our patient with MS was similar to many community-dwelling patients with MS in that he maintained gainful employment, did not receive any financial assistance, and exhibited significant depressive symptomatology. Based on these observations, we expect that our results will generalize not only to other patients with MS, but also to patients with memory deficits arising from differing neuropathological processes. We also do not expect that the behavior change agent (therapist) or the setting will influence the generalizability of the current results because we administered the memory training technique in a standardized manner via computer under the direction of a trained technician. We believe that different clinician researchers could replicate our results in d.ifferent settings, given the availability of necessary equipment and appropriate training. Uncontrolled sources of variability also present significant threats to the generalizability of results derived from single subject studies. In the current investigation, we have controlled for several sources of variability that could impact memory functioning by assessing affective state (depression and anxiety) and medication use. Results suggest that these factors did not change over the course of the study in a manner that would improve memory functioning. More specifically, it appears that depression did not influence the subject's performance because his BDI scores indicated that he felt less depressed at pretesting than he did at posttesting. If affective state were influencing his memory functioning, one would expect decreased performance at posttesting because his level of depression increased. Similarly, it does not appear that changes in anxiety positively influenced his test performance because anxiety (as assessed by the BAI) remained stable from pretest to posttest. Finally, because medication and disease symptom profiles remained stable across

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the study, variability in medication use or disease activity does not appear to account for the improvement in memory functioning. The current investigation contributes to a growing body of literature that, while at times controversial, generally supports the efficacy of mnemonic-based memory training programs. Some of the controversy arising from the computer-assisted cognitive rehabilitation literature is a direct result of the lack of studies, such as ours, that demonstrate the efficacy of specific rehabilitation programs designed to rehabilitate specific cognitive deficits. Also, debate has arisen over the role of computers in treatment of cognitively disabled individuals. These issues and others have prompted the development of guidelines for the use of computers in cognitive rehabilitation (Matthews et al., 1991). We strongly recommend that clinicians and researchers interested in developing cognitive rehabilitation programs and/or applying currently existing technologies to assist the rehabilitative process consult these guidelines. However, several of the points made by Matthews and colleagues (1991) are worth noting. First, computers and computer software provide practical advantages that support their continued use and development in the rehabilitation process. However, it is most proper to view computers and software as one of many rehabilitative tools applied in the rehabilitation of any particular cognitive deficit. Second, in most instances, application of computer-based rehabilitation programs in clinical settings is justifiable only when there is ample evidence to support efficacy of these treatments. So, for example, based on the empirical evidence, there is little justification for the use of memory drills as a method of improving generalized memory functions. Third, clinicians can reduce the risks to consumers of rehabilitation services by providing computer-assisted cognitive rehabilitation within the context of a comprehensive rehabilitation program. This approach, typically accomplished under the direction of an interdisciplinary treatment team, allows the rehabilitation of the total individual (occupational, psychological, interpersonal). We acknowledge that several factors limit the results from the current study. First, we were able to obtain only 1-month follow-up, which did not allow us to determine the durability of the effects of memory training over an extended period of time. Second, although we were able to provide some evidence for the generalization of memory training within the experimental setting, we were not able to determine if the use of memory strategies had any meaningful impact on performante of daily activities requiring memory functioning. Third, it is possible that uncontrolled sources of variability (e.g., historical events) are responsible for the current results; although, if this is the ease, these sources are not readily apparent. In the future, investigators could clearly establish generalizability of the current results by using memory rehabilitation with larger numbers of patients who have MS. In addition, functional assessments that would allow investigators to determine the impact, if any, that improvements in memory functioning assessed in the laboratory setting have on the ability to complete daily activities effectively would be useful. Ecologically relevant memory tests may also help clarify whether memory training programs, such as our own, have positive effects on tasks that are similar to those required for adequate day-to-day functioning.


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ACKNOWLEDGMENTS Ms. Longmore and Dr. Goldstein received partial support from a Veterans Affairs Medical Center Grant to Dr. Goldstein. We gratefully acknowledge the assistance of Carrie Burns in preparing the manuscript.

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