6.2 Remediation of Learning and Memory Deficits

6.2.1  Treatment of Learning and Memory Deficits

Memory impairment is one of the most common symptoms following brain injury and it is estimated that time and cost of care would be reduced if effective medical treatments were found to improve memory 18

Describe the two major approaches to learning and memory deficits post ABI.

1.    Restoration: remediation of memory deficits.

2.    Compensation:  circumventing the difficulty which arises because of the memory deficit.

What are different examples of these two approaches?

Restoration: remediation of memory deficits.

  • External compensatory aids including computers, pagers and notebooks
  • Individualized remediation programs
  • Family/social support
  • Enviornmental adaptations
  • Didactic lessons and homework

Compensation:  circumventing the difficulty which arise because of the memory deficit.

  • Rehearsal
  • Organizational strategies
  • Visual imagery
  • Verbal labeling
  • Use of mnemonics
  • Implicit memory tasks

When evaluating intervention strategies to improve memory performance following brain injury, the literature indicates that there are two main approaches to rehabilitation: restoration or compensation.  Compensation includes “training strategies or techniques that aim to circumvent any difficulty that arises as a result of the memory impairment.”  Compensatory techniques include internal aids, which are “mnemonic strategies that restructure information that is to be learned.”  Various interventions have focused on: 1) Remediation of memory deficits in individuals with TBI, including external compensatory aids (computers, pagers, and notebooks), individualized remediation programs, family/social support and environmental adaptations, didactic lessons and homework; 2) Compensatory Strategies including rehearsal, organizational strategies, visual imagery, verbal labeling, and use of mnemonics, as well as implicit memory tasks.        

Cicerone et al. 1reviewed 42 studies examining the effectiveness of various interventions to improve memory impairment following stroke and TBI. It should be noted that studies were not included in our review if the population did not comprise of more than 50% brain-injured patients, or if the sample size (n) was less than 3.  For this reason, only those studies dealing with moderate-to-severe brain-injured individuals are included in our review.  Thirteen additional studies were added to the review in 2005 2.

In an updated review by Cappa et al. 19strategies used to improve memory deficits without the use of electronic, external aids were judged to be “possibly effective.”  Specific learning strategies (e.g. errorless learning) were found to be “probably effective” depending upon the task used, the type of memory involved and the severity of impairment. 

Several studies were identified examining interventions to improve learning and memory following acquired brain injury.  Studies were categorized into the following groupings: external aids used to enhance memory, internal strategies used during learning to enhance recall, and memory intervention programs consisting of a number of sessions. 

 

According to ABIKUS Recommendations 3

Learning and Memory

Cognitive rehabilitation should include the use of self instructional training/internal training (e.g. self cueing, self talk).  (ABIKUS A) (G37-p.22)

Cognitive rehabilitation should include the use of errorless learning for task specific learning for people with severe memory impairment.  (ABIKUS B) (G38-p.22)

6.2.2 External Aids

What evidence is there for external memory aids?
  1. There is conflicting evidence as to whether external memory aides are an effective strategy for memory-impaired individuals.

External aids assist memory by use of external methods of recording and accessing information.  In an updated review by Cappa et al. 19, the use of external, electronic assistive devices were assessed as “probably effective.”  Fourteen studies examined how external aids could be used to enhance memory following brain injury.

Wright et al. 20examined the effect of two pocket computer systems containing three memory aides: appointment diary, notebook, and a to-do-list with a group of 12 ABI participants (9 TBI, 2 ABI).  The type of pocket computer was counterbalanced and participants used each one for 8 weeks.  No significant difference in use was found between type of pocket computer (they differed in terms of text entry – physical keyboard or touch- screen keyboard), and the majority (83%) used the three aids.  Those participants who had previously used a memory aid made significantly more diary entries compared to those who had not previously used a memory aid.  Severity of injury as well as level of cognitive function was not reported in this study.  In another study by Wright et al. 21, findings were similar (i.e. no differences between computer systems in terms of use of memory aids).

Wilson et al. 22evaluated the efficacy of NeuroPage, a portable paging system, in reducing everyday memory problems in 15 ABI participants (10 TBI, 5 ABI).  Using an A-B-A design, results indicated that all subjects significantly benefited from using the NeuroPage system and that following 12 weeks of use, performance remained at improved levels compared to baseline for another 3 weeks.  Wilson et al. 23conducted a randomized controlled cross-over trial with 143 memory impaired patients, many – how many having sustained a TBI. The objective for this study was to evaluate a paging system designed to improve independence in people with memory problems as well as to reduce deficits in executive function. Results demonstrated that the pager system significantly increased patients’ ability to carry out daily tasks, and successful task achievement was more efficient after the pager intervention was introduced.

Hart et al. 24used hand-held recorders to remind moderate-to-severely impaired patients of their therapy goals (within subject design).  Six individual goals were determined and half were recorded onto a hand-held organizer with an alarm preprogrammed to review the goals 3 times a day throughout the week.  The other half of the goals were not recorded but were summarized at the weekly clinical management meetings.  Goals were correctly recalled when using the hand held recorder compared to when goals were reviewed.  It should be noted that the study examined only if the goals could be elicited during recall (either free recall or cued) and did not examine whether the subjects actually followed through with their goals.

Burke et al. 25used a complex computerized tracking system (patient locater and reminder system – PLAM) to remind and direct 5 patients on an acute rehabilitation unit to their next therapy appointment.  The electronic tracking system prompted patients 10 minutes in advance of their appointments and continued to do so until the patient started moving toward the therapy room.  If patients were going in the wrong direction, the system would prompt them on how to get to the appointment and would offer positive reinforcement as the patient made their way to the therapy room.  Using a case series design, baseline data was gathered for a week and included the number of staff prompts needed to get the person to scheduled therapy and the time the person arrived at the therapy.  Once the patients were introduced to the PLAM system, data was collected for a 3-day period.  Results indicated that the subjects arrived earlier to their appointments and required fewer prompts (i.e. the number of sessions that did not require prompting increased from 7% to 44%).

Using a memory notebook as the external memory aid, Schmitter-Edgecombe et al. 26assigned 8 individuals with severe closed-head-injury and memory deficits into either a notebook-training group or an interpersonal support group (control).  Groups were matched on a number of demographic variables.  Outcome measures included both performance on memory tests as well as observation and responses to a questionnaire on everyday memory failures.  Both groups received 2, 1-hour sessions per week for 8 weeks (16 sessions).  Results indicated that, on cognitive measures of memory functioning, there was no difference between groups.  However, on observed everyday memory failures (questionnaire), performance improved (i.e., less failures) following treatment, although performance was not maintained at 6-month follow-up.

In a randomized controlled trial, Watanabe et al. 27examined whether use of a calendar would enhance orientation following an acquired brain injury.  Results indicated that the presence of a calendar did not enhance performance on a temporal orientation test(date and time).  It is difficult to judge the outcome of this study as no scores were reported for either the control or treatment group, and it is not clear whether post-traumatic amnesia, and/or severity of injury had an impact on performance.

Ownsworth and McFarland 28evaluated two different training approaches in the use a diary to compensate for memory problems.  They randomly assigned 20 ABI volunteers (15 TBI; 5 ABI) to either a Self-Instructional Training (SIT) approach or to a task-specific learning approach.  The Diary-SIT approach trains compensation using higher cognitive skills of self-regulation and self-awareness.   That is, participants where taught to question themselves with the following script (WSCT): What are you going to do?  Select strategies; Try it out; Check how it’s working.  By using this training approach, the researchers speculated that it provides direct, internal feedback, which can generalize to other situations involving memory.  In contrast the Diary-Only approach taught subjects how to use the diary.  Results indicated that those in the Diary-SIT group made consistently more diary entries, reported a reduction in everyday memory problems and made more positive ratings on treatment efficacy compared to the Diary-Only group. 

Cicerone et al. 1recommended that the use of memory notebooks or other external aids “may be considered for persons with moderate to severe memory impairments after TBI [and] should directly apply to functional activities, rather than as an attempt to improve memory function per se.”

 

6.2.3 Internal Aids

What is the evidence for internal memory aids?
  1. There is Level 2 evidence (from several studies) that internal strategies appear to be an effective aid in improving recall performance. 
  2. There is Level 3 evidence from several case-control studies that internal strategies appear to assist in improving recall performance.

Four randomized controlled trials, seven prospective controlled trials (plus one follow up study) and three single group interventions examined the effect of strategy use on memory following brain injury.

 

Twum and Parente 29randomly assigned 60 TBI patients into one of 4 groups (one control and three mnemonic strategy groups) counterbalanced.  The researchers demonstrated improved performance for subjects who were taught a strategy (either verbal labeling or visual imagery) while learning paired-associations.  Treatment groups showed greater efficiency in learning and greater delayed recall information.

 

Ryan and Ruff 30used mnemonic strategies, including visual imagery in a memory group and found that these strategies enhanced performance for mildly impaired subjects only (severely impaired group showed non-significant findings between control and treatment groups). 

 

Goldstein et al. 31and Malec et al. 32evaluated a visual-imagery technique (“Ridicuously Imaged Story” technique (RIS)) in training severely brain injured individuals to learn and recall lengthy word lists.  Goldstein et al. 31evaluated whether there were differences between a computerized and non-computerized version of RIS and another visual imagery technique (Pictorial Imagery).  Results indicated that although the computerized versions resulted in a slightly better performance on learning trials, the difference was non-significant.   Malec et al. 32used the RIS technique to examine the predictors of memory training success and found that the “better subjects did at tasks similar to those which they were trained, the better their learning and capacity to generalize.”

 

By using the various visual imagery techniques to aid learning and recall, researchers have demonstrated that increasing the saliency of features encoded, results in an increase in the amount recalled.  Milders et al. 33examined performance on a name learning task by increasing the meaningfulness of people’s names with various strategies (e.g. when learning a new name-face association try to think of an occupation or object with the same name or a famous person with a similar name etc).  When subjects (13 severely TBI vs. 13 matched controls) were tested on 3 different memory tasks, results indicated a significant difference following training, more so for the control group than the TBI group.  Also, learning procedures were more effective on one task (where subjects were required to learn the name-occupation-and town) compared to the other two tasks (famous-faces or name learning), which supports Malec et al. 32findings of generalization when tasks are similarGoldstein et al. 34found that semantic processing aids recognition of to-be-recalled words compared to processing words at a more perceptual level in both closed head injury patients and control subjects (of course the degree of facilitation is reduced in the TBI group compared to controls).

 

Zencius et al. 35examined the differential effects of various strategies on recall of information.  Six TBI patients were asked to find two jobs from the help wanted column of a newspaper extracting 3 pieces of information for each job.  They were asked either to learn the information for later recall using one of the following strategies: verbal rehearsal, written rehearsal, acronym formation or notebook logging.  All strategies resulted in improved performance (number of information correctly recalled) with the exception of written rehearsal (performance similar to baseline).  Notebook logging resulted in the best performance.

 

Berg et al. 36demonstrated that severely brain injured patients demonstrated improved effects on objective measures of memory at 4 months following training in a strategy-use group compared to a pseudo-treatment and a no treatment control group.  In the strategy group, individuals were taught general cognitive principles of memory functioning and aids (i.e., internal and external strategies were taught and practiced).  In contrast, the pseudo-treatment group practiced memory games and tasks with no explanation.  In a 4 year follow up study Milders et al. 37results demonstrated that the effects at 4 months were no longer evident at 4 years (all groups were equivalent).

 

How individuals learn (i.e., encode) information will determine to a large extent what is later recalled.  Twum and Parente 29demonstrated that if an active strategy (either verbal labeling for visual information or visual imagery for verbal information) is taught to individuals while learning the paired associations, learning and recall is enhanced (i.e., fewer trials needed to reach criterion during learning and improved recall following a delay).  Tailby and Haslam 38also examined how learning can improve or limit later recall of information.  They had 24 ABI subjects matched on basis of age, gender, premorbid and current intellectual status divided into 3 groups based on performance of verbal memory (mild, moderate & severe).  Each group (n=8) was randomly assigned to one of 3 learning conditions: errorless learning, self-generated; errorless learning, experimenter generated; and errorful learning.  Results showed that regardless of severity level, subject recalled more information in the errorless learning conditions (with self-generated superior to experimenter generated) than in the errorful learning condition.

 

Constantinidou and Neils 39examined the effects of stimulus modality on verbal learning of patients with moderate-to-severe closed head injury and a matched control group.  Results indicated that when information is presented visually (with and/or without auditory presentation of names) more information is learned than when information is presented within the auditory modality alone.  As expected, patients learn new information at a significantly slower rate compared to controls.

 

It is generally thought that while patients are experiencing post-traumatic amnesia (PTA), they are not able to learn and retain new information, and as a result, cognitive rehabilitation is usually postponed until PTA has resolved. This tends to be true if using tasks of explicit or declarative learning and recall. Two studies were reviewed that reported that PTA patients were capable of learning and retaining new information when task demands were dependent on implicit/procedural learning.  Glisky and Delaney 40evaluated implicit memory (priming using a stem completion task) and the use of vanishing cues when learning semantic information in a small number of TBI patients (n=8 & 4) who were still experiencing PTA and a matched control group.  Findings revealed that learning and recall of information (once PTA has resolved) had occurred, albeit at reduced levels compared to controls.  Ewert et al. 41also demonstrated procedural learning and retention in a group of 16 severely closed head injured participants and matched controls.

6.2.4 Memory Programs

What is the evidence for memory-retraining programs post ABI?
  1. There is Level 2 evidence, based on a single RCT, that memory-retraining programs appear effective, particularly for functional recovery although performance on specific tests of memory may or may not change.

Ryan and Ruff 30randomly assigned 20 severely brain injured individuals, matched for age, gender, education, and time since injury, to either a memory retraining group or a psychosocial group (control).  Treatment lasted for 6 weeks (4 days per week, 5.5 hours per day for each group.  Initially no differences were observed between groups on neuropsychological measures of memory.  When groups were subdivided based on neurocognitive severity (mild vs severe), results indicated that the mildly impaired group benefited more than the severely impaired group from memory retraining.

Freeman et al. 42conducted a matched-controlled treatment outcome study to evaluate executive and compensatory memory retraining in traumatic brain injured patients. 12 patients were included in this study; six who received remediation treatment, which involved repeated presentation of various paragraphs, and six who received no treatment. A significant difference was found between the treatment group and the control group’s post-training measures with the experimental group improving considerably more than the control group. Results suggest that memory remediation is effective for brain-injured patients with memory impairments.

Evans and Wilson 43examined the effects of a memory group that met weekly for 11 months (2 hours a week for approximately 48 weeks).  Family and individuals reported an increase in using memory aides and strategies at 7 months and at 11 months compared to baseline (no objective measures were given and it is unclear if beneficial).  Scores on neuropsychological measures of memory did not change over time.  A main drawback of this study is the researchers’ failure to describe the nature and content of the memory program.

Quemada et al. 44examined memory rehabilitation following severe TBI in 12 individuals. The program ran for 6 months (50 minute sessions 5 days a week for 5 months and then 3 days a week for one month) and followed a specified format utilizing behaviouralcompensation techniques, mnemonic strategies, environmental adaptations, external and internal aides.  Results indicated little improvement in standard measures of memory functioning, although patients and family members report meaningful functional gains (self-report and observed behaviour in everyday functioning).

Hux et al. 45examined the effect of training frequency on face-name recall.  The study included 7 TBI patients with demonstrated memory impairment in a modified multiple-baseline design utilizing 3 training phases (daily sessions, twice a week session and 5 times a day).  The phases were counterbalanced, thereby eliminating any order effect.  Daily sessions as well as twice a week sessions were found to be more effective than sessions that occurred 5 times a day.  Mnemonics and visual imagery strategies were effective for 4 of the 7 participants regardless of frequency of intervention sessions.

6.2.5 Cranial Electrotherapy Stimulation and Memory

What is the evidence for cranial electrostimulation in improving memory?
  1. There is Level 1 evidence, from one RCT, that cranial electrotherapy stimulation did not help to improve memory and recall following brain injury.

Cranial electrotherapy stimulation (CES) is the application of less than 1 mA of electric current to the cranium.  This application has been used to treat a variety of disorders, including treatment of withdrawal of patients with substance abuse 46. The effect of CES for the improvement of memory following brain injury was investigated. 

Michals et al. 46studied cranial electrotherapy stimulation and its effect on post-traumatic memory impairment in clinical care patients with closed head injury.  Patients received CES or sham CES treatments for 40 minutes daily over a period of four weeks. The group receiving CES treatment did not improve in their memory performance, nor did their immediate or delayed recall improve.  Further, with retesting, both the CES and the sham CES group showed a similarly significant trend with no group performing any better than the other. These results suggest that CES stimulation in brain-injured patients does not improve memory functioning.