Journal of the New Zealand Medical Association, 25-January-2008, Vol 121 No 1268
Memory deficit after traumatic brain injury: how big is the problem in New Zealand and what management strategies are available?
Suzanne Barker-Collo, Valery L Feigin
TBI is a leading cause of disability and death in young adults and has a significant impact not only on the individual, but also on their family, whānau (immediate and extended family), friends, and society. In the United Kingdom, Australasia, and North America, 200–300 people per 100,000 will be admitted to hospital with a TBI each year.1 By comparison, incidence in New Zealand is reportedly 560/100,000 yearly.2
Thus, in New Zealand, there are about 20,000–30,000 new cases of mild and 2000 to 3000 cases of moderate to severe TBI annually. TBI-related mortality peaks from 15–to 24 years of age,1 and the risk of TBI peaks between 15 and 30 years, with motor vehicle accidents (MVA) and interpersonal violence contributing significantly to these rates.1
Approximately 70% of head injuries are the result of MVA, with other causes including industrial or sporting accidents, falls, assaults, and bicycle accidents.3 Because of the high incidence of TBI at an early age, and long-term impact on employment, TBI-related disability has enormous economic and social consequences across the lifespan, with estimated direct costs ranging from approximately NZ$69 million to $103 million.4 Further, it has been suggested5 that there is a higher rate of brain injury in New Zealand Māori, with "New Zealand Māori featuring disproportionately in all the negative social statistics" which "offers poor prognosis for Māori quality of life and it follows that Māori will be likely to suffer brain damage (e.g. closed head injury, and alcohol and drug-related damage) at a higher rate than their Pākehā (New Zealand European) and other ethnic group peers".5
Further, TBI results in emotional distress in family members who take on caregiving roles, with resultant increases in use of tranquilisers, alcohol, and counselling services.6,7 Caregivers are described as often being overwhelmed and ill-equipped to provide for the complex needs of individuals with TBI.8,9
Disturbances in memory functioning are the most marked and persistent sequels of closed TBI, often persisting beyond the period of immediate recovery.10–13 The most frequent sites of cerebral contusion in closed TBI are the temporal and basal-frontal regions, both of which are associated with memory.10
Memory deficits due to TBI have been reported to occur in 69% to 80% of individuals.14,15 In 36% of people with severe TBI, these memory impairments will be permanent.16 McKinlay17 reported memory deficits in 73% of the cases of severe TBI at 3 months post-injury. The severity of TBI, which is typically determined at the time of injury using the Glascow Coma Scale (which indicates level of consciousness) and length of post-traumatic amnesia, is related to both the degree and persistence of the resulting memory deficit, with more severe injuries producing greater deficits.11 Longitudinal studies do not demonstrate significant decreases in complaints of memory deficits 1,17 5,14 or even 7 years post-injury.18
Simplistically, memory can be seen to involve four sequential, interrelated processes: paying attention, encoding, storage, and retrieval of information. Memory difficulties experienced following TBI may reflect impairment in any one or more of these processes. In approximately one-quarter of survivors of closed TBI, impairment of encoding and storage persist.11 Individuals often experience significant memory loss for events around the time of injury and persistent impairment of the ability to create (i.e. encode) new memories.11
For the majority of individuals with a mild to moderate brain injury, memory difficulties result from a disruption at the attention level, the retrieval level, or a combination of both.19 In general, following a TBI, memory-impaired people experience problems in new learning and retrieval of new information (i.e. anterograde amnesia).16,19 Following severe brain injury, working memory and/or encoding deficits are likely to result.19 TBI may result in a disturbance across memory areas or more material-specific deficits (i.e. specific problems with visual or verbal information).11 This is shown in individuals who have left temporal-lobe lesions, which typically results in specific deficits in verbal memory and learning.11
Memory deficits can profoundly impact a person's day-to-day functioning, often preventing them from returning to work, or impacting their capacity to engage in independent living.20 Memory impairment has been linked to increased disability and reduced quality of life in a number of populations.21,22 Within the literature on TBI, the extent of memory impairment has been linked to patient’s presence of major depression,23 and level of caregiver distress.24
Given the foregoing, it would seem imperative that these deficits be addressed as part of any rehabilitative efforts. Indeed, the rehabilitation of memory deficits through use of memory aids has been associated with increased ability to live independently.25,26
Teaching brain-injured people to compensate or bypass memory problems, or use their residual skills more efficiently will make their lives and those of their families/caregivers more satisfactory and tolerable.10 Memory deficits should be an important focus of treatment efforts as they often interfere with other areas of rehabilitation.27,28 For example, occupational, speech, and physical therapies rely (to some extent) on behavioural techniques that require both learning and memory.27
Thus, addressing memory deficits is of paramount importance if the goal of rehabilitative efforts is to reduce disability and handicap across this and other areas of deficit, and increase an individual's ability to function independently.
Early memory rehabilitation research concentrated on the direct retraining approach, teaching paired associates or lists of words rather than identifying or treating practical problems experienced by people with memory impairment.29 However, it is now generally agreed that it is not possible to directly restore/remediate memory.29,30
Once the period of natural recovery is over, which is most noted in the first 6 months post-injury, lost memory functioning is less likely to be restored.16 Thus, while efforts to restore impaired memory function have been considered ineffective,25 cognitive rehabilitation to introduce compensatory strategies to improve how an individual copes with memory impairment have produced functional improvements.31,32 Hence, in recent years, the focus of rehabilitative efforts has shifted to teaching compensatory strategies, to optimize residual abilities, and/or overcome other cognitive problems (such as attention problems) which contribute to memory deficit.19,28
Use of memory compensatory strategies is crucial for an independent life of reasonable quality.25,26 As such, an increasing number of studies have focusing on the use of aids or mnemonic strategies to improve the individuals’ ability to cope with activities in everyday life.25,26,31,33 Indeed, Wilson26 has demonstrated that the number of memory aids used in everyday life is an important factor in determining whether people with memory disorders are able to live independently.
Previous investigations of compensatory memory rehabilitation have typically focused on the use of isolated techniques designed to improve discrete types of memory impairment.31,32,34,35 It is increasingly difficult to justify isolated techniques and individual rehabilitation programs. These approaches are often not adequately comprehensive due to the limitations in the number of techniques applied, especially when dealing with clients that require treatment that is multi-focal due to the diffuse nature of their impairments. In addition, advances in medical technology have resulted in an increased number of individuals surviving serious TBI, with an associated rise in the number of persons requiring rehabilitation.28
Thus, there are an increasing number of patients, while there are decreasing resources, resulting in a reduced number of therapeutic staff providing services to a greater number of clients. This has led to the development of group format memory rehabilitation programs in an effort to streamline services and provide an economical and effective way of working with those who experience memory deficits.
Over the past two decades several group format memory rehabilitative programs have been developed for persons with brain injuries; results have been mixed.27,36–38 Group format cognitive rehabilitation has a number of benefits when compared to individual rehabilitation programs such as improved accuracy of self-perception through reality testing and feedback from others; modelling and reinforcement of appropriate behaviours in a social group setting; and increased ability to generalise skills to realistic settings and interactions.39
Wilson and Moffat,38 and Wilson,16 discuss other advantages of memory rehabilitation in group formats, namely, they provide a more economic staff-client ratio; the interaction with others with similar difficulties is beneficial in normalisation of fear reactions; social relationships and support networks can develop; and groups promote likelihood of using techniques and skills through modelling by peers. Memory groups have also been observed to have face validity: “participants (and their relatives) believe that treatment given in groups is effective, and this in itself may have indirect therapeutic value”.38
The aim of memory groups is to teach aids/strategies and to decrease the emotional side effects of memory impairment.16 While there is some evidence from single case experimental designs that memory rehabilitation can be effective for individual patients; few studies have involved randomised controlled trials.34 While some authors have not found group memory rehabilitation to have any significant effect,40 Evans and Wilson41 found that overall use of memory strategies and aids were significantly increased and some patients experienced reduced depression and anxiety as a result of group memory rehabilitation.
Other small sample controlled studies report that group memory training is effective in improving verbal memory.42 A non-randomised controlled trial comparing computerised memory training to therapist administered memory groups found them equally superior to controls.43 A number of studies have reported that while group memory rehabilitation does not impact on memory performance in lab based tests, they may have an impact on day-to-day indices of memory.
The lack of significant impact on lab-based memory assessments is not unexpected, given that the nature of such tasks often precludes the use of memory strategies. For example, Schmitter-Edgecombe et al39 evaluated a 9-week memory notebook treatment 2 years post severe closed TBI. Eight participants were randomly allocated to receive notebook training or supportive therapy. Notebook training resulted in significantly fewer everyday memory failures, though no significant treatment effects were found for laboratory-based memory measures.
Ryan and Ruff27 assembled empirically proven mnemonic techniques into a comprehensive 6-week memory retraining treatment program following TBI. Twenty subjects were matched and randomly assigned to either a psychosocial support (control) group or the memory retraining (experimental) group. Both groups improved on neuropsychological measures of memory, however the only significant gains from memory rehabilitation were for patients with mild deficits. It should be noted here that the nature of many lab-based assessments of memory functioning are not amenable to the use of compensatory strategies and, as the focus of group format memory rehabilitation has been on the use of such strategies, their impact on lab-based tasks can be expected to be reduced in comparison to indices of everyday memory difficulties, for which compensatory strategies are specifically targeted.
One feasibility and one non-randomised wait-list control pilot study of the MRG with small samples have been conducted.44,45 The feasibility study indicated overall satisfaction with group content, format, and pacing. In the culturally heterogeneous (8 Pākehā, 4 Māori, 2 Samoan) waitlist pilot of moderate-to-severe TBI survivors, word list delayed recall improved significantly as did paragraph delayed recall; other-ratings of the use of aids, and performance on a quiz regarding memory and memory strategies.
Though not statistically significant, self- and other- ratings of everyday memory difficulties also improved the positive effects of the group intervention were maintained at one-month follow-up.44,45 The pilot studies also allowed further development of the MRG strategy and testing of the feasibility of implementation in a group setting. The development and implementation of the MRG technique, and preliminary evidence of its benefits for memory in TBI patients provides the framework and opportunity for this innovative technique to be evaluated in a randomised controlled trial. This will provide high-level evidence of the cost-effectiveness of MRG in a significant sample of TBI patients.
To summarise, while the findings in regards to laboratory-based tasks is conflicting, the advantages of the group format memory rehabilitation are multi-fold, including: reduced behaviours indicative of everyday memory failures in relation to increased use of compensatory strategies; coverage of multiple domains of memory functioning; the ability to tailor to individual needs, reduced therapist to client ratios which are more cost-effective than individual memory rehabilitation; as well as the benefits of group interaction (e.g. normalisation, social support, role modelling, and reinforcement). However, to date there have been no full scale randomised controlled trials (RCTs) of such interaction.
In 2000, Barker-Collo44 developed an innovative multifaceted (rather than isolated) memory rehabilitation strategy for a group setting. This Memory Rehabilitation Group (MRG) adopts a compensatory approach incorporating training in using both internal strategies and external memory aids, with the focus of training being on those techniques that have received the most empirical support (e.g. diary, repetition). The group employs techniques to address each of the four processing stages of memory (attention, encoding, storage, retrieval), and incorporates empirically supported strategies such as rehearsal, organisation, errorless learning, and distribution of practice not only as techniques taught in the group, but as guiding principles for the group itself.
There are two main types of external memory aids, those which cue the user to access internally stored information (e.g., an alarm to prompt taking medication), and those which record information externally (e.g., diaries, lists, calendars). While external memory aids are arguably the best means of compensating for memory deficits,46 these aids are often difficult to use. As noted by Wilson et al47 individuals who need to use memory aids often have difficulty as their use is itself a memory task; and they may use aids in a disorganised or unsystematic way.
It has been suggested that an electronic memory aid that is programmed externally can help overcome these difficulties.48 Indeed, with advancements in technological resources over recent decades, attempts have been made to increase independence of memory-impaired individuals through the design and implementation of electronic memory aids which rely on caregiver input to prompt the memory impaired person. Such devices combine built-in alarms and external information storage to remind patients to carry out tasks at particular times and display messages to prompt details of the task (e.g. “Occupational Therapist—Claire—visiting at 10:30am”).
For example, in 1994, Wilson and her group began their evaluations of NeuroPage alphanumeric paging system47,49 by which an individuals reminders are entered into a computer, and then transmitted to the individual at a specified time and date. Initial evaluations of the system showed statistically significant improvement from baseline,49 though there was evidence of some individual differences in the need to maintain use of the system over the long-term.50,51
In a more recent randomised crossover trial,47 the NeuroPage system was found to improve success in everyday activities for 80% of 143 participants when compared to baseline, and this was maintained 7 weeks after the intervention was discontinued. Further, success in using the system was not influenced by age, gender, diagnostic group, level of impairment (as measured by neuropsychological tests), time since insult, or social circumstances.
A criticism of NeuroPage is that of ecological validity, as it separates the user from the ‘normal’ population, as embarrassment about using a device specifically for memory prompts may prevent a number of individuals from using such a system effectively.48 More recent efforts have therefore begun to focus on using technologies which are part of everyday life, such as cell phones and Personal Digital Assistants (PDAs), and not used solely as a memory aid.
A recent development using PDAs52 known as the Memory Aiding Prompting System (MAPS)-LifeLink is a guided prompting system that supports those with both memory and organisational/executive dysfunctions and allows caregivers to both support and track clients in remote locations. As with NeuroPage, caregivers use a desktop computer to develop scripts or prompts. The MAPS portion of the programme is a context-aware prompting system, while the LifeLinks portion of the device provides a remote monitoring and intervention system that can be used to supervise and support clients remotely.52
Unlike NeuroPage, MAPS-LifeLink allows caregivers to create detailed scripts using both text and visual prompts. These scripts are sufficiently detailed and unique to the individual (e.g. step-by-step instructions to catch a particular bus). In addition, the LifeLink provides information to the caregiver about the status and immediate needs of the client—for example it uses GPS and other sensor data to match a client’s actual position with expectations specified in the MAPS scripts allowing identification of errors in context.
In a similar description of 5 case studies in which cell phones were implemented in conjunction with a computer software company,48 daily diary records and qualitative feedback suggested 92–100% successful completion of target tasks while using the technology, as compared to 48–80% completion prior to the trial.
Unfortunately the evaluations noted above were linked only to specific tasks for which prompts/scripts were provided. As such, the impact of using these devices more generally on outcomes such as quality of life were not assessed, impacts on caregivers were not specifically explored, and the ability of clients or caregivers to generalise their use to new tasks was not assessed.
In a survey of the use of portable electronic devices post-TBI, Hart and colleagues53,54 found that 66% of the 80 people surveyed had access to a home computer, with two-thirds of the sample reporting regular computer use. However, only 29% had used/attempted to use a portable electronic device.
Participants were consistent in their reports of preferences for important device features, such as extended battery-life, simplicity, and availability of technical support. Similar preferences have also been noted by DePompei55 and others.56
Wade and Troy48 note the following advantages of cell phone technologies over text-based paging systems when used in the TBI population:
These authors further note that accessing prompts should be voice-activated by the recipient to ensure that no part of a message is missed between the time of pressing the answer button and placing the phone to the ear; each prompt should be preceded by an explanation that the message is recorded to avoid confusion about the source of the call, re-sending of any prompts that are met with an engaged tone or unanswered, and that messages identified as ‘high priority’, if unanswered, be transferred to the caregiver to alert them the message has not been received.
They further suggest that in conducting research effective use of the technology be monitored through collecting user information such as time to answer, calls missed, and calls transferred to the caregiver. Users could also be asked to confirm completing each prompted task by keying in a brief code (e.g. confirm taking medication) in order to increase autonomy and reassure carers. While the research is moving forward in determining how best to adapt this latest technology for use in post-TBI populations, to date there have been no full scale randomised clinical trials to determine their efficacy in improving independence.
In summary, TBI is a leading cause of disability and death whose incidence peaks in young adulthood. As many as 80% of those who experience a TBI will have memory problems, and these may persist, with as many as 73% of cases reporting memory deficits at 3 months post-injury. Impairments in memory are linked to reduced functional outcomes and independence. Further, it is agreed that once the period of natural recovery is over there is generally no significant improvement in underlying memory functioning. Therefore, memory-impaired individuals need help to manage, bypass, understand, and compensate for everyday memory problems in order to improve outcomes.
Everyday memory problems can be helped through environmental restructuring, and by using internal strategies (mnemonic rehearsal and external aids). The literature generally agrees that although internal strategies are useful; these individuals do not use these techniques spontaneously to help with everyday memory problems; they are more likely to use external memory aids to compensate.
Individual rehabilitation has been used to teach various techniques; however it has often only focused on one memory domain at a time. The literature has demonstrated that group approaches to memory rehabilitation have many advantages. They provide a place to introduce the use and practice of internal and external memory strategies; they facilitate an increase in social contacts; and produce social and emotional benefits for the participants. Further, they are both cost- and time-effective.
Barker-Collo has developed and piloted an effective memory rehabilitation technique for implementation in a group setting. However, as noted by Cicerone et al “...the effectiveness of various assistive technologies to compensate for severe memory impairment should be investigated through additional prospective controlled studies”.57
In addition to group rehabilitation approaches, the research is moving forward in determining how best to adapt latest technologies for use in post-TBI populations, particularly in relation to memory deficits, and a number of such technologies are currently available, such as the NeuroPage and MAPS-Lifelink systems described earlier. To date, however, there have been no full scale randomised clinical trials to determine their efficacy in improving independence. Thus, there is a need for high-level evidence for effectiveness of these most promising and practicable individual and group memory rehabilitation strategies in larger sample of TBI patients over longer timeframes.
Competing interests: None known.
Author information: Suzanne Barker-Collo, Senior Lecturer1; Valery L Feigin, Associate Professor and Senior Research Fellow2
Correspondence: Dr Suzanne Barker-Collo, Department of Psychology, Faculty of Science, The University of Auckland, Private Bag 92019, Auckland, New Zealand. Fax: +64 (0)9 3737450; email: email@example.com
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