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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
The burden of traumatic brain injury (TBI)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
Memory deficits are the most marked sequels in traumatic brain injuryDisturbances 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
Relationship of post-TBI memory deficits and functional outcomesMemory 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
Individual approaches to reducing memory deficitsTeaching 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.
Group format memory rehabilitationPrevious 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.
Using technology to aid memoryThere 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.
Can people with TBI use technologies?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.
ConclusionsIn 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: s.barker-collo@auckland.ac.nz
References:
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