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Cochrane Database of Systematic Reviews Protocol - Intervention

Cognitive rehabilitation for executive dysfunction in patients with stroke or other adult non‐progressive acquired brain damage

Authors' declarations of interest

Version published: 17 March 2010 Version history

https://doi.org/10.1002/14651858.CD008391

This is not the most recent version

view the current version 30 April 2013
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Abstract

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

To determine whether cognitive rehabilitation after stroke or other adult non‐progressive acquired brain damage improves executive function.

Specific research questions

In adults with stroke or other non‐progressive acquired brain damage with executive function problems:

  1. is cognitive rehabilitation more effective than no or placebo intervention at improving executive function? No intervention will include participant groups who did not receive any specific cognitive rehabilitation training or functional training. Placebo includes interventions which have been determined by the researchers to have no active impact on the aspect of cognition being studied, for example, a repetitive container filling task to work on problem solving skills;

  2. is cognitive rehabilitation more effective than standard care at improving executive function? Standard care will include stroke and brain injury sensorimotor rehabilitation programmes without specific cognitive rehabilitation components. Sensorimotor interventions are defined as those intended to improve physical function including movement, strength, balance, co‐ordination, dexterity sensation and endurance. As most therapeutic interventions contain aspects of cognition training in the form of increasing awareness, improving attention and problem solving, only those which explicitly state the intention of improving an aspect of cognition will be defined as cognitive rehabilitation;

  3. are some cognitive rehabilitation interventions more effective than other cognitive rehabilitation interventions at improving executive function? This could include comparisons of attention training with goal management training for self monitoring, or electronic memory devices versus mental imagery techniques for improving decision making.

Background

Executive functions are the controlling mechanisms of the brain and include the processes of planning, initiation, organisation, inhibition, problem solving, self monitoring and error correction (Evans 2003). They are essential for goal‐oriented behaviour and responding to new and novel situations. These processes are executed through the mechanism of working memory where the cognitive processes of attention and memory are controlled by a central executive system (Baddeley 1974). As 75% of stroke survivors experience working memory impairment (Riepe 2003), they will also experience executive dysfunction as a consequence. Spontaneous recovery is also limited at three months in both individuals with stroke and brain injury (Stablum 2000). Thus, even when the basic cognitive functions of attention and memory are intact, around three‐quarters of individuals with stroke and brain injury will have ongoing difficulties due to executive dysfunction.

Several systematic reviews have concluded that the effectiveness of cognitive rehabilitation interventions cannot be supported or refuted (Bowen 2006; Cicerone 2005; Lincoln 2000). Despite authors finding some evidence that cognitive rehabilitation improved attention and unilateral neglect (UN) on paper‐and‐pen tests, there was no evidence of improved functional ability. These reviews, with the exception of one (Cicerone 2005), focused on attention and memory, but not executive function. Thus, the relationship between functional ability and executive function requires investigating.

Description of the condition

The impact of executive dysfunction was demonstrated in a cohort study by Walter et al who investigated the progress of 30 participants with stroke in regaining the ability to put on a polo shirt independently (Walker 2004). They found that those with cognitive impairment, but no motor impairment, were successful in putting on the polo shirt. Those with motor impairment but whose cognition was intact also regained independence in the dressing task. However, the participants with both motor and cognitive impairment did not regain independence.

A possible explanation for these findings is related to the ability to plan, problem solve, and self monitor, i.e. executive function. There was no requirement for problem solving in the group with intact motor ability as they were not required to change their dressing method, and despite having impaired cognition, only basic levels of attention and memory were required for this routine task. The participants with impaired motor ability were able to use their intact executive function to problem solve and develop alternative methods for putting on the polo shirt. However, the participants with both motor and cognitive impairment could not use a routine method for putting on the polo shirt, and did not have the necessary executive function to support this process.

The development of basic cognition may not be adequate to develop the ability to perform complex, novel and adaptive tasks without addressing executive function. Thus, interventions to reduce executive dysfunction may be the key to improved function.

Description of the intervention

Cognitive rehabilitation is a 'systematic, functionally oriented service of therapeutic activities that is based on assessment and understanding of the patient's brain‐behavioural deficits' (Cicerone 2005). Executive function training is a component of cognitive rehabilitation which also includes attention and memory training. There are a variety of cognitive rehabilitation interventions which may be used in the rehabilitation of patients with executive function problems. They can be divided into one or more of three broad categories.

  1. Cognitive rehabilitation interventions which are specifically targeted at improving components of executive function. Methods are characterised by patients working to improve the actual skill through improved awareness, performance opportunity and repetition. These interventions include:

    1. planning and organisation skills development;

    2. problem solving and strategy formation techniques;

    3. self awareness and self regulation of behaviour;

    4. initiation of behaviours;

    5. inhibition of prepotent responses.

  2. Cognitive rehabilitation interventions which compensate for executive function impairment. Methods are characterised by the use of internal cognitive devices to compensate for fragmented or disorganised executive function processes, or external methods to increase patients' awareness of their own performance to inform strategy formation. These interventions include:

    1. goal management training;

    2. use of written strategies and electronic technology;

    3. self instruction techniques;

    4. feedback methods including mirror and video feedback;

    5. systematic problem solving procedures.

  3. Cognitive rehabilitation interventions which develop individuals' cognitive abilities to formulate adaptive methods for increasing independence in activities of daily living skills. Methods are characterised by the training of patients in using external mechanisms to compensate for attention, memory or sequencing impairment when applied to specific activities of daily living (ADL), training in alternative techniques for undertaking specific ADLs including simplification, and environmental adaptation such as written cues within the house. These interventions include:

    1. techniques and equipment which compensate for sensorimotor impairment, e.g. developing one‐handed dressing techniques, or visually checking on hand grip when pulling trousers up using the weak upper limb;

    2. the use of written lists and diaries which compensate for impaired organisation and planning skills, e.g. following a shopping list step‐by‐step, or using a systematic problem solving procedure during meal preparation.

How the intervention might work

As executive function is a complex process involving a number of different skills, there are many different interventions which will work in different ways. Interventions may restore the functional loss (through the stimulation of neuronal growth), substitute for the functional loss (by teaching new strategies to replace the lost functioning) or compensate for the functional loss (by increasing awareness and teaching ways to cope with the lost functioning). Additionally, interventions may contain a combination of the above categories; for example, restoring attention to enable an individual to use a memory aid.

The results of the polo shirt dressing study by Walker et al support the theory that executive function impairment may have decreased participants’ ability to dress due to decreased ability to problem solve the new situation created by upper limb weakness (Walker 2004). Interventions may contribute to functional recovery by working to restore an individual's ability to problem solve, form strategies or increase self‐awareness. Alternatively, they may increase the individual's ability to compensate for impaired executive function by using strategies or technology to provide feedback or instruction in relation to functional tasks. Furthermore, interventions which are intended to restore or compensate for impaired attention and memory may improve executive function by increasing the accessibility of information to the individual.

Why it is important to do this review

If executive function is directly related to functional ability, a systematic review on the effectiveness of cognitive rehabilitation interventions for improving executive function in patients with stroke and brain injury is indicated. Although Cicerone et al included executive function in their systematic review (Cicerone 2005), only one study of nine reviewed was a randomised controlled trial (RCT) (Levine 2000). This study investigated the effectiveness of an executive function intervention, goal management training, and produced a positive conclusion in favour of the intervention. However, the outcome was based on pencil‐and‐paper tests, and the impact of an executive function intervention on functional ability remains uncertain. Additionally, only studies up to 2002 were included and further studies may have been published since then.

A Cochrane Review protocol has been published with the intention to review cognitive rehabilitation in occupational therapy (Hoffmann 2007). Although this is an important review to undertake, it is also important to review the impact of cognitive rehabilitation specifically on executive dysfunction to build on the reviews of attention, unilateral neglect and memory (Bowen 2006; Lincoln 2000) and to include studies from the wider field of neuropsychology.

The intention of this proposed review is to evaluate studies which specifically contain cognitive rehabilitation interventions with executive function outcomes.

Objectives

To determine whether cognitive rehabilitation after stroke or other adult non‐progressive acquired brain damage improves executive function.

Specific research questions

In adults with stroke or other non‐progressive acquired brain damage with executive function problems:

  1. is cognitive rehabilitation more effective than no or placebo intervention at improving executive function? No intervention will include participant groups who did not receive any specific cognitive rehabilitation training or functional training. Placebo includes interventions which have been determined by the researchers to have no active impact on the aspect of cognition being studied, for example, a repetitive container filling task to work on problem solving skills;

  2. is cognitive rehabilitation more effective than standard care at improving executive function? Standard care will include stroke and brain injury sensorimotor rehabilitation programmes without specific cognitive rehabilitation components. Sensorimotor interventions are defined as those intended to improve physical function including movement, strength, balance, co‐ordination, dexterity sensation and endurance. As most therapeutic interventions contain aspects of cognition training in the form of increasing awareness, improving attention and problem solving, only those which explicitly state the intention of improving an aspect of cognition will be defined as cognitive rehabilitation;

  3. are some cognitive rehabilitation interventions more effective than other cognitive rehabilitation interventions at improving executive function? This could include comparisons of attention training with goal management training for self monitoring, or electronic memory devices versus mental imagery techniques for improving decision making.

Methods

Criteria for considering studies for this review

Types of studies

We will include RCTs including randomised crossover trials (using data from first phase only, where the order of assignment has been determined randomly). Random allocation will include trials using computer‐generated random numbers, or sequentially‐numbered opaque sealed envelopes. 

Types of participants

We will include adults (16 years and older) with executive dysfunction caused by stroke or other adult acquired non‐progressive brain damage. Adult acquired brain damage will include brain injury, encephalitis, abscess and arteriovenous malformations. We will exclude participants with progressive neurological conditions such as dementia, space occupying lesions and multiple sclerosis.

Types of interventions

Restorative interventions

Interventions which are specifically targeted at restoring components of executive function including goal management training, planning and organisation skills development, problem solving and strategy formation techniques, self awareness and self regulation of behaviour, initiation of behaviours, and inhibition of prepotent responses.

Compensative interventions

Interventions which compensate for executive function impairment such as use of written strategies and electronic technology, self instruction techniques and feedback methods including mirror and video feedback.

Adaptive interventions

Interventions which develop individuals' executive function processes to enable the formulation of adaptive methods for increasing independence in activities of daily living skills such as the use of techniques and equipment which compensate for sensorimotor impairment, the use of written lists and diaries which compensate for impaired working and prospective memory, and systematic problem solving procedures.

Comparators include no intervention, standard care (sensorimotor intervention), placebo or other cognitive rehabilitation approaches.

Types of outcome measures

The primary outcome will be global executive function, and the secondary outcomes will be components of executive function, functional ability in activities of daily living, functional ability in extended activities of daily living, participation in vocational activities, quality of life and social isolation, adverse events and death. We will exclude studies without specific executive function outcomes as it will not be possible to evaluate the intervention effectiveness of executive function.

If possible, we will assess outcome at the end of the intervention period and at a follow‐up point (ideally six months and one year after the intervention has finished).

Primary outcomes
Global executive function

We will include assessment batteries which provide a general total score of executive function. Known assessment batteries include:

The total scores for these test batteries are calculated from the sum of the scores for the subtests. All raw scores are converted into standardised profile scores and constitute continuous data.

If we find any other assessments specifically designed to measure executive function we will include these. However, we will plan sensitivity analyses to explore the effect of including these less well‐known assessments.

Secondary outcomes
Executive function component outcomes

The scoring of the BADS and Hayling and Brixton Test batteries produce raw scores which are converted into standardised profile scores for each subtest. It will, therefore, be possible to combine scores from different tests which measure the same component of executive function. In addition, the Wisconsin Card Sorting Test (Berg 1948) can be scored on the number of achieved categories, number of perseverative responses, or the number of perseverative errors, and the Tower Tests are scored on the number of successful completed stages or number of moves required for completion (Lezak 2004). The data from the tests are continuous, affording the possibility of combining them with specific subtests from the assessment batteries. We will therefore include five components of executive function as follows.

  1. Initiation: assessments include: Hayling Test Part 1 (Burgess 1997), Behavioural Assessment of Dysexecutive Syndrome (BADS) Rule Shift Part 1 (Wilson 1996).

  2. Inhibition: assessments include: Hayling Test Part 2, Tower of Hanoi (Goel 1995).

  3. Concept formation: assessments include: Brixton Test, Wisconsin Card Sorting Test.

  4. Planning: assessments include: Tower of London (Culbertson 2001), Tower of Toronto (Saint‐Cyr 1992), BADS Zoo Map, Action Program and Modified Six Elements Test.

  5. Flexibility: assessments include: Wisconsin Card Sorting Test, Brixton Test, BADS Rule Shift.

Functional ability in activities of daily living

We will include the following validated scales: Barthel ADL Index (Mahoney 1965), Rivermead ADL assessment (Lincoln 1990), Rivermead Motor Ability scale (Lincoln 1979), Functional Independence Measure (FIM) (Keith 1987), Frenchay Activities Index (Wade 1985), Katz Index of Activities of Daily Living (Katz 1963), Rehabilitation Activities Profile (Jelles 1995), and Rankin ADL (van Swieten 1988). If more than one of these functional ability scales is reported, we will use the scale listed earliest in this list.

Functional ability in extended activities of daily living

Nottingham Extended Activities of Daily Living scale (Nouri 1987), Nottingham Stroke Dressing Assessment (Walker 1990).

Mood and anxiety level

Hospital Anxiety and Depression Scale (HADS) (Zigmond 1983).

Participation in vocational activities

Vocational Assessment Protocol (Thomas 1997).

Quality of life and social isolation

EQ5D (health‐related quality of life scale) (The EuroQol Group 1990), Quality of Well Being Scale (Anderson 1989).

Adverse events

Any reported adverse events (excluding death).

Death

If we find any other assessments specifically designed to measure any of the above secondary outcomes we will include these. However, we will plan sensitivity analyses to explore the effect of including these less well‐known assessments.

Search methods for identification of studies

See the 'Specialized register' section in the Cochrane Stroke Group module.

We will develop search strategies in consultation with the Cochrane Stroke and Cochrane Injuries Groups' Trials Search Co‐ordinators to avoid duplication of effort and will perform the following electronic and handsearches.

Electronic searches

We will search the trials registers of the Cochrane Stroke Group and the Cochrane Injuries Group. In addition, we will search the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, latest issue), MEDLINE (1950 to present) (Appendix 1), EMBASE (1980 to present), CINAHL (1982 to present), Psycinfo (1806 to present) and AMED (1985 to present). We will also search the following specialist bibliographic databases:

  • British Nursing Index (1985 to present);

  • Linguistics and Language Behaviour Abstracts (1973 to present);

  • OTseeker (http://www.otseeker.com/);

  • Physiotherapy Evidence database (PEDro, http://www.pedro.org.au/),

  • Chartered Society of Physiotherapy Research Database;

  • Psychological Database for Brain Impairment Treatment Efficacy (PsycBITE, http://www.psycbite.com/);

  • REHABDATA (http://www.naric.com/research/rehab/).

Searching other resources

In an effort to identify further published, unpublished and ongoing trials, we will:

  • check reference lists of all relevant articles;

  • search ongoing trials and research registers including the Internet Stroke Center Stroke Trials Registry (http://www.strokecenter.org/trials/); ClinicalTrials.gov (http://www.clinicaltrials.gov/); the National Research Register (https://portal.nihr.ac.uk/Pages/NRRArchiveSearch.aspx); UK Clinical Research Network Portfolio Database (http://public.ukcrn.org.uk/search/) and Current Controlled Trials (http://www.controlled‐trials.com/) (which also includes the UK Clinical Trials Gateway);

  • find and contact investigators known to be involved in research in this area from published research, conference abstracts and from searches of the above databases;

  • search Science Citation Index using the cited reference search;

  • search PsycEXTRA (http://www.apa.org/psycextra/) and PsycARTICLES (http://www.apa.org/psycarticles/) databases;

  • identify and search neuropsychology abstracts targeting the following conferences: (USA) National Academy of Neuropsychology, American College of Professional Neuropsychology, American Academy of Clinical Neuropsychology and British Neuropsychological Society.

  • search the Proquest Dissertations and Theses (PQDT) database;

  • contact the authors of all included trials to enquire about other published and ongoing trials of cognitive rehabilitation for executive function.

Data collection and analysis

From the list of titles identified by the search strategy, handsearches, searches of unpublished dissertations and theses, and conference proceedings searches, one review author (CC) will eliminate studies which are clearly not relevant. Two reviews authors (CC and one of either AP or TC) will independently determine from the abstracts which of the remaining titles meet the inclusion criteria of study type, participants, interventions, comparisons and outcomes.

Selection of studies

We will obtain full text copies of the selected studies (or those labelled as uncertain) and the three review authors will independently determine which studies will be included during the second study selection stage. We will resolve any disagreements through discussion and if resolution is unsuccessful, we will consult the fourth review author (BD). We will contact the authors of all included studies to enquire about any other published or ongoing trials.

Data extraction and management

We will use a pre‐designed data extraction form to extract data from the studies which meet the inclusion criteria. We will test this form on one paper with any shortcomings discussed and modifications made. Two review authors (CC, and either AP or TC) will perform the extraction independently, and collect data related to the study population, intervention types, intervention comparisons, and outcomes. As in the study selection stages, we will consult the fourth review author (BD) if there is uncertainty or disagreement. If possible, we will document:

  1. participant details (including age, gender, place of residence, type of stroke, time since stroke, initial functional ability, co‐morbid conditions, premorbid disability);

  2. the inclusion and exclusion criteria;

  3. the duration/intensity/frequency of intervention;

  4. a brief description of the intervention (we will classify the intervention using the three groups defined in 'Types of interventions' and will document details including, if relevant, the nature of the intervention, duration and intensity of the intervention, involvement of treating therapist and qualifications and experience of treating therapist(s));

  5. the comparison intervention;

  6. the outcomes.

Assessment of risk of bias in included studies

Two review authors (CC and one of either AP or TC) will independently assess all relevant trials for potential sources of bias including selection bias, performance bias, detection bias, and attrition bias (Juni 2001), with consideration given to methods of participant allocation and concealment, blinding of those assessing and providing interventions to participants, and the completeness of data reporting.

Measures of treatment effect

We will use RevMan 5 (RevMan 2008) to carry out statistical analyses to determine the treatment effect of:

  1. cognitive rehabilitation versus sensorimotor therapy on executive function;

  2. cognitive rehabilitation versus placebo on executive function;

  3. cognitive rehabilitation versus no therapy on executive function;

  4. cognitive rehabilitation versus another cognitive rehabilitation approach on executive function.

For dichotomous variables we will calculate the treatment effect using a fixed‐effect model and report them as Peto ratios with 95% confidence intervals (CI). For continuous data we will calculate the treatment effect using standardised mean differences (SMD) and 95% CI where different scales were used by different studies for the assessment of the same outcome, and using mean differences (MD) and 95% CI where studies have all used the same method of measuring outcome.

For all meta‐analyses we will apply both a fixed‐effect and a random‐effects model. We will consider non‐identical results indicative of statistical heterogeneity, and will report the most conservative outcome.

Unit of analysis issues

The primary outcome is global executive function. The scores from the executive function assessment batteries produce continuous data from conversion to standardised profile scores. Where an executive assessment battery not listed in this protocol provides ordinal data, we will treat this as continuous data. The secondary outcomes of executive function components will also be continuous data, and we will also treat any ordinal data as continuous. Secondary outcomes also include functional ability and quality of life which are commonly measured with ordinal scales. We will also treat these as continuous data.

Where reported outcomes have a scale where a lower value is indicative of a better outcome (e.g. Hospital Anxiety and Depression Scale) we will multiply the reported values by ‐1, so that in all analyses a higher value will be indicative of a better outcome.

If studies report change values and the baseline value is available, we will calculate the value at follow up (change value ‐ baseline value). If studies report change values and the baseline value is available, we will use these data in meta‐analyses, but plan sensitivity analyses to investigate the effect of including these data.

We will analyse discharge destination, adverse events and death as dichotomous variables.

Dealing with missing data

Studies adequately addressing incomplete outcome data will either have no missing outcome data; missing outcome data which are unlikely to be related to true outcome; missing outcome data which are balanced in numbers across intervention groups, with similar reasons for missing data across groups; a reported effect size (difference in means or standardised difference in means) among missing outcomes which are not enough to have a clinically relevant impact on observed effect size; or missing data which have been imputed using appropriate methods.

Studies inadequately addressing incomplete outcome data will either have missing outcome data which are likely to be related to true outcome, with either imbalance in numbers or reasons for missing data across intervention groups; a reported effect size (difference in means or standardised difference in means) among missing outcomes enough to induce clinically relevant bias in observed effect size; as‐treated analysis done with substantial departure of the intervention received from that assigned at randomisation.

We will document addressing of incomplete outcome data as unclear if there is insufficient reporting to allow this to be assessed, or if this is not addressed in the report.

We will contact the original study authors to obtain missing data.

If an included study does not report (or we cannot obtain from a study author) a particular outcome, we will not include that study in the analyses of that outcome.

If an included study has missing data (e.g. reports means but not standard deviations for the follow‐up data) we will take logical steps to enter an assumed value. Such steps may include estimating a standard deviation based on a reported standard error, or estimating a follow‐up standard deviation based on a baseline value. We plan to undertake sensitivity analyses to investigate the effect of entering assumed values.

Assessment of heterogeneity

We will determine heterogeneity using the I2 statistic. If I2 is greater than 50%, we will consider this as substantial heterogeneity. If I2 is less than 50%, we will used a fixed‐effect meta‐analysis. If I2 is greater than 50%, we will explore the individual trial characteristics to identify potential sources of heterogeneity, using pre‐planned subgroup analyses. Where there is substantial heterogeneity, we will perform meta‐analysis using both fixed‐effect and random‐effects modelling to assess sensitivity to the choice of modelling approach. If we find non‐identical results we will report the most conservative outcome.

Assessment of reporting biases

We will use the domain‐specific risk‐of‐bias assessment tool in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2008), which replaces rating scales and checklists as the preferred method of assessing the impact of bias.

Data synthesis

Two review authors will independently extract data from the included trials. One review author will enter the data into RevMan5 (RevMan 2008), and the other review author will check the entries. We will resolve any disagreements through discussion, with reference to the original report.

Subgroup analysis and investigation of heterogeneity

We will conduct subgroup analyses on the conditions of stroke, head injury, and encephalitis to determine the effect of cognitive rehabilitation on the executive function of each group.

If possible, we will also conduct grouping by intervention, with subgroups to include:

  • interventions which aim to:

    • restore executive function;

    • compensate for executive dysfunction; and

    • enable the participant to formulate adaptive strategies to increase independence with ADL.

In addition, we will conduct subgroup analyses on clinical presentation including:

  • stroke versus brain injury;

  • time since stroke onset: less than three months, between three and six months, six months to 12 months, more than 12 months;  

  • Initial level of executive function;

  • Initial level of function.

Sensitivity analysis

We will undertake sensitivity analyses in respect of the inclusion (studies where some participants are not in the defined inclusion criteria) and methodological quality (randomisation process, and blinding of outcome assessor) of the included studies. We will include all studies having any ratio of participants with the defined inclusion criteria, and we will conduct the sensitivity analysis with studies containing less than 75% of the defined inclusion criteria being removed. We will use a criteria list and tick box format to indicate whether studies meet, do not meet, or are unclear about meeting the pre‐defined methodological quality requirements and explore the effects of including the trials which have an unclear criteria match.

As attrition in studies of cognitive rehabilitation create a significant source of bias due to the possibility that the most challenging to treat participants are the ones most likely to drop out, we will attempt to conduct intention‐to‐treat analyses where we can obtain incomplete data from the original study authors. Where we cannot obtain data, we will record the possibility of significant bias.

We will undertake a further sensitivity analysis on the effect of clinical diagnosis of executive dysfunction versus diagnosis by standardised assessment.