Session Nine (Executive Function and Neuro-Rehab)

Question 1

What is Executive Function?

Answer 1

• Abilities that enable a person to determine goals, work out ways of achieving them and then follow through with them in the face of competing demands and changing circumstances over long periods of time.
• Allow the person to engage in independent, purposive, self-directed and self-serving behaviour.
• So long as EF are intact, a person can sustain considerable cognitive loss and still continue to lead an independent and self-serving life.

Question 2

How do you distinguish Cognitive from Executive functions?

Answer 2

• EF relates to how a person goes about doing something (will they do it? how? when?)
• CF relates to whether a person can do something (can they do this? how much of this can they do?)

Question 3

What area of the brain has been historically associated with EF? Based on what evidence?

Answer 3

• Frontal lobes
• Believed to be somehow related to the programming, verification and regulation of human behaviours. Damage to the FL leads to complex behaviour being replaced by more basic and stereotypic behaviour.
• As exampled by Phineas Gage, 19th century man who received substantial damage to the frontal lobe and displayed marked ‘animal’ and ‘instinctive’ behaviour’

Question 4

How did Luria divide the brain?

Answer 4

Into 3 functional units:

• Brain stem; maintains and regulates cortex arousal
• Temporal, Parietal and Occipital lobes; encode, process, store information
• Frontal lobes; Programme, verify and regulate human behaviour.

Therefore, damage to the frontal systems results in complex behaviour being replaced by basic/stereotyped behaviour.

Question 5

Outline Shallice’s initial SAS model of executive function?

Answer 5

• Supervisory Attentional System model
• Multi-process model that improved on Luria by utilising two new components, the Supervisory Attentional System (SAS) and Contention Scheduling (CS)
• Suggests that specific schemas triggered by environmental stimuli lead to a series of automatic actions without the need for conscious control.
• CS is the step between schemas and actions that unconsciously decides which actions will be taken.
• However, the SAS can exert top-down, supervisory control on the CS in cases where routine actions are not appropriate.
• Leading to novel behaviour in certain circumstances.

Question 6

What specifically does the SAS do in Shallice’s initial model of executive functioning?

Answer 6

• Has control over CS
• Monitors conscious, deliberate planning of action
• Handles novel situations that cannot be solved by previously learned schemata
• Creates new schemata as and when necesarry.

Shallice described 5 circumstances when the SAS becomes activated:

1) Planning or decision making
2) Error correction or trouble shooting
3) Novel or unlearned sequences of actions
4) When threatened
5) When trying to overcome habitual or automatic responses

Question 7

How did Shallice build on his initial model of SAS?

Answer 7

Outlined the 3 procedures SAS is capable of:

• Construction of temporary schema
• Implement temporary new schema held in working memory
• Assess and verify new schema (can lead to rejection, alteration or incorporation as new schema)

Essentially expanded upon it by delineating processes involved in SAS. Supported by lesion and computational modelling studies e.g. Hewitt (2006) and Fish (2007)

Question 8

Outline Stuss and Benson’s Tripartite model of Executive Function?

Answer 8

3 systems interact to monitor attention and executive functions:

• Anterior Reticular activating system
• Diffuse Thalamic projection system
• Fronto-Thalamic gating system

Question 9

What is the role of the Anterior Reticular activating system in Stuss’ model of Executive functioning?

Answer 9

• Maintains general arousal of individual

- Damage therefore results to loss of consciousness

Question 10

What is the role of the Diffuse Thalamic projection system in Stuss’ model of Executive functioning?

Answer 10

• Alertness to external stimuli over short periods

- Damage therefore leads to distraction by external stimuli

Question 11

What is the role of the Fronto-thalamic gating system in Stuss’ model of Executive functioning?

Answer 11

• Responsible for higher level cortical functioning

- Damage therefore results in inattention, lack of insight and goal-neglect

Question 12

Outline Stuss’ detailed analysis of frontal lobe function?

Answer 12

Suggested the frontal lobe has 4 key functions:

• Executive cognitive functions (e.g. task setting and monitoring)
• Energisation
• Behavioural and emotional self-regulation
• Metacognition

Based this on highly detailed focal lesion studies, however emphasised how interconnected the frontal lobe is with other areas of the brain therefore we can’t be entirely sure which areas relate to what.

Question 13

Outline the Elephant and Rider theory of executive function?

Answer 13

• Elephant represents 99% of our mind; our emotions and automatic thought processes
• The elephant is powerful but not very sophisticated
• The rider attempts to exert some control
• Sometimes this is possible but the elephant is hard to control

Question 14

How did Goldstein (2014) describe executive function?

Answer 14

• As 33 different but over-lapping functions
• Including planning, working memory, attention, self-monitoring and inhibition
• Made the point that EF is an umbrella term used to describe a diverse range of cognitive processes associated with the frontal lobes.

Question 15

How can you summarise the different models of executive function?

Answer 15

• Different models emphasise different components, but share some overlapping themes e.g. organised representations of actions, goal neglect
• Some evidence for localisation of different executive function in PFC
• Role of emotions acknowledged, but less models representing mechanisms of influence.

Question 16

Why do we test executive functioning?

Answer 16

• To make inferences about neural basis of underlying function through lesion studies
• Use test results to guide diagnosis, treatment and outcome measurement

Question 17

How do we test executive functioning?

Answer 17

• Verbal fluency
• Stroop (inhibition)
• Trails (switching or dividing attention)

Question 18

What were Roca’s criticisms of measures of executive function?

Answer 18

• Most of the differences in scores achieved by patients could be explained in terms of differences in fluid intelligence (therefore are inaccurate)
• Others only measure deficits that arise from lesions to the most anterior regions of the right frontal lobe (therefore are incomplete)

Question 19

What is the Stroop method of measuring executive function?

Answer 19

• First asks patients to name the colour of a box (colour naming)
• Then read a colour word in black and white (reading)
• Then read a colour word in a different ink colour than the word itself (inhibition)
• Then alternate between ink colour and word reading (inhibition and switching)

Question 20

What is important to consider when interpreting executive functioning test results?

Answer 20

• How do they compare to other individuals their age/ education/ intelligence…
• At what level are they performing at a level below the general population?
• Could other factors such as pain/ anxiety/ medication/ motivation have affected their performance on that day

Question 21

What are some more general criticisms of neuro-psych measures of EF?

Answer 21

• Lack ecological validity, the extent to which they predict an individual’s ability to drive/work is limited
• This is obviously the most important thing from a medico-legal and treatment perspective
• But these tests are mostly able to detect abnormalities, not predict function
• And in fact many patients struggle with the novelty of the test but when presented with a familiar task can perform quite well
• Absence/ presence of cues and distractions as well as degree of effort and emotional issues will be different between test and real life conditions

Question 22

What is an alternative to traditional measures of executive functioning believed to have greater ecological validity?

Answer 22

Performance based tests

• = alternative approach that involves studying patient performance in real-world tasks
• More in line with OT approach than clinical neuro-psych

Question 23

Give some examples of performance based tasks of EF?

Answer 23

• Multiple errand test
• Multi-level action task
• Naturalistic action test

Question 24

What are some issues with performance based tests as a way of measuring EF?

Answer 24

• Difficult to standardise as performance can vary according to the environment in which assessment carried out
• Often lacks a norm to compare to, so almost entirely qualitative approach

Question 25

When do we use standardised and functional measures of EF and what are their fundamental differences?

Answer 25

S better prior to treatment, F better during treatment.

S = based on what a person has/is, diagnostic, indirectly related to treatment, only tests one situation

F = based on what a person really does, helps select treatment, tests a number of situations

Question 26

What are some issues with use of observational methods of measuring EF?

Answer 26

• Limited experimental control
• Time consuming
• Expensive
• Risky
• Aversive

Question 27

What factors are important to consider when dealing with difficult behaviour in a brain injury/ neuro-rehab patient?

Answer 27

• Effects of the Injury (e.g. decreased noise tolerance, communication difficulties, fatigue, poor impulse control, other ef difficulties)
• Feelings caused by being Injured (e.g. frustration, anger, anxiety, intimidation)
• Factors that can maintain these feelings (e.g. inability to verbalise discomfort, struggles making sense of environment, perception of others as confrontational)
• Environmental triggers (tiredness, hunger, noise, other patients, memories)

Question 28

Which patients are typically put forward for NR?

Answer 28

• Brain injury
• Spine injury
• Peripheral neurology
• Progressive conditions

Normally caused by; stroke, inflammatory conditions, trauma, anoxic injuries…

Question 29

What are some stroke risk factors?

Answer 29

• Male
• Age
• Ethinicity (south asian, African)
• High BP
• AF
• Cholesterol
• Smoking
• Alcohol
• Diet
• Weight
• Fitness

Question 30

What are the most common causes of TBI?

Answer 30

Traumatic Brain Injury:

• RTAs
• Falls
• Assaults

Question 31

What are the risk factors for TBIs?

Answer 31

• Male (3x)
• Age (tri-modal distribution; below 4, 15-29, above 65)
• Risk taking behaviour (mainly alcohol)

Question 32

What are the two types of TBI?

Answer 32

• Primary = mechanical effects of applied force e.g. skull fracture, haemorrhage, acceleration-deceleration forces and diffuse axonal injury
• Secondary = resulting from a compromised oxygen supply, swelling, raised ICP

Question 33

What are the initial management steps involved in brain injuries?

Answer 33

1) Minimise factors likely to lead to secondary BIs e.g. with neurosurgery, medications, ventilation…
2) Stabilise other injuries and manage other needs e.g. seizure, physiotherapy, nutrition
3) Examine and monitor neurological status e.g. GCS

Question 34

What is the ICF model and how does it relate to Neuro-Rehab?

Answer 34

Tate (2010), model for explaining how a condition affects what a patient can and can’t do.

Health condition (e.g. stroke) affects…

• Body function and structure
• Activity
• Participation

Also bares in mind that all 3 of these factors are influenced by contextual factors such as personal factors and environmental factors

Question 35

What are the two main principles of NR and the three processes used to achieve them?

Answer 35

Principles:

• Restoration
• Compensation

Processes:

• Direct retraining (e.g. motor aphasia post-stroke)
• Substitution (the building of a new method of response to replace one damaged irreparably by a cerebral lesion e.g. reading by letter tracing)
• Compensation (reorganisation of psychological function so as to minimise or circumvent a particular disability e.g. alternative communication strategies such as writing on a slate)

Question 36

What is neuro-rehabilitation?

Answer 36

Neuro-rehab can be described as any intervention strategy or technique which enables patients/clients and their families or carers to live with, manage, by-pass, reduce or come to terms with cognitive deficits precipitated by injury to the brain.

It is concerned with the amelioration of cognitive, emotional, psychosocial and behavioural deficits caused by an insult to the brain. Focuses on the cognitive, emotional and psychosocial factors.

Question 37

How did Robertson and Murre (1999) describe functional losses seen in NR patients?

Answer 37

Triad of post-lesion states characterised by loss of connectivity:

• Small loss- autonomous recovery
• Large loss- permanent loss of function so need for external support
• Middle loss- this is the difficult group to manage, potentially rescuable lesioned circuits but guided recovery depends on precisely targeted bottom-up and top-down inputs

Question 38

What are the different routes to recovery in NER in terms of neuro-plasticity?

Answer 38

• Repairing the damaged area (restoration)
• Having the remaining cells work harder (restoration)
• Re-tunning cells (compensation and restoration)
• Have another area or network take over (compensation and restoration)
• use a different behavioural strategy (compensation)

Animal and human studies support the existence of neural plasticity in functional recovery, both spontaneously and in response to treatment.

Question 39

What are the 3 natural recovery mechanisms seen post brain injury that make up the idea of neuro-plasticity?

Answer 39

1) Synaptic plasticity, changing synaptic strengths
2) Micro-structural changes (increased synaptic density, remyelination, axonal and dendritic growth and sprouting)
3) Making new neutrons (neurogenesis)

Question 40

What does the recovery curve look like after a brain injury?

Answer 40

• Rapid improvement followed by a slow improvement and plateau
• Some skills more likely to return than others but many will stop short of premorbid level
• Reason for slow recovery is processes such as oedema, perfusion changes, inflammation and oxidative stress continue to occur during the period immediately after injury
• As these slow off and plasticity processes steps in, recovery occurs.
• N.B. Curve can also dip back down e.g. through learned disuse of a limb

Question 41

What drives recovery post brain injury in the weeks, months and years following the injury?

Answer 41

• Weeks; recovery driven by resolution of pathological processes (oedema, inflammation)
• Months; recovery driven by spontaneous recovery of neural circuits (possibly caused by resolution of path processes)
• Years; recovery driven by learning and rehabilitation

Question 42

What does the recovery curve look like for a degenerative condition?

Answer 42

• In neurodegenerative diseases plasticity mechanisms act to maintain function against an overall decline
• Primary disease processes cause decline
• Secondary processes such as inflammation, reduced perfusion and oxidative stress all contribute
• Interventions such as cholinesterase inhibitors may lead to an uptick or slow the decline process

Question 43

What does the body of evidence suggest about the success of “restoration” interventions?

Answer 43

Some evidence of effectiveness at training specific cognitive functions e.g.

• Goal management (executive function)
• Attention (visual attention therapy)
• Working memory

But current clinical data is overall disappointing, suggests that training can provide short term benefits on tasks that are trained, or similar tasks, but with very little generalisability.

Melby-Lervag et al (2016) however showed that there might be some transferability in patients trained on a working memory task, but only to very similar tasks not distant tasks like reading.

Question 44

What is INCOG and what did they decide about Cognitive Rehabilitation?

Answer 44

International Congress of researchers and clinicians that tried to evaluate the mixed evidence about the efficacy of NR.

Confirmed that certain patients will benefit from it and therefore should be offered. Produced guidelines that provide clinicians with evidence based options.

Question 45

What evidence is there in favour of “Compensation” neuro-rehab training?

Answer 45

Waldron et al (2012):

• 5 participants with ABI trained to use digital PDAs
• Tasks were set up for them across the week
• Compared how well they were able to perform these tasks in comparison to those relying on memory alone
• All 5 did significantly better during the two weeks in which they used the PDA

Question 46

Why is it important to measure the outcomes of NR?

Answer 46

• Determine whether they lead to better outcomes compared to natural recovery
• If they do, by what mechanism
• Justify the cost of the service
• Obtain information needed to modify programmes
• Obtain information necessary to guide NHS prioritisation
• Medicolegal reasons e.g. how much compensation is owed to an accident victim
• Patient centred reasons such as preventing early death, enhancing QoL, helping people recover from episodes of ill health, provision of a safe environment
• Allows us to set goals for patients, which can then provide them with motivation

Question 47

What psychological changes are common post brain injury or illness?

Answer 47

• Adjustment and loss of our sense of self (i.e. our role at home, ability to work and do the things we enjoy, loss of hopes and dreams, loss of agency)
• Stress, anxiety and depression coming from major life changes e.g. marital/ sexual/ change of home/ loss of job/ loss of friends/ unable to do things they enjoy/ difficulties in making new friends.

Question 48

What biopsychosocial changes are common post brain injury or illness?

Answer 48

• Physical changes: movement, communication, speech, bowel control, eating
• Lifestyle changes: independence, choices, self-care skills, where living, who living with
• Social network: reduces to people who are committed to you, close family and friends
• Life role may become destabilised
• Social role and personality can be affected (e.g. may be harder to be as funny or insightful)

Question 49

What evidence exists about the effectiveness of Neuro-Rehabilitation?

Answer 49

Cochrane review of 16 RCTs of multidisciplinary rehabilitation programmes for brain injuries performed by Turner-Stokes in 2011:

• Mild BI = Good recovery when given appropriate info
• Moderate-Severe BI = Benefits from formal intervention, more intensive programmes associated with earlier functional gains
• Continued outpatient rehab helps sustain early gains
• Severe BI = Limited evidence for benefit from specialist care, but no other real options

Question 50

What did Zeiler et al (2015) suggest about neuro-rehab?

Answer 50

• Mouse study
• Induced strokes
• Showed that early implementation of training lead to better outcomes
• Suggests that in the period immediately following a stroke the brain enters a period of heightened responsiveness to training and mediates full recovery from a stroke.
• Also suggests early rehab should focus on IMPAIRMENT, later rehab should focus on COMPENSATION

Question 51

What was UKROC?

Answer 51

• Study that compared complexity and cost of rehab needs, necessary input from services and patient outcome
• Basically sought to identify which patients it was cost-effective to provide long term support for (in terms of drop in necessary care later in life) and which it wasn’t.