Models Mechanisms and Measurement Dr Kathryn Greenwood Department of Psychology University of Sussex amp Sussex Partnership NHS Foundation Trust Overview Personal Accounts Theories of symptoms cognition and function in schizophrenia ID: 268301
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Slide1
Impaired Functioning in Schizophrenia: Models, Mechanisms and Measurement
Dr Kathryn Greenwood
Department of Psychology, University of Sussex & Sussex Partnership NHS Foundation TrustSlide2
Overview
Personal Accounts
Theories of symptoms, cognition and function in schizophrenia
Studies
1 Executive impairment profiles in Schizophrenia (JINS)
2 Executive impairments and symptoms models (Schiz Bull)
(including in materials in preparation)
3 Cognitive impairments and Awareness (Schiz Bull)
4 Genes and outcome (Neuroscience letters)
5 VR as a measurement tool (in preparation)
Clinical implications and future directionsSlide3
Personal AccountsSlide4
“My concentration is very poor. I jump from one thing to another. If I am talking to someone they only need to cross their legs or scratch their head and I am distracted and forget what I was saying.”
McGhie and Chapman, 1961Slide5
“I was looking at A or B for some subjects now I’m looking at C or D if I’m lucky.”
“Memory loss is the new thing that’s bothering me.”
“I have low concentration”
“I’m coming to terms with the fact that I have got a learning difficulty.”
Michael, Aged 16 years
Inside my head - Channel 4, June 2002Slide6
Work
“I want to be able to do things that other people do, like have a boyfriend and a job …”
Social Functioning
“I want to have friends”
Community Function
“I want to be able to cook and eat when I want”
“I want to live in my own place not a hostel”
Slide7
Theoretical BackgroundSlide8
Crow 1980
Type I schizophrenia
Type II schizophrenia
Positive symptoms
Negative symptoms
Intact cognition
Impaired cognition
Dopamine abnormalities
Ventricular and other structural abnormalities
Good treatment response
Poor treatment response
Good outcome
Poor outcomeSlide9
Liddle 1987, 1991
Reality Distortion
Disorganisation
Psychomotor Poverty
Hallucinations/
Delusions
Disorders of thinking and affect
Flat affect
Poverty of speech movement, gesture
Impaired figure-ground perception
Initiation
Orientation
Attention
Inhibition
Working memory
Initiation
Strategy use
Processing in LTM
Poor self care and occupation fx
Poor poor social and recreational fxSlide10
Baddeley’s Working Memory Model
Central Executive
Visuospatial Sketchpad
Phonological
Loop
Store
Baddeley and Hitch, 1978; Baddeley and Della Sala 1996Slide11
Goldman-Rakic 1987
Adjacent modality-specific working memory systems in DLPFC with own control systems: a fundamental impairment in schizophreniaSlide12
Shallice’s Supervisory Attentional System
Automatic contention scheduling
Until
i) novel environment
ii) requirement to inhibit one strong or several weak competing schema
New Schema construction
Implementation in working memory
Monitoring and Inhibition
Norman and Shallice 1982; Shallice and Burgess 1992; 1996Slide13
Frith’s Cognitive Neuropsychology of Schizophrenia 1992
Three main (theory of mind) disorders:
Disorders of willed intentions (action driven by intention)
Disorders of self-monitoring
Monitoring the Intentions of others
Negative symptoms = absence of initiation of willed intentions, plans and strategies and impaired monitoring of others so missed communication cues
Thought disorder (incoherence of behaviour/affect) = poor inhibition of stimulus driven responses by intentions, as well as impaired self monitoring of communication goal to output and impaired monitoring of listener’s understandingSlide14
Do Specific Cognitive deficits predict specific domains of function?
Velligan et al. 2000Slide15
Neurocognition and function: Are we measuring the right stuff? Green 2000
learning potential and skill acquisition as mediators of functional outcome
Card Sort
Immediate verbal
memory
Community/daily
activities
Social problem solving/
instrumental skills
Psychosocial skill
acquisition
Verbal fluencySlide16
Green’s conclusions 2000‘We have learned whether but not HOWneurcognition is related to functional outcome?’
Need to know what mediates relation between neurocognition and outcome?
Processes (learning potential) that underlie the ability to acquire and perform life skills
Social cognitionSlide17
There is a need for new cognitive models of negative symptoms and function in order to improve functional outcomesSlide18
Lincoln et al. (in press)
Negative symptoms associated with Impaired Social Cognition:
difficulties in ToM
lower self-esteem
less self-serving bias
Negative self-concepts related to interpersonal abilities
Dysfunctional acceptance beliefs.
Some social cognitive impairments (ToM) were associated with negative symptoms only in people with low self-esteem.
So self-concepts related to social abilities, dysfunctional beliefs and global self-worth alone and in interaction with skill-deficits are associated with negative symptomsSlide19
Rector, Beck and Stolar (2005)
Low expectancies for pleasure, success, acceptance & perception of limited resources play a major role in the formation of negative symptoms
Dysfunctional performance beliefs (e.g. If I fail partly, it is as bad as being a complete failure) associated with negative symptoms
Indirect pathways between functional capacity (cognitive impairment), dysfunctional performance beliefs, and negative symptoms and real-world functioningSlide20
Past and current studiesSlide21
Research Aims
To understand the mechanisms through which bio-psychosocial factors including
Gene markers
Phenomenology of schizophrenia
Cognitive function &
Psychological function (thinking, mood and behaviour)
Affect functional outcome in schizophreniaSlide22
Study 1 Aims
Categorisation of sub-groups by neuropsychological profile in all cases confounds the relationship between symptoms and chronicity.
Aims
To explore the severity and profile of executive functioning in relation to disorganisation and psychomotor poverty and simultaneously
To investigate the early and late profiles in first episode and chronic schizophrenia.
Hypothesis
Chronicity will associate with similar but more severe impairment
Disorganisation will associate with broad executive deficit
Psychomotor poverty with impaired working memory and response initiationSlide23
Study 1 Measuresworking memory
Digit span, word span, executive golf
planning and strategy formation
Tower of london, hayling and executive golf strategy scores
response initiation
Verbal fluency
response inhibition
Hayling test and complex reaction time test
IQ
WAIS-R and NART-RSlide24
Novel measures – the question
To assess similar processes in cognitive & function task
Working memory example
3KA27
Crunchy Green salad 250g £1.09
Crunchy Green salad 500g £1.24
Mixed Salad 250g £1.15
Caesar Salad 120g £ 1.05 Slide25
Example using Search Strategy
Slide26
Novel measures – the answer
Example using Working Memory
3KA27
237AK
Caesar Salad 120g £ 1.05
Crunchy Green salad 250g £1.09
Mixed Salad 250g £1.15
Crunchy Green salad 500g £1.24Slide27
Example using Search Strategy
Slide28
Study 1 Analysis
Group differences in executive function
MANCOVA’s controlling for WAIS IQ
Executive profiles
Converted to z-scores and compared using generalised estimating equations (GEE). Group as between and executive function as within subject factor
Specific islets of strength/deficit
Domain score compared to average of all others while holding IQ constant Slide29
Study 1 Symptom study
Controls
(n = 28)
Psychomotor Poverty ( n = 29)
Disorganisation
(n = 29)
Statistical Test
_______________
Test statistic df p
Age (Years)
33.1
(7.34)
33.9
(8.81)
36.2
(8.04)
F=1.2
2,83
.31
Sex (%Male)
89
93
86
X
2
=.74
2
.69
Parental SES
3/15/10
4/13/9 (n=7)
2/18/8 (n=8)
X
2
=1.4
4
.48
Education(Yrs)
14.5
(2.81)
12.8
(2.37)
12.1
(2.19)
F=7.0
2,83
.00
Premorbid IQ
110.0
(6.54)
97.0
(12.1)
96.8
(11.5)
F=14.8.
2,83
.00
Current IQ
113.2
(16.0)
90.0
(17.6)
88.7
(12.7)
F=22.2
2,83
.00
Illness Length (Yrs)
7.83
(7.4)
11.9
(8.55)
F=3.9
1,56
.05Slide30
Study 1 Chronicity study
Controls
(n = 28)
First Episode
(n = 22)
Chronic
(n = 35)
Statistical Test
______________
Test statistic df p
Age (Years)
33.1
(7.34)
28.6
(9.9)
38.1
(6.9)
*
Sex (%Male)
89
82
94
X
2
= 2.2
2
.33
Parental SES
3/15/10
1/12/8
(n=21)
4/19/11
(n=5)
X
2
= .87
4
.93
Education(Yrs)
14.5
(2.81)
13.1
(2.98)
12.6
(2.25)
F=4.1
2,82
.02
Premorbid IQ
110.0
(6.54)
93.7
(8.9)
99.5
(12.4)
F=17.8
2,82
.001
Current IQ
113.2
(16.0)
92.2
(17.2)
91.1
(14.1)
F=18.3
2,82
.001
Reality Distortion
19.2
(9.19)
16.9
(9.17)
F=.78
1,55
.38
Disorganisation
4.5
(5.9)
10.6
(7.6)
F=10.5
1,55
.002Psychomotor Poverty7.8(7.9)11.6 (8.7)F=2.9 1,55 .095General Negative11.5 (7.5)18.7 (4.7)F=19.7 1,55 .001Slide31
Distinct profiles and poorer performance in schizophrenia/and disorganisation than controls/ppSlide32
Parallel non-flat profiles and poorer performance in chronic schizophrenia (and FE) compared to controlsSlide33Slide34Slide35Slide36
Study 1 Conclusions
Schizophrenia - characterised by a single executive profile that reflects the make up of symptoms (psychomotor poverty / disorganisation) but not chronicity
Parallel but attenuated profile at first episode due to incorporation of those with intact function
Disorganisation - broad impairment profile incorporating planning and working memory
Psychomotor poverty - particularly impaired response initiation
Predictive power of either symptoms or cognition on outcome is short lived but stable symptom-cognition markers should be targets of intervention Slide37
Study 2
Schizophrenia - characterised by a single executive profile that reflects the make up of symptoms (psychomotor poverty / disorganisation) but not chronicity
Parallel but attenuated profile at first episode due to incorporation of those with intact function
Disorganisation - broad impairment profile incorporating planning and working memory
Psychomotor poverty - particularly impaired response initiation
Predictive power of either symptoms or cognition on outcome is short lived but stable symptom-cognition markers should be targets of intervention Slide38Slide39
Negative Symptoms matter in the Leap from Cognition to Community Function in Schizophrenia:
Dr K Greenwood, Dr S Landau, Professor T Wykes
Department of Psychology, Institute of Psychiatry,
London, UK.
e-mail: k.greenwood@iop.kcl.ac.uk
Implications for Intervention Slide40
IntroductionPeople with schizophrenia and negative symptoms have poor functioning (occupation, community and daily living skills)
Poor functioning is a source of distress for both people with schizophrenia and their familiesSlide41
Negative Symptoms associated with Community FunctionNegative symptoms (
flat affect, poverty of speech, apathy)
affect function:
Only Indirectly through link with Cognition
Independently
Slide42
Cognitive Impairments associated with Community Function
Executive function
predicts
Community function, Occupation, Daily living
Working Memory
predicts
Occupation
Global cognition
predicts
Daily living
Cognition is a stronger predictor than symptoms (Green 2000)Slide43
Cognitive Impairments associated with negative symptoms
Negative symptoms:
Linked theoretically with : Executive function and Working memory
Initiation/generation of strategies (Frith) Working memory (Goldman-Rakic)
Linked Empirically with:
Response Initiation (Franke et al. 1993)
Immediate/working memory (Pantelis et al 2001)
Focused/switching attention (Buchanan et al 1994) Initiation/working memory/strategy use (Greenwood 2000)
Slide44
Objective
To investigate specific relationships between negative symptoms, executive/working memory functions and community function and in particular to investigate the independent effect of negative symptoms
Reducing confounding of negative symptoms and low IQ
Using process approach and theoretically driven framework
Also using a novel measure to directly assess community functionSlide45
DesignCross sectional Comparison:
22 Healthy controls
28 Schizophrenia & negative symptoms balanced general
22 Schizophrenia & no negative symptoms cognitive impairment
Balancing
: Age, Sex, Premorbid IQ,
Predictors:
working memory, initation, inhibition, strategy, symptoms
Analysis:
Identify individual associations to function, interactions, and final regression modelSlide46
The measure A test of supermarket shopping Skills
Participants had to select 10 items from a
shopping list.
Measures were taken of:
accuracy (items correct)
Efficiency (time/route length)
Redundancy (no. aisles entered above minimum)
Strategy
(adapted from Test of Grocery Shopping Skills, Hamera and Brown 2000)Slide47
Research QuestionsIs directly assessed community function more impaired in people with schizophrenia and negative symptoms
(when directly assessed and without IQ confound)
Do specific executive processes predict specific community functions
(working memory-accuracy; strategy-strategy)
Do the associations differ in different symptom groups (use of theoretical rationale to investigate moderator effect of negative symptoms)Slide48
Subject Characteristics
Controls
Non-negative
Negative
Age (Years)
36.23
35.28
35.07
Sex (M/F)
16/6
19/6
20.8
Premorbid IQ
89.77
91.12
91.36
RBMT Score
15.24
2-23
13.52
7 – 23
WCST Score
2.88
0 - 6
2.07
0 - 6
Total PANSS
50.88
35 - 76
62.11*
42 - 88
Slide49
Statistical Analyses
Association Analyses
(GLR – with
binomial, Poisson, normal distribution)*
Stage 1: Identify individual associations
(cognition x function)
Stage 2: Identify individual interactions
(cognition x symptom group x function)
Stage 3: Conduct final regression model
Premorbid IQ controlled
Slide50
Poorer strategy, working memory, initiation in negative group
0
1
2
3
4
control
non-neg
neg
Spatial Strategy Score
0
2
4
6
8
10
12
control
non-neg
neg
Verbal working memory
score
0
5
10
15
20
25
30
35
40
control
non-neg
neg
Verbal fluency initiationSlide51
Community function: Poorer accuracy, efficiency and strategy in negative group
Correct lowest price
0
1
2
3
4
5
6
7
8
control
non-neg
neg
Time Taken
0
10
20
30
40
50
60
control
non-neg
neg
Time taken
0
2
4
6
8
10
12
14
16
control
non-neg
neg
Aisles above MinimumSlide52
The results
Some cross group predicted associations between cognition and function (e.g. accuracy and strategy, efficiency and working memory)
Some executive-function associations
only
with negative symptoms
(working memory and accuracy, IQ and efficiency)
Not
just because of poor general cognition and
Not
a threshold effect but a true interactionSlide53
Executive & premorbid factors associated with community functionWorking memory associated with all function measures
(p = .01- < .001)
Strategy associated with strategy measures and route length
(p = .04- < .001)
Initiation associated with correct items, efficiency and strategy
(p = .02 - <.001)
Premorbid IQ associated with most measures
(p = 0.04-<0.001)Slide54
Independent cognition to community function associations are present only for specific groupsIn Negative group
Working memory associated with size accuracy
price accuracy
Verbal fluency associated with aisles above minimum
Premorbid IQ associated with correct items
time
In Controls
Working memory associated with aisle strategy
Verbal fluency associated with aisles above minimumSlide55
Conclusion so far…
Community functions are more impaired in schizophrenia with negative symptoms
even
compared to a group with equivalent general cognitive function
Executive functions associated with community function
only
in negative not non-negative schizophreniaSlide56
Negative symptoms moderate the association between impaired executive and community functions
No significant interaction of working memory severity factor within negative group
Moderating effect is not a cognitive threshold effect
Slide57
A synergistic cognition-symptom interaction predicts community function: A working memory model
Core Working Memory
Negative Symptoms
Community
Function
Ability
Domain Specific WM
CF exp.Slide58
Research Question - 2Do cognition or symptoms predict changes in community function when investigated longitudinally?
Slide59
Design - 2Longitudinal follow-up of shopping function
(n=43)
:
Comparing baseline (t1) to 6 months (t3)
Broader range Demographics, Cognition, Symptoms and functionSlide60
Influences on recovery
Differences in baseline measures between improvers (n=21) and non-improvers (n=22)
initial community function
(p <.001)
self-esteem
(p = 0.026)
working memory
(p=0.047)
Independent predictors of improvement on
Initial community function
(p = 0.004)
Self esteem
(p <0.001)
Working memory
(p = 0.088)Slide61
A synergistic cognition-symptom interaction predicts community function: A working memory model
Core Working Memory
Negative Symptoms
Community
Function
Ability
Domain Specific WM
CF Level
Self esteemSlide62
The design III: the relationship of SST to other functions
Cross sectional comparison of standardised shopping function to other function measures
(n=53)
:
Accuracy correlated with social behaviour (SBS) (r = -0.4 p = 0.001) but not level of independence in day care, number of activities or self-reported shopping activities
Efficiency correlated with level of independence in day care and independence in handling money (Spearman’s rho = -0.4 p = 0.005 and -0.3 p = 0.047) but not with social behaviour, number of activities or other self-reported shopping activities
The ability to shop accurately seems linked to the appropriateness of other social behaviours and the ability to shop efficiently seems linked to other measures of independence in function. Shopping function is unrelated to activity levels in shopping or other behaviours.Slide63
ImplicationsSynergistic interaction between negative symptoms and working memory impairments may contribute to progressively poorer community function
Remediation programmes that employ CBT/ CRT to target negative symptoms/ low self esteem AND domain specific cognition/working memory may break the reciprocal link, enhance generalisation and improve functional outcome Slide64Slide65
Why consider a VR assessment of function?
Most commonly used measures are the GAF and employment status (recent review Greenwood et al. unpublished data)
Rehabilitation may be maximised by identifying cognitive targets for intervention through refined assessment (Greenwood et al. 2005)
But few brief direct standardised assessments (McKibbin et al. 2004)
Need for brief, easily administered community function assessments in schizophrenia,
validated against real life functions and underlying cognitive processesSlide66
The Use of Virtual Reality in Assessment and Intervention
VR apartment for medication management and adherence
VR functional skills assessment for social competence
VR avatar for assessment of social approach and anxiety
VR street, tube train and library for understanding thinking patterns underpinning to psychosis
VR Park and Maze for real world navigation (allocentric and egocentric memory)
VR maze for real world sensory integration in working memory
VR supermarket to assess executive function in different clinical groups
BUT no studies in schizophrenia have compared RL and VR performance on same task and some suggest differential performance in VR dependent on environment and associated cognitive processes
Freeman et al. 2003;2005; Jang et al. 2005; Baker et al 2006; Sorkin et al. 2006; 2008; Kurtz et al. 2007; Ku et al. 2007; Weniger et al 2008; Kim et al. 2008; Park et al. 2009; Zanyi et al. 2009; Josman et al. 2009; Landgraf et al. 2010
Slide67
The research questions1. Does performance in VR relate to the same in RL?
2. Do they share common or distinct cognitive processes?
3. Do these processes differ in different symptom groups?Slide68
Community Function Measure
Supermarket Shopping Task
(adapted from TOGSS: Hamera and Brown, 2000)
Virtual Reality Shopping Task
presented on flat screen computer with joystick
(RG Morris et al.)
In each task p
articipants had to select 10 items from a shopping list. Measures were taken of:
accuracy
(items correct)
time
redundancy
(no. aisles entered above minimum)Slide69
Slide70
Slide71Slide72Slide73Slide74Slide75Slide76Slide77Slide78Slide79
Cognitive measures Memory and Working Memory
Visual Reproduction and Letter-Number Span
Executive function
BADS- key search & Verbal fluency
Social Cognition
Intention Inference Test (Sarfarti et al. 1997)
(IQ NART-R and WASI also assessed)Slide80
Participant Demographics
Participants (n=43)
Mean (n)
s.d.
range
Age (Years)
39.5
11.9
21-63
Sex (M/F)
23/21
-
-
PANNS positive
14.6
6.5
7 – 28
PANSS negative
13.4
5.5
8-27
PANSS total
57.8
18.6
32-103Slide81
Participant Cognition
Participants (n=43)
Mean (n)
s.d.
range
Premorbid IQ
103.6
11.9
74-129
mean scaled score
(WASI)
9.2
3.3
3-16
Verbal Fluency
33.2
12.2
8-62
Strategy (BADS KS)
2.0
1.1
0-4
Working Memory (L-N)
8.3
3.3
2-16
Spatial Memory (Vis Rep)
6.3
4.7
0-17
Social Cognition
(comic strip
20.2
5.8
5-27Slide82
Does performance in VR relate to the same in RL?
RL accuracy
RL time
RL aisles
VR accuracy
VR time
VR aisles
RL accuracy
\
-.21 p=.20
-.18 p=.27
.30 p=.05
-.18 p=.25
-.08 p=.61
RL time
\
.69 p<.001
-.58 p<.001
.35 p=.02
.45 p= .003
RL aisles
\
-.42 p=.006
.65 p<.001
.75 p<.001
VR accuracy
\
-.26 p=.087
-.21 p=.19
VR time
\
.81 p<.001
VR aisles
\
*Significance remained (except trend for RL/VR accuracy) when IQ controlled
**No correlations with symptom measuresSlide83
Does performance in VR relate to the same in RL?
Accuracy
Aisles
*
*Slide84
Do
RL
and
VR
shopping share the same cognitive underpinnings?
Accuracy
Time
Efficiency
Verbal Fluency
Verbal Fluency
Verbal Fluency
Verbal Fluency
Working Memory
Strategy
Spatial Memory
Social Cognition
R=0.35 p=0.02
R=0.29 p=0.06
R=-0.26 p=0.09
R=0.29 p=0.058
R=-0.27 p=0.08
R=-0.32 p=0.05Slide85
Do Cognitive underpinnings of
RL
and
VR
differ in Negative symptom group
Accuracy
Time
Efficiency
Verbal Fluency
Verbal Fluency
Verbal Fluency
Verbal Fluency
Working Memory
Strategy
Spatial Memory
Social Cognition
R=0.47 p=0.04*
R=0.57 p=0.013
R=-0.52 p=0.02
R=0.47 p=0.05*Slide86
Do Cognitive underpinnings of
RL
and
VR
differ in Negative symptom group
Accuracy
Time
Efficiency
Verbal Fluency
Verbal Fluency
Verbal Fluency
Verbal Fluency
Working Memory
Strategy
Spatial Memory
Social Cognition
R=0.47 p=0.04*
R=0.57 p=0.013
R=-0.52 p=0.02
R=0.47 p=0.05*Slide87
Conclusions
Does performance in VR relate to the same in RL?
Yes
2. Do they share common or distinct cognitive processes?
Some shared (WM and strategy) but some distinct underlying cognitive processes
3. Do these processes differ in different symptom groups?
Some different and some similar cognitive underpinnings, greater overlap of VR and RL and stronger correlations in Negative symptom sub-group
Particular role for Social Cognition in RL where the social environment is more important (and in VR with negative symptoms where avatars treated as real) and for spatial memory in VRSlide88
Conclusions and Limitations
VR may be seen as an intermediate assessment between cognition and RL but care should be taken in considering the nature of the VR environment, the underlying cognitive processes, and the clinical presentation of the client group
Risk of type 1 errors with current comparatively small sample
Participants had a wide range of cognitive performance with mean cognitive function largely in the average range and with mild-moderate negative symptoms.
A greater contribution of cognition to community function may occur when cognition is impaired and symptoms greater
(Greenwood, Landau & Wykes 2005)
Future study will consider the validity of VR assessments of community function within a cognitively impaired sample for whom interventions are developed
Slide89
Executive function
A variety of fractionated cognitive processes concerned with the control, organisation and sequencing of higher cognition.
27-46% of people with schizophrenia have selective ‘executive’ profiles and 54-90% have at least one executive impairment (Johnson-Selfridge and Zalewski, 2001; Kremen et al. 2004; Chan et al. 2006a & b). Executive dysfunction is associated with poor social outcome (Kopelowicz et al. 2005, Laes and Sponheim 2006) . In studies of single symptoms, both syndromes have been associated with impaired verbal initiation and working memory and disorganisation also with attention, inhibition, discourse planning and monitoring (Liddle and Morris 1991; Hoffman et al. 1986; Pantelis et al 2001). First episode schizophrenia shows executive dysfunction at this early stage, with some degree of clinical heterogeneity (Joyce et al. 2005; 2007; Chan et al 2006b), but less impairment than is found in chronic schizophrenia (Saykin et al. 1994; Chan et al 2006b). Profiles have varied between studies, with parallel flat profiles of diffuse general impairment, parallel non-flat profiles with selective impairments, and selective impairments specific to chronic schizophrenia (Saykin et al. 1994, Blanchard and Neale 1994; Albus et al. 1996; Chan et al. 2006 a & b). These variations might result from studies that collapse test scores across broad domains. Slide90
Frith
Disorganisation symptoms arise from impaired inhibition of habitual responses when plans must be constructed and implemented using working memory, whilst psychomotor poverty results from deficits in the initiation of activities due to impaired initiation of plans. Slide91
Conclusions
Theoretical understanding of function can provide target cognitive processes for remediation
Individual approach is important because of complex relationship between symptoms, cognition and function
Remediation should link to day-to-day function ti improve outcome