Is processing speed predictive of functional outcome in psychosis?

Article (PDF Available)inSocial Psychiatry and Psychiatric Epidemiology 43(6):437-44 · July 2008with19 Reads
DOI: 10.1007/s00127-008-0328-y · Source: PubMed
Abstract
To investigate the contribution of processing speed in the prediction of various domains of outcome in psychosis. Data were drawn from the UK700 Case Management Trial of 708 patients with chronic psychotic illness. Regression analyses were applied to investigate cross-sectional and longitudinal associations between processing speed at baseline and measures of service use, social outcome and subjective outcome, taking into account current psychopathology and adjusting for baseline values of the outcome measure. Cross-sectionally, processing speed was associated with all three domains of outcome, although only associations in the social and subjective outcome domain remained significant after controlling for psychopathology and the effects differed between and within domains of outcome. Prospectively, only the subjective outcome measure of number of met and unmet needs (CAN) was weakly associated with baseline neurocognitive performance after adjustment for baseline needs. Other associations disappeared after adjustment for the baseline measure of outcome and/or baseline psychopathology. The finding of weak cross-sectional associations in the absence of specific and unconfounded longitudinal associations suggests that processing speed is an independent dimension of disease severity rather than a causal factor impacting on social outcome. Nevertheless, longitudinal change in patient reported needs may be weakly sensitive to baseline cognitive impairment.
ORIGINAL PAPER
Nienke Jabben Æ Jim van Os Æ Tom Burns Æ Francis Creed Æ Theresa Tattan Æ John Green Æ Peter Tyrer Æ
Robin Murray Æ Lydia Krabbendam Æ the UK700 Group
Is processing speed predictive of functional outcome
in psychosis?
Received: 29 June 2007 / Accepted: 8 February 2008 / Published online: 29 February 2008
j Abstract Objective To investigate the contribu-
tion of processing speed in the prediction of various
domains of outcome in psychosis. Method Data were
drawn from the UK700 Case Management Trial of 708
patients with chronic psychotic illness. Regression
analyses were applied to investigate cross-sectional
and longitudinal associations between processing
speed at baseline and measures of service use, social
outcome and subjective outcome, taking into account
current psychopathology and adjusting for baseline
values of the outcome measure. Results Cross-sec-
tionally, processing speed was associated with all
three domains of outcome, although only associations
in the social and subjective outcome domain
remained significant after controlling for psychopa-
thology and the effects differed between and within
domains of outcome. Prospectively, only the sub-
jective outcome measure of number of met and unmet
needs (CAN) was weakly associated with baseline
neurocognitive performance after adjustment for
baseline needs. Other associations disappeared after
adjustment for the baseline measure of outcome and/
or baseline psychopathology. Conclusion The finding
of weak cross-sectional associations in the absence of
specific and unconfounded longitudinal associations
suggests that processing speed is an independent
dimension of disease severity rather than a causal
factor impacting on social outcome. Nevertheless,
longitudinal change in patient reported needs may be
weakly sensitive to baseline cognitive impairment.
j Key words functional outcome psychosis
processing speed symptoms
Introduction
Given the substantial heterogeneity in course among
individuals with a diagnosis of schizophrenia, iden-
tifying course predictors remains crucially important.
In the search for predictors of outcome, the roles of
various clinical and demographic characteristics have
been investigated [3, 22, 32, 39], and there is now an
The UK700 Group is a collaborative study team involving four clinical cen-
tres—Manchester: Tom Butler, Francis Creed, Janelle Fraser, Richard Gater,
Peter Huxley, Nick Tarrier, Theresa Tattan. Kings/Maudsley, London: Tom Fahy,
Catherine Gilvarry, Kwame Mc Kenzie, Robin Murray, Jim van Os, Elizabeth
Walsh. St Marry’s/St Charles, London: John Green, Anna Higgit, Elizabeth van
Horn, Donal Leddy, Patricia Thornton, Peter Tyrer. St George’s, London: Rob
Bale, Tom Burns, Matthew Fiander, Kate Harvey, Andy Kent, Chiara Samele.
York (Health Economics Centre) Sarah Byford, David Torgerson, Ken Wright.
Statistical Centre, London: Simon Thompson, Ian White.
N. Jabben Æ J. van Os Æ L. Krabbendam (&)
Dept. of Psychiatry and Neuropsychology
Maastricht University
P.O. BOX 616 (VIJV)
6200 MD Maastricht, The Netherlands
Tel.: +31-43/3688-682
Fax: +31-43/3688-689
E-Mail: l.krabbendam@sp.unimaas.nl
J. van Os Æ R. Murray
Division of Psychological Medicine
Institute of Psychiatry
London, UK
T. Burns
Dept. of Psychiatry
University of Oxford
Oxford, UK
F. Creed
Manchester Royal Infirmary
Manchester, UK
T. Tattan
West of England Forensic Mental Health Service
Fromeside, Bristol, UK
J. Green
Central and Northwest London Mental Health NHS Trust
London, UK
P. Tyrer
Division of Neuroscience and Psychological Medicine
Imperial College
London, UK
Soc Psychiatry Psychiatr Epidemiol (2008) 43:437–444 DOI 10.1007/s00127-008-0328-y
SPPE 328
impressive quantity of literature showing the impor-
tance of neurocognitive deficits in functional outcome
in schizophrenia in terms of statistical associations
[13, 14]. In particular neurocognitive functioning in
domains of verbal memory, vigilance and executive
functioning has been emphasized to be important
predictor of functional outcome [14], although other
studies also demonstrated the importance of pro-
cessing speed in the prediction of everyday func-
tioning [8, 29].
It has been suggested that outcome in psychosis is
more strongly associated with stable characteristics,
such as cognitive functioning, than to the much more
variable positive symptoms of psychosis [5, 13].
However, there is evidence that the symptoms of
psychosis do impact on various measures of outcome
[34] and studies comparing neurocognitive and
symptom measures in their relative associations with
subsequent outcome do not entirely support the
conclusion that cognition is a better predictor than
symptomatology [2, 9, 29, 31]. Some researchers
proposed that it is not so much the absolute level of
symptoms at the time of an acute episode, that at
baseline typically are uniformly high and therefore
not discriminative, but rather the level of subsequent
persistence of symptoms that predict outcome [31].
Therefore, it is important to investigate symptoms
and neurocognition in the same group of patients in a
stable phase of the illness so the prognostic value of
both indices can be compared.
A large proportion of studies investigating the
relationship between cognition and outcome use a
cross-sectional design, while reports on longitudinal
relationships between predictors and baseline-ad-
justed outcome are essential to evaluate their true
long-term prognostic value [25]. In a review of lon-
gitudinal studies [15], it was concluded that there was
considerable support for longitudinal associations
between neurocognition and community outcome.
Other longitudinal studies, however, found that neu-
rocognition at onset was only weakly associated with
outcome at follow-up compared to the much stronger
cross-sectional associations, indicating that neuro-
cognition explains less of the variance in outcome
than cross-sectional studies would suggest [24, 29,
44]. Moreover, only few studies examined neurocog-
nition in relation to changes in functional outcome, by
taking into account baseline level of functioning. If
baseline levels of the outcome measure are not taken
into account, ‘‘predictive’’ associations with follow-up
measures may merely reflect associations that were
already apparent at baseline, and serve as passive
indicators of disease severity [35].
The inconsistency of findings may also partly be
due to the fact that outcome is not a unitary concept,
and different domains of outcome may differ in their
cognitive and symptom correlates. For example, one
study suggested that the used cognitive measures were
only prognostic of the subjective outcome domain of
quality of life (QoL), whereas the objective outcome
measure of rehospitalization was better predicted by
demographic and clinical variables [42]. Also, differ-
ent symptoms differentially influence outcome. A
previous analysis of the current data [34] revealed
that reductions in psychopathology were associated
longitudinally with improvement in outcome, but the
size of associations was different for the various
dimensions of symptoms and functioning.
The aim of the current study was to clarify the role
of processing speed as a prospective predictor of
various domains of outcome in a large sample of
stable patients with chronic psychotic illness.
Extending a previous analysis of the same data [34],
in which the impact of psychopathology dimensions
on outcome was assessed, this study investigated the
relative importance of processing speed in the pre-
diction of functional outcome. First, the cross-sec-
tional relationship between processing speed and
various measures of outcome was investigated, in
order to evaluate whether processing speed was
associated with baseline measures of the outcomes
examined over and above measures of symptomatol-
ogy. Secondly, the prognostic value of processing
speed on functional outcome was examined by
investigating longitudinally whether processing speed
at baseline was, over and above symptomatology,
associated with baseline-adjusted outcome measures
at follow-up.
Methods
j Sample
Data were drawn from the baseline and year 2 assessments of the
UK700 Case Management Trial, a 2-year randomized controlled
trial comparing the efficacy of different intensities of case man-
agement in psychotic patients [6, 28]. The rationale and detailed
methodology of the UK700 study have been reported elsewhere [46,
47]. The 708 patients in the UK700 study were recruited at the point
of discharge from the hospital or in the community. Criteria for
inclusion were: (1) presence of a psychotic illness according to the
Research Diagnostic Criteria [43], (2) aged between 16 and
65 years, (3) hospitalized for psychotic symptoms at least twice, the
most recent admission within the past 2 years, (4) absence of
obvious organic brain damage or a primary diagnosis of substance
abuse.
Subjects were interviewed at baseline and at one and 2-year
follow-up. Baseline assessments took place prior to randomization
and involved the collection of socio-demographic data and a clin-
ical and neuropsychological assessment. Clinical assessments were
also carried out 1 and 2 years after randomization. For the present
study data were drawn from the baseline and year 2 follow up
assessment.
j Neuropsychological assessment
A short neuropsychological assessment took place at baseline and
consisted of the trail making test (TMT) parts A and B [38] and the
national adult reading test (NART) [30]. The TMT is primarily a
test of visual conceptual and visuomotor tracking and can be
considered a measure of processing speed [21]. In part A, subjects
438
had to draw lines to connect consecutively numbered circles. In
part B, subjects connected the same number of consecutively
numbered and lettered circles by alternating between the two se-
quences. It therefore, reflects more complex information processing
than part A. The score is the time to complete each part of the test.
Additionally, level of premorbid intelligence was estimated
using the NART. This reading test makes minimal demands on
current cognitive capacity and is relatively resistant to neurological
and psychiatric disorder. Therefore, it can be considered a useful
measure of premorbid intellectual functioning in the group of pa-
tients with a psychotic illness.
j Psychopathology assessment
At baseline, the operational criteria checklist for psychotic illness
(OCCPI) [26] was completed for all patients and the computer
program OPCRIT was used to derive diagnoses. For the present
study, the RDC diagnostic system was used [43].
At baseline and at follow up, current psychopathology was
measured using the Comprehensive Psychopathology Rating Scale
[19]. For the purpose of this research the symptom dimensions
derived from previous factor analysis were used [34]. Four psy-
chopathology dimensions were retained, reflecting depressive,
manic, negative and positive symptoms. Standardized factor scores
were calculated and had a mean of zero and a standard deviation
of 1.
j Functional outcome assessment
Functional outcome was assessed at baseline and at 2-year follow-
up. Service use was assessed by the number of hospital admissions
and by the number of days spent in hospital over the past 2 years,
measured using a slightly modified version of the Life Chart
Schedule [49].
Social outcome was assessed using measures of employment,
independent living and social disability. The number of months in
employment and independent living over the past 2 years were
measured using the Life Chart Schedule [49]. Employment was
composed of fulltime and part-time jobs, sheltered jobs, retirement
or being a student. Independent community living was defined as
the total number of months in independent community living over
the past 2 years. Social disability was assessed using the WHO
disability assessment schedule (DAS) [18, 49]. The two ‘‘overall
behaviour’’ items and the nine ‘‘social roles’’ items were used to
rate the level of social disability, higher scores indicating higher
rates of disability.
Subjective outcome was measured by reported QoL and needs
for care. QoL was rated using a structured self-report interview
(Lancashire QoL Profile [33] based on the Lehman QoL Interview
[20]. It consists of 100 items assessing QoL and life satisfaction in
nine areas (subscales). The mean of the subscales was used as the
dependent variable, higher scores reflecting better QoL. The
Camberwell assessment of need (CAN) [36] assesses 22 areas of
need, each area including four sections. In the current study only
the first section was used; this establishes whether there is a need,
by asking about difficulties in that area. Responses are rated on a
three point scale [0 = no serious need; 1 = no/moderate problem
because of continuing intervention (met need); 2 = current serious
problem (unmet need)]. The number of met and the number of
unmet needs were used as dependent variables. Needs were scored
as viewed by the patient, thus constituting a subjective outcome.
j Statistical analyses
For convenience of interpretation of the data, TMT variables were
recoded so that a higher score on neurocognitive variables indi-
cated a better performance. First, to investigate the extent of the
relationship between the processing speed variables and symp-
tomatology partial correlations were calculated, adjusting the
symptom dimensions for each other. For the investigation of cross-
sectional associations between cognitive variables and outcome,
multiple linear regressions, a priori adjusted for the basic con-
founders age, sex, educational qualifications, ethnicity, and centre,
were applied. Separate models were used for each of the three
neurocognitive variables. Functional outcome at baseline was used
as dependent variable, and the neurocognitive measure and the
basic confounders as independent variables. In case of significant
or near significant associations (P £ 0.10), psychopathology
dimensions were additionally entered into the equation simulta-
neously in order to investigate whether the cognitive variable had
prognostic value in addition to current symptoms.
Likewise, for the investigation of longitudinal associations
between cognition at baseline and outcome at follow-up, multiple
linear regression analyses, a priori adjusted for age, sex, educa-
tional qualifications, ethnicity, centre and case management
intervention, were applied. First, a single neurocognitive variable
was entered as predictor of functional outcome at follow up. In
case of significant or near significant associations (P £ 0.10),
analyses were repeated, adjusted for the equivalent of the out-
come variable at baseline, in order to examine the true associa-
tion with change in the functional outcome variable over time. If
a (near) significant association remained, psychopathology
dimensions at baseline were additionally entered into the equa-
tion in order to examine whether the neurocognitive variable had
longitudinal prognostic value in addition to symptoms. Finally, a
sensitivity analysis was done, in which the cross-sectional and
longitudinal analyses were repeated excluding patients with an
RDC diagnosis of affective or unspecified psychosis in order to
examine whether correlations were confounded by the inclusion
of individuals with a diagnosis other than schizophrenia spectrum
disorders. Effect sizes were expressed as standardized regression
coefficients (b).
Results
j Demographic characteristics
Seven-hundred and eight patients entered the study.
Mean age of participants at study entry was 38.3 years
(SD 11.6); there were more men (57%) than women
(43%). Just over half (52%) of the patients was white,
28% was African-Caribbean and 20% pertained to
other ethnic groups. Forty-five per cent of the par-
ticipant had no educational qualifications, 32% was
classified as CSE/GCSE/O level and 23% had an A
level or degree. The most common RDC diagnosis at
study entry was schizophrenia (49%) followed by
schizoaffective disorder (38%). Other patients were
diagnosed as suffering from affective or non-specified
psychosis.
Of the 708 patients who entered the study, 15% did
not complete TMT A, 38% did not complete TMT B,
and 38% of the participants did not complete the
NART. Characteristics of the patients with missing
data are described in detail elsewhere [11]. Briefly,
patients who did not complete TMT were more likely
to have negative symptoms, positive symptoms, to
have less education and to be older. Those with
missing TMT B scores were additionally more likely
to be from lower socioeconomic groups. Patients not
completing the NART were less likely to be white,
more likely to be older, less educated and to show
more negative, and more positive symptoms [11].
439
Summary scores of neurocognitive and functional
outcome variables are presented in Table 1.
Regarding the extent of the relationship between
predictor variables of processing speed and symptom
dimensions, partial correlation analyses revealed that
TMT A was significantly associated with positive
symptoms (r = 0.12, P = 0.05) and there was a trend
towards an association with negative symptoms
(r = 0.07, P = 0.09). No significant correlations were
found for the other symptom dimensions (depression:
r = 0.02 and mania: r = 0.05). TMT B was signifi-
cantly associated with negative (r = 0.20, P = 0.00)
and positive (r = 0.14, P = 0.01) symptoms, but not
with mania (r = )0.03) and depression (r = 0.01).
j Cross-sectional associations between cognition
and outcome
In the outcome domain of service use, multiple
regression analysis showed a trend towards a signifi-
cant association between number of hospital admis-
sions and performance on TMT B (b = )0.10,
P = 0.07) (Table 2), a better test performance pre-
dicting fewer hospital admissions. Entering psycho-
pathology dimensions into the equation reduced the
strength of this association (b = )0.08, P = 0.17). For
time in the hospital a weak trend towards an associ-
ation was found with TMT A (b = )0.08, P = 0.07)
that was reduced only marginally after correcting for
current psychopathology (b = )0.08, P = 0.09).
Regarding social outcome, a significant cross-sec-
tional association was found between performance on
TMT B and employment; a better cognitive perfor-
mance was associated with a longer duration of
employment (b = 0.12, P = 0.02). Entering dimen-
sions of psychopathology in the equation reduced the
association (b = 0.08, P = 0.13). TMT A was signifi-
cantly associated with months in independent living
(b = 0.11, P = 0.01) and this association remained
significant after entering psychopathology dimen-
sions in the equation (b = 0.10, P = 0.02). The trend
towards an association between TMT B and inde-
pendent living was reduced after entering psychopa-
thology (b = 0.04, P = 0.50). The outcome measure of
social disability, measured with the DAS, was associ-
Table 1 Neurocognitive and
functional outcome measures:
summary
Baseline Follow up Change scores
n Mean (SD) n Mean (SD) n Mean (SD)
Neuropsychological tasks
TMT A 599 60.8 (39.5)
TMT B 437 119.20 (62.2)
Nart 586 106.40 (10.5)
Service use (range)
Number of hospital admissions (0–13) 707 1.9 (1.2) 703 1.1 (1.5) 703 )0.8 (1.7)
Time in hospital (0–730) 707 108.9 (112.6) 703 81.3 (125.4) 703 )28.0 (141.4)
Social outcome (range)
Employment, months (0–24) 705 3.1 (6.6) 685 2.6 (6.5) 683 )0.3 (6.5)
Independent living, months (0–24) 707 16.8 (7.6) 698 15.7 (9.3) 698 )1.0 (7.0)
DAS total score (0–4.8) 696 1.2 (0.9) 596 1.1 (0.8) 587 )0.1 (0.9)
Subjective outcome (range)
QoL (1.2–6.8) 689 4.3 (0.7) 526 4.6 (0.7) 513 0.3 (0.8)
CAN number of needs (0–14) 699 6.0 (3.0) 585 6.5 (3.1) 579 0.4 (3.5)
CAN number of unmet needs (0–14) 699 2.6 (2.3) 585 2.0 (2.4) 579 )0.7 (2.9)
Table 2 Associations between neurocognitive variables and outcome mea-
sures
Estimates cross-sectional Estimates longitudinal
b P value b P value
Service use
Hospital admissions
TMT A 0.02 0.69 0.06 0.15
TMT B )0.10 0.07 0.03 0.60
Nart )0.04 0.40 0.08 0.13
Time in hospital
TMT A )0.08 0.07 0.04 0.33
TMT B )0.00 0.95 0.04 0.50
Nart 0.01 0.83 0.02 0.77
Social outcome
Employment
TMT A 0.04 0.32 )0.03 0.52
TMT B 0.12 0.02 0.05 0.35
Nart 0.03 0.60 0.08 0.14
Independent living
TMT A 0.11 0.01 0.08 0.09
TMT B 0.09 0.10 0.08 0.16
Nart 0.01 0.92 0.03 0.56
Social disability
TMT A )0.09 0.03 )0.08 0.09
TMT B )0.09 0.08 )0.11 0.05
Nart )0.11 0.02 )0.06 0.31
Subjective outcome
QoL
TMT A 0.02 0.67 0.02 0.67
TMT B )0.07 0.21 )0.04 0.50
Nart )0.10 0.04 0.07 0.28
CAN needs
TMT A )0.04 0.40 )0.09 0.05
TMT B )0.08 0.11 )0.19 0.00
Nart )0.05 0.37 )0.10 0.08
CAN unmet needs
TMT A 0.01 0.90 )0.11 0.02
TMT B )0.14 0.01 )0.21 0.00
Nart
)0.08 0.10 )0.03 0.56
All analyses adjusted for age, sex, educational qualifications, ethnicity and
centre
440
ated with TMT A and NART (see Table 2). After
adjustment for psychopathology, however, only the
association with NART remained equally large and
significant (TMT A: b = )0.03, P = 0.45, TMT B:
b = )0.01, P = 0.90, NART: b = )0.12, P = 0.01).
In the subjective outcome domain, QoL score was
significantly associated with NART performance
(b = )0.10, P = 0.04); better NART performance was
associated with a lower QoL score. This association
was reduced but not nullified after adjustment for
current psychopathology (b = )0.08, P = 0.08). For
TMT performance no association with QoL was
found. Number of met needs (CAN) was associated
with none of the neurocognitive measures. The
number of unmet needs (CAN) showed a significant
association with TMT B (see Table 2), worse cognitive
performance being associated with an increased
number of unmet needs. Adjustment for psychopa-
thology dimensions only marginally reduced the
strength of this association (b = )0.12, P = 0.02).
j Longitudinal associations between cognition
and outcome
Longitudinally, no significant associations were found
for service use measures: number of hospital admis-
sions and time in the hospital at follow up were not
associated with TMT or NART performance at base-
line (see Table 2).
As to the social outcome domain, no longitudinal
association was found between neurocognitive pre-
dictors and months of employment (see Table 2). The
trend towards a significant positive association be-
tween independent living at follow-up and TMT A
performance at baseline (b = 0.08, P = 0.09) was re-
duced after adjustment for independent living at
baseline (b = 0.01, P = 0.73). Social disability (DAS)
at follow-up was associated with TMT performance at
baseline (see Table 2). However, after adjustment for
social disability at baseline these associations were
much reduced (TMT A: b = )0.03, P = 0.50, TMT B:
b = )0.07, P = 0.17).
Regarding subjective outcome, no association was
found between the neurocognitive variables at base-
line and QoL at follow-up (see Table 2). Number of
met needs (CAN) however, showed a significant
negative association with TMT A and B, impaired
neurocognitive performance at baseline being asso-
ciated with an increased number of needs at follow-
up. Adjustment for the number of met needs at
baseline did not reduce these associations (TMT A:
b = )0.08, P = 0.09, TMT B: b = )0.16, P = 0.00) nor
did additional adjustment for psychopathology (TMT
A: b = )0.07, P = 0.10, TMT B: b = )0.17, P = 0.00).
A similar pattern was found for the number of unmet
needs at follow-up.
Repeating cross-sectional and longitudinal analy-
ses, excluding patients with an RDC diagnosis of
affective or unspecified psychosis, did not change the
pattern of results.
Discussion
The findings can be summarized as follows. Cross-
sectionally, processing speed was associated with all
three domains of outcome, although only the asso-
ciations in the social and subjective outcome do-
main remained significant after controlling for
psychopathology. Generally, processing speed but
not premorbid intellectual performance was associ-
ated with objective outcome measures of hospital
admissions, independent living and employment,
whereas both the measures of premorbid intellectual
functioning and processing speed were associated
with subjective appraisal of outcomes, although not
consistently so. The present results suggest that
processing speed is associated with social and sub-
jective outcomes over and above psychopathology,
but not to services use.
The prospective prognostic value of processing
speed and premorbid intelligence on functional out-
come was less evident. Only the subjective outcome
measure of number of met and unmet needs (CAN)
was weakly associated with baseline processing speed
performance after adjustment for the baseline level of
needs.
The finding of weak cross-sectional associations in
the absence of specific and unconfounded longitudi-
nal associations suggests that processing speed is an
independent dimension of disease severity rather than
a causal factor impacting on aspects of social out-
come.
j Associations with service use
In the current study no clear cross-sectional or
longitudinal association between processing speed
and hospitalization was found. In a previous study
[10] TMT B performance was prognostic of total
duration of hospital inpatient status. Other pro-
spective studies, however, did also not find an
association between cognitive measures and hospi-
talization during the follow up period [42, 44]. Pre-
vious analyses on the current data set showed that
reduction of positive and manic symptoms was
strongly associated with a reduction in the number
of hospital admissions [34], which is in accordance
with the suggestion of Green [13] that psychotic
symptoms may be a better predictor of clinical
outcome measures of psychosis.
j Associations with social outcome
Cross-sectionally, cognitive speed was weakly associ-
ated in the expected direction with all three measures
441
of social outcome. However, only the association with
independent living remained significant after adjust-
ment for current symptoms. The absence of an
association between processing speed and months at
work is in contradiction with other studies that did
find a significant association between neurocognition
and work performance in schizophrenia [1, 23, 29].
Social disability was associated with premorbid
intellectual functioning, also after controlling for
psychopathology, suggesting that premorbid intellec-
tual functioning explained variance in social outcome
in addition to the four psychopathology dimensions
that were previously reported to be strongly and
independently associated with social disability [34].
The lack of longitudinal associations between
processing speed, premorbid intellectual functioning
and changes in the measures of social outcome is in
accordance with a previous study [48] in which no
associations between cognitive variables and social
outcome measured by employment and independent
living were found. Other studies, however, did report
an association between neurocognitive functioning
and vocational functioning [5, 12, 27]. Previous
analyses of this dataset showed that symptomatology
was associated with social outcome since a reduction
in positive and negative symptoms was associated
with more time living independently and a reduction
in all four psychopathology dimensions was associ-
ated with improvement in social disability [34].
j Associations with subjective outcome
In cross-sectional analyses, premorbid intellectual
functioning, measured by NART, was weakly though
significantly associated with QoL, in the direction that
a better premorbid intelligence was associated with a
lower appraisal of QoL. This is consistent with the
results of Prouteau et al. [37] who reported a similar
relationship between neurocognitive functioning and
self-rated QoL. Although, this appears to be a para-
doxical finding as, generally, a better cognitive per-
formance is associated with better outcome, it has
been hypothesized that people with worse neuropsy-
chological functioning have a lesser capacity for
complex self-referencing. They therefore can directly
translate improvements in their objective psychoso-
cial status into enhanced subjective experience
without being hindered by external or premorbid self-
referencing [4]. Longitudinally, subjective QoL was
not predicted by neurocognitive measures at baseline,
which is in accordance with a previous study in which
positive and negative symptoms were more important
predictors of QoL than neurocognitive functioning in
the long run [2]. Previous research also taking into
account depressive symptomatology, indicated that
measures of subjective outcome were strongly asso-
ciated with depression and to a lesser extent with
negative symptoms [34, 41].
Number of unmet needs (CAN) showed a weak
association in the hypothesized direction with TMT B
performance when measured at the same point in
time, independent from psychopathology. Longitudi-
nally the number of met and unmet needs on the CAN
was strongly predicted by TMT performance at
baseline, even after controlling for baseline levels of
the outcome variable and for baseline psychopathol-
ogy. This in accordance with a previous study that
also found that need for care was predicted by speed
of processing [17].
j Methodological considerations
The results of the present study should be viewed in
the light of several methodological issues. First, the
current study only considered processing speed,
while previous research has demonstrated the
importance of other cognitive domains, for example
verbal memory and executive functioning, in the
prediction of functional outcome. Also, as different
domains of outcome may differ in their cognitive
correlates, a more extensive cognitive assessment
will be required to investigate whether the same re-
sults will apply for other cognitive domains. How-
ever, previous research indicated that the attention/
speed domain is one of the cognitive domains most
relevant to functional outcome in schizophrenia [23,
29] and that cognitive abnormalities in schizophre-
nia are mediated through a single common cognitive
factor [8]. Second, as mentioned in the results sec-
tion, a proportion of the subjects did not complete
the neuropsychological testing. There is reason to
assume that these missing data are not random, as
patients who did not complete the testing were most
adversely affected by their illness. This may have
biased the research population to be less impaired
than the original sample thereby causing less varia-
tion in outcome and its predictors. Third, in the
current study a relatively chronic population was
studied. This may have caused less variation in
outcome than when first episode patients would have
been investigated, and the results may not generalize
to first episode patients. However, much of the work
suggesting true predictive power of baseline cogni-
tion, summarized by Green [13], was on chronic
patients. Fourth, the current sample consisted of
patients with a diagnosis of psychosis in general, and
did not focus on one diagnostic category. A cate-
gorical approach does not capture the broad heter-
ogeneity of psychosis and schizophrenia and
therefore it was suggested that outcome may be best
investigated using a dimensional approach to psy-
chopathology of psychosis [7, 40]. The previously
reported absence of any pattern of interaction with
diagnostic category in the current sample [34] and
the stability of findings when repeated in schizo-
phrenia and schizoaffective diagnoses only, appears
442
to justify this approach. Finally, although the current
results did not show a consistent relationship be-
tween processing speed, premorbid intellectual
functioning and outcome, previous results in the
UK700 study, examining the effect of different
intervention types on outcome, showed a significant
interaction effect between type of case management
and borderline-intelligence status [45]. Patients with
borderline intellectual functioning treated with
intensive case management had a mean of only
47 days in hospital compared with 105 days for
those treated with standard care. No differential ef-
fects of intervention type were found for the group
with normal intelligence [45]. Similar gains for
borderline IQ patients, treated with intensive case
management were shown in satisfaction with ser-
vices, total costs and needs [16]. Therefore, neuro-
cognition, at least at the level of basic intelligence, is
a relevant factor in the selection of appropriate
treatment and this finding should not be obscured
by the lack of any important associations between
neurocognition and outcome in the current study.
Conclusion
The current findings suggest that, cross-sectionally,
processing speed is associated with measures of social
and subjective outcome, but not consistently so, as
the effects of the predictors differ between and within
domains of outcome. Prospectively, the evidence for
an association between change in outcome and neu-
rocognition is highly inconsistent; after adjustment
for the baseline levels only the number of met and
unmet needs measured by the CAN were weakly
sensitive to baseline neurocognitive performance.
This is in contradiction with studies supporting lon-
gitudinal associations between cognition and com-
munity outcome [7, 15], but in accordance with other
studies reporting a relationship between cognition
and outcome when measured concurrently, but not
prospectively [2]. The present results are in accor-
dance with previous findings that neurocognition is
longitudinally more associated with subjective mea-
sures of outcome [42]. Altogether, the associations
between processing speed and outcome, cross-sec-
tionally and longitudinally, are not substantially
stronger than the associations with psychopathology.
j Acknowledgments The UK700 trial was funded by grants from
the UK Department of Health and NHS Research and Development.
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    • "These findings are in line with Jabben and colleagues [17] who found weak cross-sectional associations between information processing speed in the absence of specific and unconfounded longitudinal associations. Also, most cognitive measures did not uniquely contribute to the explained variance, as results showed that symptoms and particularly negative symptoms −in line with previous literature [14,16,17,45] − meditated the association between cognitive functioning and social functioning. This may imply that factors such as a motivational deficits, social withdrawal, and impaired initiative may be underlying variables in the association between cognition and social functioning, which is in line with a previous study [46] suggesting that levels of intrinsic motivation are robustly and reliably associated with performance on cognitive tests, suggesting that shared motivation-cognition mechanisms should be investigated to enhance efforts to improve social functioning. "
    [Show abstract] [Hide abstract] ABSTRACT: Objective: Studies have linked cognitive functioning to everyday social functioning in psychotic disorders, but the nature of the relationships between cognition, social cognition, symptoms, and social functioning remains unestablished. Modelling the contributions of non-social and social cognitive ability in the prediction of social functioning may help in more clearly defining therapeutic targets to improve functioning. Method: In a sample of 745 patients with a non-affective psychotic disorder, the associations between cognition and social cognition at baseline on the one hand, and self-reported social functioning three years later on the other, were analysed. First, case-control comparisons were conducted; associations were subsequently further explored in patients, investigating the potential mediating role of symptoms. Analyses were repeated in a subsample of 233 patients with recent-onset psychosis. Results: Information processing speed and immediate verbal memory were stronger associated with social functioning in patients than in healthy controls. Most cognition variables significantly predicted social functioning at follow-up, whereas social cognition was not associated with social functioning. Symptoms were robustly associated with follow-up social functioning, with negative symptoms fully mediating most associations between cognition and follow-up social functioning. Illness duration did not moderate the strength of the association between cognitive functioning and follow-up social functioning. No associations were found between (social) cognition and follow-up social functioning in patients with recent-onset psychosis. Conclusions: Although cognitive functioning is associated with later social functioning in psychotic disorder, its role in explaining social functioning outcome above negative symptoms appears only modest. In recent-onset psychosis, cognition may have a negligible role in predicting later social functioning. Moreover, social cognition tasks may not predict self-reported social functioning.
    Full-text · Article · Apr 2016
  • [Show abstract] [Hide abstract] ABSTRACT: Intensive Case Management (ICM) is a community based package of care, aiming to provide long term care for severely mentally ill people who do not require immediate admission. ICM evolved from two original community models of care, Assertive Community Treatment (ACT) and Case Management (CM), where ICM emphasises the importance of small caseload (less than 20) and high intensity input. To assess the effects of Intensive Case Management (caseload <20) in comparison with non-Intensive Case Management (caseload > 20) and with standard community care in people with severe mental illness. To evaluate whether the effect of ICM on hospitalisation depends on its fidelity to the ACT model and on the setting. For the current update of this review we searched the Cochrane Schizophrenia Group Trials Register (February 2009), which is compiled by systematic searches of major databases, hand searches and conference proceedings. All relevant randomised clinical trials focusing on people with severe mental illness, aged 18 to 65 years and treated in the community-care setting, where Intensive Case Management, non-Intensive Case Management or standard care were compared. Outcomes such as service use, adverse effects, global state, social functioning, mental state, behaviour, quality of life, satisfaction and costs were sought. We extracted data independently. For binary outcomes we calculated relative risk (RR) and its 95% confidence interval (CI), on an intention-to-treat basis. For continuous data we estimated mean difference (MD) between groups and its 95% confidence interval (CI). We employed a random-effects model for analyses.We performed a random-effects meta-regression analysis to examine the association of the intervention's fidelity to the ACT model and the rate of hospital use in the setting where the trial was conducted with the treatment effect. We included 38 trials (7328 participants) in this review. The trials provided data for two comparisons: 1. ICM versus standard care, 2. ICM versus non-ICM.1. ICM versus standard care Twenty-four trials provided data on length of hospitalisation, and results favoured Intensive Case Management (n=3595, 24 RCTs, MD -0.86 CI -1.37 to -0.34). There was a high level of heterogeneity, but this significance still remained when the outlier studies were excluded from the analysis (n=3143, 20 RCTs, MD -0.62 CI -1.00 to -0.23). Nine studies found participants in the ICM group were less likely to be lost to psychiatric services (n=1633, 9 RCTs, RR 0.43 CI 0.30 to 0.61, I²=49%, p=0.05).One global state scale did show an Improvement in global state for those receiving ICM, the GAF scale (n=818, 5 RCTs, MD 3.41 CI 1.66 to 5.16). Results for mental state as measured through various rating scales, however, were equivocal, with no compelling evidence that ICM was really any better than standard care in improving mental state. No differences in mortality between ICM and standard care groups occurred, either due to 'all causes' (n=1456, 9 RCTs, RR 0.84 CI 0.48 to 1.47) or to 'suicide' (n=1456, 9 RCTs, RR 0.68 CI 0.31 to 1.51).Social functioning results varied, no differences were found in terms of contact with the legal system and with employment status, whereas significant improvement in accommodation status was found, as was the incidence of not living independently, which was lower in the ICM group (n=1185, 4 RCTs, RR 0.65 CI 0.49 to 0.88).Quality of life data found no significant difference between groups, but data were weak. CSQ scores showed a greater participant satisfaction in the ICM group (n=423, 2 RCTs, MD 3.23 CI 2.31 to 4.14).2. ICM versus non-ICM The included studies failed to show a significant advantage of ICM in reducing the average length of hospitalisation (n=2220, 21 RCTs, MD -0.08 CI -0.37 to 0.21). They did find ICM to be more advantageous than non-ICM in reducing rate of lost to follow-up (n=2195, 9 RCTs, RR 0.72 CI 0.52 to 0.99), although data showed a substantial level of heterogeneity (I²=59%, p=0.01). Overall, no significant differences were found in the effects of ICM compared to non-ICM for broad outcomes such as service use, mortality, social functioning, mental state, behaviour, quality of life, satisfaction and costs.3. Fidelity to ACT Within the meta-regression we found that i. the more ICM is adherent to the ACT model, the better it is at decreasing time in hospital ('organisation fidelity' variable coefficient -0.36 CI -0.66 to -0.07); and ii. the higher the baseline hospital use in the population, the better ICM is at decreasing time in hospital ('baseline hospital use' variable coefficient -0.20 CI -0.32 to -0.10). Combining both these variables within the model, 'organisation fidelity' is no longer significant, but 'baseline hospital use' result is still significantly influencing time in hospital (regression coefficient -0.18 CI -0.29 to -0.07, p=0.0027). ICM was found effective in ameliorating many outcomes relevant to people with severe mental illnesses. Compared to standard care ICM was shown to reduce hospitalisation and increase retention in care. It also globally improved social functioning, although ICM's effect on mental state and quality of life remains unclear. ICM is of value at least to people with severe mental illnesses who are in the sub-group of those with a high level of hospitalisation (about 4 days/month in past 2 years) and the intervention should be performed close to the original model.It is not clear, however, what gain ICM provides on top of a less formal non-ICM approach.We do not think that more trials comparing current ICM with standard care or non-ICM are justified, but currently we know of no review comparing non-ICM with standard care and this should be undertaken.
    Article · Oct 2010
  • [Show abstract] [Hide abstract] ABSTRACT: Despite significant advances in the field of social neuroscience, much remains to be understood regarding the development and maintenance of social skills across the life span. Few comprehensive models exist that integrate multidisciplinary perspectives and explain the multitude of factors that influence the emergence and expression of social skills. Here, a developmental biopsychosocial model (SOCIAL) is offered that incorporates the biological underpinnings and socio-cognitive skills that underlie social function (attention/executive function, communication, socio-emotional skills), as well as the internal and external (environmental) factors that mediate these skills. The components of the model are discussed in the context of the social brain network and are supported by evidence from 3 conditions known to affect social functioning (autism spectrum disorders, schizophrenia, and traumatic brain injury). This integrative model is intended to provide a theoretical structure for understanding the origins of social dysfunction and the factors that influence the emergence of social skills through childhood and adolescence in both healthy and clinical populations.
    Article · Jan 2010
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