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Am J Psychiatry 164:12, December 2007 1791
Reviews and Overviews
ajp.psychiatryonline.org
A Meta-Analysis of Cognitive Remediation in Schizophrenia
Susan R. McGurk, Ph.D.
Elizabeth W. Twamley, Ph.D.
David I. Sitzer, Ph.D.
Gregory J. McHugo, Ph.D.
Kim T. Mueser, Ph.D.
Objective: This study evaluated the ef-
fects of cognitive remediation for improving
cognitive performance, symptoms, and
psychosocial functioning in schizophrenia.
Method: A meta-analysis was conducted
of 26 randomized, controlled trials of cog-
nitive remediation in schizophrenia in-
cluding 1,151 patients.
Results: Cognitive remediation was asso-
ciated with significant improvements
across all three outcomes, with a medium
effect size for cognitive performance
(0.41), a slightly lower effect size for psy-
chosocial functioning (0.36), and a small
effect size for symptoms (0.28). The ef-
fects of cognitive remediation on psycho-
social functioning were significantly stron-
ger in studies that provided adjunctive
psychiatric rehabilitation than in those
that provided cognitive remediation
alone.
Conclusions: Cognitive remediation pro-
duces moderate improvements in cogni-
tive performance and, when combined
with psychiatric rehabilitation, also im-
proves functional outcomes.
(Am J Psychiatry 2007; 164:1791–1802)
Cognitive impairment is a core feature of schizophre-
nia, with converging evidence showing that it is strongly
related to functioning in areas such as work, social rela-
tionships, and independent living (1, 2). Furthermore,
cognitive functioning is a robust predictor of response to
psychiatric rehabilitation (i.e., systematic efforts to im-
prove the psychosocial functioning of persons with severe
mental illness) (3), including outcomes such as work, so-
cial skills, and self-care (1, 4, 5). Because of the importance
of cognitive impairment in schizophrenia, it has been
identified as an appropriate target for interventions (6).
Currently available pharmacological treatments have
limited effects on cognition in schizophrenia (7, 8) and
even less impact on community functioning (9). To address
the problem of cognitive impairment in schizophrenia, a
range of cognitive remediation programs has been devel-
oped and evaluated over the past 40 years. These programs
employ a variety of methods, such as drill and practice ex-
ercises, teaching strategies to improve cognitive function-
ing, compensatory strategies to reduce the effects of per-
sistent cognitive impairments, and group discussions.
Several reviews of research on cognitive rehabilitation in
schizophrenia have been published (10–13). The general
conclusions from these reviews have been that cognitive
remediation leads to modest improvements in perfor-
mance on neuropsychological tests but has no impact on
functional outcomes. However, these reviews were limited
by the relatively small number of studies that actually mea-
sured psychosocial functioning, precluding any definitive
conclusions about the effects of cognitive remediation on
psychosocial adjustment or the identification of program
characteristics that may contribute to such effects. The ra-
tionale for cognitive remediation is chiefly predicated on
its presumed effects on psychosocial functioning and im-
proved response to rehabilitation. Therefore, a critical ex-
amination of the effects of cognitive remediation on func-
tional outcomes is necessary in order to determine its
potential role in the treatment of schizophrenia.
In recent years, the number of studies that examined
psychosocial functioning has grown sufficiently to permit
a closer look at the impact of cognitive remediation. We
conducted a meta-analysis of controlled studies to evalu-
ate the effects of cognitive remediation on cognitive func-
tioning, symptoms, and functional outcomes. We also ex-
amined whether characteristics of cognitive remediation
programs (e.g., hours of cognitive training), the provision
of adjunctive psychiatric rehabilitation, treatment set-
tings, patient demographics, or type of control group was
related to improved outcomes. We hypothesized that cog-
nitive remediation would improve both cognitive func-
tioning and psychosocial adjustment. We also hypothe-
sized that programs that provided more hours of cognitive
training would have stronger effects on cognitive func-
tioning and that adjunctive psychiatric rehabilitation
would be associated with greater improvements in func-
tional outcomes.
Method
Studies for the meta-analysis were identified by conducting
MEDLINE and PsycINFO searches for English language articles
published in peer-reviewed journals. The following search terms
were used: cognitive training, cognitive remediation, cognitive re-
habilitation, and schizophrenia. Studies meeting the following cri-
teria were included: 1) a randomized, controlled trial of a psycho-
social intervention designed to improve cognitive functioning; 2)
an assessment of performance with at least one neuropsychologi-
cal measure that had the potential to reflect generalization of ef-
1792 Am J Psychiatry 164:12, December 2007
COGNITIVE REMEDIATION IN SCHIZOPHRENIA
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TABLE 1. Neuropsychological Assessments Included in Each Cognitive Domain
Domain Assessment
Attention/vigilance Wechsler Memory Scale (WMS) information and mental control subtests
Search-a-Word
Cancellation tasks
Continuous Performance Tests
Span of apprehension
Labyrinth Test
Sustained Attention Test
Span: hits, time, and overall
Preattentional processing
Cross-over reaction time
Cross-modal reaction time
Embedded Figures Test
COGLAB apprehension/masking
Dichotic listening tasks
Speed of processing Trail Making Test, Parts A and B
WAIS, WAIS-R, or WAIS-III digit symbol subtest
Stroop Test, color and word conditions
Reaction time tests
Letters and category fluency
Verbal working memory WAIS, WAIS-R, WAIS-III, or WMS digit span
WAIS-III letter-number sequencing and arithmetic subtests
Digit Span Distractibility Test
Other digit span tasks
Trained Word Recall Task
Other arithmetic tasks
Sentence span
Dual span
Paced Auditory Serial Addition Test
Nonverbal working memory Wechsler Memory Scale—Revised (WMS-R) visual span
Dual span
Verbal learning and memory WMS, WMS-R, or WMS-III logical memory and verbal paired associates subtests
California Verbal Learning Test
Rey Auditory Verbal Learning Test
Hopkins Verbal Learning Test
Word List Recall Task
Verbal learning paradigm
Denman Neuropsychological Memory Test
Span-Completeness Verbal Learning Test
Visual learning and memory WMS, WMS-R, or WMS-III visual recall, visual reproduction, faces, and figural memory subtests
Memory for Designs Test
Rey-Osterrieth Complex Figure Test
Kimura recurring figures
Denman Neuropsychological Memory Test
Reasoning and problem solving WAIS, WAIS-R, or WAIS-III similarities and picture arrangement subtests
Wechsler Intelligence Scale for Children mazes subtest
Stroop Test interference condition
Independent Living Scale—problem solving
Gorham’s Proverbs Test and other proverb interpretation tasks
Wisconsin Card Sorting Test
Trail Making Test (B – A)
Hinting Task
Labyrinth Test
Tower of Hanoi
Tower of London
Response inhibition
Six elements
Categories
COGLAB card sorting test
Social cognition Social perception (Emotion Matching Test and Emotion Labeling Test)
Bell-Lysaker Emotion Recognition Test
Social cognition
Other cognitive
Cognitive measures of multiple domains Global cognitive scores
Mini-Mental State Examination
Cognitive measures not considered sensi-
tive to change Peabody Picture Vocabulary Test
Shipley Institute of Living Scale IQ estimate
WAIS-R comprehension subtest
Verbal IQ
Cognitive measures lacking consensus Cognitive style
Hayling Sentence Completion Task
(continued)
Am J Psychiatry 164:12, December 2007 1793
McGURK, TWAMLEY, SITZER, ET AL.
ajp.psychiatryonline.org
fects rather than assessments on trained tasks only; 3) data avail-
able on either group means and standard deviations for baseline
and postintervention cognitive tests or statistics from which effect
sizes could be calculated; 4) a minimum of 75% of the sample re-
ported to have schizophrenia, schizoaffective disorder, or schizo-
phreniform disorder.
Categorization of Neuropsychological Tests
Neuropsychological tests were grouped into the following cog-
nitive domains described by the Measurement and Treatment Re-
search to Improve Cognition in Schizophrenia (MATRICS) con-
sensus panel (6): attention/vigilance, speed of processing, verbal
working memory, nonverbal working memory, verbal learning
and memory, visual learning and memory, reasoning/problem
solving, and social cognition. Each of the neuropsychological
measures used in the studies meeting the inclusion criteria was
assigned to one cognitive domain by consensus of the first three
authors. Measures for which no consensus could be reached, that
were judged to reflect more than one cognitive domain, or that
the MATRICS panel deemed not sensitive to change were not in-
cluded in the meta-analysis. Table 1 summarizes which neuro-
psychological tests were included in each cognitive domain.
Calculation of Effect Sizes
Effect sizes were calculated by using posttreatment group
means and standard deviations (14), pre-post difference scores,
or analysis of covariance (ANCOVA) or multivariate analysis of co-
variance (MANCOVA) F values that covaried baseline scores on
the dependent measures. Effect sizes can generally be catego-
rized as small (0.2), medium (0.5), or large (0.8) (15). When a study
reported data from multiple measures classified in the same cog-
nitive domain, the mean of the effect sizes from those measures
was used. Effect size distributions were evaluated for outliers, re-
sulting in exclusion of results of one study from the functional
outcome analyses (16).
Meta-Analytic Procedure
Meta-analyses were conducted with BioStat software (17). In
order to control for study differences in sample size when mean
effect sizes were computed, studies were weighted according to
their inverse variance estimates. To determine whether mean ef-
fect sizes were statistically significant, the confidence interval (CI)
and z transformation of the effect size were used. The homogene-
ity of the effect sizes across studies for each outcome domain was
evaluated by computing the Q statistic (18). Then the significance
level of the mean effect sizes was computed by conducting fixed-
effects linear models except when the Q statistic indicated signif-
icant within-group heterogeneity, in which case we used random
effects models. Moderator analyses were then conducted on
those domains with significant heterogeneity, based on the Q sta-
tistic, to determine whether any participant, setting, or program
variables explained variations between studies in effect sizes.
These analyses were performed by clustering studies into two
contrasting groups based on the moderator variable and comput-
ing the Q between and Q within statistics (18).
Moderator Variables
Several variables were considered as potential moderators of
cognitive remediation. Each moderator variable was divided into
two levels based on a median split. The moderator variables and
levels were 1) participant characteristics: age (years) (15–37/38–
50), 2) the setting (inpatient/outpatient), 3) the type of control
group (active control [e.g., another intervention, such as cogni-
tive behavior therapy or motivational interviewing]/passive con-
trol [e.g., viewing educational videos or treatment as usual]), 4)
program characteristics: type of intervention (drill and practice/
drill and practice plus strategy coaching or strategy coaching
alone), hours of practice (determined for the overall program as
well as individual cognitive domains), and the provision of ad-
junctive psychiatric rehabilitation (no/yes).
Some programs that provided training in social cognition em-
ployed a combination of cognitive remediation and other rehabil-
itation approaches, such as social skills training (19, 20), whereas
others employed strictly cognitive remediation methods, such as
computer-based training tasks (21). The number of hours of social
cognition training was included in the total number of cognitive
remediation hours only for the programs that did not combine the
training with another rehabilitation approach. A variety of psychi-
atric rehabilitation approaches were provided in conjunction with
cognitive remediation, including social skills training (20, 22), so-
cial skills/social perception training (19, 23), supported employ-
ment (24), vocational rehabilitation (25), and vocational rehabili-
tation and social information processing groups (26).
Results
Data from 26 studies (1,151 subjects) were included.
The studies, characteristics of participants and programs,
TABLE 1. Neuropsychological Assessments Included in Each Cognitive Domain (continued)
Purdue Pegboard
Tactile performance
WMS orientation subtest
Symptoms Scale for the Assessment of Positive Symptoms
Scale for the Assessment of Negative Symptoms
Positive and Negative Syndrome Scale
Brief Psychiatric Rating Scale
Holtzman Inkblot Test
Paranoid Depression Scale
Present State Exam
Thought, language, and communication
Functioning Bay Area Functional Performance Evaluation
Percent “sick talk”/incoherence during the interview
Life skills profile
Global Assessment Scale
Nurses’ Observation Scale for Inpatient Evaluation
Disability Assessment Schedule
Employment
Social Behaviour Schedule
Micro-Module Learning Test
Assessment of Interpersonal Problem-Solving Skills
Social adjustment
1794 Am J Psychiatry 164:12, December 2007
COGNITIVE REMEDIATION IN SCHIZOPHRENIA
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TABLE 2. Description of Randomized, Controlled Trials of Cognitive Remediation in Schizophrenia
Author
Sample Characteristics—
Inpatient/Outpatient; Mean Age
(years); Mean Education (years);
% Male Treatment group (N)
Drill and Practice/
Drill and Strategy
Coaching
Cognitive Remedia-
tion Program In-
cluded Psychiatric
Rehabilitation
Wagner (1968) (45),
treatment 1
Inpatients; 44.8; not reported;
100%
Noncomputerized attention
training (N=8)
Drill and practice No
Wagner (1968) (45),
treatment 2
Inpatients; 44.8; not reported;
100%
Noncomputerized abstraction
training (N=8)
Drill and practice No
Wagner (1968) (45),
treatment 3
Inpatients; 44.8; not reported;
100%
Noncomputerized attention and
abstraction training (N=16)
Drill and practice No
Meichenbaum & Cameron
(1973), includes 3-week
follow-up (16)
Inpatients; 36.0; not reported;
100%
Noncomputerized training using
self-talk (N=5)
Drill and practice No
Benedict & Harris (1989)
(46)
Inpatients; 30.3; not reported;
not reported
Computerized training with
advancement criteria (N=10)
Drill and practice No
Olbrich & Mussgay (1990)
(43)
Inpatients; 30.7; 10.2; 57% Noncomputerized training (N=15) Drill and practice No
Hermanutz & Gestrich
(1991) (42)
Inpatients; 31.0; 11.0; not
reported
Computerized attention training
(N=10)
Drill and practice No
Benedict et al. (1994) (47) Outpatients; 38.8; 11.0; 52% Computerized attention training
(N=16)
Drill and practice No
Burda et al. (1994) (48) Inpatients; 46.6; 12.5; 97% Computerized training using
Captain’s Log (N=40)
Drill and practice No
Field et al. (1997) (49) Outpatients; 28.6; not reported;
90%
Computerized training (N=5) Drill and practice No
Medalia et al. (1998) (50) Inpatients; 32.5; 10.8; 78% Computerized attention training
using orientation remedial mod-
ule (N=27)
Drill and practice No
Spaulding et al. (1999) (20) Inpatients; 35.7; 11.9; 63% Noncomputerized training using
integrated psychological therapy
(N=49)
Drill and strategy
coaching
Social skills training
groups
Wykes et al. (1999) (27);
Wykes et al. (2003) (30),
6-month follow-up
Outpatients; 38.5; 12.0; 76% Noncomputerized training with
errorless learning (N=17)
Drill and strategy
coaching
No
Medalia et al. (2000) (51),
treatment 1
Inpatients; 37.7; 11.5; 59% Computerized problem-solving
training (N=18)
Drill and strategy
coaching
No
Medalia et al. (2000) (51),
treatment 2
Inpatients; 36.5; 10.5; 59% Computerized memory training
(N=18)
Drill and practice No
Am J Psychiatry 164:12, December 2007 1795
McGURK, TWAMLEY, SITZER, ET AL.
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Control Group (active/
passive control, N)
Hours/Weeks of
Cognitive Remediation
(excluding other
treatment)
Cognitive Effect Size
(follow-up effect size in
parentheses)
Average Effect Size
for Cognitive
Measures
Average Effect
Size for Symptom
Measures
Average Effect
Size for
Functioning
Measures
Viewing treatment group
stimuli without
responding (active
control, N=8)
3 hours/1 week Visual learning memory=
0.80; reasoning and
problem solving=1.40
1.10
Viewing treatment group
stimuli without
responding (active
control, N=8)
3 hours/1 week Visual learning memory=
–1.21; reasoning and
problem solving=1.12
–0.04
Viewing treatment group
stimuli without
responding (active
control, N=8)
3 hours/1 week Visual learning memory=
–0.09; reasoning and
problem solving=0.55
0.32
Task practice without self-
talk (active control, N=5)
4.1 hours/3 weeks Verbal working memory=
0.77 (1.31); reasoning
and problem solving=
1.26 (1.99)
1.02 (1.65) 1.89 (2.08) 3.50 (3.99)
1. Computerized training
without advancement
criteria (active control,
N=10); 2. Treatment as
usual (passive control,
N=10)
12.5 hours/8–14
weeks
Speed of processing=1.57 1.57
Arts and crafts groups
(active control, N=15)
12 hours/3 weeks Attention/vigilance=0.52;
Verbal working mem-
ory=0.43; reasoning and
problem solving=0.26
0.40 0.00
1. Integrated psychologi-
cal therapy focusing on
cognitive, communica-
tion, and social training
(active control, N=10);
2. Treatment as usual
(passive control, N=10)
7.5 hours/3–4 weeks Treatment versus active
control: attention/vigi-
lance=0.18; treatment
versus passive control:
attention/vigilance=
–0.09
Treatment versus ac-
tive control=0.18;
treatment versus
passive control=
–0.09
Treatment versus
active control=
0.43; treatment
versus passive
control=0.24
Treatment
versus active
control=–0.47;
treatment
versus passive
control=–0.46
Treatment as usual
(passive control, N=17)
12.5 hours/3–5 weeks Attention/vigilance=0.41;
verbal learning and
memory=0.13
0.27
Treatment as usual
(passive control, N=29)
12 hours/8 weeks Speed of processing=0.58;
attention/vigilance=
0.65; verbal working
memory=0.89; verbal
learning and memory=
0.69; visual learning
memory=–0.26
0.51
Graphics-based computer
games (active control,
N=5)
6 hours/3 weeks Speed of processing=0.74;
attention/vigilance=
1.08; reasoning and
problem solving=0.54;
other=0.00
0.79
Watching National Geo-
graphic documentaries
(passive control, N=27)
6 hours/6 weeks Attention/vigilance=0.19 0.19 0.24
Group supportive therapy
emphasizing social skills
(active control, N=42)
68.3 hours/26 weeks Speed of processing=0.02;
attention/vigilance=
0.38; verbal learning
and memory=–0.06;
visual learning memory=
–0.06; reasoning and
problem solving=0.14
0.08 0.55 0.53
Intensive occupational
therapy (active control,
N=16)
24–40 hours/8–10
weeks
Speed of processing=0.26;
verbal working mem-
ory=0.27 (0.07); nonver-
bal working memory=
0.06; reasoning and
problem solving=0.20
(0.33)
0.20 (0.20) 0.59 0.05
Treatment as usual
(passive control, N=18)
4.2 hours/5 weeks Verbal learning and
memory=–0.43
–0.43
Treatment as usual
(passive control, N=18)
4.2 hours/5 weeks Verbal learning and
memory=0.39
–0.39
(continued)
1796 Am J Psychiatry 164:12, December 2007
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TABLE 2. Description of Randomized, Controlled Trials of Cognitive Remediation in Schizophrenia (continued)
Author
Sample Characteristics—
Inpatient/Outpatient; Mean Age
(years); Mean Education (years);
% Male Treatment group (N)
Drill and Practice/
Drill and Strategy
Coaching
Cognitive Remedia-
tion Program In-
cluded Psychiatric
Rehabilitation
Bell et al. (2001) (26) Outpatients in work therapy;
43.6; 13.2; 78%
Computerized training using
CogReHab plus weekly social
information processing group
(N=31)
Drill and practice Vocational rehabilita-
tion and social
information
processing groups
Bell et al. (2003) (52),
includes follow-up
Same as above (N=47)
Fiszdon et al. (2004) (53),
includes follow-up
Same as above (N=45)
Fiszdon et al. (2005) (54) Same as above (N=57)
Van der Gaag (2002) (23) Inpatients; 31.1; not reported;
64%
Noncomputerized training (N=21) Drill and strategy
coaching
Social skills/social
perception training
Bellucci et al. (2002) (34) Outpatients; 42.0; 12.6; 47% Computerized training using
Captain’s Log (N=17)
Drill and practice No
López-Luengo & Vázquez
(2003) (55)
Outpatients; 33.5; not reported;
83%
Noncomputerized training using
attention process training (N=13)
Drill and practice No
Hogarty et al. (2004) (19),
includes 12-month
follow-up
Outpatients; 37.3; not reported;
59%
Computerized training using
orientation remedial module and
CogReHab plus group social
cognition exercises (N=67)
Drill and strategy
coaching
Social skills/social
perception training
groups
Ueland & Rund (2005) (21);
Ueland & Rund (2004)
(44), 12-month follow-up
Inpatients; 15.3; not reported;
50%
Computerized and non-
computerized training (N=14)
Drill and strategy
coaching
No
McGurk et al. (2005) (24) Outpatients in supported
employment; 37.5; 11.2; 55%
Computerized training using
Cogpack (N=23)
Drill and strategy
coaching
Supported
employment
Sartory et al. (2005) (56) Inpatients; 36.4; 10.3; 67% Computerized training using
Cogpack (N=21)
Drill and practice No
Silverstein et al. (2005) (22) Inpatients; 39.3; 10.6; 87% Noncomputerized training using
attention process training and
shaping (N=18)
Drill and practice Social skills training
groups
Vauth et al. (2005) (25) Inpatients in vocational
rehabilitation; 30.0; 12.5; 65%
Computerized training using
Cogpack and noncomputerized
training, plus cognitive
adaptation therapy (N=47)
Drill and strategy
coaching
Vocational
rehabilitation
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Control Group (active/
passive control, N)
Hours/Weeks of
Cognitive Remediation
(excluding other
treatment)
Cognitive Effect Size
(follow-up effect size in
parentheses)
Average Effect Size
for Cognitive
Measures
Average Effect
Size for Symptom
Measures
Average Effect
Size for
Functioning
Measures
Treatment as usual
(passive control, N=34)
36 hours/26 weeks Speed of processing=0.31;
verbal working mem-
ory=0.30; reasoning and
problem solving=0.50;
social=0.90
0.50
Passive control, N=55 Verbal working memory=
0.40 (0.48)
0.40 (0.48)
Passive control, N=49 Verbal working memory=
0.53 (0.66)
0.53 (0.66)
Passive control, N=68 Verbal learning and mem-
ory=0.36
0.36
Leisure/games group
(active control, N=21)
4 hours/11 weeks Speed of processing=
–0.02; attention/vigi-
lance=0.09; verbal
learning and memory=
0.41; visual learning
memory=0.47; reason-
ing and problem solv-
ing=0.09; social=0.51
0.26
Treatment as usual
(passive control, N=17)
8 hours/8 weeks Speed of processing=0.56;
verbal working mem-
ory=0.52; verbal learn-
ing and memory=0.49
0.52 0.32
Treatment as usual
(passive control, N=11)
24 hours/43 weeks Speed of processing=0.32;
attention vigilance=
0.54; verbal working
memory=0.48; verbal
learning and memory=
0.57; reasoning and
problem solving=0.45
0.53
Enriched supportive ther-
apy including psychoed-
ucation, illness self-
management, and stress
management (active
control, N=54)
75 hours/104 weeks Speed of processing=0.83
(0.86); social=0.36 (0.66)
0.60 (0.67) –0.07 (0.09) 0.37 (0.51)
Treatment as usual
(passive control, N=12)
30 hours/12 weeks Attention/vigilance=0.31
(0.28); verbal working
memory=0.54 (0.60);
verbal learning and
memory=0.33 (0.29);
visual learning mem-
ory=0.11 (0.17); reason-
ing and problem solv-
ing=0.57 (0.31)
0.37 (0.33) 0.25 (0.51) 0.31 (0.16)
Treatment as usual
(passive control, N=21)
24 hours/12 weeks Speed of processing=0.27;
verbal working mem-
ory=0.42; verbal learn-
ing and memory=0.45;
reasoning and problem
solving=0.18
0.33 0.45 1.76
Treatment as usual
(passive control, N=21)
15 hours/3 weeks Speed of processing=0.69;
verbal learning and
memory=0.88
0.78
Treatment as usual
(passive control, N=13)
18 hours/6 weeks Attention/vigilance=0.25;
verbal working mem-
ory=0.38; verbal learn-
ing and memory=0.48
0.37 0.41 0.68
1. Vocational rehabilita-
tion and self-manage-
ment training for nega-
tive symptoms (active
control, N=45); 2. Treat-
ment as usual (passive
control, N=46)
24 hours/8 weeks Treatment versus active
control; attention/vigi-
lance=0.46; verbal
learning and memory=
0.61; treatment versus
passive control; atten-
tion/vigilance=0.46; ver-
bal learning and mem-
ory=0.55; reasoning and
problem solving=0.60
Treatment versus
active control=
0.54; treatment
versus passive
control=0.54
Treatment versus
active control=
0.44; treatment
versus passive
control=0.19
Treatment
versus active
control=0.10;
treatment
versus passive
control=0.46
(continued)
1798 Am J Psychiatry 164:12, December 2007
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and effect sizes are displayed in Table 2. The mean sample
size was 50 (SD=36, range=10–138). The mean age of the
participants was 36.3 years (SD=6.0, range of means=15–
47), the mean years of education was 11.8 (SD=1.0, range
of means=10–13), 69% of the participants were men, and
60% were inpatients. The mean duration of cognitive re-
mediation programs was 12.8 weeks (SD=20.9, range=1–
104). Programs targeted for training an average of 2.9 cog-
nitive domains (SD=1.6, range=1–6), whereas changes in
cognitive functioning were assessed on an average of 3.1
cognitive domains (SD=1.6, range=1–6). Sixty-nine per-
cent of the programs used a drill and practice interven-
tion; 23% provided adjunctive psychosocial rehabilitation.
Effects on Cognitive Performance
Only one study examined changes in nonverbal working
memory (27), so this domain was not included in the
meta-analysis. The effect sizes and related statistics for
overall cognition and the other seven individual cognitive
domains are provided in Table 3. In addition, the effect
sizes for overall cognitive functioning for each study are
depicted in Figure 1. The effect size for overall cognition
was significant, as well as for six of the seven domains of
cognitive performance. Most of the effects were in the me-
dium or low-medium effect size range, indicating im-
proved cognitive performance after cognitive remedia-
tion. The effect size for visual learning and memory was
not significant (0.09).
Six studies also reported cognitive data at follow-up (16,
19, 21, 28–30). For these studies, the average effect size at
posttreatment was 0.56 (t=4.8, df=5, p<0.001, CI=0.33–
0.79; Q=3.4, df=5, n.s.), and at follow-up, it was 0.66 (t=5.7,
df=5, p<0.001, CI=0.43–0.89; Q=7.8, df=5, n.s.). Similar to
the results at posttreatment, cognitive remediation was
associated with improved overall cognitive performance
an average of 8 months later.
Hedges’s Q was significant for only one cognitive do-
main, verbal learning and memory, indicating significant
heterogeneity in effect sizes to evaluate the effects of mod-
erators. For this domain, a larger effect size was associated
with more hours of cognitive remediation (0.57) com-
pared with fewer hours (0.29) (Q=3.7, df=1, p<0.05) and
with drill and practice (0.48) compared with drill and prac-
tice plus strategy coaching (0.23) (Q=2.0, df=1, p<0.05);
hours of cognitive remediation were unrelated to program
type (χ
2
=0.4, df=1, n.s.).
Effects on Symptoms and Functioning
Cognitive remediation was associated with a small ef-
fect size for symptoms (0.28) and between a small and a
medium effect size for functioning (0.35). There was sig-
nificant heterogeneity in the effect sizes for functioning
(Q=25.7, df=11, p<0.01), but not for symptoms. Moderator
analyses indicated that cognitive remediation resulted in
stronger effect sizes for improved psychosocial function-
ing in studies that provided adjunctive psychiatric rehabil-
itation (0.47) compared to no psychiatric rehabilitation
(0.05) (Q=5.5, df=1, p<0.01.), cognitive remediation pro-
grams that used drill and practice plus strategy coaching
(0.62) compared to drill and practice only (0.24) (Q=4.6,
df=1, p<0.05), and studies that included older (0.55) rather
than younger (0.18) patients (Q=5.7, df=1, p<0.05). Pro-
gram type was unrelated to age and to adjunctive psychi-
atric rehabilitation, but age and adjunctive psychiatric re-
habilitation were significantly associated (χ
2
=6.7, df=1,
p<0.05). Studies that provided psychiatric rehabilitation
tended to serve older patients.
Discussion
The results provide support for the effects of cognitive
remediation on improving cognitive functioning in
schizophrenia, with effect sizes in the medium range for
overall cognitive functioning (0.41) and six of the seven
cognitive domains (0.39–0.54). The effects of cognitive re-
mediation on cognitive performance were remarkably
similar across the 26 studies included in the analysis de-
spite differences in length and training methods between
cognitive remediation programs, inpatient/outpatient
setting, patient age, and provision of adjunctive psychiat-
ric rehabilitation. The results indicate that cognitive reme-
diation produced robust improvements in cognitive func-
tioning across a variety of program and patient conditions.
The effect sizes of cognitive remediation were homoge-
neously distributed across studies for overall cognitive
functioning and six of the seven cognitive domains, pre-
cluding the examination of moderators of treatment ef-
fects for most cognitive outcomes. Thus, contrary to our
TABLE 2. Description of Randomized, Controlled Trials of Cognitive Remediation in Schizophrenia (continued)
Author
Sample Characteristics—
Inpatient/Outpatient; Mean Age
(years); Mean Education (years);
% Male Treatment group (N)
Drill and Practice/
Drill and Strategy
Coaching
Cognitive Remedia-
tion Program In-
cluded Psychiatric
Rehabilitation
Penadés et al. (2006) (29),
includes 6-month follow-
up
Outpatients; 35.1; 10.2; 57% Noncomputerized training using
frontal/executive program with
errorless learning (N=20)
Drill and practice No
Am J Psychiatry 164:12, December 2007 1799
McGURK, TWAMLEY, SITZER, ET AL.
ajp.psychiatryonline.org
hypothesis, the number of hours programs devoted to
cognitive remediation was not related to the amount of
improvement in overall cognitive functioning. However,
hours of training, as well as use of drill and practice rather
than combined drill and practice with strategy coaching,
were related to improvements in verbal learning and
memory, suggesting that this domain may be more sensi-
tive to the method and extent of cognitive remediation.
It is possible that a relatively limited amount of cogni-
tive remediation (e.g., 5–15 hours) is sufficient to produce
improved cognitive functioning and that all studies pro-
vided an adequate amount of treatment. Alternatively, the
amount of cognitive remediation may not be related to
immediate gains in cognitive functioning but could con-
tribute to the retention of improvements following the ter-
mination of treatment. The impact of amount of cognitive
remediation on the maintenance of treatment effects
could not be evaluated in this meta-analysis because only
six studies conducted follow-up assessments an average
of 8 months after completion of the program. However,
the mean effect size for overall cognitive performance for
these studies was in the medium range (0.66), comparable
in magnitude to the immediate effects of cognitive reme-
diation. These findings provide preliminary support for
the longer-term benefits of cognitive remediation on cog-
nitive performance and point to the need for more re-
search on the maintenance of treatment effects.
The overall effect size of cognitive remediation on im-
proving symptoms was significant but in the small range
(0.28). Previous reviews of the effects of cognitive remedi-
ation either have not examined symptoms (10, 11) or were
inconclusive because of the small number of studies (12,
13). The apparently limited impact of cognitive remedia-
tion on symptoms is consistent with numerous studies
showing that cognitive impairment is relatively indepen-
dent of other symptoms of schizophrenia (31–33). Cogni-
tive remediation may have some beneficial effects on
symptoms by providing positive learning experiences that
serve to bolster self-esteem and self-efficacy for achieving
personal goals, thereby improving depression. Several
studies have reported that cognitive remediation im-
proved mood (24, 27, 34).
Cognitive remediation also had a significant effect on
improving psychosocial functioning, with an average ef-
fect size of 0.35, just slightly lower than the average effect
size of 0.41 for improved cognitive performance. For ex-
ample, patients who participated in cognitive remediation
showed greater improvements in obtaining and working
competitive jobs (24, 25), the quality of and satisfaction
with interpersonal relationships (19), and the ability to
solve interpersonal problems (20). These findings are
unique because until recently a sufficient number of stud-
ies had not measured functional outcomes from which to
draw firm conclusions. The impact of cognitive remedia-
tion on improved functioning is important because the
primary rationale for cognitive remediation in schizo-
phrenia is to improve psychosocial functioning (35).
In contrast to the uniform effects across studies of cog-
nitive remediation on overall cognitive performance and
symptoms, there was significant variability in its effects on
psychosocial functioning. Furthermore, as hypothesized,
cognitive remediation programs that provided adjunctive
psychiatric rehabilitation had significantly stronger ef-
fects on improving functional outcomes (0.47) than pro-
grams that did not (0.05). This effect is consistent with pre-
vious research showing that cognitive impairment
attenuates response to psychiatric rehabilitation (1, 36,
37) and suggests that improved cognitive performance
may enable some patients to benefit more from rehabilita-
tion. The findings are also consistent with the results of a
meta-analysis of integrated psychological therapy (38) in
which the strongest effects on functioning were found in
programs that integrated cognitive remediation and social
skills training rather than programs that provided either
intervention alone (39).
Cognitive remediation programs that included strategy
coaching had stronger effects on functioning than pro-
grams that focused only on drill and practice. Strategy
coaching typically targets memory and executive func-
tions by teaching methods such as chunking information
to facilitate recall and problem-solving skills. It is unclear
whether strategy coaching is more effective because peo-
ple are better able to transfer skills from the training set-
ting into their daily lives (35) or because teaching such
strategies helps patients compensate for the effects of per-
Control Group (active/
passive control, N)
Hours/Weeks of
Cognitive Remediation
(excluding other
treatment)
Cognitive Effect Size
(follow-up effect size in
parentheses)
Average Effect Size
for Cognitive
Measures
Average Effect
Size for Symptom
Measures
Average Effect
Size for
Functioning
Measures
Cognitive behavioral ther-
apy for psychosis (active
control, N=20)
40 hours/16 weeks Speed of processing=0.56
(1.02); verbal working
memory=0.80 (0.76);
verbal learning and
memory=1.19 (2.07);
visual learning mem-
ory=0.75 (1.22); reason-
ing and problem solv-
ing=1.76 (2.05)
1.01 (1.42) –0.15 (–0.15) 0.42 (0.45)
1800 Am J Psychiatry 164:12, December 2007
COGNITIVE REMEDIATION IN SCHIZOPHRENIA
ajp.psychiatryonline.org
sistent cognitive impairments on functioning (24) or both.
Further research is needed to address this question.
The effects of cognitive remediation were not influ-
enced by the nature of the control condition. Thus, simply
actively or passively engaging patients in treatments de-
signed to control for the amount of clinician contact did
not appear to confer any benefit in cognitive functioning
beyond the provision of usual services. These findings are
consistent with the meta-analysis of the cognitive remedi-
ation-based integrated psychological therapy program
(39) but differ from the psychotherapy literature, where
there is ample evidence for nonspecific effects related to
therapist attention (40). The mechanisms underlying the
effects of cognitive remediation on improved cognitive
performance, functioning, and symptoms appear to differ
from those involved in psychotherapy. The results raise
questions about the need to control for the amount of cli-
nician attention given to treatment control groups in re-
search on cognitive remediation.
So what has been learned after almost 40 years of re-
search on cognitive remediation for schizophrenia? Al-
though a great deal more is known about schizophrenia
and its neurocognitive underpinnings and the technology
for assessing and remediating cognitive impairments has
evolved (e.g., most programs now employ at least some
computer-based training), the effect sizes on cognitive
functioning do not appear to have increased appreciably
in recent years. The failure to develop more potent pro-
grams could be due to limitations imposed by the illness
itself and not the fault of treatment developers. It may be
argued that a similar phenomenon has occurred in the
pharmacological treatment of schizophrenia, where de-
spite the enormous investment of resources into the de-
velopment of new drugs, the clinical gains in treating
symptoms over the past 50 years are debatable (41).
Alternatively, the ability to improve the effectiveness of
cognitive remediation may depend on attention to critical
issues in research design. Two such issues deserve special
consideration: the evaluation of the persistence of reme-
TABLE 3. Results of Meta-Analysis of Randomized, Controlled Trials of Cognitive Remediation in Schizophrenia
a
Outcome Domain Effect Size 95% CI T Score
Subjects
(N)
Cognitive
Remediation Hours Analysis
Median Range Hedges’s Q df
Global cognition 0.41 0.29 to 0.52 6.9*** 1,214 12.5 3–75 35.3 28
Attention/vigilance 0.41 0.25 to 0.57 5.1*** 659 6.6 0–14 9.8 14
Speed of processing 0.48 0.28 to 0.69 5.9*** 655 0.0 0–3 20.7 13
Verbal working memory 0.52 0.33 to 0.72 5.2*** 428 0.4 0–8 3.9 10
Verbal learning and memory 0.39 0.20 to 0.58 5.5*** 858 0.0 0–8 26.6* 15
Visual learning and memory 0.09 –0.26 to 0.43 0.6 424 0.0 0–3 14.5* 7
Reasoning/problem solving 0.47 0.30 to 0.64 5.4*** 564 3.0 0–32 21.8 14
Social cognition 0.54 0.22 to 0.88 3.9*** 228 26.0 2–84 2.8 2
Symptoms 0.28 0.13 to 0.43 3.6*** 709 12.2 14
Functioning 0.35 0.07 to 0.62 1.9* 615 25.7** 10
a
After consideration of the consistency of effect sizes across six of the seven cognitive domains and overall cognitive functioning, the clinical
and theoretical significance of these moderator effects on verbal learning and memory is unclear.
*p<0.05. ** p<0.01. ***p<0.001.
FIGURE 1. Effect Sizes for Overall Cognition in Random-
ized, Controlled Trials of Cognitive Remediation in Schizo-
phrenia
Benedict & Harris (46), treatment as usual
Benedict & Harris (46), active control
Wagner (45), treatment 1
Meichenbaum & Cameron (16)
Penadés et al. (29)
Field et al. (49)
Sartory et al. (56)
Hogarty et al. (19)
Vauth et al. (25), active control
Vauth et al. (25), treatment as usual
López-Luengo & Vázquez (55)
Bellucci et al. (34)
Burda et al. (48)
Bell et al. (26, 52); Fiszdon et al. (53, 54)
Olbrich & Mussgay (43)
Silverstein et al. (22)
Ueland & Rund (44)
McGurk et al. (24)
Wagner (45), treatment 3
Benedict et al. (47)
van der Gaag et al. (23)
Wykes et al. (27)
Medalia et al. (50)
Hermanutz & Gestrich (42), active control
Spaulding et al. (20)
Wagner (45), treatment 2
Hermanutz & Gestrich (42),
treatment as usual
Medalia et al. (51), treatment 2
Medalia et al. (51), treatment 1
–2.0 –1.0 0.0 1.0
Effect Size
2.0 3.0
Am J Psychiatry 164:12, December 2007 1801
McGURK, TWAMLEY, SITZER, ET AL.
ajp.psychiatryonline.org
diation effects on cognitive functioning and the assess-
ment of the impact of remediation on functional out-
comes. Despite the number of controlled studies of
cognitive remediation, only six studies (16, 19, 21, 28–30)
examined whether improvements in cognitive function-
ing were maintained at a posttreatment follow-up, pre-
cluding the exploration of moderators of treatment ef-
fects. The relative lack of data addressing this question
may be important because different program, patient, or
setting factors could influence the long-term mainte-
nance of cognitive effects compared to short-term effects.
Similarly, only 11 studies evaluated functional out-
comes (16, 19, 20, 22, 24, 25, 27, 29, 42–44), and this was
the first meta-analysis to quantitatively demonstrate that
cognitive remediation improved psychosocial function-
ing. Furthermore, the impact of cognitive remediation on
functioning was moderated by several factors, including
the provision of adjunctive psychiatric rehabilitation, cog-
nitive training method, and patient age, suggesting poten-
tially important factors for improving the impact of treat-
ment programs. Thus, the ability to make cognitive
remediation programs more effective may have been con-
strained by the neglect of most studies to measure the
long-term effects of remediation and its impact on func-
tional outcomes, resulting in the inability to identify mod-
erators of treatment that could be the focus of efforts to
hone and refine the intervention. Future research on cog-
nitive remediation should routinely evaluate psychosocial
functioning and the long-term effects of treatment on all
outcomes of interest. In addition, research that systemati-
cally examines the interactions between cognitive remedi-
ation and psychiatric rehabilitation is warranted.
In summary, cognitive remediation was found to have
consistent effects on improving cognitive performance,
functioning, and symptoms. In addition, the impact of
cognitive remediation on functional outcomes was signif-
icantly greater in studies that also provided psychiatric re-
habilitation, suggesting that these two treatment ap-
proaches may work together in a synergistic fashion.
These findings challenge the assumption that simply im-
proving cognitive functioning in schizophrenia will spon-
taneously lead to better psychosocial outcomes. The re-
sults do suggest, however, that cognitive remediation may
improve the response of some patients to psychiatric re-
habilitation. Overall, this meta-analysis indicates that cog-
nitive remediation may have an important role to play in
improving both cognitive performance and functional
outcomes in schizophrenia.
Received June 8, 2007; revision received Aug. 27, 2007; accepted
Aug. 28, 2007 (doi: 10.1176/appi.ajp.2007.07060906). From the
Dartmouth Psychiatric Research Center, the Department of Commu-
nity and Family Medicine, and the Department of Psychiatry, Dart-
mouth Medical School; the Department of Psychiatry, University of
California, San Diego; and the School of Psychology, Argosy Univer-
sity, Santa Monica, Calif. Address correspondence and reprint
requests to Dr. McGurk, Dartmouth Psychiatric Research Center, Main
Building, 105 Pleasant St., Concord, NH 03301; susan.r.mcgurk@
dartmouth.edu (e-mail).
All authors report no competing interests.
Supported by NIMH grant MH77210 and National Institute on Dis-
ability and Rehabilitation Research grant H133G050230.
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