Letter to the Editor
The game of chess enhances cognitive abilities
Chess is a classic board game that relies on simple rules
and complex cognitive strategies. At the same time, there is a
growing body of evidence demonstrating the efﬁciency of
targeted and standardized cognitive interventions for restor-
ing altered cognitive functions in patients with schizophrenia
(McGurk et al., 2007; Demily and Franck, 2008). Originally, it
was tempting to investigate whether chess playing could help
restoring executive functions in patients with schizophrenia.
Twenty-six medicated clinically stable patients meeting
DSM-IV-TR criteria for schizophrenia (APA, 2000)were
enrolled in an open and unblinded study. Exclusion criteria
included evidence of mental retardation or superior cognitive
level, resistance to usual treatment, traumatic brain injury,
presence or history of neurologic or mental illnesses other
than schizophrenia. The assessment of intellectual efﬁciency
(WAIS-III; Wechsler, 2000) showed a mean ‘Total IQ’that did
not differ from the normal range value. All patients with
schizophrenia involved in this study completed written
informed consent. They were randomly assigned to one of
two treatment groups: Game of Chess (GC); Treatment As
Usual (TAU). Seven patients of both groups were full-time
hospitalized, the others being in day hospital. Patients were
evaluated by trained physicians (author CD and CC), before
and after treatment on the basis of a comprehensive
neuropsychological test battery (Trail Making Test part A
and B, Wisconsin Card Sorting Test, Stroop and Tower of
A randomized 2 groups pre/post-test design was used to
investigate the effect of our experimental factor (Chess factor:
GC Vs. TAU). The procedure lasted 5 weeks. During these
5 weeks, the TAU group did not receive any speciﬁc cognitive
rehabilitation (unspeciﬁc activities). The GC group practiced
chess 10 times (twice per week; 60 min per session, total
training: 10 h). For the GC group, the treatment began with a
short introduction during which the main rules of the game
were explained (position and displacement of each piece).
The patients started playing one against another under the
supervision of one experienced player (authors CC or MB-M).
Because the criteria of normality and variance homogene-
ity were not met, nonparametric tests were used for statistical
analyses. All patients (n=26) completed the study. The GC
group involved 13 patients (12 males, mean age: 34.7 years,
mean age disease onset: 23.5 years, mean SAPS/SANS total
score: 57/43). The TAU group involved 13 patients (12 males,
mean age: 38.9 years, mean age at disease onset: 20.7 years,
mean SAPS/SANS total score: 53/44). All patients received
atypical antipsychotic medication at the time of the experi-
ment. None of the patients received anticholinergic agent,
sedative treatment, mood stabilizer, antidepressant, or other
Main results are:
–Trail Making Test: no signiﬁcant difference was observed
between the two groups for intergroup evaluations (all
–Wisconsin Sorting Card Test: the GC group made more
perseverative errors than the TAU group in the pre-test
assessment (U=46; Z=2.02; pb.05; +161.54%). This differ-
ence was no longer present in the second assessment
–Stroop Test:in the GC group, the number of read items was
increased in the second assessment for the Stroop A
(Colour) and C (Interference) (Z=2.55; pb.05; +12.81% and
Z=2.16; pb.05; +19.79% respectively). By the contrary, no
signiﬁcant difference was observed for the TAU group
Schizophrenia Research 107 (2009) 112–113
Fig. 1. Mean latency time according to the numberof movements required to
perform the task.
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–Tower of London Test: latency times in the Tower of
London Task (see Fig. 1) were shorter in the GC group than
in the TAU group for the post-test evaluations for exercises
requiring 2 and 4 movements (U=18; Z=−3.41; pb.05;
−39.96% and U=27; Z=−2.95; pb.05; −40.58% respec-
tively). In the GC group, the ﬁrst evaluation did not reveal
any signiﬁcant difference in response latencies for the 4
different types of exercises. In the second evaluation,
latency time was found to increase with the number of
required movements (all differences signiﬁcant pb.05).
Studies investigating relationships between planning
abilities and chess practice have shown that chess players
are better than naive subjects at solving the Tower of London
task (Unterrainer et al., 2006), corresponding to a higher
degree of frontal lobe involvement (Nichelli et al., 1994).
Task improvements speciﬁctotheGCgroupwere
observed for the Stroop test and the Tower of London task.
For the Stroop task, his result can be interpreted as a better
voluntary processing accompanied by a better inhibitory
capacity. The latency time of the ToL was signiﬁcantly
normalized after chess-training. This parameter is frequently
called « initial planning time » (Carlin et al., 2000). It is thus
tempting to speculate that chess-training has improved the
planning abilities of patients with schizophrenia.
When considered together,our results suggest that playing
chess for mere 10 h can restore (at least partially) executive
functions of patients with schizophrenia. It may be interesting
to note that chess can be proposed easily –at almost no cost –
to all psychotic patients. Most of the patients kept playing
chess on their own, after completion of the study.
American Psychiatric Association, 2000. Diagnostic and Statistical Manual of
Mental Disorder, 4th edition Revised. American Psychiatric Association,
Carlin, D., Bonerba, J., Phipps, M., Alexander, G., Shapiro, M., Grafman, J., 2000.
Planning impairments in frontal lobe dementia and frontal lobe lesion
patients. Neuropsychologia 38, 655–665.
Demily, C., Franck, N., 2008. Cognitive remediation: a promising focus for
treatment of schizophrenia. Exp. Rev. Neurother. 8, 1029–1036.
McGurk, S.R., Twamley, E.W., Sitzer, D.I., McHugo, G.J., Mueser, K.T., 2007. A
meta analysis of cognitive remediation in schizophrenia. Am. J. Psychiatry
164 , 1791 –1802.
Nichelli, P., Grafman, J., Pietrini, P., Always, D., Carton, J.C., Miletich, R., 1994.
Brain activity in chess playing. Nature 369, 191.
Unterrainer, J.M., Kaller, C.P., Halsband,U., Rahm, B., 2006. Planningabilities and
chess: a comparison of chess and non-chess. Br. J. Psychol. 97, 299–311.
Wechsler, D., 2000. Manuel de l’échelle d’intelligence pour adultes, WAIS-III
(3e éd.). ECPA, Paris.
Center for Cognitive Neuroscience,
UMR 5229 (CNRS & Université Lyon 1), Bron, France
⁎Corresponding author. Center for Cognitive Neuroscience,
67 Boulevard Pinel, 69675 Bron, France.
Tel.: +33 437911223; fax: +33 437911210.
E-mail address: firstname.lastname@example.org (C. Demily).
Centre Hospitalier Saint Jean de Dieu, Lyon, France
EART, TREAT VISION, Fondation Ophtalmologique Rothschild,
Centre Hospitalier le Vinatier, Bron, France
16 May 2008
Associated ﬁrst authors.
113C. Demily et al. / Schizophrenia Research 107 (2009) 112–113