Cognitive deficits in relatives of patients with schizophrenia: a meta-analysis.
BACKGROUND
Schizophrenia is characterized by a generalized cognitive impairment with pronounced deficits in the domains of verbal memory, executive functioning and attention.


OBJECTIVE
To investigate whether cognitive deficits found in patients with schizophrenia are also found in non-affected relatives.


METHODS
A meta-analytic review of the published literature on cognitive performance between relatives of schizophrenic patients and healthy controls.


RESULTS
The meta-analyses yielded nine weighted effect sizes from 37 studies comprising 1639 relatives of schizophrenia patients and 1380 control subjects. The largest differences were found on verbal memory recall (d=0.54, 95% CI=0.43-0.66) and executive functioning (d=0.51, 0.36-0.67). Attentional functioning showed smaller effect sizes (d=0.28, 0.06-0.50). These effect sizes are in the moderate range.


CONCLUSIONS
Cognitive deficits found in patients with schizophrenia are also found in non-affected relatives. This finding is consistent with the idea that certain cognitive deficiencies in relatives are caused by familial predisposition to schizophrenia and that these deficiencies might be putative endophenotypes for schizophrenia. However, our results do not address genetic causes directly. Further work is needed to determine whether certain cognitive traits are familial and whether there is co-inheritance of these traits with schizophrenia within families.
Sitskoorn
Margriet M
MM
Rudolf Magnus Institute of Neuroscience, Department of Psychiatry (B01.206), University Medical Center Utrecht, PO Box 85500, Utrecht 3508 GA, The Netherlands. M.Sitskoorn@azu.nl
Aleman
André
A
Ebisch
Sjoerd J H
SJ
Appels
Melanie C M
MC
Kahn
René S
RS
D003072:Cognition Disorders / Q000175:diagnosis / Q000453:epidemiology* / Q000209:etiology*; D006801:Humans; D009483:Neuropsychological Tests; D012559:Schizophrenia / Q000150:complications* / Q000235:genetics*; D012720:Severity of Illness Index