Tests of executive functions in first-degree relatives of schizophrenic patients: a meta-analysis.
BACKGROUND
Executive dysfunctions in relatives of schizophrenic patients may be trait markers of genetic liability and thus help us to elucidate the aetiology of schizophrenia. As a large amount of data has been published, a synthesis through a meta-analysis was needed to demonstrate the existence of executive impairments in relatives of schizophrenic patients and to assess their magnitude.


METHODS
We conducted a meta-analysis of articles that compared performances of controls and relatives of schizophrenic patients on the four tests most frequently used to assess executive functions: the Wisconsin Card Sorting Test (WCST), the Trail Making Test (TMT), the Stroop Test and the Verbal Fluency (VF) Test. When needed and possible, published data were supplemented with information from the authors. After assessing the homogeneity of the data, effect sizes were estimated and publication bias was tested by use of funnel plots.


RESULTS
Relatives of schizophrenic patients performed less well than controls on all executive tests analysed. Effect estimates were in the small to moderate range (from 0.26 to 0.49) for Stroop, WCST and TMT, but were greater for the fluency tests (0.65 for phonological and 0.87 for semantic VF).


CONCLUSIONS
Relatives of schizophrenic patients appear to have wide, although not severe, executive dysfunctions. As the sensitivity of the different tests for impairments in relatives is not the same, the choice of test and method used should be carefully assessed.
Service de Psychiatrie Adulte, Hôpital Albert Chenevier et Henri Mondor (Assistance Publique - Hôpitaux de Paris, 94000 Créteil, France. Andrei.szoke@ach.ap-hop-paris.fr
Andrei
A
Szöke
Franck
F
Schürhoff
Flavie
F
Mathieu
Alexandre
A
Meary
Serban
S
Ionescu
Marion
M
Leboyer
D003072:Cognition Disorders / Q000175:diagnosis* / Q000209:etiology*; D006801:Humans; D009483:Neuropsychological Tests; D012559:Schizophrenia / Q000150:complications* / Q000235:genetics*