Cognitive deficits and ethnicity: a cohort study of early psychosis patients in The Netherlands.
OBJECTIVE
Incidence rates of psychotic disorders are higher in immigrant groups compared to native populations. This increased risk may partly be explained by misdiagnosis. Neurocognitive deficits are a core feature of psychotic disorders, but little is known about the relationship between migration and cognition in psychotic disorders. We examined whether immigrant patients have cognitive deficits similar to non-immigrant patients, in order to investigate the plausibility of misdiagnosis as explanation for increased incidence rates.


METHODS
Patients who made first contact for non-affective psychotic disorder were assessed in the cognitive domains sustained attention, immediate recall and delayed recall. Immigrant patients were compared to Dutch patients on cognitive performance.


RESULTS
407 Patients diagnosed with a non-affective psychotic disorder completed cognitive assessment (157 Dutch, 250 immigrants). Both Dutch and immigrant patients showed large cognitive deficits. Between-subgroup comparisons revealed large cognitive deficits for immigrants compared to Dutch, especially for immigrants from Morocco, Turkey and other non-Western countries.


CONCLUSIONS
These results indicate that immigrant status is associated with poorer cognitive functioning in early psychosis. The findings argue against diagnostic bias as an explanation for the increased incidence of psychotic disorders in immigrants.
Centre for Early Psychosis, Parnassia Psychiatric Institute, Lijnbaan 4, 2512 VA, The Hague, The Netherlands. l.stouten@parnassia.nl
Luyken H
LH
Stouten
Wim
W
Veling
Mischa
M
van der Helm
Winfried
W
Laan
Mark
M
van der Gaag
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D003072:Cognition Disorders / Q000175:diagnosis / Q000208:ethnology*; D015331:Cohort Studies; D003431:Cross-Cultural Comparison; D004641:Emigration and Immigration / Q000706:statistics & numerical data*; D005006:Ethnicity / Q000523:psychology* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009426:Netherlands / Q000453:epidemiology; D011618:Psychotic Disorders / Q000175:diagnosis / Q000208:ethnology* / Q000209:etiology; D012559:Schizophrenia / Q000208:ethnology; D017678:Sex Distribution; D012959:Socioeconomic Factors; D055815:Young Adult