Psychosis risk for parents and siblings of Dutch and Moroccan-Dutch patients with non-affective psychotic disorder.
BACKGROUND
Studies in the UK compared psychosis risks for first-degree relatives of White and African-Caribbean patients and found "normal" risks for the parents of Caribbean patients, but very high risks for siblings of second-generation Caribbean patients.


OBJECTIVE
To compare the risk of non-affective psychotic disorder (NAPD) for the parents and siblings of Moroccan-Dutch patients to that for the parents and siblings of Dutch patients. The "Moroccan-Dutch" are Dutch residents of Moroccan origin (first or second generation).


METHODS
Informants related to 29 Moroccan-Dutch and 63 Dutch patients were interviewed about the presence of psychiatric disorders in first-degree relatives (N=508), by means of the Family Interview for Genetic Studies.


RESULTS
The risks for NAPD in both parent groups were similar (age and sex-adjusted odds ratio 1.0; 95% CI: 0.3-3.8). However, among the siblings, the risk for NAPD was significantly higher for the Moroccan-Dutch than for the Dutch (sex-adjusted hazard ratio 4.5; 95% Confidence Interval: 1.5-14.0). This was due to a large number of cases among the brothers of the Moroccan-Dutch patients (N=14), not among their sisters (N=1). Owing to small numbers separate hazard ratios for the first and the second generation were not calculated.


CONCLUSIONS
These preliminary results suggest that environmental factors in the Netherlands have a great impact on the psychosis risk for male immigrants from Morocco.
Rudolf Magnus Institute of Neuroscience, Department of Psychiatry, University Medical Centre, Utrecht, The Netherlands. j.p.selten@umcutrecht.nl
Jean-Paul
JP
Selten
Jan Dirk
JD
Blom
Ingeborg
I
van der Tweel
Wim
W
Veling
Boukje
B
Leliefeld
Hans W
HW
Hoek
D000328:Adult; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009018:Morocco; D009426:Netherlands; D010290:Parents; D011618:Psychotic Disorders / Q000175:diagnosis / Q000208:ethnology* / Q000235:genetics*; D035781:Siblings; D055815:Young Adult