SYNOPSIS Twin studies of psychiatric illness assume that the genetic and environmental risk factors for psychiatric illness are similar in twins and non-twins and in monozygotic (MZ) and dizygotic (DZ) twins.
To test this assumption, we examine whether the treated incidence of psychiatric illness in twins deviates from population expectations or differs between MZ and DZ twins.
Using first admissions to the Swedish Psychiatric Registry for the years 1979-83 for all twins born 1886-1958 from the Swedish Twin Registries, we calculated Standardized Morbidity Ratios (SMRs) using national incidence rates together with individually computed person-years at risk in the twin cohort.
The diagnoses examined, for which there was more than 393000 person-years of risk, were schizophrenia, other non-affective psychoses (ONAP), bipolar affective illness (BPAI), unipolar affective illness (UPAI) and neurotic depression (ND).
The SMRs (and 95% CIs) for all twins were :
schizophrenia 0.86 (0.69-1.06),
ONAP 1.05 (0.88-1.24),
BPAI 1.09 (0.90-1.32),
UPAI 1.05 (0.85-1.29) and ND 0.99 (0.88-1.10).
This pattern of results did not differ substantially when examined separately by gender or birth cohort.
Relative risks for first admissions for MZ v. same-sex DZ twins or same v. opposite-sex DZ twins did not differ significantly from unity for any of the disorders examined. (...)
Mots-clés Pascal : Trouble humeur, Psychose, Epidémiologie, Etiologie, Interaction génotype environnement, Jumeau monozygote, Jumeau dizygote, Etude longitudinale, Facteur risque, Incidence, Suède, Europe, Etude familiale, Homme
Mots-clés Pascal anglais : Mood disorder, Psychosis, Epidemiology, Etiology, Genotype environment interaction, Monozygotic twin, Dizygotic twin, Follow up study, Risk factor, Incidence, Sweden, Europe, Family study, Human
Notice produite par :
Inist-CNRS - Institut de l'Information Scientifique et Technique
Cote : 97-0004037
Code Inist : 002B18C14. Création : 21/05/1997.