title: Investigation of shared genetic effects for psychotic and obsessive symptoms in young adult twins.
abstract: Genetic and environmental architecture of psychotic and obsessive symptoms are not completely elucidated. This study estimated for these symptoms (i) the genetic and environmental components, (ii) the within-individual association, and (iii) the extent to which this association originates from common genetic and environmental factors. Young adult twins (N=701) from the population-based Italian Twin Register were assessed for psychotic and obsessive-compulsive symptoms by using the Symptom Check List (SCL-90). Multivariate Cholesky models were fitted by the Mx statistical program. No previous study used this design to examine the same dimensions. The best-fitting model included additive genetic and nonshared environmental components, each accounting for about half of total variance in the symptoms. Genetic influences on the different symptoms overlapped considerably (r(g)=0.81 to 0.99). Phenotypic correlations of psychotic symptoms and of psychotic with obsessive symptoms were high (r=0.61 to 0.76), with 53% to 69% explained by shared genetic effects. This study shows substantial genetic influence on psychotic and obsessive symptoms, and indicates that their co-occurrence may be due to genetic factors to a greater extent than to environmental effects. These results encourage the search for genetic and environmental factors underlying the covariance between different psychotic traits as well as between psychotic and obsessive traits.
authors.affiliation: National Centre for Epidemiology, Surveillance and Health Promotion, Genetic Epidemiology Unit, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Corrado
authors.initials: C
authors.lastname: Fagnani
authors.forename: Marcella
authors.initials: M
authors.lastname: Bellani
authors.forename: Michele
authors.initials: M
authors.lastname: Tansella
authors.forename: Matteo
authors.initials: M
authors.lastname: Balestrieri
authors.forename: Virgilia
authors.initials: V
authors.lastname: Toccaceli
authors.forename: Valeria
authors.initials: V
authors.lastname: Patriarca
authors.forename: Maria Antonietta
authors.initials: MA
authors.lastname: Stazi
authors.forename: Paolo
authors.initials: P
authors.lastname: Brambilla
mesh_terms: D018672:Community Health Planning; D004200:Diseases in Twins; D004777:Environment; D005260:Female; D006801:Humans; D007398:Interpersonal Relations; D008297:Male; D008957:Models, Genetic; D009771:Obsessive-Compulsive Disorder / Q000453:epidemiology* / Q000235:genetics*; D016017:Odds Ratio; D011618:Psychotic Disorders / Q000453:epidemiology* / Q000235:genetics*; D012737:Sex Factors; D013223:Statistics as Topic; D055815:Young Adult