INCREASED OCCURRENCE OF SCHIZOPHRENIA AND OTHER PSYCHIATRIC ILLNESSESAMONG TWINS

Background. We wished to establish whether the occurrence of schizophr enia among twins is the same as among the general population. Method. Through record linkage between the New Danish Twin Register and the Da nish Psychiatric Case Register, the twins who have ever received a dia gnosis of schizophrenia were identified. Through indirect standardisat ion for age, sex and dates of admission, the rate of first admission w ith diagnosis schizophrenia among twins is compared to the same rate i n the general population. Results. A 28% increase in the rate of first admissions for schizophrenia in twins compared to the general populat ion was found. This is statistically significant and does not seem to be caused by any known methodological problems. Twins also had an incr eased first-admission rate of any psychiatric disorders. Conclusion. T his increased risk does not seem to be explained by known methodologic al problems, but does differ from earlier studies.