The main aim of this thesis has been to investigate trauma and dissociation among Swedish adolescents and to evaluate the psychometric properties such as reliability and various kinds of validity of three screening instruments for assessment of dissociation and other symptoms of post traumatic stress. The three instruments in question have been Dis-Q-Sweden, A-DES and TSCC, the symptoms measured by these instruments are neither easy to capture nor easy for the adolescent to talk about. Therefore these self report scales are essential. A second aim has been to compare the results with results from other countries and to develop preliminary Swedish norms for the clinician to use. Age and gender differences have been looked upon as well as assessed symptoms connected to known experienced trauma/sexual and/or physical abuse and self-reported trauma in normal and clinical populations.

The populations, in this thesis have been children and adolescents age 10 -19 years old from the general population; the clinical groups have had the same age range. All children and adolescents in the clinical groups have been sexually and/or physically abused. Participants have answered the questionnaires Dis-Q-Sweden, A-DES and/or TSCC and their answers have been statistically analysed.

All three instruments have been shown to have good reliability, such as internal consistency and test-retest. Validity has been established through factor analyses, concurrent, and criterion related validity. Clinical groups with known experienced trauma/sexual abuse and/or physical abuse gave significantly higher scores on all the instruments compared to normative groups. Also self-reported trauma in a normative group gave significantly higher scores even if the significances are not as high as between the normative and clinical groups. Girls scored significantly higher than boys in both the clinical and normative groups. Girls in the age range 14-15 years old gave the significantly highest scores on both Dis-Q-Sweden and ADES. Swedish adolescents gave lower mean scores on all three instruments than have been reported from other studies in other countries. The scores from the clinical groups gave about the same mean as have been reported elsewhere.

The conclusion from this thesis is that all the three questionnaires Dis-Q-Sweden, A-DES and TSCC have shown satisfactory psychometrics properties and can very well be used by Swedish clinicians in Child and Adolescents Psychiatry.