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CATSS15 - The Child and Adolescent Twin Study in Sweden (15 years)

CATSS overview: The Child and Adolescent Twin Study in Sweden (CATSS) is an ongoing longitudinal twin study targeting all twins born in Sweden since July 1, 1992. Since 2004, parents of twins are interviewed regarding the children's somatic and mental health and social environment in connection with their 9th birthday (CATSS-9). At age 15 (CATSS15) and 18 (CATSS18), twins and parents complete questionnaires that, in addition to assessments of somatic and mental health, include measures of personality development and psychosocial adaptation. At the age of 24 (CATSS24) only twins participate in a web survey that mainly focuses on mental health. CATSS15: CATSS15 started in 2010. The study includes all 15-year-old twins and their parents, regardless of whether they participated in CATSS9 or not. The response rate for the twin survey is 52% and for the parent survey it is 48%. The sample consists of both identical (monozygotic) and fraternal (dizygotic) twins, including same-sex and opposite-sex pairs. The total number of participating twins (through parent and/or twin participation) in CATSS15 is currently 24,800 out of 42,500 invited (December 2025). The combined response rate is currently 58%. Participants who have not already provided a DNA sample via saliva are requested to do so again. The saliva sample is used for zygosity determination and genotyping. The number of genotyped twins in CATSS15 is currently 15,500 (December 2025). The question areas in the CATSS15 surveys are listed below. For detailed information about variables, visit strdata.se Question areas in parent survey: Administrative Information AUDIT - Alcohol Use Disorders Identification Test CMRS - Child Mania Rating Scale CMO - Child Monitoring DUDIT - Drug Use Disorders Identification Test LSC-R - Life Stressor Checklist- Revised PCR - Parent Child Relationship PPCP - Parents' Perception of Child's Peers PLE - Psychotic-like Experiences Somatic diseases Spare time activites SDQ - Strength and Difficulties Questionnaire Question areas in twin survey: CMRS - Child Mania Rating Scale DCQ - Dysmorphic Concerns Questionnaire EDI-2 - Eating Disorder Inventory - 2 HRS-I - Hoarding Rating Scale-Interview Physical acitivity PMS PLE - Psychotic-like Experiences Quality of Friendship RPQ - Reactive and Proactive Aggression Questionnaire OBVQ - Revised Olweus Bully/Victim Questionnaire SRD - Self-Reported Delinquency Self-Reported Alcohol and Drug Use Sexuality Somatic diseases SDQ - Strength and Difficulties Questionnaire TCI - Temperament and Character Inventory Tics Weight and height
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https://ki.se/en/research/research-infrastructure-and-environments/core-facilities-for-research/swedish-twin-registry-core-facility
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Documentation files

  • CATSS15 parents survey.pdf
    918.23 KiB
  • CATSS15 twins survey.pdf
    711.1 KiB

Citation and access

Data access level:

Creator/​Principal investigator(s):

Research principal:

Data contains personal data:

Yes

Type of personal data:

Pseudonymised, health data, social security number, lifestyle, exposures, names, addresses, survey responses

Code key exists:

Yes

Sensitive personal data:

Yes

Citation:

License:

Language:

Method and outcome

Unit of analysis:

Population:

15-year old twins born in Sweden on or after 1st January, 1994

Time method:

Study design:

  • Cohort study
  • Observational study

Description of study design:

Data collection was conducted through a paper questionnaire during the first two years. After that the collection was conducted online through a web survey. Until 2020 paricipants still had the possibility to choose a paper survey if they wished. Participation in the study is based on informed consent.

Sampling procedure:

Description of sampling:

All 15-year-old twins born in Sweden on or after 1994, according to the Medical Birth Registry (the National Board of Health and Welfare) and living in Sweden at the time of study invitation. Twins who have declined further participation in the twin registry, have protected identity, have emigrated, or died are excluded. Only complete twin pairs are invited to participate. Data from whole twin pairs and single twins are collected.

Time period(s) investigated:

Number of individuals/​objects:

24800

Response rate/​participation rate:

58%

Description of the response rate/​participation rate:

The total number of participating twins (through the participation of twin and/or parent) is 24,800 out of 42,500 invited (December 2025), resulting in a response rate of 58%.

Data format/​data structure:

Samples/material Collected from scientific collection/biobank

Name:

KI Biobank

Type(s) of sample:

DNA from saliva

Data collection Self-administered questionnaire

Mode of collection:

Self-administered questionnaire

Description of the mode of collection:

Paper or web questionnaire

Time period(s) for data collection:

2010-03 - Ongoing

Data collector:

Source of the data:

  • Registers/Records/Accounts: Medical/Clinical
  • Registers/Records/Accounts

Instrument

Name:

SDQ

Type:

Structured questionnaire

Description of the instrument:

Strengths and Difficulties Questionnaire (SDQ) is an assessment method used to measure the mental health of children and young people. The form is based on experiences from two other established and internationally widespread instruments ,the Rutter questionnaire and the Child Behavior Checklist (CBCL). DOI: 10.1111/j.1469-7610.1997.tb01545.x

Name:

RPQ

Type:

Structured questionnaire

Description of the instrument:

The Reactive-Proactive Aggression Scale (RPQ) is a self-report measure of two main forms of aggression – proactive and reactive DOI:10.1002/ab.20115.

Name:

DCQ

Type:

Structured questionnaire

Description of the instrument:

Dysmorphic Concerns Questionnaire (DCQ) is a self-report measure with seven items which ask about cognitive and behavioural aspects of dysmorphic concern. It has been validated as a screening tool for body dysmorphic disorder. DOI: 10.3109/00048679809062719 DOI: 10.1046/j.1440-1614.2001.00860.x DOI: 10.3109/00048671003596055

Name:

EDI-2

Type:

Structured questionnaire

Description of the instrument:

The Eating Disorder Inventory (EDI) is a self-report questionnaire used to assess the presence of eating disorders. DOI:10.1002/1098-108X(198321)2:23.0.CO;2-6 DOI: 10.1080/08039480500504537

Name:

LSC-R

Type:

Structured questionnaire

Description of the instrument:

The Life Stressor Checklist-Revised (LSC-R) is a self-report measure that assesses traumatic or stressful life events. DOI: 10.1017/S0033291711003060

Name:

PLE

Type:

Structured questionnaire

Description of the instrument:

Psychotic like experiences (PLE) - Five items adapted from the Diagnostic Interview Schedule for Children (DIS-C) to screen for psychotic-like experiences in children. DOI:10.1016/j.schres.2006.11.006

Name:

TCI

Type:

Structured questionnaire

Description of the instrument:

The Temperament and Character Inventory (TCI) is a self-report personality questionnaire based on Cloninger's psychobiological model of personality DOI: 10.1001/archpsyc.1993.01820240059008 DOI: 10.1016/0959-4388(94)90083-3 DOI:10.1027/1015-5759.24.1.14 DOI: 10.1016/s0010-440x(98)90070-0

Name:

OBVQ

Type:

Structured questionnaire

Description of the instrument:

Revised Olweus Bully/Victim Questionnaire (Perpetrator + Victim, OBVQ-R) is a self-report questionnaire with 42 items, which has been used in different countries, and has adequate psychometric properties to assess the prevalence of victimization and aggression and various forms of bullying worldwide. This version uses 24 of the items. DOI:10.1007/BF02195509 DOI:10.1348/000709905X53499

Name:

HRSI

Type:

Structured questionnaire

Description of the instrument:

Hoarding Rating Scale-Interview (HRS-I) is a five-item semi-structured interview that assesses the features of compulsive hoarding (clutter, difficulty discarding, acquisition, distress and impairment). DOI: 10.1016/j.psychres.2009.05.001

Name:

AUDIT

Type:

Structured questionnaire

Description of the instrument:

Alcohol Use Disorders Identification Test (AUDIT) is an instrument used to identify risky and harmful alcohol consumption. The instrument was originally developed by the World Health Organization (WHO). The questions are asked in the parent survey and addresses the parent's own drug consumption. DOI: 10.15288/jsa.1995.56.423 DOI: 10.1093/alcalc/37.3.245 DOI:10.1111/j.1530-0277.1997.tb03811.x DOI: 10.1111/j.1360-0443.1993.tb02093.x

Name:

DUDIT

Type:

Structured questionnaire

Description of the instrument:

Drug Use Disorders Identification Test (DUDIT) is an 11-item self-administered screening instrument for drug-related problems, giving information on the level of drug intake and selected criteria for substance abuse/harmful use and dependence according to the ICD-10 and DSM-4 diagnostic systems. The questions are asked in the parent survey and addresses the parent's drug consumption. DOI: 10.1159/000081413

Geographic coverage

Geographic location:

Geographic description:

Nationwide

Administrative information

Responsible department/​unit:

Department of Medical Epidemiology and Biostatistics [C8]

Ethics Review:

Stockholm - 2009/739-31/5

Ethics application approved on 28th of May 2009

Funding

Funding agency:

  • Karolinska Institutet

Funding information:

Government grants

Funding agency:

Award number:

2017-00641_VR, 2021-00180_VR

Funding information:

Grant numbers: 2017-00641, 2021-00180

Topic and keywords

CESSDA Topic Classification:

Standard för svensk indelning av forskningsämnen 2025:

Keywords:

Relations

Homepage:

Related resource:

The Swedish Twin RegistryOpens in a new tab

Publications

Citation:

Anckarsäter H, Lundström S, Kollberg L, Kerekes N, Palm C, Carlström E, Långström N, Magnusson PK, Halldner L, Bölte S, Gillberg C, Gumpert C, Råstam M, Lichtenstein P. The Child and Adolescent Twin Study in Sweden (CATSS). Twin Res Hum Genet. 2011 Dec;14(6):495-508.

Contact

Metadata

Version 1
doris
ki
Published:|Updated: