CATSS24 - The Child and Adolescent Twin Study in Sweden (24 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 (CATSS9). 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.
CATSS24:
CATSS24 started in 2016. The study includes all 24-year-old twins, regardless of whether they participated in earlier CATSS-studies or not. The sample consists of both identical (monozygotic) and fraternal (dizygotic) twins, including same-sex and opposite-sex pairs. The total number of twins participating in CATSS24 is currently 11,600 out of 21,900 invited (December 2025). The response rate is 53%. 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 CATSS24 is currently 7,300 (December 2025).
The question areas in the CATSS24 survey are listed below. For detailed information about variables, visit strdata.se.
AUDIT - Alcohol Use Disorders Identification Test
CES-D - Center for Epidemiologic Studies Depression Scale
DUDIT - Drug Use Disorders Identification Test
DCQ - Dysmorphic Concerns Questionnaire
HADS - Hospital Anxiety and Depression Scale
HRS-I - Hoarding Rating Scale-Interview
LHA - Life History of Aggression
OCI-R - Obsessive-Compulsive Inventory-Revised
PLE - Psychotic-like Experiences
EDI-2 - Eating Disorder Inventory-2
Zygosity
Premenstrual syndrome
Suicidal thoughts/attempts
Asthma and allergies
FFQ2020 - Food Frequency Questionnaire (updated version)
Go to data source
https://strdata.se
Documentation files
Documentation files
Citation and access
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:
Method and outcome
Method and outcome
Unit of analysis:
Population:
24-year old twins born in Sweden on or after 1st July, 1992
Study design:
- Cohort study
- Observational study
Description of study design:
Data collection is conducted through a web survey. Until the end of 2020, participants 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 24-year-old twins born in Sweden on or after 1st July 1992, 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:
11600
Response rate/participation rate:
53%
Description of the response rate/participation rate:
The total number of participating twins is 11,600 out of 21,900 invited, resulting in a response rate of 53%.
Samples/material - Collected from scientific collection/biobank
Samples/material - Collected from scientific collection/biobank
Name:
KI Biobank
Type(s) of sample:
DNA from saliva
Data collection - Self-administered questionnaire
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:
2016-11 - Ongoing
Data collector:
- Karolinska Institutet
Opens a new window at ror.org.
ROR
Source of the data:
- Registers/Records/Accounts: Medical/Clinical
- Registers/Records/Accounts
Instrument
Instrument
Name:
LHA
Type:
Structured questionnaire
Description of the instrument:
LHA (Life History of Aggression) is a widely used instrument which aims to measure trait aggression and antiscocial behavior. LHA consists of 11 items divided into three subscales: agression, self-directed aggression and consequences/antisocial behavior.
DOI: 10.1016/s0165-1781(97)00119-4
Name:
Suicide
Type:
Structured questionnaire
Description of the instrument:
Six questions to assess the prevalence of sucidal thoughts and attempted suicide.
DOI: 10.1176/ajp.149.1.41
Name:
CESD
Type:
Structured questionnaire
Description of the instrument:
The Center for Epidemiologic Studies Depression Scale Revised (CESD-R) is used to rate how often respondents have experienced symptoms associated with depression over the past week, such as restless sleep, poor appetite, and loneliness.
DOI: 10.1016/j.psychres.2010.08.018
Name:
HADS
Type:
Structured questionnaire
Description of the instrument:
Hospital Anxiety and Depression Scale (HADS) is a self-report questionnaire designed to measure anxiety and depression in patients within somatic care. The scale is used to assess and/or detect changes in anxiety and depressive symptoms in patients outside psychiatric care.
DOI: 10.1111/j.1600-0447.1983.tb09716.x
Name:
DCQ
Type:
Structured questionnaire
Description of the instrument:
Dysmorphic Concerns Questionnaire (DCQ) is a self-report questionnaire consisting of seven items designed to assess cognitive and behavioral aspects of dysmorphic disorder. It has been validated as a screening tool for body dysmorphic disorder (BDD).
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:
HRSI
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:
OCI-R
Type:
Structured questionnaire
Description of the instrument:
The Obsessive–Compulsive Inventory (OCI) is a self-report measure for assessing symptoms of obsessive–compulsive disorder (OCD). In this questionnaire a shortened version is used, OCI-R.
DOI.10.1037/1040-3590.14.4.485
Name:
PLE
Type:
Structured questionnaire
Description of the instrument:
Psychotic like experiences (PLE) - eight items adapted from the Diagnostic Interview Schedule for Children (DIS-C) to screen for psychotic-like experiences.
DOI:10.1016/j.schres.2006.11.006
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).
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.
DOI: 10.1159/000081413
Name:
FFQ2020
Type:
Structured questionnaire
Description of the instrument:
An updated version of the Food Frequency Questionnaire (FFQ), used to monitor dietary habits.
DOI: 10.1186/s12937-024-00984-8
Geographic coverage
Geographic coverage
Geographic location:
Geographic description:
Nationwide
Lowest geographic unit:
Parish
Highest geographic unit:
Country
Administrative information
Administrative information
Responsible department/unit:
Department of Medical Epidemiology and Biostatistics [C8]
Ethical Review
Ethical Review
Reviewer:
- Stockholm Ethical Review Board
Registration number:
2015/1947-31/4
Ethical review information:
Ethics application approved on 21st of December 2015
Funding
Funding
Funding agency:
- Karolinska Institutet
Opens a new window at ror.org.
ROR
Funding agency:
- Swedish Research Council
Opens a new window at ror.org.
ROR
Award number:
2017-00641_VR
Award title:
Swedish twin registry
Funding information:
The Swedish Twin Registry (STR) is a national research register open to academic and industrial users. The mission of the STR is to provide a longitudinal research resource for epidemiological and molecular studies of twins. It was originally established in 1959 with particular focus on cardiovascular disease and cancer. Since then, interest has expanded to almost all common diseases and health problems. The STR has contacted all living Swedish born twins (over 9 years) and is the world´s largest twin registry. The current system of twin ascertainment, which has been running in perpetual mode for 13 years, is done through parental interviews when the twins turn 9 years of age. Nationwide questionnaires and telephone interviews have been conducted for different birth cohorts since the beginning of the 1960s. Longitudinal information about health and disease is obtained through regular linkages to the Swedish health registries. DNA from 55 000 twins and serum of 13 000 twins are stored at KI Biobank and is subject to use to new investigations and analyses. Genome-wide genotyping of more than 30 000 participants has been completed and genotypes can be used for co-analysis for different outcomes and characteristics. We apply for funds to keep up the register, continue the ascertainment of 9-year old twins and introduce, in parallel, a nation-wide system for ascertainment of new-born twins with concomitant sampling of umbilical cord blood and immediate zygosity testing.
Funding agency:
- Swedish Research Council
Opens a new window at ror.org.
ROR
Award number:
2021-00180_VR
Award title:
The Swedish Twin Registry
Funding information:
We apply for a continuation of the support of the Swedish Twin Registry (STR), a research infrastructure for population based, epidemiological and molecular studies of twins. The purpose of the STR is to enable research about the importance of genetic and environmental factors for health, lifestyle and behavior.The STR facilitates access to data, samples and twin-contacts for de novo data-collection. For more than 60 years, it has been used for research on a large number of diseases, behaviors and health problems. All living Swedish born twins over the age of 9 years have been contacted by the STR and it is thereby the largest twin registry in the world.Nationwide questionnaires, measurements and telephone interviews have been conducted for different birth cohorts since the 1960s. Broad consents and a unified system make it possible to combine data and samples over the sub-studies to address new research questions. Beside self-reported health and exposures, additional critical information is obtained through regular linkages to the national health registers. At present, the STR holds DNA and other biological samples from more than 58 000 twins to be used for new analyses. Genome-wide genotyping is available for the vast majority.The STR is managed by Karolinska Institutet and led by a Steering Group with mandate for periods of 3 years. There is also an advisory National Council with members from several universities that meets two times per year. It provides an academic arena for input and communication regarding strategies impacting the research enabled by the STR in the future. The grant will support the running costs of the new twin contacts, sample and data collections, upholding the secure database and provide access to data for researchers. The national added value consists in the opportunity to manage and develop an already productive infrastructure in directions that benefits a national range of researchers in a cross disciplinary and transparent manner.
Topic and keywords
Topic and keywords
CESSDA topic classification:
Swedish Standard Classification of Research Subjects 2025:
Relations
Relations
Website:
Related resource:
Publications
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.
