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CATSS18 - The Child and Adolescent Twin Study in Sweden (18 years)

CATSS18 - The Child and Adolescent Twin Study in Sweden (18 years) Overview CATSS The Child and Adolescent Twin Study in Sweden (CATSS) is an ongoing longitudinal twin study that targets all twins born in Sweden since July 1, 1992. Since 2004, parents of twins have been interviewed about the children's somatic and mental health and social environment in connection with their 9th birthday (CATSS9). At ages 15 (CATSS15) and 18 (CATSS18), twins and parents complete a web questionnaire that, in addition to assessments of somatic and mental health, includes 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. CATSS18: CATSS18 started in 2011. The study includes all 18-year-old twins and their parents, regardless of their participation in CATSS9 or CATSS15. The response rate is 50% for the twin survey and 40% for the parent survey. The sample comprises 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) is currently 22,000 out of 38,400 invited twins (December 2025). The combined response rate is 57%. Participants who have not yet provided a DNA sample via saliva are requested to do so. The saliva sample is used for zygosity determination and genotyping. Currently, 13,700 twins have been genotyped in CATSS18 (December 2025). The question areas in the CATSS18 surveys are listed below. For detailed information about variables, visit strdata.se. Question areas in parent survey: ABCL - Adult Behavior Checklist A-TAC - Autism - Tics, ADHD and other Comorbidities inventory (only Autism-questions) Demography Asthma Eating disorders LEC - Life Events Checklist LSC-R - Life Stressor Checklist MDQ - Mood Disorder Questionnaire PCR - Parent Child Relationship PPCP - Parents' Perception of Child's Peers PLE - Psychotic-like Experiences Parents physical activity Social Interventions Spare Time Activities Question areas in twin survey: AUDIT - Alcohol Use Disorders Identification Test A-TAC - Autism - Tics, ADHD and other Comorbidities inventory (only Autism-questions) BOCS - Brief Obsessive Compulsive Scale CES-D - Center for Epidemiologic Studies Depression Scale CMRS- Child Mania Rating Scale Demography DAWBA - Development and Well-Being Assessment DUDIT - Drug Use Disorders Identification Test DSM-IV Criteria for Major Depressive Episode DCQ - Dysmorphic Concerns Questionnaire EDI-2 - Eating Disorder Inventory - 2 Friends' Behavior HRS-I - Hoarding Rating Scale-Interview LEC - Life Events Checklist LHA - Life History of Aggression LSC-R - Life Stressor Checklist- Revised Love Relationship MDQ - Mood Disorder Questionnaire Nicotine Use PCR - Parent Child Relationship Phobias Physical Activity PLE - Psychotic-like Experiences Premenstrual syndrome Quality of Friendship SCARED - Screen for Child Anxiety Related Emotional Disorders SRD - Self-Reported Delinquency Sexuality Social Interventions Spare Time Activities Synesthesia TCI - Temperament and Character Inventory YPI - Youth Psychopathic Traits Inventory Weight & height
Go to data source
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https://ki.se/en/research/research-infrastructure-and-environments/core-facilities-for-research/swedish-twin-registry-core-facility
Download documentation (3 files / 2.33 MiB)

Documentation files

  • CATSS18 parents survey.pdf
    743.94 KiB
  • CATSS18 twins survey.pdf
    761.37 KiB
  • SMART (2009) - Best Practices for Asking Questions about Sexual Orientation on Surveys.pdf
    885.51 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:

18-year-old twins born in Sweden on or after July 1, 1992.

Time method:

Study design:

  • Cohort study
  • Observational study

Description of study design:

Data collection is conducted through a web survey. Until 2020, participants had the option to choose a paper survey if they preferred. Participation in the study is based on informed consent.

Sampling procedure:

Description of sampling:

All 18-year-old twins born in Sweden on or after July 1, 1992, according to the Medical Birth Registry (the National Board of Health and Welfare), and living in Sweden at the time of the study invitation are included. Twins who have declined further participation in the Swedish twin registry, have protected identity, have emigrated, or have passed away are excluded. Only complete twin pairs are invited to participate, although data from both complete twin pairs and individual twins are collected.

Time period(s) investigated:

Number of individuals/objects:

22000

Response rate/participation rate:

57%

Description of the response rate/participation rate:

The total number of participating twins (through the participation of twin and/or parent) is 22,000 out of 38,400 invited (December 2025), resulting in a response rate of 57%

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:

2011-01 - Ongoing

Data collector:

Source of the data:

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

Instrument

Name:

EDI-2

Type:

Structured questionnaire

Description of the instrument:

The Eating Disorder Inventory (EDI) is a self-report questionnaire designed 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 used to assess 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) are used 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 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:

HRSI

Type:

Structured questionnaire

Description of the instrument:

Hoarding Rating Scale-Interview (HRS-I) is a five-item semi-structured interview designed to assess 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 Organisation (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 designed for drug-related issues. It provides information of the level of drug intake and selected criteria for substance abuse/harmful use and dependence, based on the ICD-10 and DSM-IV diagnostic systems. The questions are included in the parent survey and concerns the parent's drug consumption. DOI: 10.1159/000081413

Name:

DCQ

Type:

Structured questionnaire

Description of the instrument:

DCQ is a self-report measure consisting of seven items that assess cognitive and behavioural aspects of dysmorphic concern. See document YATSS_Instrument_DCQ_svensk.pdf DOI: 10.3109/00048679809062719 DOI: 10.1046/j.1440-1614.2001.00860.x DOI: 10.3109/00048671003596055

Name:

PCR

Type:

Structured questionnaire

Description of the instrument:

Parent Child Relationship - An instrument assessing the relationship between parents and children. DOI: 10.2307/1166050 DOI: 10.1037/0012-1649.30.1.32

Name:

MDQ

Type:

Structured questionnaire

Description of the instrument:

MDQ is a self-report questionnaire designed to screen for the presence of bipolar disorder. DOI: 10.4088/jcp.v67n0518 (parental report) DOI: 10.1176/appi.ajp.157.11.1873 (twin report)

Name:

LHA

Type:

Structured questionnaire

Description of the instrument:

The Life History of Aggression (LHA) scale is used for assessing trait aggression. It consists of 11 items that evaluate aggressive and antisocial behaviors that may have occurred during one's lifetime since age 13. The items are categorised into three subscales: aggression (5 items), self-directed aggression (2 items), and consequences/antisocial behavior (4 items). DOI: 10.1016/s0165-1781(97)00119-4

Name:

SCARED

Type:

Structured questionnaire

Description of the instrument:

The SCARED (Screen for Child Anxiety Related Emotional Disorders) is a questionnaire designed to measure five dimensions of anxiety symptoms in children and adolescents. DOI: 10.1097/00004583-200503000-00013

Name:

YPI

Type:

Structured questionnaire

Description of the instrument:

The Youth Psychopathic Traits Inventory (YPI) is a self-report measure of psychopathic personality traits in adolescents. DOI: 10.1177/1073191106298286

Name:

TCI

Type:

Structured questionnaire

Description of the instrument:

The Temperament and Character Inventory (TCI) is a self-report questionnaire based on Cloninger's psychobiological model of personality. It is used to assess various aspects of temperament and character. The twin questionnaire includes 50 questions from this inventory. DOI: 10.1001/archpsyc.1993.01820240059008

Name:

ASRS

Type:

Structured questionnaire

Description of the instrument:

ASRS is a self-report questionnaire consisting of 18 questions that assess symptoms of ADHD in adults according to DSM-IV criteria. DOI: 10.1017/S0033291704002892

Name:

BOCS

Description of the instrument:

The Brief Obsessive–Compulsive Scale (BOCS) is a short self-report scale used for the assessment and diagnosis of obsessive-compulsive disorder (OCD). DOI: 10.3109/08039488.2014.884631 DOI: 10.1016/0005-7967(94)00076-V DOI: 10.1001/archpsyc.1989.01810110048007

Name:

DAWBA

Description of the instrument:

DAWBA (Development and Well-Being Assessment) is a tool used to diagnose and measure mental health problems in children and adolescents. DOI: 10.1111/j.1469-7610.2000.tb02345.x

Name:

ABCL

Type:

Structured questionnaire

Description of the instrument:

The Adult Behavior Checklist (ABCL) is designed for assessing adaptive behaviour and internalising problems and externalising problems. The eight empirically based scales are as follows: Anxiety/Depression, Withdrawal, Somatic problems, Thought Problems, Attention Problems, Aggressive Behaviour, Rule Breaking Behaviour, Obsession-Compulsion. Achenbach, T. M., & Rescorla, L. A. (2003). Manual for the ASEBA adult forms & profiles. Research Center for Children, Youth, & Families, University of Vermont, Burlington, VT, USA. ISBN: 0938565869, 9780938565864

Name:

ATAC

Type:

Structured questionnaire

Description of the instrument:

Only the autism section of the ATAC questionnaire, used in CATSS9 (see separate data description), is used here. The questions were slightly modified to suit 18-year-olds. DOI: 10.1192/bjp.187.3.262 DOI: 10.1186/1471-244X-10-1 DOI: 10.1186/1471-244X-13-233

Name:

DSM-IV MDE

Type:

Structured questionnaire

Description of the instrument:

Screening of depression based on the DSM-IV Criteria for Major Depressive Episode (MDE). DOI: 10.1176/appi.books.9780890420249.dsm-iv-tr

Name:

CESD

Type:

Structured questionnaire

Description of the instrument:

The Center for Epidemiologic Studies Depression Scale Revised (CESD-R) assesses the frequency of depression-related symptoms experienced by respondents over the past week, including restless sleep, poor appetite, and feelings of loneliness. DOI: 10.1016/j.psychres.2010.08.018

Name:

Friendship Quality

Type:

Structured questionnaire

Description of the instrument:

Questions to measure quality of friendship, adapted from the Parent-Child Relationship (PCR) scale. DOI: 10.2307/1166050

Name:

Love Relationship

Type:

Structured questionnaire

Description of the instrument:

Love relationship questions, adapted from the Parent-Child Relationship (PCR) scale. DOI: 10.2307/1166050

Name:

SRD

Type:

Structured questionnaire

Description of the instrument:

Self-reported Delinquency (SRD) - 25 questions to assess criminal or problematic behavior. ISBN: 91-7153-983-2 (Swedish only)

Name:

Friends behavior

Type:

Structured questionnaire

Description of the instrument:

12 questions to assess substance use and criminal behavior among peers. ISBN: 91-7153-983-2 (Swedish only)

Name:

CMRS

Type:

Structured questionnaire

Description of the instrument:

Child Mania Rating Scale (CMRS) - Diagnostic screening measure designed to identify symptoms of mania in children and adolescents. DOI: 10.1002/jclp.20464

Name:

Sexuality

Type:

Structured questionnaire

Description of the instrument:

Four questions about sexual orientation. For more information on these questions, see the attached report "Best Practices for Asking Questions about Sexual Orientation on Surveys," created by the Sexual Minority Assessment Research Team (SMART).

Geographic coverage

Geographic location:

Geographic description:

Nationwide

Administrative information

Responsible department/unit:

Department of Medical Epidemiology and Biostatistics [C8]

Ethics Review:

Stockholm - Dnr: 2010/1410-31/1

The ethical application was approved on September 29, 2010.

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:

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

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