Table 1.
Summary of instruments included in the study.
| Instrument | Description | Outcome measure(s) |
|---|---|---|
| Measures collected in current data round | ||
| BIS-11 Brief version (Stanford et al., 2016; Steinberg et al., 2013) | BIS-11 Brief version: The BIS is an extensively used scale used for the classic measurement of impulsivity. We used the eight-item version, which has been previously validated in several studies. The questionnaire asks about impulsive tendencies and behaviours; for each item, the individual indicates the extent to which it applies to them (not at all, a little, quite a lot or very much; scored 0–4 per item) | Total score |
| Antisocial personality disorder symptoms (American Psychiatric Association, 2013) | Antisocial personality disorder symptoms were quantified using a tick-list of DSM-5 criteria. For each symptom criterion, participants indicated whether the item applied to them or not | Total number of criteria endorsed |
| Padua Obsessive–Compulsive Inventory (Washington State University–Revision version; Burns et al., 1996; Sanavio, 1988) | This is a 39-item questionnaire measuring obsessive–compulsive symptoms in normative and clinical settings | Symptom domain scores (per Burns et al., 1996) |
| CHI-T (Chamberlain and Grant, 2018) | This is a 15-item scale capturing day-to-day aspects of compulsivity. For each item, the individual indicates whether the statement (e.g. ‘I hate leaving a task unfinished’) applies to them. Response options are as follows: strongly disagree (0), disagree (1), agree (2) or strongly agree (3) | Total score |
| OBQ Short Form (Moulding et al., 2011) | This is a 20-item short version of a widely used questionnaire to assess obsessional beliefs in the context of OCD. For each item, the person indicates how much they agree with a given statement, ranging from disagree very much (scored 1) to agree very much (scored 7) | Summary scores: Threat perception, perfection/intolerance of uncertainty, inflated responsibility and importance/control of thoughts |
| OCPD traits (American Psychiatric Association, 2013; Sheehan et al., 1998) | The diagnostic screening questions from the MINI were used for OCPD traits. For each item, participants were asked whether the statement applied to them, taking into consideration not only their own view but also what they felt other people (close associates) would think | Total number of OCPD traits endorsed |
| General psychopathology (depression/anxiety) from the MINI (Sheehan et al., 1998) | General psychopathology (depression/anxiety): The diagnostic screening questions from the MINI were used for depressive and anxiety disorders | Presence or depressive and/or anxiety symptoms (total items endorsed) |
| BBQ (Lindner et al., 2016) | The BBQ is a previously validated self-report quality of life scale, which covers six life areas (leisure time, view of life, creativity, learning, friends/friendship and view of self) that are important determinants of overall quality of life. This scale has been validated in various normative and clinical population settings | Total quality of life score |
| Measures collected at study baseline (2012–2014) | ||
| BIS 11 full version (Patton et al., 1995) | This questionnaire asks about impulsive tendencies and behaviours; for each, the individual indicates the extent to which it applies to them (not at all, a little, quite a lot or very much; scored 0–4 per item) | Total score |
| The APSD (Munoz and Frick, 2007) | This is a 20-item questionnaire developed to assess psychopathy in young people. For each item, the individual indicates whether a given statement (e.g. ‘You engage in illegal activities’) is not true at all (0), sometimes true (1) or definitely true (2) | Total score |
| Padua Obsessive–Compulsive Inventory (Washington State University–Revision version; Burns et al., 1996; Sanavio, 1988) | Per current data round | Per current data round |
| General psychopathology (K10; Kessler et al., 2002) | The K10 was developed for the assessment of generalised psychological distress, including distress arising from anxiety and depression symptoms. There are 10 items each asking about experiences over the preceding 30 days. For each item, responses are as follows: none of the time (0), a little of the time (1), some of the time (2), most of the time (3) or all of the time (4) | Total score |
| FAD (Ridenour et al., 1999), PPQ, APQ-Child Short Form (Elgar et al., 2007) and MOPS (Parker et al., 1997) | Several complementary questionnaires relating to parenting approaches were included. The reader is referred to the cited manuscripts for more detailed descriptions of these instruments, except for the PPQ, which was developed bespoke for the NSPN study. The PPQ asks the extent to which each of 26 positively worded items related to one’s family when living at home (e.g. ‘We spent quality time together’; ‘If I was angry, I was still listened to’.) Each item is responded to with always (scored 0), mostly (scored 1), sometimes (scored 2) or rarely (scored 3). EFA was used to identify the optimal data structure across all these questionnaires’ items considered collectively (Supplementary Table 2) | Factor scores: General parenting, dysfunctional parenting (paternal side) and dysfunctional parenting (maternal side) |
| Friendship questionnaire (Goodyer et al., 1997; Van Harmelen et al., 2017) | This questionnaire assesses the number, availability and adequacy of friendships as well as self-disclosure and difficulties in friendships, and was adapted from previous research work. The individual questions were as follows: Are you happy with the number of friends you have? How often do you arrange to see friends other than at school, college or work? Do you feel that your friends understand you? Can you confide in your friends? Do your friends ever laugh at you or tease you in a hurtful way? Do people who aren’t your friends laugh at you or tease you in a hurtful way? Do you have arguments with your friends that upset you? Overall, how happy are you with your friendships? Item response options differed depending on the question but involved four to six possible responses (e.g. for the question ‘Do you feel that your friends understand you?’, the response options were most of the time, sometimes, not often or not at all, which were scored 0, 1, 2 or 3, respectively). EFA was used to determine the latent structure of the questionnaire (Supplementary Table 3) | Factor scores: Happiness/number of friends, confiding/understanding and teasing/arguments |
BIS: Barratt Impulsiveness Scale; DSM-5: Diagnostic and statistical manual of mental disorders (5th ed.); CHI-T: Cambridge–Chicago Trait Compulsivity Scale; OBQ: Obsessive Beliefs Questionnaire; OCD: obsessive–compulsive disorder; OCPD: Obsessive–Compulsive Personality Disorder; MINI: Mini-International Neuropsychiatric Inventory; BBQ: Brunnsviken Brief Quality of life scale; APSD: Antisocial Process Screening Device; FAD: Family Assessment Device; PPQ: Positive Parenting Questionnaire; APQ: Alabama Parenting Questionnaire; MOPS: Measure of Parenting Style; NSPN: Neuroscience in Psychiatry Network; EFA: exploratory factor analysis.
Full details for the instrument citations are provided in the online supplement, due to space limitations.