Toward earlier identification and preventative intervention in schizophrenia: evidence from the London Child Health and Development Study

The CHR state is also known as the “at-risk mental state” (ARMS) and “ultra-high-risk” (UHR) state [1].

Established methods (reviewed in [1]) for the identification of individuals in this prodromal phase include the complementary UHR [4] and basic symptoms [5] criteria assessed via clinical interview, with the latter possibly identifying an earlier phase of the prodromal state than UHR criteria.

Items assessed psychotic-like experiences (child- and caregiver-report), internalising and externalising psychopathology (emotional symptoms, peer relationship problems, conduct problems, and hyperactivity–inattention; child- and caregiver-report using the Strengths and Difficulties Questionnaire [11, 12]), and delays or abnormalities in speech and/or motor milestone development (caregiver-report). Additional items assessed family history of mental health problems including SSD (caregiver-report), and demographic items (child- and caregiver-report). See Table 2 (screening phase) for further detail.

Collaborating schools spanned the range of socio-economic disadvantage represented in London schools (as indexed by eligibility of children to receive free school meals; with oversampling of deprived inner-London communities) and included state and religious schools of variable enrolment size. Eighty percent of children attended school within the inner-city London Boroughs of Lambeth* (35.1 %), Southwark* (22.1 %), Lewisham* (18.6 %), Tower Hamlets* (2.6 %), and Westminster (1.6 %), with the remaining fifth sampled from the outer London Boroughs of Croydon (8.5 %), Bromley (7.0 %), Brent* (3.2 %), and Harrow (1.4 %). Boroughs indicated by * are among the most deprived 10 % of all English local authorities according to the Index of Multiple Deprivation 2010 [13] and the lowest scoring 10 % on the Local Index of Child Well-Being [14]. School-level data obtained from the Office for National Statistics at the time of sampling indexed the socio-economic status and ethnic diversity of the sample: On average, 31.2 % of children in participating schools were eligible to receive free school meals (range 1.9–62.2 %; cf. Greater London average 25.3 %, and England average 15.8 %); 24.9 % of children were of white British ethnicity (range 0–80.8 %; cf. Greater London average 37.1 %, and England average 80.3 %), with the remainder of black (45.2 %), Asian (11.4 %), other white (9.0 %), or other (9.5 %) ethnicities.

Representative indices (by child self-report) include basic demographic information (age, sex), PLEs [7, 15], and emotional symptoms, peer relationship problems, conduct problems, and hyperactivity–inattention [11, 12]. Few differences between the cross-sectional and longitudinal community samples are notable on these measures (see primary publications and [9]).

Assessment phases in the longitudinal selected sample include: screening (9–11 years), baseline (9–12 years), and first (11–14 years), second (13–16 years), and third follow-up (17–18 years). Measures that were assessed more widely, in the longitudinal community sample, are indicated in Table 2 using the symbol “+”. The initial questionnaire assessment which provided cross-sectional data in the community sample (from which the longitudinal community sample and longitudinal selected samples were derived) is summarised under the screening phase.