Psychotic experiences in adolescents

In 2002/2003 almost all 7 and 8 year old children in the province of Groningen
were screened on auditory hallucinations. The assessments were carried out by
well-trained research nurses of GGD Groningen, who were screening the children
of this age yearly on acuity of vision and hearing. Before starting the
project, a pilot was carried out, to make sure that the children very well
understood the questions, whereas from literature it became clear that such
young children can very well distinguish auditory hallucinations from imaginary
companions.
Nine percent of the 3870 children screened indicated to have heard one or more
voices in the past year, without anyone being around. Most of the children were
not bothered by the voices, but in a small part of them, a considerable impact
was found.
In order to investigate differences between children with and without auditory
hallucinations, a case-control group was made, consisting of the 347 children
with voices and an equal group of control children who were matched on age (7
or 8 years old), gender and urbanicity. This case-control sample thus comprised
694 children. Parental reported behavior problems did not occur more often in
children with auditory hallucinations than in controls. However, according to
the parents, these children had significantly more somatic complaints
(Bartels-Velthuis et al 2010).

In wave 2, the 5-year follow-up in school year 2007/2008, the case-control
group was again interviewed. In total, 337 children could be included in this
measurement. For the assessment, the children were visited at home by
well-trained (female) interviewers. Twenty-five percent of the children with
auditory hallucinations still heard voices in the past five years. Five-year
incidence rate in the control group was 9%. Only children who were
substantially suffering from their voices, showed more often behaviour problems
(Bartels-Velthuis et al 2011). Children with auditory hallucinations had
experienced more and more often traumatic and stressful life events, and this
effect was stronger when these children also had delusional ideas
(Bartels-Velthuis et al 2012).
A better social cognition appeared to be protective against the development of
delusional ideation in children with voices (Bartels-Velthuis et al 2011).

Rationale
Because of the longitudinal design of this project, risk factors for auditory
hallucinations can be investigated. The ultimate goal is to establish whether
auditory hallucinations at the age of 7 or 8 years, will induce psychic
problems in adulthood, which we intend to measure when the participants are 24
and 25 years old. The follow-up measurement at issue, at the age of 18/19
years, will offer the possibility to map out the course and incidence of
auditory hallucinations even more precisely.
-In the first (5-year) follow-up of the case-control sample, it was shown that
children with auditory hallucinations who had experienced many negative and
stressful events, more often reported delusions. This result will be replicated
in the intended third measurement (the second follow-up).
-Hearing voices may often lead to anxious and / or depressive feelings (Cotton
et al 2012). However, also a reverse association has been shown: psychotic
symptoms often co-occur with anxiety and depression (Krabbendam et al 2004;
Wigman et al 2012). Thus, Wigman and colleagues consider psychopathology as a
network, or as an overlapping and reinforcing dimensional vulnerability.
Therefore, in the intended study both anxiety and depressive symptoms will be
assessed.
-Research has shown that a diminished social functioning of adolescents may be
a precursor of future psych(ot)ic problems (see also Salokangas & McGlashan
2008). Assessing level of social functioning is thus important.
-The association of trauma and psychic problems has been demonstrated in many
studies (Morrison et al 2003; Read et al 2005). For that reason, also in this
study traumatic events will be assessed.
-Many studies have shown the relationship between cannabis use and psychotic
symptoms (Henquet et al 2005; Hides et al 2009; Rubino et al 2012), as well as
between cannabis use and affective disorders (Barragan et al 2011; Rubino et al
2012). In the first (5-year) follow-up (when the participatns were 12/13 years
of age), cannabis use hardly occurred (only in three children). It is to be
expected that cannabis use will be reported more frequently in 18/19-year-old
participants, so that associations with (onset of) auditory hallucinations can
be examined.
-In the 5-year follow-up, the 12/13-year-olds with auditory hallucinations were
found to be protected against delusional ideation by a better developed social
cognition. A similar study had never been done in that age group before.
Replication of this study is appropriate in adolescents.

Primary Objective:
(i) To assess the course (persistence, remittance, onset) of auditory
hallucinations (AH) in the case-control sample.
(ii) To investigate associations of AH with psychic experiences, cannabis use,
traumata, social functioning, social cognition, and with anxiety and
depression:
(1) Are AH associated with psychic experiences, like delusions, anxiety and
depressive symptoms?
(2) Is social functioning influenced (negatively) by hearing voices?
(3) Do external factors influence course or onset of AH, like (i) negative life
events or traumatic experiences and (ii) cannabis use?
(4) Is a better social cognition protective against the onset of delusional
ideation in those who hear voices?

Secondary Objective(s):
To update our address file, in order to facilitate contact with the
participants at the final, important, measurement, planned in 2018.

The design of the study is a cohort study, i.e. the second follow-up of the
case-control sample of 7-and-8-year old children with auditory hallucinations.
Duration of datacollection will amount to 4 months (September 2013 - January
2014).
Total duration of the study (data validation, analyses and publications) will
amount to 16 months (September 2013 - January 2015).
The study setting is a web-based assessment.
First, subjects will be receive a link to the questionnaire by e-mail.

Completion of the questionnaire will be preceded by an informed consent
procedure. The participants will receive information and a consent form by post
(medio 2013) and are requested to send the completed and signed consent form in
a postage paid envelope to the researcher. Besides, they will be requested to
agree with being contacted about the final measurement (in 2018) and whether
the researcher is allowed to look up their address in the municipal personal
records database if necessary.
A link to the questionnaire will subsequently be sent between September 2013
and January 2014 to those who have returned the signed consent form.

Participants will complete questionnaires through the internet. In total, there
is a considerable amount of questions, however, in view of the age group (18
and 19 years of age) we do not consider this to be a burden. Among these
questionnaires, there are 2 about experienced traumatic events, but these are
considered to be non-eliciting.