Background of the study:
Over the years, a large body of research has shown that adolescents with intellectual
disability are 3-4 times more likely to develop severe behaviour problems than
adolescents without intellectual disability. Families in which adolescents and/or one or
both parent(s) have an intellectual disability (from now on, families with ID) often deal
with complex problems, putting the adolescent at an increased risk of out-of-home
placement. Multisystemic therapy (MST) is an intensive home-based treatment, effective in
reducing severe behaviour problems and preventing the out-of-home placement of
adolescents. A specialisation of MST has been developed for families with ID: MST-ID. In
MST-ID, among other alterations, simplified language and visual support is used, sessions
are more structured and more time is scheduled for practicing exercises, and extra
attention is paid to the generalisation of what has been learned in the sessions (with
the aim of attaining long-term outcomes). Pilot studies show that when compared to
standard MST, MST-ID shows similar or better treatment outcomes in families with
adolescents with ID. Meanwhile, MST-ID has been disseminated more widely and the target
population extended by including families in which only the parent(s) have an ID.
Objective of the study:
The aim of this study is to investigate the effectiveness of MST-ID for adolescents with
severe behavioural problems from families with an intellectual disability (ID), compared
to standard MST. It is hypothesised that MST-ID is more effective - in terms of fewer
behavioural problems, more adolescents living at home, being in school/work, no new
police contacts, less parenting stress - than standard MST. Treatment outcomes are
considered both quantitatively and qualitatively.
Study design:
Quantitatively, the Propensity Score (PS) method is used to balance treatment groups and,
combined with Multilevel Modelling (MLM), to estimate treatment effect over time.
Qualitatively, the experiences of approximately 10 adolescents and/or parents are
centralised. The qualitative research methods will be decided upon in a participatory
manner with respondents (examples of potential research methods are interviews, focus
group discussions, or photo elicitation).
Study population:
Adolescents (10-19y) with severe behavioural problems or delinquent behaviours, and their
parent(s) receiving MST(-ID) treatment. All research participants must be from families
where either the adolescent and/or parent(s) has/have ID.
Intervention:
Following standard referral procedures, families were either referred to standard MST or
MST-ID treatment (i.e., non-randomly). Both standard MST and MST-ID are intensive,
home-based treatments with 3-5 home visits per week, targeting the severe behavioural
problems of adolescents across multiple life domains. MST-ID is tailored to the needs and
skill deficits of adolescents and/or parents with ID. Concretely, more attention is paid
to how therapists create engagement, implement interventions, and realise support from
informal supports, in a tailored, developmentally appropriate, and simplified manner
(meaning in a more structured way and using accessible language, among others), when
compared to standard MST.
Research questions:
Building on the objectives, the following research questions were formulated:
Primary research questions:
Is MST-ID superior, when compared to standard MST, in reducing rule-breaking
behaviour of adolescents, according to parents?
Is MST-ID superior, when compared to standard MST, in reducing rule-breaking
behaviour of adolescents, according to adolescents?
Secondary research questions:
Is MST-ID superior, when compared to standard MST, in reducing externalising and
internalising behavioural problems of adolescents, according to parents?
Is MST-ID superior, when compared to standard MST, in reducing externalising and
internalising behavioural problems of adolescents, according to adolescents?
Is MST-ID superior, when compared to standard MST, in reducing parenting stress?
Is MST-ID superior, when compared to standard MST, in preventing short and long term
out-of-home placement, delinquency, truancy or joblessness, and addictions of
adolescents?
Is MST-ID superior, when compared to standard MST, in realising improvements on
family's social networks?
Is MST-ID superior, when compared to standard MST, in improving the instrumental
outcome parenting skills?
Is MST-ID superior, when compared to standard MST, in improving the instrumental
outcome family relations?
Is MST-ID superior, when compared to standard MST, in improving the instrumental
outcome social support?
Is MST-ID superior, when compared to standard MST, in improving the instrumental
outcome adolescent success in an educational or vocational setting?
Is MST-ID superior, when compared to standard MST, in improving the instrumental
outcome adolescent involvement with pro-social peers?
Is MST-ID superior, when compared to standard MST, in improving the instrumental
outcome change in adolescent problem behaviour?
What are the experiences of adolescents and/or parents receiving MST-ID treatment?
Do effects across subgroups of adolescents and/or parents with ID differ?
MST-ID is expected to be superior in achieving the aforementioned outcomes (#1-13) when
compared to standard MST. Research questions #14-15 will be assessed exploratively,
therefore no hypotheses have been formulated.