Content uploaded by Beate Oerbeck
Author content
All content in this area was uploaded by Beate Oerbeck on Dec 26, 2021
Content may be subject to copyright.
A randomized controlled trial of a home and school-
based intervention for selective mutism –defocused
communication and behavioural techniques
Beate Oerbeck
1
, Murray B. Stein
2
, Tore Wentzel-Larsen
1,3
, Øyvind Langsrud
4
&
Hanne Kristensen
1
1
Centre for Child and Adolescent Mental Health, Eastern and Southern Norway, PO box 4623 Nydalen, Oslo, N-0405,
Norway. E-mail: b-oerbe@online.no
2
University of California San Diego, La Jolla, CA, USA
3
Norwegian Centre for Violence and Traumatic Stress Studies, Oslo, Norway
4
Norwegian Statistics, Oslo, Norway
Background: Randomized controlled psychosocial treatment studies on selective mutism (SM) are lacking.
Method: Overall, 24 children with SM, aged 3–9 years, were randomized to 3 months treatment (n=12) or
wait list (n=12). Primary outcome measure was the School Speech Questionnaire. Results: A significant time
by group interaction was found (p=.029) with significantly increased speech in the treatment group
(p=.004) and no change in wait list controls (p=.936). A time by age interaction favoured younger children
(p=.029). Clinical trail registration: Norwegian Research CouncilNCT01002196. Conclusions: The treatment
significantly improved speech. Greater improvement in the younger age group highlights the importance of
an early intervention.
Key Practitioner Message
•Early detection and treatment of children with selective mutism is crucial due to the elevated risk for chronicity
of symptoms.
•The preschool arena is an important setting for the recognition of anxious and withdrawn behaviour that often
precedes selective mutism.
•Evidence supports the use of a home- and school-based psychosocial intervention to increase speech.
•Greater improvement in younger children (preschool) highlights the importance of early intervention.
Keywords: Selective mutism; randomized controlled trial; behavioural intervention; social phobia; childhood
anxiety
Introduction
Children with SM are characterized by a consistent lack
of speech in specific social situations in which there is
an expectation for speaking (e.g. school) despite speak-
ing in other situations (e.g. home) (American Psychiatric
Association, 2000). SM is found to be associated with co-
morbid anxiety diagnoses, in particular with social anxi-
ety disorder, as well as neurodevelopmental disorders
(Kristensen, 2000). Age of onset is typically before age
5 years (Black & Uhde, 1995). SM is relatively rare, with
a prevalence of about 0.7–0.8% in childhood, somewhat
more frequent in girls (Bergman, Piacentini, & McCrac-
ken, 2002). A 0.1% prevalence of SM was found in a rep-
resentative sample of Norwegian 4 year olds using a
preschool diagnostic interview (Wichstrom et al., 2012).
SM is considered to be hard to treat and the literature
on treatment for SM is dominated by case studies or case
series. One review describes that the few existing studies
(since 1980) with samples above five children have
mainly used behavioural, cognitive-behavioural or mul-
timodal interventions (Manassis, 2009). Another review
states that behavioural interventions (including stimu-
lus fading, desensitization, shaping, modelling and con-
tingency management) are most frequently used
(Cohan, Chavira, & Stein, 2006). Only two studies
include a comparison group. The first study examined
retrospectively the records for 25 children with SM trea-
ted either with behavioural therapy or a school-based
remediation programme. The children treated with
behavioural therapy showed a greater improvement
compared to the group which received the school-based
remediation intervention (Sluckin, Foreman, & Herbert,
1991). In the second and more recent study (Vecchio &
Kearney, 2009) an alternating treatment design was
applied in nine children with SM. Greater effectiveness
was described for exposure-based practice versus con-
tingency management. Children, parents and teachers
rated outcome in terms of words spoken, and the
reported effect sizes suggested improvement by children
©2013 The Authors. Child and Adolescent Mental Health published by John Wiley & Sons Ltd on behalf of the Association for Child and
Adolescent Mental Health.
This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use
and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or
adaptations are made.
Child and Adolescent Mental Health 19, No. 3, 2014, pp. 192–198 doi:10.1111/camh.12045
and parents with somewhat less favourable teacher rat-
ings. More treatment studies with sound methodology,
larger sample sizes, and systematic descriptions of the
treatment content and duration, diagnostic procedures
and evaluation instruments, are needed. To date no pro-
spective psychosocial randomized controlled treatment
(RCT) studies of children with SM are published.
In Norway, the first and last author established a mul-
tidisciplinary project group in 2007 and subsequently
developed a home and preschool/school-based interven-
tion for children with SM 3–9 years of age.
The intervention includes defocused communication,
psychoeducation and behavioural techniques.
Defocused communication (developed based on clini-
cal experience with a considerable number of children
with SM) was used as a general treatment principle to
decrease social anxiety (see Content of sessions, page 8).
In line with the previously mentioned review of the
treatment literature (Cohan et al., 2006) psychoeduca-
tion was chosen along with behavioural interventions
[stimulus fading in the form of gradually increased expo-
sure as well as contingency management (use of positive
reinforcement for speaking behaviour)] that were applied
in a joyful play activity inspired by the Selective Mutism
Resource Manual (Johnson & Wintgens, 2007).
We found favourable treatment outcome in a pilot
study of seven preschool children (five girls and four
bilinguals) diagnosed with long-standing SM (mean
20 months) (Oerbeck, Johansen, Lundahl, & Kristen-
sen, 2012). Six children spoke freely in all preschool set-
tings after a mean of 14 weeks treatment, and at follow-
up 1 year after end of treatment. These children were
recruited from the local Oslo area, and the members of
the project group treated six of the seven children.
This article will present results from the RCT compo-
nent of a study using this intervention involving 24
children with SM 3–9 years of age recruited from South-
ern Norway and treated by local therapists at community
health clinics. The children were randomized to 3
months of treatment or to 3 months as wait list controls.
Due to the situational nature of SM, we hypothesized
that the children in the active treatment group, com-
pared to controls would show increased speaking behav-
iour (rated by teachers and parents) in preschool/
school, where the targeted problem behaviour and the
treatment took place.
Given an increased neurodevelopmental plasticity
and less entrenched mutism in young children, we fur-
ther hypothesized that younger children would benefit
more than older ones.
Method
Design
This is a randomized controlled trial (RCT) of a psychoso-
cial intervention for SM where participants were allocated
to the intervention group or to the wait list controls.
Figure 1 shows the participant flow through the trial.
Randomized (N = 24)
Assessed for eligibility (N = 34)
Allocated to intervention
(N = 12)
Excluded (N = 10)
(Did not fulfill inclusion
criteria)
Allocated to wait list controls
(N = 12)
Analysed at post intervention
(N = 12)
Analysed at post intervention
(N = 12)
Figure 1. The flow diagram of participants in each stage of the RCT
©2013 The Authors. Child and Adolescent Mental Health published by John Wiley & Sons Ltd on behalf of the Association for Child and
Adolescent Mental Health.
doi:10.1111/camh.12045 Selective mutism: RCT study 193
Participants
The sample consists of 24 children with SM, 3–9 years of
age [16 girls, mean age 6.5 years (SD =2.0), 9 children
in preschool; age 3–5 years, 15 school children; age 6–
9 years]. The exact onset of SM was hard to pinpoint for
the parents, especially for the older children, but the
long-standing nature of SM was highlighted, and most
mentioned the start in preschool as a crucial point in
symptom development. Six children were bilingual.
Twenty-two children lived with both biological parents
(one adopted child, one child with divorced parents). The
educational level of the parents was ≤12 years (N=23)
and >12 years (N=25) (See Table 1 for background
variables).
Inclusion criteria: Children aged 3–9 years, consecu-
tively referred for SM during a 9-month period from out-
patient Child and Adolescent Mental Health Clinics
(CAMHS) or school psychology services in Southern Nor-
way, whose parents consented to the randomization pro-
cedure and fulfilled DSM-IV diagnostic criteria for SM. In
addition, we specified that the children should not speak
to adults in preschool/school, and that mutism was
present also in the native language for bilingual chil-
dren.
Exclusion criteria: 1. Parents who did not speak Nor-
wegian or 2. Children with IQ <50, psychosis or a Perva-
sive Developmental Disorder. 3. Children who were on
psychotropic medication or receiving another active
treatment for SM.
Power
On the basis of the recruitment to our pilot study, we
found it likely that a minimum of 24 children would be
referred within the planned time frame and the extended
geographical area of this study. The pilot study showed
that six children started to talk in preschool within
3 months. A power analysis showed that with 24 chil-
dren, 80% power was achieved if 75% of the children (9
of 12) in the treatment group started to talk within
3 months compared to the possibility of a spontaneous
onset of talking in 25% of the wait list controls (3 of 12)
during the 3-month waiting list period.
Recruitment
The CAMHS and school psychology services in Southern
Norway received written information about the treat-
ment study resulting in 34 age-appropriate referrals. All
parents were contacted by phone by the principal inves-
tigators (first and last author) and interviewed about the
SM symptomatology and the general development of the
child, and the mother completed the Selective Mutism
Questionnaire (SMQ) (Bergman, Keller, Piacentini, &
Bergman, 2008). This screening led to the exclusion of
10 children [Pervasive Developmental Disorder (N=2),
no mutism in native language (N=1), use of speech to
some adults in preschool/school (N=7)]. A phone call to
the local CAMHS was made to ensure that all remaining
24 children were registered, and that a local therapist
would be made available. The final inclusion of the 24
children was based upon a confirmation of the SM diag-
nosis after a home visit where a diagnostic interview was
conducted with the parents (by the last author), and the
children were assessed (by the first author) to rule out
severe intellectual and/or language problems. In addi-
tion, parents and the staff/teachers in preschool/school
completed questionnaires. All the baseline assessments
were made blind to the randomized group allocation.
Randomization procedure
The randomized group allocation was made by the
fourth author based on information from the screening
interview. To reduce the risk of imbalance regarding four
predefined variables (symptom severity as assessed by
SMQ, age group (preschool/school), bilingualism and
gender) the children were allocated to the treatment or
control group according to the algorithm of Hofmeijer,
Anema, and van der Tweel (2008). This method is a mod-
ified minimization procedure that involves a random
component. The parameter (between 0 and 1) that con-
trols the degree of randomness was set to 0.4. When
using this procedure the four variables had equal weight
and the method was restricted to ensure 12 children in
each group. The algorithm was implemented by using
the Matlab programming language (Natick, MA). The
results of the randomized group allocation was kept in a
sealed envelope by the fourth author and revealed to the
principal investigators after baseline assessments had
taken place.
Initial psychoeducation of all participants
For each of the 24 participants, one initial psychoeduca-
tional session (including information about SM, as well
as on how to use defocused communication) was held by
phone with the staff/teachers from preschool/school
and parents together. The practical arrangement for par-
ticipants in the treatment group was also planned in this
phone call, while the wait list group only received infor-
mation on the assessment and treatment procedures
that would take place after 3 months, with no further
contact with the investigators or therapists during this
time period.
Therapist training
The 12 children in the treatment group were treated by a
total of 10 therapists registered to a local CAMHS who
Table 1. Background variables for children in the intervention
group (N=12) and waitlist group (N=12)
Intervention group
N=12
Wait list group
N=12
Gender 3 boys 5 boys
Age group N=5in
preschool
N=4in
preschool
Severe SM (SMQ
School subscale ≤0.5)
N=8N=8
Bilinguals N=3N=3
Educational level mother
≤12 years/>12 years N=5/N=7N=7/N=5
Educational level father
≤12 years/>12 years N=6/N=6N=5/N=7
Age mean (SD) 6.59 (2.35) 6.47 (1.53)
Vocabulary (PPVT)
mean (SD)
92.50 (8.98) 97.08 (9.23)
Non-verbal IQ mean (SD) 97.08 (11.77) 98.33 (8.35)
Children with comorbid
diagnoses other than
SM/Social Phobia
N=8N=8
SM in other
family members
N=5N=5
©2013 The Authors. Child and Adolescent Mental Health published by John Wiley & Sons Ltd on behalf of the Association for Child and
Adolescent Mental Health.
194 Beate Oerbeck et al. Child Adolesc Ment Health 2014; 19(3): 192–8
received a detailed manual describing the use of defo-
cused communication as a general treatment principle
and how to arrange the behavioural interventions of the
stimulus fading/sliding-in technique. The manual
required the checking off of planned tasks and interven-
tions in each session, and all therapists used the treat-
ment manual under close guidance and supervision
related to each session by phone from the first or last
author. No further treatment adherence measures were
included in this study. All but one therapist had a mini-
mum of 10 years of clinical experience including some
(N=4) or extensive (N=5) work with selectively mute
children.
Intervention
Frequency, location and participants. The intervention
group received a total of 21 sessions by the therapist over
a 3-month period. The first three 1-hr sessions were car-
ried out weekly in the child’s home with the parents
present, primarily to get to know the child, establish an
alliance and train on procedures that later would be car-
ried out in preschool/school. The next sessions took
place at preschool/school twice a week, each lasting half
an hour. The intervention at preschool/school was
divided into six modules/speaking levels according to
the progress of the child (see Table 2). The parents par-
ticipated in the first module; the teachers from modules
III to VI and peers/classmates from modules IV to VI.
Content of sessions. Defocused communication and
behaviorial interventions (including rewards) were our
two main components.
1. Defocused communication was a general treatment
principle in all sessions. Central components of defo-
cused communication are: to sit beside rather than
opposite the child; to create joint attention using an
activity the child enjoys rather than focusing on the
child; to ‘think aloud’rather than asking the child direct
questions; to give the child enough time to respond
rather than talking for the child, to continue the dialogue
even though the child does not respond verbally; and try
to receive a verbal answer in a neutral way rather than
praising the child.
2. The behavioural intervention is presented in some
detail below (see Second session). The principle for when
to use rewards was to reward the child immediately if
she or he talked to adults (with a normal or near-normal
voice) in accordance with the levels described in Table 2.
The three home-based sessions
First session: The therapist (T) explained to the child
(adjusted to the age of the child) the purpose of the visit;
the fact that many other children also struggle with mute-
ness outside home; that most do not know why and that
they really want to start to speak, but do not know how to
do it; that it is possible to work with the problem and
practice in small steps and that they will be prepared for
what to do and receive small gifts for speaking behaviour.
T introduced a workbook (including talking map, stickers,
drawing sheets) and audio tape (tell a joke, sing, count,
etc.); both only for optional use as a tool to enhance report
in the sessions. The workbook was similar for all ages. T,
child and parents chose a favourite game with speech
demand (e.g. counting or naming) and prepared the stim-
ulus fading situation for the next session.
Second session: T and child reviewed session one and
workbook/audiotape if these had been used between
sessions. The stimulus fading situation was carried out.
I. The stimulus fading situation was divided into six
stages: I. Parent and child playing a game; T outside the
room with the door closed; II. T outside the room with the
door open; III. T visiting the room during the game; IV. T
in the room but not playing; V. T sitting beside but not
playing; VI. T participating in the game.
Third session: Similar to session two. The stimulus
fading situation continued from where the child left off in
the previous session. In addition, T prepared for the next
session at preschool/school.
Sessions 4–21: Similar content with session three, but
in another location (preschool/school). The intervention
followed the six modules in Table 2 according to the child’s
progress. The sessions were held in a separate room until
thechildreachedmoduleV.InmoduleVandVItheinter-
vention was moved to other rooms/settings, including the
classroom to facilitate generalization of speech.
Instruments
In addition to the outcome measures, the following
instruments were included to give an adequate descrip-
tion of the sample.
Diagnosis of SM and comorbid problems. SM was diag-
nosed using the SM module from the Anxiety Disorders
Interview Schedule (ADIS-IV) (Albano & Silverman,
1996). ADIS is a semi-structured interview with good
construct validity (Langley, Bergman, McCracken, & Pia-
centini, 2004). The SM module relates to the speaking
behaviour of the child in different social situations. In
addition, we gathered detailed information on whether
the child talked to adults in the preschool/school.
To assess comorbidity, we used the revised version of
the Schedule for Affective Disorders and Schizophrenia
for School-Aged Children: Present and Lifetime Version
Table 2. Predetermined treatment goals reflecting increasingly
difficult speaking levels (I–VI) to be obtained in the preschool/
school setting from the basic level of zero; does not speak to
adults (as defined by the diagnosis of SM in this study) and the
number of children in the active treatment group (N=12) who
achieved the different treatment goals
Speaking
Level
Description of the goal to be obtained in
each speaking level N=12
I Speaks to the therapist (T) in a separate
room with parent (P) present
0
II Speaks to T in a separate room without
P present
3
III Speaks to one teacher in a separate
room with T present
2
IV Speaks to other teachers/carers and
children in a separate room with
T present
4
V Speaks to teachers/carers and children in
some settings without T present (speaks
to some adults but not to all or most
adults; speaks in some groups but not in
most or all groups)
3
VI Speaks to teachers/carers and children in
all settings without T present (normal
speech, indistinguishable from other
children)
0
©2013 The Authors. Child and Adolescent Mental Health published by John Wiley & Sons Ltd on behalf of the Association for Child and
Adolescent Mental Health.
doi:10.1111/camh.12045 Selective mutism: RCT study 195
(K-SADS-PL) (Kaufman et al., 1997). This study
included nine children below age 6 years, but adequate
diagnoses can be made as long as the behavioural
concepts and the understanding of life interference is
adapted to be relevant to a preschool child (Birmaher
et al., 2009).
Questions were also asked pertaining to the motor-
and language development of the child (whether it was
considered to be delayed, normal or advanced, compared
to peers), the family history of SM, and whether the par-
ents described themselves as socially anxious in child-
hood years.
Interviews were conducted by the last author, with
extensive experience with ADIS/K-SADS interviews from
research and clinical work, who at the time of assess-
ment was blind to treatment group membership.
Testing of non-verbal IQ and receptive vocabulary. The
Stanford-Binet Nonverbal Fluid Reasoning subtest
(Roid, 2003) was used as a screening tool for non-verbal
IQ. The Stanford-Binet Scales show good psychometric
properties and the abbreviated forms are highly related
to full-scale IQ. The Peabody Picture Vocabulary Test
(PPVT-IV) (Dunn & Dunn, 2007) assesses receptive
vocabulary in the form of words read aloud to the child,
who in turn points to the appropriate picture. The PPVT
has acceptable correlations with standardized verbal IQ
measures, such as the Vocabulary subtest of the Stan-
ford-Binet Scale (Roid, 2003). A computed standard
score (mean =100; SD =15) is reported for both the
Stanford-Binet Scale and the PPVT.
The children were tested at home with a parent pres-
ent by the first author, an experienced neuropsycholo-
gist, who at the time of testing was blind to treatment
group membership.
Outcome measures. The School Speech Questionnaire
(SSQ) (Bergman et al., 2002). Our primary outcome
measure was the SSQ (based on speech frequency in the
school context) rated by the child’s teacher at baseline
and after 3 months, as it was expected that teachers
would have the most accurate information on speaking
behaviour in this setting. The SSQ, a quantitative mea-
sure with no cut-off score, includes 10 questions and is
modified from the SMQ (see below) with acceptable inter-
nal consistency. Six of the SSQ questions (identical to
the SMQ) are used to compute a mean score (range =
0–3), computed as the mean of the valid items, if at least
half the items were valid. We used the Norwegian
translation with permission from Lindsey Bergman, the
developer of the measure. Internal consistency was
somewhat low (a=.64).
The Selective Mutism Questionnaire (SMQ) (Bergman
et al., 2008). We also included the SMQ rated by moth-
ers at baseline and after 3 months for two reasons; to
have multiple raters of speaking behaviour in the pre-
school/school setting, and to look at possible changes in
two additional settings (at home and in public). The SMQ
includes 32 questions scored from 0 to 3, where 0 indi-
cates that speaking behaviour never occurs, and 1, 2
and 3 refer to seldom, often and always speaking respec-
tively. Seventeen of the SMQ questions are used to com-
pute three subscale mean scores [preschool/school (six
items), at home (six items) and in public (five items)] with
the same 0–3 scoring range, computed as the mean of
the valid items, if at least half the items were valid. The
SMQ total factor score was computed from the sum of
three subscales divided by three. In this study, one child
had one missing item on one subscale. We used the
Norwegian translation with permission from Lindsey
Bergman, the developer of the measure. Acceptable
internal consistency was found for the three subscales
and the total score respectively (a=.68, .73, .76, .77).
Finally, an additional outcome measure was the
achieved treatment goal, ranging from I to VI rated by
the therapist (Table 2). For the 12 children who received
active treatment, the achieved treatment goal (I–VI) was
compared to the baseline value of zero indicating that
the child did not speak to adults in the preschool/school
setting.
Ethical approval
Written informed consent was provided by the parents.
The study was granted approval by the Norwegian Social
Science Data Services and the Regional Committees for
Medical and Health Research Ethics.
Data analysis
To account for clustering of the data, we used mixed
effects models (Pinheiro & Bates, 2000) to investigate
group differences at baseline and 3 months. As group
differences were expected at 3 months, but not at base-
line, a time by group interaction was included. The
model was repeated with adjustment for age at baseline
including a time by age interaction. In the age adjusted
model, age was centred at 6.5 years, close to the mean
age in our sample. The level of significance was defined
as p<.05.
Results
Diagnosis of SM and comorbid problems
Mothers reported that 15 of the 24 children were some-
what delayed in their motor or language development,
but all children now spoke freely in full sentences at
home. The selective mutism diagnosis was confirmed
using the appropriate module on the ADIS diagnostic
interview. Using the K-SADS interview, all 24 children
with SM suffered from social phobia. Furthermore, 16
children presented with one or more additional lifetime
diagnoses of Separation Anxiety (n=7), Specific Phobia
(n=6), Generalized Anxiety Disorder (n=2), OCD
(n=2), Tics (n=2), Enuresis (n=6), Encopresis (n=1).
This did not only apply to older children, as seven of the
nine children aged 3–5 years had one or more additional
diagnoses. In 10 of the 24 families, there was a positive
history of SM in family members (in parents: n=5, other
relatives: n=5). In all but one family, one or both par-
ents described the presence of social anxiety symptoms
in their own childhood (see Table 1).
Testing of non-verbal IQ and receptive vocabulary.
Results were within the average range (see Table 1).
Outcome
The School Speech Questionnaire (SSQ) rated by the
teacher. On our primary outcome measure, the SSQ,
there was a significant difference favouring the interven-
tion group [a significant time by group interaction
(F
1,22
=5.44, p=.029)]. In the wait list control group,
©2013 The Authors. Child and Adolescent Mental Health published by John Wiley & Sons Ltd on behalf of the Association for Child and
Adolescent Mental Health.
196 Beate Oerbeck et al. Child Adolesc Ment Health 2014; 19(3): 192–8
there was no significant change from baseline to
3 months [prescore =0.44; postscore =0.40
(T
22
=0.08, p=.936)], whereas in the treatment group
there was a significant increase in speech [pre-
score =0.68, postscore =1.22 (0.54, 95% CI 0.19–0.89,
T
22
=3.22, p=.004)].
In the model that also included a time by age interac-
tion, using 6.5 years as a reference age, there was a sig-
nificant time by age (F
1,21
=5.47, p=.029) interaction,
indicating a more pronounced increase in speech in the
treatment group for younger children. Again there was a
significant time by group interaction (F
1,21
=6.93,
p=.016) and in the treatment group there was a signifi-
cant increase from baseline to 3 months (0.55, 95% CI
0.23–0.87, T
21
=3.61, p=.002), with no significant
change for wait list controls (T
21
=0.12, p=.908).
Selective Mutism Questionnaire (SMQ) rated by the
mother. For the SMQ School- and Total scores (Table 3)
there was a significant difference in time changes
between groups with an improvement in the intervention
group, and this was essentially unchanged with age
adjustment. For the other two SMQ subscales (Table 3)
there was a similar but somewhat weaker pattern, with-
out significant group differences in time changes.
The achieved treatment goal (Table 2) ranging from I to
VI rated by the therapist. Compared to the baseline
value of zero, all children started to speak to the thera-
pist within the preschool/school setting (see Table 2 for
more details on this second outcome measure). While
three children spoke to the therapist only, not to other
adults, another three children achieved level 5 (spoke
freely in some but not all groups and/or to some but not
all adults. The last three were aged 3–5 years.
Discussion
To our knowledge, this is the first published RCT of a
psychosocial treatment for children with SM. We found
that the home- and school-based intervention was, as
hypothesized, significantly more effective than a wait list
control. In addition, we expected that younger children
would benefit more than older ones. Support was found
on our primary outcome measure, the SSQ rated by the
teachers, and also by the fact that the three children
who spoke freely in some settings were 3–5 years of age
(therapist rated). The SMQ, our second outcome mea-
sure confirmed the findings on the SSQ. On the other
hand, the SMQ school subscale showed that the moth-
ers in the intervention group had the impression of
increased speech in the school settings irrespective of
age. With regard to this finding, one must remember that
the parents did not have first-hand information on
speech in this setting. So, in summary, although the
treatment was also efficacious for children above age
5 years, the finding of greater improvement in the
younger age group should be seen as highlighting the
importance of early interventions in children with SM.
The children in this study seem to resemble children
with SM from other studies in the sense that the group
included a high percentage of bilinguals (Elizur & Pered-
nik, 2003) children with comorbid anxiety disorders,
and-/or some developmental delay (Kristensen, 2000).
In line with earlier studies, we found a parent-reported
familial accumulation of SM (Black & Uhde, 1995) and of
social phobia (Chavira, Shipon-Blum, Hitchcock, Co-
han, & Stein, 2007). Our findings also support the new
DSM-V classification of SM as an anxiety disorder and
that it is upheld as a separate diagnosis from social pho-
bia due to frequent comorbid language delays/disorders
(American Psychiatric Association, 2013). Concerning
severity of SM, there are no Norwegian norms on the SM
questionnaires, but the present baseline data resemble
the children in our pilot preschool study (Oerbeck et al.,
2012) as well as in a sample of children aged 3–11 years
(Bergman et al., 2008) with scores <1 indicating no or
rare speaking behaviour.
Compared to our pilot study that only included chil-
dren aged 3–5 years who received treatment within the
preschool, fewer children spoke freely after 3 months in
this study. This could be due to a possibly less
entrenched mutism in the younger children and/or the
difference of the preschool and the school arena. At least
in Norway the structure of the day (both in the form of
activities, personnel, available rooms) is easier to change
in preschool. A third plausible explanation was that the
children were treated by local therapists rather than
therapists expert in this treatment modality.
One could question why the RCT period was only
3 months. In Norway, referred children have the right to
receive treatment free of charge within CAMHS after a
maximum waiting of 3 months. In our pilot study, the
parents refused to participate in the planned design
Table 3. SMQ results, analysed with mixed effects models
SMQ school subscale SMQ home subscale SMQ public subscale SMQ total score
Coefficient [95% CI], pCoefficient [95% CI], pCoefficient [95% CI], pCoefficient [95% CI], p
Model 1
a
Time 9Group F
1,22
=10.9, .003 F
1,22
=2.8, .106 F
1,22
=3.4, .080 F
1,22
=9.1, .006
Time, intervention 0.74 [0.40–1.08], <.001 0.47 [0.18–0.76], .003 0.34 [0.11–0.57], .006 0.52 [0.29–0.74], <.001
Time, wait list Ctr 0.03 [0.37 to 0.31], .867 0.14 [0.15 to 0.43], .331 0.05 [0.18 to 0.28], .661 0.05 [0.17 to 0.28], .626
Model 2
b
Time 9Group F
1,21
=10.8, .004 F
1,21
=2.7, .112 F
1,21
=3.2, .088 F
1,21
=8.8, .007
Time 9Age F
1,21
=0.5, .506 F
1,21
=0.1, .823 F
1,21
=0.03, .863 F
1,21
=0.1, .713
Time, intervention,
6.5 years
0.74 [0.40–1.08], .004 0.47 [0.18–0.77], .003 0.34 [0.10–0.58], .007 0.52 [0.29–0.75], <.001
Time, wait list ctr,
6.5 years
0.03 [0.37 to 0.32], .862 0.08 [0.44 to 0.59], .763 0.05 [0.19 to 0.29], .668 0.05 [0.18 to 0.28], .637
a
Model by time, group with interaction.
b
Model by time, group, age and interaction/time by group and age.
©2013 The Authors. Child and Adolescent Mental Health published by John Wiley & Sons Ltd on behalf of the Association for Child and
Adolescent Mental Health.
doi:10.1111/camh.12045 Selective mutism: RCT study 197
comparing our intervention with treatment as usual. To
ensure an RCT design in this study, and to follow
national regulations, we found wait list controls for
3 months to be the best alternative. Inclusion in the
study was based upon acceptance of the possibility to
enter the wait list control group.
To our knowledge, this is the first controlled study to
demonstrate that a psychosocial treatment can be effec-
tive for SM in children aged 3–9 years. The therapists
used treatment including defocused communication as
a general treatment principle, and a home and formal
day care/school-based intervention with gradual expo-
sure to the feared situations in which speech is expected.
Future research, including a larger and more methodo-
logically rigorous efficacy trial is needed to ascertain the
active treatment components. In this regard, the fact
that we could observe a significant and substantial effect
of the intervention –even in the hands of therapists who
were not experts in SM –speaks to the robust nature of
the intervention and the likelihood of being able to
disseminate it in future.
Limitations
The relatively small sample size is an important limita-
tion. This is nonetheless the only psychosocial RCT of
SM we are aware of and, small sample notwithstanding,
the results were positive. Second, the three outcome rat-
ers were not blind to whether treatment had taken place;
only the baseline assessments were masked. Third, the
internal consistency of the primary outcome measure
(SSQ) was somewhat low. Fourth, the lack of a blind
assessment of treatment adherence is also a limitation.
Conclusions
This is the first RCT of a psychosocial treatment for chil-
dren with SM. A statistically significant and clinically
meaningful group effect was found after 3 months of a
treatment including defocused communication as a gen-
eral treatment principle, and behavioural interventions in
the form of stimulus fading/sliding-in technique. How-
ever, a cautious interpretation is needed given the lack of
blinded outcome assessments, independent therapist
integrity ratings and a relatively small sample size.
Acknowledgement
This research was funded by the Norwegian Research Council,
clinical trials registration: NCT01002196.
The authors have declared that they have no competing or
potential conflicts of interest.
References
Albano, A.M., & Silverman, W.K. (1996). Anxiety disorders
interview schedule for DSM-IV. San Antonio, TX: Graywind
Publications Inc.
American Psychiatric Association (2000). Diagnostic and statis-
tical manual of mental disorders: DSM-IV-TR. Washington,
DC: American Psychiatric Association.
American Psychiatric Association. (2013). Diagnostic and
statistical manual of mental disorders: Fifth edition. DSM-V.
Washington, DC: American Psychiatric Association.
Bergman, R., Keller, M.L., Piacentini, J., & Bergman, A.J.
(2008). The development and psychometric properties of the
Selective Mutism Questionnaire. Journal of Clinical Child and
Adolescent Psychology,37, 456–464.
Bergman, R., Piacentini, J., & McCracken, J.T. (2002). Preva-
lence and description of selective mutism in a school-based
sample. Journal of the American Academy of Child and Ado-
lescent Psychiatry,41, 938–946.
Birmaher, B., Ehmann, M., Axelson, D.A., Goldstein, B.I.,
Monk, K., Kalas, C., ... & Brent, D.A. (2009). Schedule for
affective disorders and schizophrenia for school-age children
(K-SADS-PL) for the assessment of preschool children–a pre-
liminary psychometric study. Journal of Psychiatric Research,
43, 680–686.
Black, B., & Uhde, T.W. (1995). Psychiatric characteristics of chil-
dren with selective mutism: A pilot study. Journal of the Ameri-
can Academy of Child and Adolescent Psychiatry,34, 847–856.
Chavira, D.A., Shipon-Blum, E., Hitchcock, C., Cohan, S., &
Stein, M.B. (2007). Selective mutism and social anxiety disor-
der: All in the family? Journal of the American Academy of
Child and Adolescent Psychiatry,46, 1464–1472.
Cohan, S.L., Chavira, D.A., & Stein, M.B. (2006). Practitioner
Review: Psychosocial interventions for children with selective
mutism: A critical evaluation of the literature from 1990-2005.
Journal of Child Psychology and Psychiatry,47,1085–1097.
Dunn, L.M., & Dunn, D.M. (2007). Peabody picture vocabulary
test-IV. San Antonio, TX: Pearson Assessments.
Elizur, Y., & Perednik, R. (2003). Prevalence and description of
selective mutism in immigrant and native families: A con-
trolled study. Journal of the American Academy of Child and
Adolescent Psychiatry,42, 1451–1459.
Hofmeijer, J., Anema, P.C., & van der Tweel, I. (2008). New algo-
rithm for treatment allocation reduced selection bias and loss
of power in small trials. Journal of Clinical Epidemiology,61,
119–124.
Johnson, M., & Wintgens, A. (2007). The selective mutism
resource manual. Brackley, UK: Speechmark Publishing Ltd.
Kaufman, J., Birmaher, B., Brent, D., Rao, U., Flynn, C., Morec-
i, P., ... & Ryan, N. (1997). Schedule for affective disorders
and schizophrenia for school-age children-present and life-
time version (K-SADS-PL): Initial reliability and validity data.
Journal of the American Academy of Child and Adolescent
Psychiatry,36, 980–988.
Kristensen, H. (2000). Selective mutism and comorbidity with
developmental disorder/delay, anxiety disorder, and elimina-
tion disorder. Journal of the American Academy of Child and
Adolescent Psychiatry,39, 249–256.
Langley, A.K., Bergman, R., McCracken, J., & Piacentini, J.C.
(2004). Impairment in childhood anxiety disorders: Prelimin-
ary examination of the child anxiety impact scale-parent ver-
sion. Journal of Child and Adolescent Psychopharmacology,
14, 105–114.
Manassis, K. (2009). Silent suffering: Understanding and treat-
ing children with selective mutism. Expert Review of Neuro-
therapeutics,9, 235–243.
Oerbeck, B., Johansen, J., Lundahl, K., & Kristensen, H.
(2012). Selective mutism: A home-and kindergarten-based
intervention for children 3-5 years: A pilot study. Clinical
Child Psychology and Psychiatry,17, 370–383.
Pinheiro, J.C., & Bates, D.M. (2000). Mixed-effects models in S
and S-PLUS. New York: Springer.
Roid, G.H. (2003). Stanford-Binet IQ scales (5th edn). Itasca, IL:
Riverside Publications.
Sluckin, A., Foreman, N., & Herbert, M. (1991). Behavioural treat-
ment programs and selectivity of speaking at follow-up in a sam-
ple of 25 selective mutes. Australian Psychologist,26,132–137.
Vecchio, J., & Kearney, C.A. (2009). Treating youths with selec-
tive mutism with an alternating design of exposure-based
practice and contingency management. Behavior Therapy,
40, 380–392.
Wichstrom, L., Berg-Nielsen, T.S., Angold, A., Egger, H.L.,
Solheim, E., & Sveen, T.H. (2012). Prevalence of psychiatric
disorders in preschoolers. Journal of Child Psychology and
Psychiatry and Allied Disciplines,53, 695–705.
Accepted for publication: 30 August 2013
Published online: 26 October 2013
©2013 The Authors. Child and Adolescent Mental Health published by John Wiley & Sons Ltd on behalf of the Association for Child and
Adolescent Mental Health.
198 Beate Oerbeck et al. Child Adolesc Ment Health 2014; 19(3): 192–8
