REVIEW ARTICLE pISSN 1225-729X / eISSN 2233-9183

J Korean Acad Child Adolesc Psychiatry 2019;30(4):136-144

https://doi.org/10.5765/jkacap.180035

Review of Early Intervention for Children

with Autism Spectrum Disorder:
Focused on Randomized Controlled Trials
Young-Hui Yang
Department of Child and Adolescent Psychiatry, National Center for Mental Health, Seoul, Korea

Early identification and intervention for autism spectrum disorder (ASD) were reported to be important for outcomes or clinical courses.
However, there have been a few robust evidences for effectiveness of early intervention until now. This review aims to identify the effec-
tiveness of early intervention by investigating the randomized controlled trial (RCT) of early intervention for autism. There are some
RCT studies using behavioral program. Although there are some significant findings, the outcome measurements and small sample size
are the limitations. Further studies are needed.

Key Words: Autism spectrum disorder; Early intervention; Randomized controlled trial.
Received: November 27, 2018 / Revision: May 7, 2019 / Accepted: August 28, 2019
Address for correspondence: Young-Hui Yang, Department of Child and Adolescent Psychiatry, National Center for Mental Health, 127 Yongmasan-ro,
Gwangjin-gu, Seoul 04933, Korea
Tel: +82-2-2204-0118, Fax: +82-2-2204-0394, E-mail: yhyang12@korea.kr

INTRODUCTION behavioral therapy [2].

ASD was first reported by Kanner in 1943 and recognized
Developmental disorders are characterized by delays, de- as a distinct disorder in the 1970–80s. This group of disorders
viations, or impairments of functions such as cognition, so- is mostly treated with special education and behavioral ther-
cial interaction, and language in early life. Developmental apy, which can improve social interaction, including com-
disorders can be broadly divided into intellectual disorders, munication.
autism spectrum disorders (ASD), and language disorders. The importance of early intervention in ASD has been em-
Intellectual disorders and language disorders are diagnosed phasized [3], but the definitions and composition of early in-
in cases where intelligence, adaptive ability, or language de- tervention are still unclear. Specifically, the timing of inter-
velopment are at least 2 standard deviations below the mean vention is uncertain, whether ‘early’ is relative to the time of
for the patient’s age group, and the patient shows a level of diagnosis, or whether intervention needs to be started before
dysfunction that restricts daily living. ASD is diagnosed in 3 years of age. According to a report on the state of focused
cases showing persistent deficits or deviations in social in- early interventions in South Korea, special education and be-
teractions and repetitive, restricted patterns of behaviors or havioral therapy are provided for over 20 hours/week for chil-
interests [1]. These disorders can exist independently but of- dren aged 2–3 years [4]. Overseas, the National Research
ten present together. ASD especially is a complex disorder Council recommends 15–25 hours/week of therapeutic in-
that can show impairments in intellect, language develop- tervention for children aged between 18 months and 5 years
ment, and social interaction simultaneously. [5]. The uncertainty regarding the definitions and methods
Intellectual disorders typically persist throughout a per- of early intervention reflects the lack of research on specific
son’s entire lifetime, but the course of the disease can differ treatment methods and their effectiveness, which, in turn, is
depending on intelligence quotient, environmental support, because these studies are difficult to undertake [3]. In partic-
and the underlying medical or genetic conditions. Daily func- ular, there are obstacles in evaluating early interventions ef-
tion can be expected to improve with special education and fectiveness, that can be readily measured. And there are is-
This is an Open Access article distributed under the terms of the Creative Commons sues of generalization because the treatment effects sometimes
Attribution Non-Commercial License (https://creativecommons.org/licenses/by-nc/4.0)
which permits unrestricted non-commercial use, distribution, and reproduction in any
are not sustained in daily living outside of the structured treat-
medium, provided the original work is properly cited. ment environment [6]. When the effects of applied behavior

136 Copyright ⓒ 2019 Korean Academy of Child and Adolescent Psychiatry

 YH Yang

intervention were analyzed based on data from previous stud- RESULTS

ies, the effects were unclear, and the authors concluded that
further research was needed [7]. We classified the selected studies based on the identity of
In spite of these restrictions, several studies have reported the person providing treatment directly to the children with
that early diagnosis and intervention for ASD results in posi- ASD. There were 12 studies where the intervention was ad-
tive effects in the later course of the disorder [8,9]. When test- ministered by the parents or guardians, 4 studies where treat-
ing the effectiveness of a treatment, randomized controlled ment was provided directly by a therapist, and 2 studies where
trials (RCTs) provide stronger evidence than single-group the intervention was administered by a school teacher or
studies or case reports. Therefore, in this study, we reviewed teaching assistant. Among interventions in which treatment
RCTs related to early intervention for ASD. was provided directly by a therapist, studies with and with-
out training for parents were both included.
METHODS The early interventions reported in the 18 studies were
broadly based on behavioral therapy but depending on the
The current study was limited to interventions based on techniques or principles presented for the main treatment
behavioral therapy and social skills training as early inter- methods, these were divided into ‘applied behavioral analy-
ventions for ASD in RCTs. Studies were restricted to original sis (ABA) early intervention,’ ‘joint attention (JA) early inter-
articles with a publication date between 2000 and 2017. This vention,’ and ‘social skill-communication (SC) early interven-
range was selected based on the considerations that RCTs af- tion.’ There are overlaps between these classifications, since
ter 2006 were reported when reviewing the American Acad- JA can be included as social skills, and ABA can improve so-
emy of Child and Adolescent Psychiatry (AACAP) practice cial skills; nevertheless, for the purposes of this review, we
parameters in 2014 [3], and that the previous AACAP ASD arbitrarily divided early interventions according to the prin-
guidelines [10] were published in 1999. ciples and technique emphasized by the authors. This classi-
fication is largely consistent with previous research, in which
Literature search and selection interventions were divided into behavioral, social-commu-
We used the following procedure to select studies for anal- nication focused, and multimodal developmental interven-
ysis in this review. For search terms, we defined the disorder tions [11]. There were 3 studies using ABA early intervention,
name as ‘autism,’ research methods as ‘randomized/random- 8 studies using JA early intervention, and 7 studies using SC
ized,’ ‘controlled,’ and ‘RCT’ and the subjects and intervention early intervention. Among the 18 studies, several studies test-
methods as ‘early,’ ‘child,’ ‘children,’ and ‘intervention.’ Then ed the effectiveness of the same early interventions under dif-
we searched using combinations of these terms. For the search ferent circumstances; in these cases, rather than selecting one
engine, we used Pubmed. We restricted the search to original representative study, we included all the studies in our analysis.
articles written in English. We excluded systematic reviews,
meta-analyses, and review articles. The initial literature search ABA early intervention (Table 1)
returned 810 studies. Of these, we excluded duplicates, and Dawson et al. [12] administered the Early Start Denver Mod-
we selected 41 studies that met the following conditions based el (ESDM), an early intervention based on the principles of
upon the inspection of the titles and abstracts. The inclusion ABA, to toddlers with ASD aged 18–30 months. Compared
criteria were: 1) participants aged 6 years or younger and di- to the control group, who only received a general intervention
agnosed with autism or ASD; 2) RCT design; and 3) compari- that could be administered in the local community, the ESDM
son groups include at least 10 persons each. The exclusion cri- group showed significant improvements in intelligence, lan-
teria were: 1) studies of participants with cerebral palsy, epilepsy, guage, adaptive behavior, and changes in autism diagnosis.
or genetic disease; 2) studies on comorbid psychiatric disor- The treatment schedule was 2 hours/session, 2 sessions/day,
der or accompanying symptoms; 3) studies of the high ASD 5 days/week and was provided directly by a therapist. The par-
risk groups; 4) studies testing the efficacy of substances, drugs, ents received education regarding the treatment twice per
or alternative therapy; 5) studies testing the efficacy of art month and participated in the treatment, as well. The ESDM
therapy, music therapy, transcranial magnetic stimulation, group showed a mean increase of 17.6 in intelligence scores,
therapy using robots or multimedia, biofeedback therapy, or where intelligence and language were measured using the
auditory therapy; and 6) case reports, open trials, or reports of Mullen Scales of Early Learning. One study examined the ef-
long-term follow-up observations. After inspecting the full fects of early intervention on language development based
text of the 41 studies, we finally selected 18 original articles on pivotal response treatment (PRT), and reported improve-
that met the inclusion/exclusion criteria. ments in language development and adaptive communica-

http://www.jkacap.org 137
 Early Intervention for Autism

tion skills. The participants in this study [13] were autistic

therapist

Caregiver

Caregiver
children with language deficits between 2 and 6 years old.

Therapist,
Main

parent
The intervention was performed through a usual local treat-
ment service, and the direct intervention was administered
every week for 12 weeks by parents who had received instruc-
Outcome

Significant

Significant

Significant
tion from a therapist. The control group received education
for parents of children with ASD for the same duration. The
usual local serive also were provided to them.

2) Shared positive affect

There was also an early intervention for ASD that aimed
communication skill

2) Adaptive behavior
communication to promote emotional reciprocity, functional communica-

3) Autism diagnosis
Measure

tion, and positive affect sharing with others. This interven-

tion, the Social ABCs, used the PRT technique and is based
1) Utterance
2) Adaptive

on ABA. This intervention was administered via the parents

1) Vocal

to ASD toddlers aged 16–30 months. The intervention was

1) IQ

added to a usual treatment service. Compared to the control

group that only received usual treatment, the toddlers in in-
Table 1. Randomized controlled trial of applied behavior analysis early intervention for children with autism from 2000 to 2017

tervention group showed significant improvements in vocal

group+community
Psychoeducation

communication [14]. However, of the total 62 participants

Control

Service as usual

in this study, 42 children had a confirmed diagnosis of ASD,

intervention
Community-
treatment

while the other 20 children only had significant ASD-relat-

ed symptoms at the beginning of the study.
Intervention

ABA: applied behavioral analysis, ASD: autism spectrum disorder, PDD: pervasive developmental disorder

JA early intervention (Table 2)

model-therapist and
The early start denver
Social ABCs+service
group+community

A study conducted by Drew et al. [15] administered an in-

parents mediated,

tervention for 12 months to pre-school children with a mean

Patients

Pivotal response

parent training

age of 23 months through parental training focused on JA.

ABA based
treatment

treatment

The intervention was performed in addition to general local

as usual

therapeutic interventions. Compared to the group that re-

ceived general local services alone, the intervention group
showed significant improvements in language according to
16 to 30 months old
deficit, 2 to 6 years

a parent-reported assessment.
ASD with language

months old (n=24)

or PDD, 18 to 30
confirmed ASD,
Control

There was one follow-up study using an early intervention

Autistic disorder
Suspected or

based on the intervention described by Drew et al. [15]. In

old (n=26)

this study [16], an intervention focusing on JA and language

(n=32)
Participants

skills was administered through parental training. Compared

to the control group, the intervention group showed no dif-
ferences in language or overall improvements. Specifically,
17 to 30 months old
deficit, 2 to 6 years
ASD with language

months old (n=24)

the intervention was administered to autistic toddlers aged

or PDD, 18 to 30
confirmed ASD,
Patients

Autistic disorder

12–42 months at home for a duration of 12 months by care-

Suspected or

givers who had received instruction from a therapist. The

old (n=27)

therapist’s caregivers was provided for 2 hours/week for 4

(n=30)

weeks, then for 3 hours at a home visit once every 6 weeks.

At the home visit, the therapist and parent defined target
behaviors, and the parents received feedback regarding the
Year

2015

2017

2010

methods applied during parent-child playtime, and dis-

cussed the possibility of generalization in daily living. In ad-
dition, the therapist taught the parent techniques to enable
Author

et al. [13]

et al. [14]

et al. [12]

the application of behavioral therapy principles, the use of

Dawson
Hardan

non-verbal communication tools, and behaviors to promote

Brian

interaction. Unlike the study by Drew et al. [15], this study

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 Table 2. Randomized controlled trial of joint attention early intervention for children with autism from 2000 to 2017
Participants Intervention Main
Author Year Measure Outcome
Patients Control Patients Control therapist
Drew 2002 Autism, mean age Autism, mean age Parent training program Usual local service 1) Autism severity Significant in Caregiver
et al. [15] 21.5 months old 23.6 months old focused on joint 2) Language language
(n=12) (n=12) attention and joint 3) IQ
action routines+usual 4) Parental stress
local service

Kasari 2010 Autism, 21 to 36 Autism, 21 to 36 Caregiver mediated Treatment as usual 1) Engagement state Significant Caregiver
et al. [6] months old (n=19) months old (n=19) joint engagement+ 2) Play type
treatment as usual
Oosterling 2010 ASD, 35.2±5.5 ASD, 33.3±6.4 Focus parent training+ Care-as-usual 1) Language Non-significant Caregiver
et al. [16] months old (n=36) months old (n=31) care-as-usual 2) General improvement
3) Engagement, early
precursor of social
communication,
parent skill
Kasari 2014 Autism, 2 to 5 years Autism, 2 to 5 years Active parents coaching Parents group 1) Joint engagement Significant in Caregiver
et al. [19] old (n=51) old (n=44) based on JASPER+ education+treatment 2) Social communication joint attention
treatment as usual as usual and play type
Kasari 2015 ASD, 22 to 36 ASD, 22 to 36 JASPER+early intervention Psychoeducational 1) Joint attention Significant, large Caregiver
et al.[20] months old (n=43) months old (n=43) program intervention+early 2) Play type effect size in joint
intervention program 3) Language engagement
4) Parenting stress
Kasari 2006 Autism, 3 to 4 years old Autism, 3 to 4 years Discrete trial training+ Existing early 1) Joint attention Significant Therapist
et al. [17] (joint attention group, old (n=17) floor intervention for intervention program 2) Play type
n=20, symbolic play each treatment goal
group n=21) (joint attention, symbolic
play)+existing Early
Intervention Program
Kaale 2012 Autistic disorder, Autistic disorder, Joint attention Preschool program 1) Joint attention Significant Teacher
et al. [18] 29 to 60 months old 29 to 60 months intervention+preschool 2) Joint engagement
(n=34) old (n=27) program
Shire 2017 Autism, mean age Autism, mean age Community-partnered Treatment as usual 1) Joint attention Significant Teaching

http://www.jkacap.org
et al. [21] 31.7 months old (n=56) 31.5 months old (n=56) JASPER program 2) Paly type assistant
JASPER: Joint Attention Symbolic Play, Engagement, and Regulation

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YH Yang
Early Intervention for Autism

did not show any significant treatment effect. The authors after 1 year. The change of engagement state and play type
proposed that this might be due to not only differences in the were two main outcomes. Engagement state was assessed us-
participants and study methods between two studies, but ing the categories of ‘unengaged/other engagement,’ ‘object
also the high standard of usual community service in their engagement,’ and ‘joint engaegemnt.’ Play type was divided
country, which was provided to both group in current study. into functional play and symbolic play. Compared to the con-
In 2006, Kasari et al. [17] performed an RCT on an early trol group, who only received usual intervention services in
intervention using JA and play. Kasari et al. names later in- general circumstances, the frequency of joint engagement
terventions based on these principles Joint Attention Symbol- was higher in the intervention group, who also showed in-
ic Play, Engagement, and Regulation (JASPER), and 5 fur- creased frequency of JA responses and functional play.
ther studies were conducted after 2006 [6,18-21]. The study In a study conducted in Norway [18], a JA-based interven-
in 2006 produced an early intervention manual that aims to tion was administered to autistic preschool children twice
improve JA and symbolic play, based on the idea that autis- per day, 5 days/week, for 8 weeks, which made a total of 80
tic children showed delays or deficits in these areas, and im- sessions. This intervention was administered by school teach-
plemented this manual for autistic children aged 3–4 years. ers under the weekly guidance of a trained therapist based
The intervention was performed for 30 minutes/day, for 5–6 on the manual developed by Kasari et al. in 2006 [17]. Both
weeks. The JA intervention group contained 20 children, the the intervention group and the control group were provided
symbolic play group contained 21 children, and the control with a preschool program, which is a professional full-day
group contained 17 children. Treatment goals were estab- early education and care program provided to preschool chil-
lished for each group. In the actual intervention, the discrete dren aged 1–5 years in the Norwegian community. The JA
trial training (DTT) technique was used for 5–8 minutes, intervention was additionally provided to the intervention
based on ABA, to train the target behaviors through prompt- group. Compared to the control group who only received the
ing and reinforcement at a table. Thereafter, the target be- preschool program, the intervention group showed a higher
haviors were trained in naturally occurring, semi-structured frequency of JA in interactions with teachers.
situations on the floor. The basic principles applied here were In one study of a JASPER early intervention [19] adminis-
to follow the child’s interests and lead, to talk about what the tered via parents to autistic children aged 2–5 years from low
child was doing, or to repeat back what the child said. Other resourced families, the intervention was performed for 2
principles were to expand on the child’s conversation and hours/week for 12 weeks. For the intervention group, a ther-
provide corrective feedback, to sit close to the child and make apist instructed caregivers about daily living based on the
eye contact, and to create environmental adjustments to en- principles of the JASPER intervention in order to increase JA
gage the child. These principles, based on previous studies, and symbolic play. This process was conducted at home. For
encouraged imitating the child’s behaviors towards toys and the control group, only the caregivers were educated for the
used the child’s interests to develop play. In the JA group, same duration. After the intervention, the intervention group
target behaviors were divided into behaviors initiating JA and showed changes in JA and play patterns. This study did not
responding to JA, and the target behaviors in these catego- measure intelligence, language, or adaptational function to
ries were then further subdivided. Similarly, in symbolic play, assess the treatment effects.
target behaviors were defined by the specific stage of play. Later, in 2015, in a study comparing the effects of a parent-
These target behaviors were trained repeatedly in treatment. mediated JASPER intervention with parent psychoeducation
As a result, the respective groups showed significant chang- [20], joint engagement showed an improved pattern in the
es in JA and play behaviors compared to the control group. JASPER intervention group. Both groups were provided usual
Kasari et al. [6] examined effects of a caregiver mediated early intervention for toddlers with autism.
joint engagement intervention for autistic toddlers aged 21– In a study examining the effectiveness of JASPER inter-
35 months in 2010. In this study, the intervention consisted vention in the local community [21], the JASPER intervention
of 24 sessions, with 3 sessions/week for 8 weeks. In this in- group showed significant improvements in JA and play be-
tervention, a therapist instructed the caregivers in child-care- haviors compared to a usual treatment group. In this study,
givers interactions, and the intervention was implemented teaching assistants were supervised by trained therapists,
by the caregivers. This treatment was based on the princi- and the intervention was performed for 10 weeks for tod-
ples in the floor of intervention from the 2006 study by Kasa- dlers with a mean age of 31 months.
ri et al. [17]. Each session was 40 minutes, and the program
was composed of 10-session modules. The study assessed Social skill-communication early intervention (Table 3)
the effects of the intervention before and after treatment, and A study by Aldred et al. [22] examined the effects of an in-

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 Table 3. Randomized controlled trial of social skill-communication early intervention for children with autism from 2000 to 2017

Participants Intervention Mian

Author Year Measure Outcome
Patients Control Patients Control therapist

Aldred 2004 Autism, 29 to 60 Autism, 24 to 56 Parent delivered social Routine care 1) Autism severity Significant Caregiver
et al. [22] months old (n=14) months old (n=14) communication 2) Language
intervention+routine 3) Parent-child
case interaction

Green 2010 Core autism, 2 to 4 Core autism, 2 to 4 Parent medicated Treatment as usual 1) Autism severity Non-significant Caregiver
et al. [23] years old (n=74) years old (n=72) PACT+treatment 2) Parent-child in reduction of autism
as usual interaction severity
3) Language and
adaptive functioning

Carter 2011 ASD, 21.11±2.71 ASD, 21.51±2.82 Hanen’s ‘More than Business-as-usual 1) Children’s Significant in children Caregiver
et al. [24] months old (n=32) months old (n=30) Words’+non-project communication with lower level
treatment 2) Parental responsivity object interest

Solomon 2014 Autism & PDD nos, Autism & PDD nos, PLAY Project home Treatment as usual 1) Autism symptoms Significant in parent- Caregiver
et al. [28] 50.5±10.0 months 49.85±10.4 months consultation 2) Parent and child child interactions and
old (n=64) old (n=64) Intervention+treatment interactions autism symptoms
as usual 3) Development
outcomes
4) Parent outcomes

Wetherby 2014 ASD, 16 to 20 ASD, 16 to 20 Individual early social Group early social 1) Social Significant Caregiver
et al. [27] months old (n=42) months old (n=40) intervention intervention communication
2) Adaptive behavior
3) Developmental level

Landa 2011 ASD, 21 to 33 ASD, 21 to 33 Interpersonal synchrony Non-interpersonal 1) SEI Significant in SEI Therapist
et al. [25] months old (n=24) months old (n=24) synchrony 2) IJA
3) SPA

Ingersoll 2012 Autism, 39.3±7.3 Autism, 36.5±8.0 Focused imitation Treatment as usual 1) Initiation of joint Significant Therapist
et al. [26] months old (n=14) months old(n=13) intervention+treatment attention

http://www.jkacap.org
as usual 2) Social-emotional skill

IJA: initiation of joint attention, PACT: preschool autism communication trial, PLAY: play and language for autistic youngsters, SEI: socially engaged imitation, SPA: sharing of posi-

141
YH Yang

tive affect
Early Intervention for Autism

tervention to improve communication during play between 3 individual parent-child sessions at home.
parents and children. In this study, the usual intervention ser- When a social communication intervention was added to
vice was maintained, and a social communication interven- supplement a preexisting comprehensive early intervention,
tion was added for children with autism aged 29–60 months. compared to a group that simply continued the preexisting
This intervention was performed directly by the parents. The intervention, there were improvements in social communi-
parents and child attended monthly treatment sessions for 6 cation. In this study [25], DTT, PRT, routine-based interac-
months, followed by a further 6 months of less frequent main- tion, visual cues, and low-tech augmentative communication
tenance sessions. The intervention group received regular systems were used for toddlers with ASD aged 21–33 months
therapist contact once per month for 6 months, and thereaf- to additionally reinforce activities related to interactions with
ter, once every 2 months for another 6 months. When the two others, such as imitation, JA, and positive affect sharing.
groups were compared after 12 months, the intervention group Then, analysis was performed to verify whether social inter-
showed improvements in autistic symptoms assessed using actions improved. The additional activities consisted of imi-
the autism diagnostic observation schedule (ADOS), as well tating another person during social interactions, placing ob-
as improvements in expressive language and parent-child jects or pictures related to a situation on a wall, or imitating
interactions. another person performing funny behaviors. The interven-
Green et al. [23] examined the effects of the parent-mediat- tion was performed for approximately 2.5 hours/day, 4 days/
ed preschool autism communication trial (PACT) interven- week for 6 months. The intervention was provided by a ther-
tion, which focuses on communication. The participants in apist in a classroom, and parent education was also provided
this study were 146 children between the ages of 2 years and to facilitate the continuation of these activities at home. The
4 years 11 months, who were evaluated for severity of ASD results showed an improvement compared to the control
according to the ADOS-generic (ADOS-G) and autism diag- group in imitation in accordance with social situations.
nostic interview-revised (ADI-R). This intervention consisted Imitation is important in social development. One study
of methods to first improve the sensitivity and responsiveness developed Reciprocal Imitation Training and examined its
of parents to the child , and then to increase communication effects on JA and social skills [26]; compared to a control
with the child using strategies such as action routines, famil- group that only received usual treatment, the intervention
iar repetitive language, and pauses. The intervention was im- group showed significant improvements. This intervention
plemented by the parents, who were guided through the 18- was administered by a therapist to ASD children between
sessions by a therapist. Each session was 2 hours long, and for 27–47 months of age for 3 hours/week for a duration of 10
the first 6 months, there was 1 session every 2 weeks. There- weeks. Although the intervention produced improvements
after, there was 1 session/month for another 6 months. The in social function, the author of this study reported that the
control group continued to receive the usual intervention pro- children’s imitation was not a major mechanism of improve-
vided in the community. When the changes in the two groups ments through a mediation analysis and further studies will
were compared 13 months after the beginning of treatment, be required to understand the treatment components under-
there was no difference in autism symptom severity, but par- lying the improvements.
ent-child interactions showed improvements in the interven- Wetherby et al. [27] compared the effects of early social in-
tion group. The effects on language were small and the two tervention provided by the parents either individually or in a
groups showed no difference in language ability measured group. The participants were toddlers diagnosed with ASD
with a standardized instrument. However, the intervention between 16–20 months old. This study educated the parents
group did show an improvement in parent-rated language. using manualized social communication, emotional regula-
The authors of this study reported that the PACT interven- tion, and transactional support curriculum. Compared to the
tion had no effect on reducing autism symptoms. group therapy group, the individual therapy group showed
Hanen’s ‘More than Words’ intervention is conceived to significant effects on social communication, adaptive behav-
improve communication in ASD. This intervention is im- iors, and developmental level.
plemented directly by the parents under the guidance of a The play and language for autistic youngsters (PLAY) in-
therapist. When this intervention was applied to ASD tod- tervention is a parent-implemented intervention focusing
dlers aged 15–25 months, there was an improvement in com- on social interactions. This intervention is based on the de-
munication ability during daily routines compared to a con- velopmental, individual differences, and relationship-based
trol group who only received usual treatment [24]. In this theory of Greenspan and Wieder. When the PLAY inter-
intervention, the therapist provides education to the parents vention was added to usual treatment for ASD children aged
in 8 group sessions, and in between these 8 sessions, there are 2–5 years, there were significant improvements in parent-

142
 YH Yang

child communication and autism symptoms [28]. In this vention were used as the efficacy outcome. For example, in-
study, the caregivers received guidance from a PLAY con- terventions targeting JA assessed increases in JA, or studies
sultant using coaching, modeling, and video feedback dur- aiming to increase interactions with parents assessed inter-
ing 3-hour home visits every month. The consultant taught actions with parents. Given that the treatment process usu-
the parent to recognize and continually respond to the child’s ally occurs in stages, the target behaviors will be better ac-
signals and guided the child to participate in interactions complished in the intervention group. These, poor JA and
effectively. During modeling, the consultant showed the par- deficit in parent-child interaction, are characteristics that
ent techniques through direct play with the child. Interven- can be observed in ASD and are major targets of treatment,
tion goals and methods were modified each time depending but if these changes cannot be generalized, or if the treated
on the child’s developmental stage, and the duration and fre- children do not show changes in overall development or au-
quency were also adjusted. Families were encouraged to al- tism symptoms, there will be limitations in assessing the ef-
locate 15–20 minutes of playtime several times a day, to fects of treatment. On the contrary, in a large study of ASD
achieve a total of approximately 2 hours of playtime per day. children with over 70 participants per group [23], the inter-
vention was reported to show no effect in reduction of autism
DISCUSSION symptoms. Therefore, it may be necessary to measure overall
or specific autism symptoms rather than only target behav-
When we reviewed RCTs on early intervention for ASD iors, and to measure long-term changes rather than only short-
from 2000 to 2017, there several more studies than expect- term changes immediately after treatment.
ed, and some studies used blinding methods in order to ex- The study by conducted Carter et al. [24] showed, differ-
amine its effectiveness. Almost all studies used a design ent effects depending on the characteristics of the ASD chil-
where the control group and intervention group both con- dren, and there was an analysis seeking to understand the
tinually received a preexisting intervention or usual local mechanisms for improvements [26]. This indicates that,
treatment service, and the intervention group additionally through similar research designs or analyses, it will be pos-
received the experimental program to test its effects. Treat- sible to individualize early intervention treatments in the
ment duration varied from as little as a few weeks up to 2 future.
years. Of the 18 studies we reviewed, 17 studies showed im- In addition, early intervention studies use diverse termi-
provement in partial or all variables of interest compared to nology to express the similar meanings, and this can lead to
the control group; in one study [16], none of the measured difficulties in understanding and implementing the inter-
variables showed any significant differences between the ventions in detail. In particular, given that 12 out of the 18 in-
groups. Of the 18 studies, the intervention was implement- terventions were implemented directly by parents or caregiv-
ed by the parents under the guidance of a therapist in 12 ers, who are non-experts, this could be an even greater obstacle
studies, directly by a therapist in 4 studies, and by school- to the early intervention approach. Early intervention devel-
teacher in 2 studies. This shows the importance of parent opers and researchers need to make efforts to clearly classify
training in early intervention. and define interventions using common, widely understood
In this review, we arbitrarily divided interventions into terms. In the case of interventions that do not belong to an
ABA, JA, and SC interventions based on the techniques and existing classification, it will be necessary to introduce the
objectives emphasized by the authors. Many programs were principles and specific implementation methods in more
based on principles of behavioral therapy and implemented detail.
interventions using methods such as play. The target behav-
iors included JA, play patterns, improved interaction with CONCLUSION
parents, language development, and parent responsiveness.
Variables used to examine the effects of the interventions There have been various RCTS between 2000 and 2017 re-
included changes in target behaviors, autism symptom se- garding early interventions. There were a large number of in-
verity, intelligence, adaptive behaviors, overall developmen- terventions implemented by the parents under the guidance
tal level, and even parental stress. of an expert therapist. When we investigated behavioral and
In most studies, the variables directly related to the target social skills therapy as early intervention for ASD, compared
behaviors showed significant improvements, but improve- to the RCTs shown in existing guidelines [3], there were more
ments in overall autism symptoms, intelligence, or language studies pursuing improvements in JA, social interactions,
were limited. This appears to be because, in many studies, social skills, and language development. In future studies, it
changes in the behaviors targeted by the experimental inter- will be necessary to measure the course of autism symptoms,

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Early Intervention for Autism

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Acknowledgments vention for toddlers with autism spectrum disorder. Autism Res 2017;
This study was supported by National Center for Mental Health. 10:1700-1711.
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The author has no potential conflicts of interest to disclose. vention for pre-school children with autism. Preliminary findings
and methodological challenges. Eur Child Adolesc Psychiatry 2002;
ORCID iD 11:266-272.
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