1) The Use of Weighted Vests with Children with Autism Spectrum Disorders and Other Disabilities PDF

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J Autism Dev Disord (2009) 39:105–114 DOI 10.1007/s10803-008-0605-3

O R IG IN AL P AP E R

The Use of Weighted Vests with Children with Autism Spectrum Disorders and Other Disabilities Jennifer Stephenson Æ Mark Carter

Published online: 1 July 2008  Springer Science+Business Media, LLC 2008

Abstract Therapists who use sensory integration therapy may recommend that children wear weighted vests as an intervention strategy that they claim may assist in remediating problems such as inattentiveness, hyperactivity, stereotypic behaviors and clumsiness. Seven studies examining weighted vests are reviewed. While there is only a limited body of research and a number of methodological weaknesses, on balance, indications are that weighted vests are ineffective. There may be an arguable case for continued research on this intervention but weighted vests cannot be recommended for clinical application at this point. Suggestions are offered for future research with regard to addressing methodological problems. Keywords Sensory integration  Weighted vests  Autism  ADHD

Sensory Integration (SI) therapy is a popular and widely used therapy for children with autism (Green et al. 2006; Roberts 2004). Green et al. reported that 38.2% of children with autism were currently receiving SI and 33.2% had received it in the past. SI has been recommended for people with autism, cerebral palsy, learning disabilities, intellectual disability, ADHD, communication difficulties and other problems (Densem et al. 1989; Mauer 1999; Olson and Moulton 2004a). Sensory integrative therapy is based on the proposition that functional performance deficits in individuals result from a failure to appropriately process sensory information. J. Stephenson (&)  M. Carter Macquarie University Special Education Centre, Macquarie University, Sydney, NSW 2109, Australia e-mail: [email protected]

Therapy is directed at altering underlying neurological processing (Ottenbacher 1982; Schaaf and Miller 2005; Vargas and Camilli 1999) rather than developing skills directly. Traditionally, intervention has involved treatment sessions delivered by an occupational therapist in which controlled sensory stimulation is provided. Such intervention typically involves such activities as brushing and rubbing of the body, deep pressure and compression of joints, as well as use of hammocks and scooter boards to provide stimulation (see Ayres 1972; Hoehn and Baumeister 1994; Smith et al. 2005). A more recent innovation has been the use of ‘‘sensory diets’’ that involve activities and environmental adjustments, purported to complement the individual’s individual sensory needs (Smith et al. 2005). A recent treatment generally included under the umbrella of SI is the wearing of weighted vests. A weighted vest is ‘‘…a vest that typically has 10% of a person’s body weight evenly distributed around the vest.’’ (Olson and Moulton 2004b, p. 53). Therapists working within a sensory integrative therapy framework believe that a range of problems, such as inattentiveness and stereotypic behaviors, may be due to over- or under-sensitivity to sensory input. A weighted vest can provide sensory input that is believed to alleviate some of these difficulties (Olson and Moulton 2004b). Specifically, it is argued that wearing weighted vests provides the individual with deep pressure stimulation that has a calming (VandenBerg 2001; Deris et al. 2006) and organizing (Deris et al. 2006) effect on the central nervous system. It has been suggested that such pressure may affect several deep brain structures, including the reticular activating and limbic systems, thus decreasing arousal (VandenBerg 2001). Changes in underlying neurological processing of sensory information associated with wearing of weighted vests are proposed to result in improvements in a range of behaviors including

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stereotypy (Deris et al. 2006; Kane et al. 2004–2005), attention (VandenBerg 2001 ; Kane et al. 2004–2005) and hyperactivity (VandenBerg 2001). There is evidence to suggest that weighted vests are used widely in clinical practice and practitioners believe they are effective. Green et al. (2006) reported that 12.8% of children with autism were currently using weighted vests or blankets and 25.7% had used them in the past. Olson and Moulton (2004a) surveyed a convenience sample of 51 occupational therapists, all of whom used weighted vests in their practice, to ascertain their experiences using weighted vests with children with developmental disorders. The therapists reported the use of weighted vests with children with Autism Spectrum Disorder, ADHD, sensory integrative disorder, cerebral palsy, developmental delay, Down syndrome and traumatic brain injury. Therapists reported increases in desirable behaviors and decreases in problem behaviors as result of vest use in children with ASD, ADHD and sensory integrative disorder, although many also noted no change for a range of behaviors. Although the vests were also used to improve posture and balance (especially in children with cerebral palsy), the main use was to ‘‘Calm a child and improve attention to academic classroom work’’ (p. 59). Most of the positive changes were noted while the children wore the vests and some were believed to be maintained after the vest was removed. Weighted vests were often used with other strategies and some therapists believed the vests alone would be insufficient to cause change. This survey showed a range of practices in the use of vests, with no consistency in the weights used (between 0.25 and 2 kg, and up to 10% of the child’s weight) or the length of time worn (10 min to most of the school day). The use of the vests did not vary across disability groups. Olson and Moulton (2004b) also carried out a mail survey of occupational therapists exploring similar questions and obtained a response rate of 68% from a random sample 514 therapists working with children. Of this sample, 56.6% used weighted vests and reported use with people with autism/ PDD, ADHD, developmental delay, cerebral palsy and Down syndrome, mostly pre-school and young elementary school students. Again there was considerable variation in the way the vests were used with weight varying from 2 lbs to over 5 lbs, length of use from under 1 h to over 4 h and from once to four times daily. Most therapists in this survey reported that they thought use of the vests could improve ontask and in-seat behavior and attention to tasks and decrease some self-stimulatory behaviors and high activity levels. Morrison (2007) recently provided an analysis of articles examining the use of weighted vests for children on the autism spectrum. Only three empirical studies were identified and critical analysis of the methodology was restricted. Nevertheless, Morrison concluded that research was limited and more compelling evidence was needed.

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J Autism Dev Disord (2009) 39:105–114

As there is little research support for Sensory Integration therapy as a general intervention strategy, it is of interest to explore the research base for this popular and readily defined practice, with a particular focus on the strength of the research methodology employed. Is there good research evidence to support the use of weighted vests to increase attentive, on-task behavior and reduce distractibility and self-stimulatory behaviors in children with disabilities?

Method A search was carried out using Google Scholar, PsychInfo, ERIC and CINAHL using the search terms ‘‘weighted vest’’ and ‘‘weighted vests’’. The reference lists of articles located in this way were checked for additional studies. Articles located were included in this review if they explored the use of weighted vests to improve the behavior of children with disabilities and presented empirical data. Initially, the intent was to limit the analysis to peer refereed sources but considering the dearth of studies, it was decided to expand the review to non-refereed sources as well.

Results Five peer-reviewed papers were located. An additional study (not peer-reviewed) was located in ERIC (Deris et al. 2006) and a recent poster presentation (Barton et al. 2007) was drawn to our attention by a colleague. See Table 1 for details of studies. Participants Overall, the studies investigated the behavior of 20 students, 9 with autism, 4 with pervasive developmental disorder (PDD), 1 with PDD (not otherwise specified), 1 identified with ASD, 1 identified with developmental delay and autistic-like behaviors, 2 with ADHD and 2 with ADHD and speech and language impairments. The students ranged in age from 2 years 7 months to 11 years, but only four children were older than 7. Participant description was extremely limited in the vast majority of cases, in most instances amounting to little more than an age, diagnostic label and description of behaviors of concern. Only three studies (Kane et al. 2004–2005; Myles et al. 2004; VandenBerg 2001) provided any documentation of how the diagnosis was made. Only two studies provided standardized information on cognitive or developmental performance, although only a disability level was provided by Carter (2005) and data were only provided on 2 of 3 participants by Myles et al. (2004).

Study

Participants and behavior

Design

Vest characteristics

Reported Outcome

Deris et al. (2006) (ERIC document)

4 year old boy with ASD. Attention to task and self-stimulation

Alternating treatment design comparing no vest, to pressure vest and weighted vest

Weight—3 lbs (approx 10% of body No clinically significant effect on selfweight). Worn for 30 min intervals stimulation or attention to task every 2 h throughout day. Assessed after having worn vest for at least 15 min

Barton et al. (2007) (Poster)

No details of weight. Tommy wore Alternating treatment design comparing No difference in engagement across irregularly and Bert wore for part of conditions weighted vest, vest without weights and no each school day vest (observers were blinded when vest was Tommy’s problem behaviors increased 4 year old boy with developmental-delay weighted. Engagement, non-engagement, while wearing the vest, but and autism-like behaviors (Bert) stereotypic behavior and problem behavior stereotypic behaviors decreased were measured during morning table-time activities (painting, gluing, coloring and cutting)

Carter (2005) (Refereed article)

4 year old boy with autism

4 year old boy with autism (Tommy)

Alternating treatment functional analysis of SIB (attention, demand, alone and play conditions) when infection was present/ absent and when vest was present/absent

Self-injurious behavior (hitting head or back of hand) Fertel-Daly et al. 2 years 7 month girl with PDD (2001) (Refereed article)

Weight—3 lb (7.5% pf body weight) SIB was more likely to be present when student had a sinus infection, high rates across all conditions showed it was maintained by automatic reinforcement Worn during 5 min assessment sessions

Observation of behavior during a 5-min fine motor activity

Presence or absence of vest had no effect

Weight of 1 lb in all vests. Worn for 2 Participant 1 showed most attention, fewest distractions in the vest hr and observations made after the condition, and least self-stimulatory vest was worn for 1.5 h behavior in baseline

2 years 10 month boy with PDD

Participant 2 showed most attention and least distraction in the vest condition and most self-stimulatory behavior in the withdrawal condition

3 years 1 month boy with PDD

Participant 3 showed most attention and least distractions and stereotypy in the vest condition Participant 4 showed most attention in the vest condition, least distraction in the vest condition and least stereotypy in the withdrawal condition

2 years 9 month girl with PDD

J Autism Dev Disord (2009) 39:105–114

Table 1 Summaries of studies reviewed

Participant 5 showed most attention in the vest condition, least distraction and least stereotypy in the vest condition

All had some self-stimulatory behavior and problems attending to task

These judgments were made on means 107

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2 years 10 month boy with autism

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Table 1 continued Study

Participants and behavior

Design

Kane et al. (2004–2005) (Refereed article)

8 year old boy (Jerry) with autism

ABC design involving baseline (no vest); Weight—5% of individual’s body weight Jerry’s attention to task increased weighted vest and vest without weights slightly with the no-weight vest, and (treatments were counter-balanced stereotypy also decreased during this across the 4 participants) condition. Stereotypy was highest during the weighted-vest condition

10 year old girl (Elsie) with autism

Vest characteristics

Reported Outcome

Placed on child 1 min before the 10 min Elsie’s stereotypy occurred during observation session 100% of intervals in all conditions. Attention to task was best in baseline Norman had high levels of stereotypy in all conditions, and attention to task was highest in baseline

11 year old girl (Eileen) with autism

8 year old boy (Norman) PDD-NOS All with stereotypic behaviors

Myles et al. (2004) (Refereed article)

VandenBerg (2001) (Refereed article)

Eileen engaged in stereotypy for 2.5% of intervals in baseline and not at all in either vest condition. Attention to task was highest in baseline Student 1, boy, 5 years 7 months, autism, ABAB designs. Comparing on task Weight—10% of child’s boy weight for Student 1—no clinically significant developmental age 20 months, nonbehavior (first and second students) and student 1 and 5% for students 2 and 3 changes verbal duration of self-stimulation (third student) during school activities. Student 2, boy, 3 years 6 months, autism, Vests worn for duration of activities for Student 2—mean increase of on task Observations were made in 5 min time from 9 to 34% (based on graphic nonverbal student 1 (5 min) and student 2 individual sessions and group sessions data) (15 min). For student 3 vest was worn of unspecified length for student 1 and for 30 min BEFORE activity and Student 3—mean time spent in selfStudent 3, boy, 4 years 11 months, group activities of 15 min for students 2 removed for the activity itself (15 min) stimulation decreased from 19 to 6% autism, developmental age 22 months, and 3 some verbal skills Student 1, girl, 6 years 10 months, speech AB design. Measured ‘‘on-task’’ behavior Weight—5% of child’s body weight Student 1—25% mean increase in time and language impairment, ADHD during a wide range of fine-motor on task while wearing vest activities. A phase, without vest and B phase with vest. Also wore vests at other times

Student 3, boy, 6 years and 9 months ADHD Student 4, boy, 5 years and 9 months, ADHD Excessive movement, overreaction to extraneous stimuli, inability to complete tasks, difficulties with finemotor tasks

15 min observations

Vests put on 5 min before the observation Student 2, 3, 4—Mean increase of 17– interval and removed after 20–30 min 18% time on task

J Autism Dev Disord (2009) 39:105–114

Student 2, girl, 6 years and 6 months speech and language impairment, ADHD

J Autism Dev Disord (2009) 39:105–114

Research Design All studies used small n research designs. Three studies used relatively weak AB (VandenBerg 2001), ABA (Fertel-Daly et al. 2001) or ABC (Kane et al. 2004–2005) designs. Kane et al. (2004–2005) also counterbalanced the treatment order across participants in the intervention phase. Three studies (Deris et al. 2006; Carter 2005; Barton et al. 2007) used variations on the stronger alternating treatment design and Myles et al. (2004) used a series of ABAB designs. Dependent Variables and Observations Results were reported for self-stimulatory or stereotypic behavior (12 students), attention to task or task engagement (17 students), distracted or off-task (5 students) and problem behavior (1 student). With the exception of Carter (2005) who used short functional analysis across 72 sessions, all studies were of relatively short length, involving a total of 11–25 sessions. While the data for student 2 in the Myles et al. (2004) study extended over a potential total of 40 sessions, a considerable amount of the data was missing. Further, the observation periods monitored were very short, between 5 and 15 min in the studies that provided this information.

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was the occupational therapist who was treating the children, and the other was an occupational therapy student. One observer collected baseline data and the other observer collected intervention data, with the observer who collected the intervention data unaware of the results from the baseline phase. In the Fertel-Daly et al. (2001) study, the first author collected all the data. While another observer also collected interobserver reliability data on 20% of sessions, problematically, this was limited to the baseline phase. That is, there was no interobserver reliability collected for the intervention conditions. Myles et al. (2004) failed to report any reliability data for student 2. For student 3, they presented duration data but reported event reliability, making the reliability data irrelevant. Kane et al. (2004–2005) collected no interobserver reliability data at all. Given the nature of the intervention, one obvious way to control for observer expectancy effects would be to use vests both with and without weights and observers blind to these conditions. Only in the study of Barton et al. (2007) were the observers blind to the presence or absence of weight in the vest. While Kane et al. (2004–2005) did include a phase where the vest was worn without weights, the observer was aware of the presence or absence of weight. Results

Independent Variables In the studies that provided both vest weight and participant body mass, vest weight ranged from 5 to 10% of body mass. In the study by Fertel-Daly et al. (2001), a fixed weight was used. There was considerable variation in procedural aspects of the studies. Vests were worn for as little as 5 min (Carter 2005; Myles et al. 2004, student 1) and as much as 2 h continuously. In some studies (Carter 2005; Kane et al. 2004–2005; Myles et al. 2004, students 1 and 2) observation started immediately or soon after vests were placed on participants and in others (Deris et al. 2006; Fertel-Daly et al. 2001; VandenBerg 2001) after a delay of 5 min to 1.5 h. Myles et al. (2004) reported that their third student wore the vest for 30 min prior to the activity and then removed it for the activity and data collection. Reliability The observation and recording arrangements in several studies were less than ideal. While VandenBerg (2001) reported that observers did practice observations on children not involved in the study beforehand to check that they could reach appropriate levels of reliability, they failed to evaluate interobserver reliability for the actual observations in the study. In this study one of the observers

The presence of a weighted vest was reported to reduce the stereotypic behavior of 5 students and attention or engagement in a task was reported as highest in the weighted vest condition for 10 students. The vest had no effect on problem behavior for the 1 student where this was measured. The authors in four studies (Barton et al. 2007; Carter 2005; Deris et al. 2006; Kane et al. 2004–2005) concluded that weighted vests were an ineffective intervention. Authors in one study found mixed results (Myles et al. 2004) and authors in the remaining two (Fertel-Daly et al. 2001; VandenBerg 2001)...