*3.5.2. Overview of the technique*

A weighted vest is a type of sensory-based intervention. A weighted vest is a garment that typically has 1–4 lbs. (approximately 10% of the child's total body weight) of total weight evenly distributed across it [56]. These vests are primarily applied to preschool and elementary school-aged children with the diagnoses of ASD or attention deficit disorder [56]. The weighted vest is worn according to a pre-determined schedule at certain times of the day, including during everyday activities and for specified tasks at home, in the classroom, or in the community. The vest is typically applied for less than 1 h, one to two times per day during tabletop type tasks [56]. These are general intervention recommendations, but not a manualized approach. Lacking a standardized protocol for the weighted vest, most occupational therapists rely on clinical reasoning in devising an appropriate wearing schedule [57].

## *3.5.3. Review of the evidence*

According to reviews, studies regarding the use of weighted vests are limited in size, scope, and quality. In a meta-analysis study of single subject designs, Stephenson and Carter reported that using weighted vests among young children was on the ineffective side, partially due to small sample sizes and poor methodology within the literature [58]. In another meta-synthesis by Losinski and associates, the research studies included were found to be of low quality, with the effects of deep pressure via weighted vests for individuals with disabilities (including ASD) were small among the variables of attention, disruptive behavior, self-injury, and stereotypy [59].

Small scale studies offer mixed results of the use of weighted vests. McGinnis and associates, reported that young children with ASD actual enjoy using weighted vests, and the application of these vests may serve as positive reinforcement, rather than bringing about changes in sensory processing [60]. Another study using an AB single subject design, found that weighted vests did not decrease problem behaviors (distraction, emotional reaction, withdrawal, escape/avoid, etc.) nor facilitate joint attention with primary caregivers among four toddlers with ASD and sensory processing difficulties [55].

The evidence in support of using weighted vests to address challenging behaviors rooted in sensory processing is almost absent, with additional research exploring the intervention with more typical behaviors among individuals with ASD. As such, AOTA does not include the use of weighted vests as a therapeutic technique in its publications. This is exemplified in two recent seminal works that therapists rely upon to guide practice: *Autism: A Comprehensive Occupational Therapy Approach* [61] and *Occupational Therapy Practice Guidelines for Individuals with Autism Spectrum Disorder* [62]. Due to the lack of evidence, weighted vests should be used with caution. Any use of weighted vests should be aligned with strong diagnostics related to sensory processing behaviors, deficits, and outcomes.
