There is a very small amount of high quality research evidence (one large controlled trial and one small controlled trial) and a small amount of low quality research (nine single-case design studies with three or more participants) into the use of weighted items for children and young people on the autism spectrum.
There is insufficient evidence to determine if weighted items provide any benefits to children and young people on the autism spectrum. There is no evidence to determine if weighted items provide any benefits to adults on the autism spectrum.
Various authors have made recommendations about the need for future research into weighted items. For example, Stephenson and Carter (2008) made a number of recommendations on future research into weighted vests.
“While it should be acknowledged there is only a limited body of research, on balance, indications are that weighted vests are ineffective. There may be an arguable case for continued research on this intervention but future investigators need to ensure that: criteria for participant selection are replicable and justifiable; participants are adequately described; interobserver reliability is satisfactorily established; observers are blinded to the presence of weight in the vests; results are appropriately interpreted with consideration of the functional magnitude of changes; more stringent research designs (such as alternating treatment or multiple baseline designs) are employed.”
We agree and would also suggest that there is a need for more research into weighted items which uses scientifically robust, experimental methodologies with larger numbers of more diverse participants. That research should investigate whether weighted items are more or less effective than other interventions designed to help with sensory issues (such as physical exercise) and whether specific individuals are more likely to benefit from weighted items than other individuals.
That research should also involve people on the autism spectrum in the design, development and evaluation of the studies.
There is also a need for a set of agreed protocols on how weighted items should be used, for example, how much they should weigh, how long they should be used for and under what circumstances.