Thursday, October 11, 2012

Do Weighted Vests Work? Two Studies


Last year, two widely different studies published in AJOT (American Journal of OT) looked at the effectiveness of a weighted vest in increasing the on-task behavior in children with poor attention. One study showed an effective protocol, the other showed a protocol that did not work.  Let's look at the methods used in the studies.

What didn’t work

In study 1, by Collins and Dworkin, children wore a standard commercial vest (based on the size of the child) for 15 or more minutes (the length of an activity). Filming of the child’s behavior was started after a 5 minute adjustment period. The recording was 10 minutes long. A total of 9 sessions were recorded over a period of 3-6 weeks.   To make that clear, each child wore a weighted vest for approximately 15 minutes on each of 9 days. They did not wear a weighted vest at other times. The authors report that their weighted vest protocol did not improve attention to task. By the way, these children were typical children in elementary school. No further information is given about them including whether or not they were known to have sensory issues or had been diagnosed with ADHD.

What appears to work

Study 2, by Fertel-Daly, et. al., had children with autism ages 2-4 in a pre-school program wear similar vests for 2 hours on and then two hours off. Children wore the vests 3 days a week. They were given 3 weeks of this protocol to adjust to the vests prior to filming behaviors. All participants had an increase in attention. The smallest child had the best increase, suggesting that the ratio of the child’s body weight to the weight in the vest made a difference. Teachers noted that the level of aggression and self-stimming behaviors were noticeably reduced at the end of the study. The children's attention skills improved overall by the end of the study and did not return to baseline once the vest was discontinued.

Conclusions that Need Re-Validation

1.       The art of “how much weight to use in a vest” says that 5-10%  of the child's bodyweight works best. In study 2, the smallest girl used weight equal to 4% of her body weight – and it worked. Other students who had less vest weight still had good results, but not as good.

2.       Vests are more effective when used consistently over time. Even 3 days a week is effective, but the gains increase as the weeks go by.

3.       The method of 2 hours on and 2 hours off appears to work. A vest that is worn for 15 minutes (as needed) is not effective.

4.       The weighted vests  appear to help pre-schoolers with autism. Would it help elementary children with autism?

5.   Children with autism tend to have sensory issues. It makes sense that a vest (a sensory solution) was successful for them.  Would it also work for a small child with ADHD?
 
6.  In the second study, the children's attention skills improved - and did not return to baseline. What would happen if the protocol were continued? Would the children lose those symptoms?

So many questions, so few answers. Ah, to have a large group, long term study!

 
References

1.       Collins, A., & Dworkin, R. J. (2011). Pilot study of the effectiveness of weighted vests. American Journal of Occupational Therapy, 65, 688–694.

2.       Fertel-Daly, D., Bedell, G., & Hinojosa, J. (2001). Effects of a weighted vest on attention to task and self-stimulatory behaviors in preschoolers with pervasive developmental disorders. American Journal of Occupational Therapy, 55, 629–640.

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