The mythology about prevalence of sensory processing disorders
I was happy to see the American Academy of Pediatrics publish their new policy statement about sensory integration. I know that a lot of people are up in arms about this policy but in my estimation the AAP presents a very fair and balanced assessment.
Defenders of 'sensory processing disoder' are quick to point out that some more recent research was not included in the AAP review. I was disappointed when I read Dr. Miller's letter to the editor where she talked about the 2007 RCT. This was a great study and I think they did an impressive job of looking at limitations in previous studies but it was only a pilot study and it lacked statistical power, there were noted blinding problems, and it relied on GAS which many people believe opens up issues of expectancy and confirmation bias.
My point here is not to rip apart people's efforts because actually it was a good step forward in our research. The problem is that we can't point to studies like this and expect to sway other people's opinions. Significant methodological problems are also present for some of the other 'newer' research that she referenced.
Herein lies the problem with too many of my occupational therapy colleagues. The best analogy I can think of is that OTs are like the kittens who had their eyes sutured shut at a critical period in their development - and then permanent changes happened in the way that they went on to process visual information. Similarly, OTs are inculcated/programmed en masse about sensory integration in their educations - and even though we STILL can't point to what sensory integration disorder even IS it doesn't stop anyone from developing questionnaires, writing books, developing intervention protocols, and in general attributing all manner of atypical childhood behavior to this undefined sensory integration process.
These attributions are taking us into really dangerous territory and in fact they are probably even contributing to AAP feeling the need to address the issue and even more directly it probably contributes to the insurance companies uniformly denying reimbursement for this intervention. We have some really bizarre claims that the evidence-based medicine world just doesn't know what to do with.
The prevalence issue may sit on top of the heap of concerns. These studies (here and here) state that between 5% and 15% of the population has a sensory processing disorder. The problem is that they rely on sensory questionnaires that DO NOTHING to contribute to differential diagnosis. So we really have no way of knowing if these children have any co-morbid disorders. Actually we shouldn't even be using the word "co-morbid" because we don't even know if sensory integration difficulties constitute a disorder and if these traits are just part of other problems. In fairness, the Ben-Hasson, Carter, & Briggs-Gowan (2009) study did control for some diagnostic conditions but the results also showed that gestational age, birth weight, and socioeconomic status were more likely to be associated with sensory over-responding. I guess that means that children who have a history of prematurity may have atypical sensory responsivity - which is no surprise - but does that mean that they have a unique sensory disorder? Or is it more accurate to describe their difficulties in terms of nervous system immaturity when they were born and long term impact of things like mild PVL or IVH? Or does environmental enrichment (or lack thereof) also play a role which is also suggested in the data?
What these studies show is that children may have difficulties with sensory processing skills - or at least they have difficulties that we want to think are associated with sensory processing skills - but that we really can't stretch this and make statements that this 'proves' anything about actual prevalence of a distinct condition.
I am not sure why but over time and after a lot of repetition it seems that people just start repeating these prevalence statements as if they are undisputed facts. In my opinion just about any statement made about prevalence of 'sensory processing disorder' has been an overstatement of our research results.
This is a major reason why I really have no problem with the AAP policy statement. I also think that if there was this kind of prevalence of children with this disorder that I would be seeing it in my clinic - but I just don't. Sure, I see kids with sensory processing difficulties, but these difficulties are almost always associated with other disorders. Most commonly these sensory differences are associated with conditions like ADHD or autism. Less frequently these sensory differences are associated with esoteric clinical problems. There was this case study about the child who had congenital adrenal hyperplasia. Or there was this case study about the child who had a conditioned fear response that caused piloerection and tooth pain. Or I could just talk about the six year old child who I saw a couple weeks ago. The parent brought him in because the child can't stand his clothing and has frequent behavioral meltdowns. All other aspects of his development are normal, and as I scratched my own head trying to figure things out I watched him scratch at his own arms - and then I saw large raised welts appear across his skin. With the parents permission I tested the skin on his legs and back - and indeed the child has dermatographia so I sent him back to the pediatrician who prescribed antihistamines as needed and magically the "tactile defensiveness" to clothing has disappeared.
Why does this matter? Well, mostly because we already know what kinds of interventions are most effective for children who have ADHD. We also know what kinds of interventions are most effective for children who have autism. If we stopped trying to define some 'new' diagnostic entity maybe we would also stop trying to create some 'new' intervention protocol. Then we could fall back to family education, trial practice, skill training, behavior modification, and adaptive/compensatory approaches that we all know work.
The AAP and others in the broader medical community would probably be happy to see some more discretion when we talk about prevalence and whether or not these problems constitute distinct diagnostic entities. OTs need to be willing to 'de-program' themselves from their educational experiences that cause them to call too many things "sensory processing disorders."
Defenders of 'sensory processing disoder' are quick to point out that some more recent research was not included in the AAP review. I was disappointed when I read Dr. Miller's letter to the editor where she talked about the 2007 RCT. This was a great study and I think they did an impressive job of looking at limitations in previous studies but it was only a pilot study and it lacked statistical power, there were noted blinding problems, and it relied on GAS which many people believe opens up issues of expectancy and confirmation bias.
My point here is not to rip apart people's efforts because actually it was a good step forward in our research. The problem is that we can't point to studies like this and expect to sway other people's opinions. Significant methodological problems are also present for some of the other 'newer' research that she referenced.
Herein lies the problem with too many of my occupational therapy colleagues. The best analogy I can think of is that OTs are like the kittens who had their eyes sutured shut at a critical period in their development - and then permanent changes happened in the way that they went on to process visual information. Similarly, OTs are inculcated/programmed en masse about sensory integration in their educations - and even though we STILL can't point to what sensory integration disorder even IS it doesn't stop anyone from developing questionnaires, writing books, developing intervention protocols, and in general attributing all manner of atypical childhood behavior to this undefined sensory integration process.
These attributions are taking us into really dangerous territory and in fact they are probably even contributing to AAP feeling the need to address the issue and even more directly it probably contributes to the insurance companies uniformly denying reimbursement for this intervention. We have some really bizarre claims that the evidence-based medicine world just doesn't know what to do with.
The prevalence issue may sit on top of the heap of concerns. These studies (here and here) state that between 5% and 15% of the population has a sensory processing disorder. The problem is that they rely on sensory questionnaires that DO NOTHING to contribute to differential diagnosis. So we really have no way of knowing if these children have any co-morbid disorders. Actually we shouldn't even be using the word "co-morbid" because we don't even know if sensory integration difficulties constitute a disorder and if these traits are just part of other problems. In fairness, the Ben-Hasson, Carter, & Briggs-Gowan (2009) study did control for some diagnostic conditions but the results also showed that gestational age, birth weight, and socioeconomic status were more likely to be associated with sensory over-responding. I guess that means that children who have a history of prematurity may have atypical sensory responsivity - which is no surprise - but does that mean that they have a unique sensory disorder? Or is it more accurate to describe their difficulties in terms of nervous system immaturity when they were born and long term impact of things like mild PVL or IVH? Or does environmental enrichment (or lack thereof) also play a role which is also suggested in the data?
What these studies show is that children may have difficulties with sensory processing skills - or at least they have difficulties that we want to think are associated with sensory processing skills - but that we really can't stretch this and make statements that this 'proves' anything about actual prevalence of a distinct condition.
I am not sure why but over time and after a lot of repetition it seems that people just start repeating these prevalence statements as if they are undisputed facts. In my opinion just about any statement made about prevalence of 'sensory processing disorder' has been an overstatement of our research results.
This is a major reason why I really have no problem with the AAP policy statement. I also think that if there was this kind of prevalence of children with this disorder that I would be seeing it in my clinic - but I just don't. Sure, I see kids with sensory processing difficulties, but these difficulties are almost always associated with other disorders. Most commonly these sensory differences are associated with conditions like ADHD or autism. Less frequently these sensory differences are associated with esoteric clinical problems. There was this case study about the child who had congenital adrenal hyperplasia. Or there was this case study about the child who had a conditioned fear response that caused piloerection and tooth pain. Or I could just talk about the six year old child who I saw a couple weeks ago. The parent brought him in because the child can't stand his clothing and has frequent behavioral meltdowns. All other aspects of his development are normal, and as I scratched my own head trying to figure things out I watched him scratch at his own arms - and then I saw large raised welts appear across his skin. With the parents permission I tested the skin on his legs and back - and indeed the child has dermatographia so I sent him back to the pediatrician who prescribed antihistamines as needed and magically the "tactile defensiveness" to clothing has disappeared.
Why does this matter? Well, mostly because we already know what kinds of interventions are most effective for children who have ADHD. We also know what kinds of interventions are most effective for children who have autism. If we stopped trying to define some 'new' diagnostic entity maybe we would also stop trying to create some 'new' intervention protocol. Then we could fall back to family education, trial practice, skill training, behavior modification, and adaptive/compensatory approaches that we all know work.
The AAP and others in the broader medical community would probably be happy to see some more discretion when we talk about prevalence and whether or not these problems constitute distinct diagnostic entities. OTs need to be willing to 'de-program' themselves from their educational experiences that cause them to call too many things "sensory processing disorders."
Comments
I believe studies will eventually show the source of behaviors known as SPD is reduced or insufficient cortical structure.
Find an occupational therapist who has some experience in this area and I am sure they can help you out. Send me an email if I can help in any way!
I have worked as a pediatric OT for more years than I care to say. Since the early 70's when SI began, the theory has unfortunately expanded beyond its original intent, well beyond the intended population it was theorized to help, and the bandwagon is incredibly huge. It goes now well beyond OT & PT, to speech therapists, and special educators. Try to do functional occupation-based OT - (even though very successfully no less) - while those around you think you should be doing SI. Yes, everyone needs a weighted vest and to be wrapped tightly in a blanket. It has become "pop culture."
I recently tested a young child who has been receiving "SI therapy" for many years, with no progress - has not progressed developmentally or in functional skills. A waste of time. Hopefully I have now offered new hope to this family. There was no reason this child could not have been helped with traditional OT methods.
On the other hand, a child with autism who has been under my care receiving traditional OT methods has made rapid gains in all functional skills and academically relevant areas such as handwriting. Now these parents have been told that I should be doing SI. They cannot say why, or what the functional goal will be. I think it comes down to the hope and desperation for a cure for the autism itself. Short-DeGraff (1988) in Sensory Integration: Theory & Practice by Bundy et. al., p. 11, stated “The goal of sensory integration therapy is to provide stimulation that will address certain brain levels (primarily subcortical), enabling them to mature [or function more normally], and thereby assisting the brain to work as an integrated whole.” On page 24 of this book, Ayres’ (1772a) is quoted as saying “The objective is modification of the neurological dysfunction interfering with learning rather than attacking the symptoms of that dysfunction.” Don’t these statements describe the hope of a cure offered to parents by SI? Instead of continuing the hard work that has been done to improve this student’s ability to be mainstreamed in the regular academic environment, and further expand language and reading comprehension, they have been sent off the “SI Cliff” so to speak. It is not their fault, certainly we can all understand why they desperately want a cure. I cannot recall the article written years ago by a psychologist, but the danger of SI as he saw it was not that SI would “hurt” a child, but that the damage was that while the child’s time was spent on this, it was not being spent in activities or therapies that would produce a functional result. I could not agree more!
SI therapists do not have a functional outcome planned. Whatever they observe improve, they claim is a result of their treatment. They never write a treatment goal ahead of time, indicating what the functional result will be of their treatment.
I do have a question about the Sensory Profile by Dunn. This is constantly being used in my local area to indicate that students need SI treatment. Unlike other parent surveys, which have a lot of questions but do not indicate topic areas, this has items listed in groups of supposed sensory processing areas of difficulty, almost “leading” the person completing it to answer a certain way. In addition, under certain headings, the same question is asked multiple times, written in a number of different ways. Has anyone done an assessment of the methodology used in this “assessment” tool?
As far as the Willbarger Protocol--yes, you can be trained. Yes--there are a lot of OT's who do it 'wrong' but it still works to a degree. But, the Willbarger method has a finite time frame. I was recently told by a parent "I can't believe this is my child!" due to the improvements in attention and level of awareness.
And lastly, Kris--let me say--don't quit your (adult) day job. Diversity is great--dysfunction is not. I would invite you anytime to come to my clinic and see just how 'diverse' we all are--until then, please be mindful of speaking about areas of practice you have no experience with--and disregarding therapeutic interventions that are effective.
My interest in this comes from having a good friend whose son was diagnosed. She never consulted a pediatrician or psychiatrist or neurologist about his issues, which are behavior problems and developmental delays. She can't answer most of my questions about the disorder or the treatment or why the medical profession doesn't recognize it, yet she's been willing to spend thousands of dollars she can't afford on therapy that has been of dubious value so far.
The story she was given explains some of her son's behaviors as sensory-seeking and some as sensory-avoiding, and it seems really unlikely to me that both things are going on at once. But she can't explain to me how anyone knows that any of his behavior is caused by sensory issues.
My biggest concern is that no physician has been consulted. With my limited knowledge, I suspect ADD in some form. I wonder what help he might be getting but isn't because of of the fact that, having found a narrative (and a community of other parents and a plethora of websites and books) she is not inclined to look any further for another one.