090: Sensory processing disorder
This episode comes to us courtesy of my friend Jess, whose daughter has Sensory Processing Disorder (SPD) and who is on a mission to make sure that as many parents as possible learn about it. She says that every time she describes it to a parent they realize that they know someone who exhibits behavior that looks like SPD that warrants following up.
I have to say that I was highly ambivalent about doing this episode, because I don’t usually deal with topics that result in medical diagnoses as I’m (obviously) not a doctor. But the more I looked into this the more I realized that helping parents to understand the mess of research on this topic is exactly the kind of thing that I usually do on this show, and that an episode on this topic could probably be useful to a number of you.
And here’s the love letter to John McPhee that I mention in the episode
Hello and welcome to the Your Parenting Mojo podcast. Today’s episode on Sensory Processing Disorder comes to you courtesy of my friend Jess, and I’m going to tell you a little about Jess and her daughter as a way to introduce the topic. Jess told me that her daughter likely had a mini-stroke either in utero or during birth that affected the left side of her body, and Jess figured this out around the time her daughter was 10 months old. So her daughter started physical therapy for that, but Jess still felt as though something wasn’t quite right, and while she already had a pediatrician, physical therapist, and neurologist, six months or so of Jess being (in her words) “a crazy parent,” along with the support of her mother who happens to be a pediatric physical therapist, to convince her daughter’s support team that something wasn’t right, and finally her daughter was evaluated for sensory processing disorder. Her daughter received occupational therapy treatment and is now doing very well.
Jess realized that if she hadn’t been especially vocal, and if she hadn’t had her own mother’s expert support, then it’s possible that her daughter’s issues would have gone undiagnosed. Jess told me she has started talking with anyone who will listen about this topic and whenever she mentions it a lightbulb goes off with whomever she is talking with about either a child in their lie or a friend of a friend who is having similar issues, so she asked me to do an episode on it so more people could learn about it.
Now I have to say that as much as I love Jess I did hesitate before taking this on. I don’t usually deal with topics that result in medical diagnoses because I’m obviously not a doctor or a psychiatrist. But the more I looked into this the more I realized that helping parents to understand the mess of research on this topic is exactly the kind of thing that I usually do on this show, and that an episode on this topic could probably be useful to a number of you. So, to reiterate, I am not a doctor or a psychiatrist, and this episode is not intended to diagnose, treat, cure, or prevent any disease. In fact, for reasons we’ll get into in the episode, it’s actually kind of difficult for a doctor to diagnose as well. So we’ll talk about diagnoses, and about the efficacy of treatment for SPD, and finally about how to chart a path forward if you suspect that your child may have difficulties processing sensory information.
So let’s get into it! For those of you who haven’t heard of it before, what is sensory processing disorder, and where did it come from? The research in this field was pioneered by Dr. A. Jean Ayres, who was an occupational therapist active from the 1960s to the 1980s. Dr. Ayres’ classic book is called Sensory Integration and the Child, and was re-released in 2005 in a 25th anniversary edition. In the book, Dr. Ayres describes sensory integration, which is the organization of our senses, which give us information about the physical conditions of our body and the environment around us. She says that the brain has to organize all of these sensations if a person is to move and learn and behave in a productive way – for example, by making your eyes, nose, mouth, skin, muscles, and joints work together to peel and eat an orange, and that an adaptive response to a sensory experience is a purposeful and goal-directed one. When we have an adaptive response we master a challenge and learn something new. Until the child is about 7, they are primarily a sensory processing machine – they sense things and respond, without having many abstract thoughts and ideas. Dr. Ayres says that the brain’s mental and social functions in the later years are based on this foundation of sensorimotor processes, and if sensorimotor processes are well organized in the first 7 years, the child will have an easier time learning mental and social skills later on.
Dr. Ayres died in 1989, and Dr. Lucy Jane Miller has carried the flag on this work. Dr. Miller is the director of the Sensory Therapies and Research Center in Denver, Colorado, and has written her own book called Sensational Kids: Hope and Help for Children with Sensory Processing Disorder. In Dr. Miller’s book she shifts Dr. Ayres’ original six syndromes of sensory integration dysfunction into three main “pattern types” with a number of subtypes.
Pattern Type 1 is Sensory Modulation Disorder (SMD), and results when a person has difficulty responding to sensory input with behavior that is appropriate to the degree, nature, or intensity of the sensory information. Dr. Miller’s book describes SMD as having three main subtypes, although her own peer-reviewed research has only found support for two of these – sensory seeking, and sensory underresponsivity.
In Subtype 1, Sensory Overresponsivity (so the one that doesn’t have peer-reviewed research support), people respond faster, with more intensity, or for a longer duration than people with typical sensory responsivity. It may occur in only one sensory system (like not wanting to be touched) or in multiple systems. Difficulties are most often seen in new situations and during transitions, and the responses may appear as willful behavior, seemingly logical, and inconsistent. For example, a child with this subtype may not be able to tolerate being jostled as coats are being put on at preschool for the transition to outdoor play, and may lash out at another child in response. Behavior may also result from cumulative stresses, so the jostle while putting coats on might just trigger the response that has built up as a result of a whole morning of being jostled and touched through normal interactions.
People with Subtype 2, Sensory Underresponsivity, disregard or do not respond to sensory stimuli. A child may seem apathetic, lethargic, and lacking an inner drive to socialize and explore. They might not notice bumps, falls, or cuts, or extreme eat or cold, and may be labeled ‘lazy’ or ‘unmotivated.’ As an infant, the child might have been considered a ‘good baby’ or an ‘easy child’ but when they become older they may not be able to maintain enough arousal to participate in family or school life.
People with Subtype 3, Sensory Seeking/Craving, crave an unusual amount or type of sensory input, possibly including spicy food, loud noises, visual stimulation, and constant spinning, which can lead to socially unacceptable or unsafe behavior and can be perceived as demanding or attention-seeking. They may become explosive or aggressive when they are unable to meet their sensory needs – for example, when they are asked to sit still and be quiet at school. This subtype can be confused with, and even co-occur with, attention deficit hyperactivity disorder, or ADHD.
People with Pattern 2, Sensory Discrimination Disorder, have trouble interpreting qualities of sensory stimuli and tell how they are similar and different; this characteristic may be present in just one or more than one sense. SDD in the tactile, vestibular, and proprioceptive systems, which tell you where your body is in the world, results in awkward motor abilities. SDD in the visual or auditory systems can lead to learning or language disabilities.
There are two sub-types to Pattern 3, which is Sensory-Based Motor Disorder. In Subtype 1, Postural Disorder, the person has difficulty stabilizing the body during movement or at rest. The child may have low muscle tone, inadequate control of muscles and movement, and poor balance.
In Subtype 2, Dyspraxia, the person has difficulty conceiving of, planning, sequencing, and executing actions. They may appear awkward and poorly coordinated in their gross motor skills like running and jumping, fine motor skills like drawing and painting, or oral-motor skills like chewing and swallowing. They seem unsure where their body is in space, have trouble with ball sports, and any actions involving coordinated timing.
Where does SPD come from? Dr. Ayres herself acknowledged that we don’t really know what causes SPD, but she goes on to make quite a variety of speculations. She says “Many people think that the increase in environmental toxins, such as air contaminants, destructive viruses, and other chemicals that we take into our bodies may contribute to the dysfunction,” without offering a shred of supportive evidence from these “many people.” She hypothesizes that hereditary and chemical factors may be combined in some children, and that genetic factors in certain children may allow environmental toxins to interfere with sensory integrative development. Some babies do not get enough oxygen at birth, which may affect brain function, and that children who lead very deprived lives – like the children in the Romanian orphanages from the 1980s who had very little human contact – don’t develop adequate sensory, motor, or intellectual functions. But lest you start blaming yourself for your child’s problems, she goes on to say that most of the children with minor irregularities in brain function have had normal sensory experiences, and their parents or guardians did do a good enough job of raising them to allow for good brain development so the parents did not deliberately or accidentally produce the dysfunction.
When I was researching this episode I got a question in the Your Parenting Mojo Facebook group about whether there’s any evidence about how children’s diets impact their sensory processing, and I have to say that this view is VERY popular in the online community groups related to SPD but I’m afraid there is zero evidence whatsoever in the peer-reviewed research, or even in the books by Dr. Ayres and Dr. Miller, that implicates children’s diets in causing or worsening SPD. The only potential connection I could see is that a child may be unwilling to eat if they find the textures of some foods to be difficult to deal with, but there is zero evidence that SPD is caused by gluten intolerance or eggs or sugar or food coloring or any other kind of food.
I want to put a couple of side notes in at this point. Firstly, I’m also looking at doing an episode on Dr. Elaine Aron’s work on Highly Sensitive People, and in one of her papers Dr. Aron actually expressly makes the distinction that being a Highly Sensitive Person is different from Sensory Processing Disorder. In her book The Highly Sensitive Child, Dr. Aron says that many parents have told her they have found sensory integration to be helpful for their highly sensitive children, but she doesn’t think that being sensitive as she defines it is a problem to be treated, much less cured.
Secondly, a couple of listeners have been in touch about unintegrated reflexes, and since the topic has a bit of an overlap with this one I’d like to address that here too. All babies have reflexes – one of the more famous ones is the Moro reflex which is when the infant spreads their arms and hands out and then pulls them in, usually while crying, when they feel they’re falling. In most infants this reflex goes away, which we call becoming “integrated,” by around four or five months of age but in some children this reflex doesn’t become integrated and the child will still produce it when they feel like they’re falling. There is quite a bit of evidence showing that unintegrated reflexes are *correlated* with a variety of developmental disabilities, but I’m afraid that’s pretty much where the evidence ends on this topic. It’s a bit hard to get your head around because nobody seems to have done any kind of meta-analysis to synthesize the results except the Wisconsin Department of Health Services which briefly reports that this therapy remains an “untested treatment, as there are no studies that have tested its effectiveness. There is no evidence to suggest that it is harmful.” Also, the main figure doing the research is Dr. Svetlana Masgutova is the creator of the Masgutova Neurosensorimotor Integration Method® and she’s also done a good chunk of the research on the effectiveness of the eponymous method. Unfortunately, methodological problems abound in the paper she’s done that’s most relevant to us, which is on the use of the Nurosensorimotor Integration Method in treating symptoms of Autism Spectrum Disorder. In that study she trated 484 children with autism, but the control groups were only 72 children with Autism who weren’t treated, and 483 children with neurotypical development. A more robust methodology would have compared the treated children with a much larger group of children who received comparable attention from a therapist and traditionally accepted treatment to compare the reflex integration treatment with traditional treatment, rather than with no treatment. It’s well-known that just attention from a therapist can produce a therapeutic effect even when the treatment itself doesn’t have any effect at all. And the results produced changes in reflex patterns, which were correlated with improvements in cognitive abilities, but since there’s no mention in the study of the children being randomly assigned to treatment or control groups, we can’t say with any certainty that the treatment *caused* these improvements. So that’s that.
And while we’re on the topic of co-morbidity, which is two or more chronic diagnoses in the same individual, some authors estimate that the majority of children with autism spectrum disorders have SPD, although not all children with SPD have autism.
SPD is also very difficult to diagnose, and this topic brings me to the part of the episode where I’m not going to just recite what Dr. Miller and Dr. Ayres say but bring a bit more of a critical perspective. SPD is actually not included in the Fifth Edition of the Diagnostic and Statistical Manual of Mental Disorders, which is abbreviated as DSM-V, which is the standard diagnostic guide for psychological diagnoses, although I should acknowledge that what makes it into the DSM is as much a political issue as a diagnostic one – the first and second editions of the DSM included homosexuality as a mental disorder and it wasn’t removed until 1973. Dr. Ayres developed a Sensory Integration and Praxis test which has been described as “the most comprehensive and statistically sound means for assessing some important aspects of sensory integration, most notably praxis and tactile discrimination,” but apparently five of the 17 subtests are unstable, which means that the same child is likely to get different results each time they are tested. Dr. Ayres reported that scores on the test were different for children with and without learning disabilities, although subsequent analyses of her work showed there were actually no reliable differences between the scores of children with and without learning disabilities, which is a pretty big problem.
The American Academy of Pediatrics published a position paper in 2012 stating “it remains unclear whether children who present with findings described as sensory processing difficulties have an actual “disorder” of the sensory pathways of the brain (and I will note, Dr. Ayres says they do), or whether these deficits represent differences associated with other developmental and behavioral disorders. Specifically, the behavioral differences seen in children with autism spectrum disorders, attention-deficit/hyperactivity disorder, and developmental coordination disorders overlap symptoms described in children with sensory processing disorders. Studies to date have not demonstrated that sensory integration dysfunction exists as a separate disorder distinct from these other developmental disabilities. Furthermore, numerous challenges exist for evaluating the effectiveness of sensory integration therapy, including the wide spectrum of symptom severity and presentation, lack of consistent outcome measures, and family factors, which make response to therapy variable.” The APA officially recommends that “At this time, pediatricians should not use sensory processing disorder as a diagnosis.” Dr. Miller’s team published a paper in 2014 describing the development of a new scale to diagnose SPD, but it focused on only some of the sub-types and the study was conducted on only 20 children, and only 10 of those actually had a developmental disorder, with the other 10 being typically developing children in a comparison group. Dr. Miller does acknowledge that “the standardization of a reliable and valid scale to assess SPD is essential for the field to move forward” but at the moment, we don’t have one.
So I want to set this issue of diagnosis aside for a bit and talk about prevalence and treatment, because that is, after all, how we got here in the first place – after occupational therapy was successful for my friend Jess’ daughter.
The most widely cited study on the prevalence of SPD was conducted by Dr. Miller and her colleagues, where the researchers sent surveys out to the parents of one suburban public school asking about whether their children exhibit symptoms of SPD. Only 39% of the parents responded, and the researchers were conservative in assuming that none of the parents who didn’t respond who had children who had these symptoms, and based on this they came up with a prevalence rate of 5.3%. If you assume that the children of the non-responding parents had symptoms at the same rate as the responding parents then the prevalence rate goes up to 13.7%. Of course, there are a variety of problems with this – firstly, that this is a suburban school district of mostly white, middle class parents who may be more likely to look for symptoms in their children and report these to a set of researchers. The second problem is that 39% of parents from one school really is a pretty low response rate to base this kind of determination on, even if you are going to assess the results conservatively. Thirdly, the researchers didn’t make any attempt to study comorbidity, which is the concept of having more than one infliction at once, and as we already know SPD has a LOT of symptoms in common with other potential diagnoses. And, finally, there’s the predictable issue we see with so much other research on this show – we see a heavily caveated result in a paper that gets grasped by other researchers and reported as if it were fact: for example, a 2013 paper reports that “Mental health practitioners, however, may have limited information or understanding of [SPD]. This is concerning, as [the disorder] is estimated to occur in 5% of the general population (Ahn et al. 2004), equating to three million children in the United States (United States Census Bureau 2008).” Another set of researchers report that “In fact, Ahn, Miller, Milberger, and McIntosh found that 5-15% of children in the general population of kindergarten-age children demonstrate difficulties with sensory modulation” when in fact it would be irresponsible to generalize from those few white children in suburban Colorado to the entire “general population” of children. Further, the researchers never actually met with any of the children to determine if they did have SPD – they just asked parents, most of whom probably knew nothing at all about SPD, whether their children might have symptoms that *could* point to SPD – or could point to a number of other disorders as well. I could ask the parents of my daughter’s preschool class how often their children report having stomach aches and perhaps 100% of them would report their children saying this every day, but that doesn’t mean the incidence of stomach cancer – which has stomach pain as a symptom – is 100% in my daughter’s classroom. As such, this 5-15% number that gets quoted in the literature with alarming frequency – even by Dr. Miller herself, who really should know better – has little basis in fact.
A subsequent study conducted in 2011 in New Haven, CT asked a reasonably representative sample of parents of children in the city whether their children were “bothered by” things like tags in clothing, cutting finger or toe nails, hair brushing, mud, alarms, sirens, or concerts. The researchers found that 16.5% of children were bothered by at least four tactile or auditory sensations, although once again the researchers made no attempt to relate being bothered by sensations to an actual assessment for SPD.
As we move on to treatment, I’m afraid the picture gets even worse – at least, on the research front. But let’s hear from Dr. Ayres first on a description of what treatment for SPD looks like. She says that the central idea of sensory integration therapy is to provide and control sensory input, especially the input from the vestibular system, muscles and joints, and skin in such a way that the child spontaneously forms the adaptive responses that integrate these sensations. Making this idea work with a child who has a sensory integrative disorder requires a skilled therapist and a large room with a lot of simple yet specialized equipment. When the therapist is doing her job effectively and the child is organizing his nervous system, it looks as if the child is merely playing. Life is full of paradoxes; this is one of them. The general idea is that children want to experience certain sensations and initiates an activity to get those sensations. The brain is designed to give itself the experiences that are necessary for its own development. The therapist’s job is to provide the right kind of activity (so the child gets the right kind of experience) and the right level of challenge so the child is able to try and succeed without getting too frustrated. The therapy itself may appear…surprising. The therapist might put the child between two mats to make a “hamburger”, and the therapist presses down on the child, pretending to put ketchup, mustard, relish, and all kinds of condiments on the “hamburger” to provide deep pressure sensations, and that children will often come out of this activity calmer and better organized than before. The therapist may offer activities that press the bones in a joint together, or ask the child to hang from monkey bars or climb up a rock wall to stimulate the sensory receptors in the joints. The child might sit or stand on a motor-driven vibration board to send impulses to the vestibular system. They might play “net hockey,” which is where the child and the therapist lie in nets suspended from the ceiling bout 10 feet apart and close enough to the floor to push themselves around with their hands, and then hit a soft ball around with plastic hockey sticks, which generates a variety of vestibular input as he figured out the placement of his body and watched the ball and stick. The child might play on a “helicopter,” where two children spin in separate seats and spin around, and then might choose to use the Play Buoy which is a plastic buoy that can move freely along two ropes about 15 feet long. Organizing sight to see the buoy coming and the arms to push it can be difficult for children with SPD but the idea is that their brain has been primed with vestibular input from the hockey and helicopter games and the child will then be able to process the sensations and movements of the Play Buoy more effectively than they would have been able to otherwise. The child might play hide and seek, which gives the child a feeling of mastery over both space and other people. Outside of the therapy sessions, parents and teachers might ask the child to do what’s called “heavy work,” which consists of pushing, pulling, or carrying heavy things. Dr. Ayres reports that a child using this kind of therapy might see improvements after just a couple of months, because the child has a strong inner drive to seek the stimuli they need and is able to follow their own internal directions. The therapy works especially well with young children, whose brains are very plastic and changeable, to develop new connections between neurons, and for older children it may make it easier to transmit messages between neurons. Dr. Ayres acknowledges that some children may have problems that are so severe that we don’t have the knowledge needed to treat them, or perhaps we can’t determine the nature of the problem with enough clarity to design an effective program for that child. Sometimes the problem is in a part of the brain that is less dependent upon organizing sensations, and these children may profit more from other kinds of therapy.
Unfortunately Dr. Ayres’ writing doesn’t tell us much about the efficacy of this therapy, probably mostly because she was pretty much writing the theory as she was figuring it out back in the ‘60s, so there just wasn’t any research on whether it was effective. More research has been conducted in the intervening years but even though the 25th anniversary edition of Dr. Ayres’ book contains a contemporary expert commentary on each chapter, the commentary on the Assessment and Intervention chapter studiously avoids mentioning any peer-reviewed research on the efficacy of this treatment. And there’s probably good reason for this – there is little peer-reviewed research showing that it is effective.
One of the most popular treatments for SPD is known as the Wilbargers’ protocol after the clinicians who developed it, which includes what is known as a sensory diet of prescribed activities, as well as brushing with what is essentially a scrubbing brush using deep pressure three times a day for six weeks by their parents at home. Even though the authors conducted a literature review and lamented the methodological constraints present in previous studies on this topic they went on to recruit just five participants themselves, all of them male, and one of the five children started refusing the brushing after two weeks but because the mother wanted to be included in the study the researchers went ahead and included this child’s results. The intervention was found to be effective, but given the tiny sample size and the absence of any kind of control group, this study has to be considered exploratory at best.
A study using a convenience sample of 10 children, mostly males, found that a therapeutic music listening program using music that had been processed using filters to create disruptions in the sound that apparently ‘exercises’ the muscles in the middle ear. The children showed on average a statistically significant improvement in scores on a test of sensory processing as well as parent reports of child behavior, although the small sample size is again concerning, along with the wide variety of diagnoses of the children who were studied, and the fact that the music therapy was combined with other sensory therapies, make it difficult to draw strong conclusions.
Dr. Miller and some colleagues did a pilot study on the effectiveness of occupational therapy for children with sensory modulation disorder and achieved mixed results; they got statistically significant results on some criteria but not on others, which may have been because of the tiny sample size of 24 children – only eight of whom received treatment. Because this study was a pilot it was never intended to reach full scale to achieve definitive conclusions, but it was published in 2007 and I was unable to find a subsequent study scaling the results. The authors themselves note that “One likely reason that many previous studies found no significant changes from occupational therapy is that the outcome measures used were not sensitive enough to detect changes. Because previous literature does not present pilot testing of instrumentation, researchers unknowingly replicate each other’s work. Outcomes research in OT-SI, therefore, is continually relegated to pilot research rather than research that moves forward and has the potential to change practice.” These impacts are compounded when you start looking at meta-analyses of endless pilot research projects with tiny sample sizes and results with low statistical power.
A 2014 meta-analysis of 27 studies over a 37-year period found a great deal of variability in the research, with potential positive outcomes in sensorimotor skills and motor planning, socialization, attention, behavioral regulation, reading-related skills, participation in active play, and achievement of individualized goals – but were severely hampered by small sample sizes, variable doses of treatment, failing to deliver the treatment as planned, and the selection of outcomes that may not be meaningful to clients and families (like IQ tests or the involuntary movements the eyes make after you spin around, which may be clinically interesting but doesn’t make much difference in the child’s or family’s life) or may not change with the amount of treatment provided. Because SPD has so many sub-types it can help us to understand the impact of treatment better if the treatment is provided to only research participants who only have that particular sub-type so you can weed out the problems of interactions with other subtypes, but that’s very difficult to do in practice and leads to a lot of variability in the response to treatment. Virtually all of the studies had very low statistical power, meaning that if a control group receiving attention from a therapist but no actual treatment was used (which wasn’t always the case), that there usually wasn’t a large difference between the two groups after the treatment period. It’s possible that a positive effect could be found if the researchers would look at more children in each study; 12 of the studies did analysis on less than 20 participants; the largest one had 78 participants and the smallest one had just five. I find it very frustrating that we *continue* to see research hampered by this issue. It seems like such an easy thing to fix – yes, it costs more to have more participants but you’d think the benefits in terms of not having to do the same research over and over again would outweigh the costs.
The typical way of doing a meta-analysis in this field seems to be to do a really wide search of more than 11,000 article abstracts, screen the results for quality, and then conduct the final analysis on the eight studies that meet the researchers’ inclusion criteria. One study that used this methodology looked at treatments like Qigong massage, weighted vests, slow swinging, and incorporation of multisensory activities into preschool routines. Strong evidence was found to support Qigong massage, although this was for children with Autism Spectrum Disorder rather than SPD specifically. Limited evidence supported weighted vests in one randomized controlled study of 30 children, and there was insufficient evidence to draw conclusions on the swinging and multisensory activities, due to the poor methodology in the original studies.
One meta-analysis on just the effectiveness of the Wilbarger protocol started with 300 studies but ended up analyzing only four, found that the sample sizes in these studies ranged from 1-4 participants with no justification provided in any study for the size of the sample; all used convenience sampling to recruit from local occupational therapy clinics; all participants were boys, and in the one study where the single participant was compared with a single control, the participants were randomly allocated to treatment and control interventions but the person giving the treatment knew which boy was in which condition which could have impacted the results. All researchers trained parents to do the brushing but didn’t ask whether the mother had adhered to the prescribed schedule of brushing or not. The meta-analysis concluded that there isn’t enough evidence to support or refute the use of the Wilbarger protocol with children, or to be able to generalize the results of these studies to other populations.
Another meta-analysis doesn’t tell us how many articles the researchers initially screened but says they ended up with 50 articles, emphasizing results from work accomplished in the last 15 years, but “some older papers were included because they are considered key in the field of neuroplasticity” – in other words, the researchers cherry-picked some older studies that would support their conclusions. The vast majority of the high quality studies were conducted on animals, usually rodents, with many of the lower quality studies with weaker designs also using animals but some were done with humans; almost always adults rather than children. Despite the problems with extrapolating from animal studies to outcomes that are actually significant for patients and families, the researchers concluded that their review “provides direct and robust support for neuroplasticity in many brain regions in response to environmental conditions or direct sensory input.”
A pretty new meta-analysis published at the beginning of 2018 identified 11,619 potential citations and abstracts to study, and then whittled this number down until five studies remained, one of which was conducted by one of the authors of the meta-analysis. The usual tiny sample sizes, confounding with other conditions as all children in all of the studies coincidentally also had autism, problems in understanding whether the treatment protocol was actually adhered to, and mixed results were somehow lost in the finding that “the evidence is strong that [sensory integration therapy] demonstrates positive outcomes for improving individually generated goals of functioning and participation as measured by Goal Attainment Scaling for children with autism.” One of the meta-analysis’ authors, Dr. Roseann Schaaf, has written elsewhere about Goal Attainment Scaling as a way to measure outcomes – it consists of the therapist and parent working together to define minimal, intermediate, and desired outcomes of therapy at the beginning of treatment that progress can then be measured against. I can see the relevance of this in the individual’s treatment plan, and it’s certainly a step above the therapist asking the parent whether the parent thinks the child is better which is the way results are gathered in some studies on this topic, but it does seem to be problematic when you’re attempting to generalize results to a much larger population that the efficacy of treatment is essentially decided by the therapist and parent rather than assessed using any standardized measure.
Moving beyond the meta-analyses, I want to tell you about a chapter I read on Sensory Integration Therapy in a book called Controversial Therapies for Autism and Intellectual Disabilities. These researchers clearly have an anti-sensory integration therapy agenda, but their position is extremely well-referenced using high-quality sources. They start out by noting that “A major limitation in Sensory Integration theory, however, is the dearth of reliable evidence for its main tenet, which is the integration of sensory input is necessary for high-level cognitive functioning.” In fact, In Dr. Lucy Miller’s book the source she cites on this topic is a researcher named Hebb who published a relevant paper in 1995, but when I went to find it I realized it was actually a paper published in 1955 that described Hebb’s untested hypothesis that “there will be an optimal level of arousal for effective behavior.” But it turns out that there is no current scientific basis for this idea. Some neuroscientists who reviewed Dr. Ayres’ work and state that: “In her classic work, Sensory Integration and the Child, Jean Ayers concludes that the symptoms reflected in Sensory Integration Disorder “are the end products of inefficient and irregular sensory processing in the brain.” She does not, however, address the significance of specific brain–behavior relationships, including the possible interactive roles of the neocortex, the basal ganglia, and cerebellum. Instead the theory of SID is based upon a pyramid of sensory, cognitive, and behavioral systems that places tactile, vestibular, and proprioceptive systems at the base, above which are the distal senses of vision and audition, while the complex sensorimotor, cognitive, and behavioral systems are found at the highest levels. While this model might make intuitive sense, the brain–behavior relationships inherent in this view of the brain’s organization have not been established. Accordingly, while the symptoms that comprise the criteria for Sensory Integration Disorder, Sensory Processing Disorder, and Sensory Modulation Disorder are common and real, the conditions lack clear operational definitions and they are poorly understood from an anatomic point of view.” The neuroscientists conclude that the symptoms of SPD probably can be classified within a neuroscientific knowledge base neuroscientists collaborate with occupational therapists to better understand the relationships between brain and behavior but I can’t find any indication that this work is underway – there’s certainly no mention of it on Dr. Miller’s Sensory Therapies and Research Center’s website.
The skeptical book chapter goes on to wonder why, given the dearth of evidence about the efficacy of sensory integration therapy, practitioners continue to recommend it and parents continue to seek it out. The authors argue that three factors contribute to continued belief in its therapeutic value – first, practitioners promise vague benefits that are difficult to test. Second, they contend that these benefits occur because the treatment corrects a central, underlying deficit. And third, the research may give providers and families the impression that the therapy “can’t hurt” and may be worth a try even if benefits are unlikely to occur. The authors cite comments from Dr. Ayres’ book to back up each of these assertions, and state that the main reasons not to use this therapy are that it may distract families from focus on educational and therapeutic practices that could actually be helpful. If it is helpful, the lack of quality in the research base doesn’t allow us to know whether it’s helpful because of the specific treatment, or because of the attention the child gets from the therapist, or because they enjoy skipping school to go to therapy. If some aspect of the treatment has produced benefits for their child then individual parents may not care why, but it would be a whole lot faster and cheaper to implement an intervention that involves playing with your child 1:1 for an hour than diagnosing a disorder and implementing therapy if it turned out that attention was the driver of the improvement. For these reasons, the insurance company Aetna maintains a web page of information related to sensory integration therapy that describes the therapy as experimental and investigational with unproven effectiveness which – I assume – means it isn’t covered by insurance. I’ve heard that some insurance companies do cover it, and some school districts apparently provide this treatment as well.
So, as you can imagine, all of this leaves me in an a rather uncomfortable position, having been asked by my friend to do this episode on a therapy that has apparently helped her daughter but concluding from the research that it’s not clear how or why or even if it was the therapy itself that helped.
This may seem like a bit of a digression but actually it won’t end up being one: As I was in the middle of writing this episode our family went on a camping trip to see the spring wildflowers in Southern California and since I only had writing to do rather than reading, I grabbed a book from my shelf to take on the trip for evening reading. Believe it or not I don’t get a lot of time these days to read anything that isn’t related to child development but John McPhee’s book Assembling California caught my eye so that’s what I took with me.
As a side note, those of you who already love John McPhee are thinking “of COURSE Jen loves John McPhee too” and if you love John McPhee and you haven’t read the love letter about him that Sam Anderson wrote in the New York Times Magazine a couple of years ago then you really must go and find that in the references. Those of you who haven’t heard of him yet should browse McPhee’s titles and find something that seems even vaguely interesting to you, and watch as his amazing writing draws you in to learn about orange farming or life as a merchant marine or the geology of California. The book I picked out, Assembling California, is told through a series of interactions with geologist Dr. Kenneth Deffeyes of the University of California Davis, who went to grad school in the 1950s before the theory of plate tectonics had been fully explained so McPhee asked Deffeyes what Deffeyes had been taught about how mountains were formed. Deffeyes had learned a couple of different theories; that either the earth’s skin contracted by shriveling up like the skin of an apple and the wrinkles became mountains, or that there were deep troughs in the ocean called geosynclines that filled up with sediments and after enough had collected and become rock it would rebound like a huge log coming up from underwater. It turned out that there was a lot of truth in geosyncline theory – you could use this knowledge to find gold, silver, antimony, and oil. And there are rocks in the mountains that were formed under the oceans. But it wasn’t until plate tectonics came along that it all started to make sense and we realized what parts of the previous theories we should keep and which we should discard.
And read that chapter I realized it held a parallel with the research on SPD. Even the skeptics agree that some children have problems processing information from their senses; the problems arise in our attempts to understand why these occur and to separate them well enough that we can see how potential treatments impact them. The earth’s plates were moving around all along, whether or not we knew how to describe it, and we may find that children have had sensory processing difficulties all along even though we can’t fully describe it. Or it’s possible that once we understand the underlying neurological mechanisms better that SPD will get subsumed under autism spectrum disorders and other diagnoses that come with sensory processing difficulties just as we know geosynclines do exist, even though they don’t explain the entirety of how mountains are formed. Unfortunately, given that the research to actually help us understand SPD is moving slower than plate tectonics, this may not be of much practical help you to you today if you suspect that your child may have sensory processing difficulties.
If you do suspect this, then Dr. Miller’s book Sensational Kids is probably the most helpful in terms of describing a series of children moving through their days that is likely to make you say “my child TOTALLY does that” which can help you to talk with your child’s pediatrician about a potential course of action. Dr. Ayres’ book is helpful too, but from a less case-study based and more descriptive approach. Since many pediatricians likely haven’t heard of SPD, you may find it to be an uphill struggle to convince them that there is anything wrong with your child, just like my friend Jess did.
If you are able to see an occupational therapist who is able to determine that your child does exhibit symptoms associated with SPD then given the state of the research on the effectiveness of treatment, I think you would be safely within your bounds to decline it if you felt the therapist was not convincing in describing the potential benefits to you. If you did decide to proceed, then you should work with the therapist to define goals for your child’s behavior – for example, the number of times the child will get up out of their seat during story time at preschool. You might decide to ask your child’s teachers to count the number of times your child gets up during story time every day for a week, and then proceed with treatment for a period of time and count the number of times the child gets up again. The child getting up is just an example; the actual variable you measure will depend on the child’s particular challenges. You should set an agreement with the therapist by when you should expect to see progress, and do not be afraid to stop the treatment then if you aren’t seeing adequate progress. It’s unfortunate that the state of the research forces parents to have to develop their own scientific study to see if the treatment is working, but hopefully this will change in the future. I have to confess that it makes me feel a little squeamish to reduce the human experience to expressed behavior but in this case it seems as though changes in behavioral expression is the only way we can know whether or not any underlying mechanisms are being affected.
So that’s where we are with the research on SPD. To summarize, I and many experts believe that some children have problems processing sensory inputs. Whether this is a specific diagnosable condition or whether it is a symptom of other diagnosable conditions remains to be seen. Given the dearth of evidence for the efficacy of treatment it would not be irresponsible of you to decline treatment if the therapist is unable to convincingly articulate its benefits but if you do proceed with treatment, you may want to approach it like a scientific study and set goals against which progress will be measured, and these goals should be ones that are meaningful for your child’s and your family’s experience, rather than being ones that are clinically interesting but otherwise irrelevant to you and your child. I hope this helps those of you with children who struggle with processing sensory input to determine a path forward that is right for your child and your family.
References for today’s episode can be found at yourparentingmojo.com/spd
References
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About the author, Jen
Jen Lumanlan (M.S., M.Ed.) hosts the Your Parenting Mojo podcast (www.YourParentingMojo.com), which examines scientific research related to child development through the lens of respectful parenting.