Sensory over-responsivity in a sample of children seeking treatment for anxiety

Sensory over-responsivity (SOR) refers to an exaggerated, intense, or prolonged behavioral response to ordinary sensory stimuli.1 Although many terms have been used to label this phenomenon (e.g., sensory intolerance, hypersensitivity, hyper-responsiveness, sensory defensiveness, sensory-processing sensitivity), all share a core symptom description of a heightened and atypical reaction to sensory stimulation to a degree that impacts daily functioning. SOR is most commonly reported in association with tactile and auditory stimuli, such as clothing textures, sticky substances, and alarms or sirens.2 Developmental research suggests that elevated SOR symptoms are early-emerging, chronic, and associated with child and family impairment and increased risk for social and emotional problems.3,4 SOR symptoms have long been recognized in the field of occupational therapy,5 but the relation of SOR to psychopathology has only begun to be studied in recent years. Existing data suggest that SOR occurs both concurrently and independently of psychiatric disorders, leading to debate about the proper nosological classification and diagnostic validity of SOR.6,7 SOR is not currently recognized in the International and Statistical Classification of Diseases and Related Health Problems8 and is included in the recent revision of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5)9 only as a symptom of autism spectrum disorders (despite evidence that SOR is not specific to autism).10 The Diagnostic Classification of Mental Health and Developmental Disorders of Infancy and Early Childhood-Revised (DC:0–3R)11 includes the provisional diagnostic category, “Regulation Disorder of Sensory Processing,” of which “hypersensitive” is a subtype (along with other provisional symptom clusters such as hyposensitive and sensory stimulation-seeking). Although this is the most commonly used DC:0–3R category, diagnostic reliability is poor among experts and existing criteria lack empirical backing.11,12 Therefore, there is no universally agreed upon operational definition of SOR, nor are there established criteria upon which to identify clinically significant SOR symptoms or to differentiate SOR from other symptoms or disorders. Controversy over how to properly conceptualize and classify SOR is largely due to limited data concerning the construct’s clinical significance, etiology, and relationship to existing psychiatric diagnoses in terms of distinct clinical characteristics and rates of co-occurrence. Recent research indicates that SOR does occur independently of existing DSM diagnoses. Two large scale studies examined rates of SOR and co-occurring DSM-IV13 diagnoses in well-characterized, population-based samples of typically developing children (i.e., children without cognitive disabilities or autism spectrum disorders).3,14,15 Both samples were school-aged children (7–10 years old;3 7 years old15) whose parents completed a structured diagnostic interview (Diagnostic Interview Schedule for Children)16 and the Sensory Over-Responsivity Inventory (SensOR),17 a parent-report measure of SOR in the tactile and auditory domains. SOR status was based on the SensOR but criteria differed in each study, such that children were classified has having SOR if parents endorsed ≥ 4 items in the Carter et al. study and ≥ 6 tactile or ≥ 4 auditory items in the Van Hulle et al. study. Across both studies, SOR was found to occur in isolation in approximately 8–15% of children. SOR co-occurred with DSM-IV disorders in about 5–12% of children, such that about 25–60% of children with SOR also met criteria for a psychiatric disorder. Rates of co-occurrence between SOR and specific DSM diagnoses remain unclear. Most research to date has focused on SOR among those with autism spectrum disorders (ASD), and estimates of SOR and ASD co-occurrence range from 23%18 to 56%.19 While some have viewed this high rate of co-occurrence as evidence that SOR is specific to ASD (as DSM 5 criteria imply), other evidence indicates that these results may be better attributable to a general maturational delay. For example, Baranek et al.10 found that mental age was an equally strong predictor of hyperresponsiveness across groups of children with autism, developmental delays, and typical development, such that increased mental age was associated with decreased hyperresponsivity across all three groups. The authors concluded that SOR may reflect an important developmental, transdiagnostic process rather than a specific ASD symptom or distinct syndrome. Among typically developing children, there are speculations in the literature that SOR is more common in those with anxiety disorders, attention-deficit hyperactivity disorder (ADHD), and oppositional defiant disorder (ODD). However, this information is largely based on anecdotal case reports,20,21 studies using a broader definition of sensory problems14 (e.g., including both over- and under-responsiveness), and research using unsystematically diagnosed or poorly characterized samples. In the Carter et al.3 and Van Hulle et al.15 studies, rates of specific psychiatric disorders were not reported, but the rate of diagnoses within the broad domains of internalizing disorders among those with SOR ranged from 10.0%3 to 70.4%15 and externalizing disorders from 18.5%3 to 50.4%.15 In order to better understand the relationship of SOR to psychopathology, quantitative research examining the construct within well-characterized clinical samples is needed. One particular clinical sample that warrants further examination in this regard is children with anxiety disorders. Anxiety is one of the most frequently implicated internalizing problems among children with both SOR and psychopathology.22 In studies examining infant and preschooler temperament, SOR in the auditory and tactile domains has been found to be positively correlated with anxiety22,23 and fearfulness.24 Among toddlers with ASD, SOR was found to emerge before anxiety and predict later development of anxiety.18 While these studies suggest a relationship between SOR and anxiety broadly defined, some have argued that SOR may be more specific to certain anxiety disorders, such as obsessive-compulsive disorder (OCD).21,25 However, research on the relationship between anxiety and SOR is extremely limited, making it difficult to evaluate the possible ways in which these constructs may be distinct or overlap. To date, no studies have examined SOR within a sample of children with clinically significant anxiety who do not have developmental delays or disabilities. Therefore, we sought to examine the SOR construct within a sample of children presenting for outpatient treatment with primary complaints of anxiety. The current study was exploratory in nature and sought to examine the phenomenology of SOR in this sample of youth who all demonstrated clinically significant psychiatric symptoms. The SOR construct was examined broadly using the SensOR, a parent-report checklist of bothersome sensory experiences. Study aims were to: 1) examine the frequency and course of SOR symptoms in this sample, 2) compare prevalence rates of SOR to those reported in population-based samples, 3) explore whether SOR symptom frequency differs across categorical demographic variables and psychiatric disorder diagnoses, and 4) examine the relationship between SOR symptoms and continuous measures of psychopathology.