Latent Constructs Underlying Sensory Subtypes in Autism: An Independent-Component Analysis

PURPOSE: To determine the latent constructs that underpin sensory subtype classification in autism spectrum disorder (ASD).

BACKGROUND: A subtype is the classification of a disorder based on specific physical and behavioral characteristics relevant to further understanding or management. Lane et al. developed a classification schema for children with ASD based on parent responses to the Short Sensory Profile (SSP). As a result, four sensory subtypes in ASD have been identified: (1) sensory adaptive, (2) taste/smell sensitive, (3) postural inattentive, and (4) generalized sensory disturbance. Clinical profile examination of the subtypes led to the hypothesis that sensory disturbance in ASD is related to dysfunction in two core sensory dimensions: (1) sensory reactivity (SR), which is the intensity of a response to a stimulus and/or (2) multisensory integration (MSI), which is the ability to process multiple concurrent stimuli.

The use of Lane et al.’s sensory subtypes allows for systematic examination of behavior and symptom profiles associated with each subtype. Further validation of this schema is required, however, before it can be adopted confidently in clinical settings. As a next step to validate this schema, we performed independent component analysis (ICA) to elucidate the latent constructs underlying sensory subtype classification.

DESIGN: The present study is a nonexperimental secondary analysis.

PARTICIPANTS: Two datasets were analyzed in the present study. The first was a sample of 228 children with ASD ages 2–10 yr. The second included 155 children ages 4–10 yr with attention deficit hyperactivity disorder or ASD and typically developing controls.

MEASURES: Parents of study participants completed the SSP, a 38-item parent-report measure. The SSP is designed to measure behaviors associated with differences in the modulation of everyday environmental sensory stimuli in children ages 3–10 yr in seven sensory domains. Parents respond to each item using a 5-point ordinal scale ranging from 1 = always to 5 = never, with higher scores indicating more typical performance.

ANALYSIS: ICA was conducted via a multistep process using z scores from the seven SSP domains and item-level data. First, our hypothesis of a two-component (SR and MSI) structure on the domain z scores was tested. Next, the z scores were analyzed using model-fitting software to determine whether any model with a different number of components better fit the data than the two-component model. The optimal number of components was determined, balancing interpretability with model fit. Last, item-level data were analyzed via ICA to determine which specific items on the SSP contribute most to the underlying latent constructs.

RESULTS: A three-component model best explained the data, each with major contributions from one of the following domains: (1) taste/smell sensitivity, (2) low energy/weak, and (3) underresponsive/seeks sensation and auditory filtering. Key items from those domains that heavily contributed to the corresponding latent components were identified.

DISCUSSION: The first and third components support our original hypothesis about SR and MSI in that they respectively represent (1) sensory overreactivity to taste and (2) behaviors in multisensory situations where the child is unable to prioritize salient sensory stimuli, filter nonsalient stimuli, and act in an adaptive manner. We assert that the second component represents the construct of perception. Items that contribute substantially to this component may describe an increased intensity of the perception of proprioceptive information.

IMPACT STATEMENT: The present study asserts a novel theoretical framework of three core sensory dimensions (SR, MSI, and perception) to guide future research and clinical practice on sensory features in ASD.