A diagnosis of Sensory Processing Disorder (SPD) is often confused with Autism Spectrum Disorder (ASD). This confusion stems from a significant overlap in observable behaviors, particularly how individuals react to sights, sounds, and textures. Sensory differences are highly prevalent in both populations, but the conditions are distinct neurological profiles. This article clarifies the differences, similarities, and diagnostic criteria for each condition.
Defining Sensory Processing Disorder
Sensory Processing Disorder (SPD) is a neurological condition that interferes with the brain’s ability to receive, organize, and respond to sensory information. This includes the five traditional senses, plus the vestibular sense (movement and balance) and proprioception (body awareness). Individuals with SPD have difficulties regulating their responses to this input, which can exist as a stand-alone diagnosis. This difficulty is broadly categorized into three main patterns.
The first pattern is Sensory Modulation Disorder, where an individual is either over-responsive (hypersensitive) or under-responsive (hyposensitive) to stimuli. Hypersensitivity may cause a child to find bright lights or certain textures overwhelming, leading to avoidance. Conversely, hyposensitivity may result in a child needing to constantly crash into objects or seek strong flavors to register the sensation.
The other two patterns are Sensory-Based Motor Disorder and Sensory Discrimination Disorder. Sensory-Based Motor Disorder causes difficulties with balance, motor coordination, and planning movements. Sensory Discrimination Disorder involves trouble interpreting the precise qualities of a stimulus. For instance, a person might struggle to tell the difference between the letters ‘was’ and ‘saw’ or be unable to gauge the appropriate force needed to hold an object. The presence of these processing difficulties, without other developmental challenges, defines SPD.
Sensory Experiences in Autism Spectrum Disorder
Sensory issues are formally recognized as one of the diagnostic criteria for Autism Spectrum Disorder (ASD). In ASD, sensory differences are listed under the domain of restricted, repetitive patterns of behavior, interests, or activities. These experiences manifest as hyper- or hyporeactivity to sensory input or an unusual interest in sensory aspects of the environment.
A child with ASD might exhibit extreme reactions to sounds or smells, demonstrating hypersensitivity. Alternatively, they may display hyposensitivity by seeming indifferent to pain or temperature, or by constantly smelling or touching objects. This sensory component is a core feature of the disorder and is often one of the earliest signs noticed by parents. A large percentage of individuals with autism experience sensory processing challenges.
The Core Differences Between the Conditions
The primary distinction between SPD and ASD lies in the mandatory deficits in social communication and interaction required for an ASD diagnosis. A diagnosis of ASD requires difficulties in areas like social-emotional reciprocity, nonverbal communicative behaviors, and developing or maintaining relationships. These social and communication challenges are not inherent to a diagnosis of SPD alone.
An individual with pure SPD struggles primarily with sensory information processing, but their ability to understand social cues and form typical relationships remains intact. For example, a child with SPD might refuse to wear socks due to texture, yet easily participate in group play. In contrast, a child with ASD will have both sensory issues and profound difficulties with social understanding and communication.
An ASD diagnosis also requires the presence of restricted and repetitive patterns of behavior beyond sensory issues. These patterns can involve an insistence on sameness, inflexible adherence to routines, or highly restricted interests. For a person with ASD, sensory issues are one component of this broader developmental profile. With SPD, however, the sensory challenges are the central issue.
Diagnostic Assessment and Professional Roles
The diagnostic process for each condition involves different professionals and tools. For Sensory Processing Disorder, the identification process is led by an Occupational Therapist (OT) who has advanced training in sensory processing and integration. OTs use specialized assessments to evaluate how an individual responds to various sensory stimuli and how these responses affect their daily functioning. Although SPD is not recognized as a separate diagnosis in the DSM-5, the OT’s assessment links sensory differences to functional impairments at home or school.
Diagnosing Autism Spectrum Disorder requires a comprehensive evaluation by a multidisciplinary team, such as a developmental pediatrician or psychologist. The diagnosis is based on the criteria outlined in the DSM-5, involving clinical observation and standardized behavioral assessments. Although OTs contribute information regarding sensory challenges, the final diagnosis of autism is made by a medical or psychological professional. This professional confirms the presence of the core social and communication deficits.