Sensory Processing Disorder: Symptoms, Types, Causes and Treatment

Sensory Processing Disorder (SPD) is a complex neurological condition that affects how the brain receives, interprets, and responds to information from the senses. For some, everyday experiences such as the sound of a fan, the texture of clothing, or bright lights can feel overwhelming, unnoticeable, or even distressing. Understanding SPD is crucial, not only for clinicians and educators but also for families and individuals navigating its challenges. This article explores the symptoms, types, causes, and treatments of SPD, synthesizing current research to provide a comprehensive, human-centered overview.

Symptoms of Sensory Processing Disorder

Sensory Processing Disorder manifests through a wide range of symptoms that can affect daily life, academic performance, social interactions, and emotional well-being. Symptoms may vary from subtle to severe, often leading to misunderstandings or misdiagnoses. Recognizing these signs is the first step in seeking appropriate support and intervention.

Symptom	Description	Impact	Source(s)
Over-responsivity	Strong, negative reactions to sensory input	Avoidance, distress	1 5 16
Under-responsivity	Diminished response to sensory stimuli	Missed cues, withdrawal	1 5 16
Sensory Seeking	Craving intense or frequent sensory experiences	Hyperactivity, risk-taking	5 7
Avoidance	Actively avoiding certain sensory situations	Social isolation	1 5 4 16
Emotional/Behavioral	Mood swings, anxiety, tantrums linked to stimuli	Disruption in routines	4 5 16
Motor Challenges	Clumsiness, poor coordination	Difficulty in daily tasks	1 5
Functional Impairment	Difficulty in school or social participation	Academic/social struggles	16 5 4

Table 1: Key Symptoms

Over-Responsivity (Sensory Sensitivity)

Many individuals with SPD experience heightened sensitivity to sensory input. This can look like covering ears in response to ordinary sounds, distress at certain clothing textures, or strong aversion to bright lights. Such over-responsivity may lead to avoidance behaviors—refusing to participate in activities, outbursts, or even panic attacks in overwhelming environments 1 5 16.

Under-Responsivity (Low Registration)

Conversely, some people with SPD appear to ignore sensory input. They might not notice their name being called or fail to respond to pain. This under-responsivity can cause them to seem disengaged or withdrawn, leading to missed social or environmental cues, and increasing the risk of accidents 1 5 16.

Sensory Seeking Behaviors

Some children and adults with SPD actively seek out intense or frequent sensory experiences. This might include excessive touching of objects, crashing into things, or making loud noises. While seeking input can sometimes be adaptive, it often disrupts routines or learning environments and may be mistaken for hyperactivity or impulsivity 5 7.

Avoidance and Emotional/Behavioral Symptoms

Avoidance of sensory-rich situations is common, especially if previous encounters have been distressing. This can result in social withdrawal, reluctance to try new things, and disruption of daily routines. Emotional symptoms—such as anxiety, mood swings, and tantrums—are frequently linked to sensory overload or deprivation 4 5 16.

Motor and Functional Difficulties

SPD often co-occurs with challenges in fine and gross motor skills. Individuals may appear clumsy, have trouble with handwriting, or struggle with balance. These difficulties further impact academic performance and participation in activities of daily living 1 5.

Types of Sensory Processing Disorder

SPD is not a one-size-fits-all diagnosis. It encompasses several types and subtypes, each reflecting different patterns of sensory processing challenges. Understanding these distinctions can guide more effective interventions and support.

Type	Core Feature	Typical Behaviors	Source(s)
Sensory Modulation	Over/under-responsivity or seeking	Avoidance, seeking, withdrawal	1 5 7 16
Sensory-Based Motor	Motor planning and coordination issues	Clumsiness, poor balance	1 5
Sensory Discrimination	Difficulty distinguishing sensory input	Mistaking similar sounds, touch	1 5
Mixed Type	Combination of above	Multiple overlapping symptoms	5 7
Subtypes (ASD-specific)	Taste/smell, tactile, movement, oral	Subgroup-specific challenges	6 7 8 11

Table 2: SPD Types and Features

Sensory Modulation Disorder (SMD)

SMD is the most commonly recognized type. It involves difficulties regulating responses to sensory input, resulting in over-responsivity, under-responsivity, or sensory-seeking behaviors. Individuals may fluctuate between these patterns depending on context or type of sensory input 1 5 7 16.

• Over-responsive (hypersensitive): Reacting strongly or negatively to ordinary stimuli.
• Under-responsive (hyposensitive): Failing to react or notice sensory input.
• Sensory-seeking: Craving additional or intense sensory experiences.

Sensory-Based Motor Disorder

This type centers on problems with motor skills and coordination. Affected individuals may struggle with balance, motor planning (dyspraxia), and execution of movements. Clumsiness, difficulty learning new motor tasks, and poor handwriting are common presentations 1 5.

Sensory Discrimination Disorder

Here, the challenge lies in distinguishing between different sensory inputs. Individuals may have trouble telling the difference between similar sounds, textures, or visual cues, leading to confusion and frustration, especially in noisy or complex environments 1 5.

Mixed Type and Overlapping Presentations

Many individuals do not fit neatly into one category. Mixed or overlapping types are common, with more than half of children in some studies displaying features of multiple SPD subtypes 5 7.

SPD in Neurodevelopmental Disorders

In autism spectrum disorder (ASD), ADHD, and Fragile X syndrome, distinct sensory processing subtypes are observed. For example, children with ASD may display heightened oral or tactile sensitivities, while those with ADHD might exhibit more visual processing differences. Recognizing these subtypes can help tailor interventions 6 7 8 11.

Causes of Sensory Processing Disorder

The exact causes of SPD remain under investigation, but research points to a complex interplay of genetic, neurological, and environmental factors. Understanding these can help demystify the condition and guide prevention and treatment efforts.

Factor	Description	Evidence/Association	Source(s)
Neurological	Atypical brain structure/function	Neocortex, basal ganglia, cerebellum	1 2 8 10
Genetic	Inherited or syndromic (ASD, FXS)	Familial patterns, animal models	8 10 11
Developmental	Prematurity, early neurobehavioral issues	Higher incidence in preterm infants	9
Environmental	Early sensory experiences, stress	NICU exposure, lack of stimulation	9 1
Biopsychosocial	Interplay of psychiatric, social factors	Comorbidity with anxiety, OCD	3 4 15

Table 3: SPD Causes and Contributing Factors

Neurological Foundations

SPD is widely believed to have roots in atypical brain structure and function. Research highlights the roles of the neocortex, basal ganglia, and cerebellum in integrating sensory input and generating adaptive responses. Disrupted connectivity or function in these regions may lead to the symptoms seen in SPD 1 2 8.

Genetic and Syndromic Associations

Genetic factors play a significant role, particularly in conditions like ASD and Fragile X syndrome, which frequently co-occur with SPD. Animal models mirror many sensory processing deficits seen in humans, suggesting a conserved biological basis. Family studies also indicate that SPD-like traits may cluster in relatives 8 10 11.

Developmental and Environmental Risks

Premature birth is a known risk factor, with preterm infants showing higher rates of SPD. Early life stress, such as intensive care or exposure to overwhelming sensory environments, may disrupt typical sensory processing development. Conversely, a lack of appropriate sensory experiences can also contribute to atypical processing 9 1.

Biopsychosocial Influences and Comorbidity

SPD often occurs alongside other psychiatric and neurodevelopmental disorders, including anxiety, OCD, functional neurological disorder (FND), and ADHD. Sensory processing difficulties can both stem from and exacerbate these conditions, pointing to a complex interplay of biological and psychosocial factors 3 4 15.

Treatment of Sensory Processing Disorder

Effective intervention for SPD requires a personalized, multidisciplinary approach that addresses each individual's unique sensory profile, functional challenges, and related emotional or behavioral concerns. While research continues to evolve, several evidence-based strategies are available.

Treatment Approach	Description	Target Symptoms/Goals	Source(s)
Sensory Integration Therapy	Structured, play-based sensory activities	Regulation, adaptive response	12 14 13
Sensory-Based Interventions	Single-sensory tools (e.g., weighted vests)	State of arousal, focus	12 14 15
Occupational Therapy	Custom plans, skills training, coping	Daily function, participation	15 16
Counseling/Psychotherapy	Emotional support, self-regulation strategies	Anxiety, behavioral symptoms	4 16
Family & School Support	Education, collaborative strategies	Consistency, advocacy	16 15

Table 4: SPD Treatment Approaches

Sensory Integration Therapy (SIT)

SIT uses guided, sensory-rich activities in a controlled environment to help individuals respond more adaptively to sensory input. Evidence suggests that SIT can improve goal attainment and reduce problem behaviors in children with SPD, especially those with comorbid ASD. Activities are typically play-based and tailored to each child's sensory needs 12 14 13.

Sensory-Based Interventions

These interventions involve specific tools or strategies—such as weighted vests, therapy balls, or noise-canceling headphones—to help regulate arousal and sensory responses. While some studies report benefits, especially when individualized and used under professional guidance, results are mixed, and more rigorous research is needed 12 14 15.

Occupational Therapy (OT)

OT is central to SPD intervention. Occupational therapists assess sensory profiles and develop individualized treatment plans focusing on daily living skills, coping strategies, and participation in meaningful activities. OT can also provide family and school consultations to ensure a supportive environment 15 16.

Counseling and Psychotherapy

Given the emotional and behavioral challenges associated with SPD, counseling can be highly beneficial. Therapists help individuals and families develop self-regulation, coping skills, and strategies to manage anxiety or mood swings. Collaborative care, involving both mental health professionals and occupational therapists, is often most effective 4 16.

Family and School Support

Education and advocacy are crucial. Families and educators benefit from understanding SPD, implementing consistent strategies, and fostering supportive environments both at home and school. Early intervention and collaboration among caregivers, teachers, and clinicians can greatly improve outcomes 16 15.

Conclusion

Sensory Processing Disorder is a multifaceted condition that can significantly impact daily life, learning, and relationships. Early recognition, comprehensive assessment, and individualized intervention are key to supporting those affected. Ongoing research continues to refine our understanding of SPD’s causes and optimal treatment approaches.

Key Takeaways:

• SPD symptoms can include over- or under-responsivity, sensory seeking, avoidance, behavioral and motor challenges, and functional impairments 1 5 7 16.
• Types of SPD include sensory modulation, sensory-based motor, and sensory discrimination disorders, with overlapping and mixed presentations common 1 5 7.
• Causes are multifactorial, involving neurological, genetic, developmental, environmental, and biopsychosocial factors 1 8 9 10.
• Treatment is most effective when multidisciplinary, tailored, and involves sensory integration therapy, occupational therapy, counseling, and strong family/school collaboration 12 14 15 16.
• Early intervention and education for families, schools, and professionals are essential in enhancing quality of life and functional outcomes for individuals with SPD.

By fostering awareness and utilizing evidence-based practices, we can empower individuals with SPD to navigate their world with greater comfort and confidence.