The Asymmetrical Tonic Neck Reflex (ATNR): Neurodevelopmental Significance, Functional Impact, and Clinical Implications for Children With Autism, ADHD, and Developmental Challenges

Author: Earl Mamaril, MS, OTR/L
Affiliation: Sensory Therapy Place, Brewer–Bangor, Maine
Article Type: Scholarly Pediatric OT Review (APA Style)

Abstract

The Asymmetrical Tonic Neck Reflex (ATNR) is a brainstem-mediated primitive reflex that emerges prenatally and typically integrates within the first six months of life. It plays a foundational role in early motor development, midline awareness, and the coordination of visual and motor systems. Evidence from pediatric neurology, physical therapy, and neurodevelopmental research indicates that persistence of ATNR beyond infancy may interfere with functional skills, including bilateral coordination, handwriting mechanics, postural stability, and oculomotor control.

Recent studies also observe higher rates of retained ATNR in children with attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD), learning difficulties, and motor coordination challenges. While associations are correlational, ATNR persistence may reflect atypical or delayed neurodevelopmental integration. This review summarizes ATNR development, function, assessment procedures, neurodevelopmental implications, and considerations for occupational therapy intervention for children presenting with autism, ADHD, sensory processing differences, and related developmental concerns.

Keywords

ATNR; primitive reflexes; neurodevelopment; sensory processing; autism spectrum disorder; ADHD; oculomotor skills; bilateral coordination; handwriting; pediatric occupational therapy

Introduction

Primitive reflexes serve as early motor programs originating in subcortical and brainstem structures. Their activation supports neonatal survival, early movement patterns, and the establishment of neural pathways that facilitate later voluntary motor control. The ATNR, often described as the “fencer’s posture,” couples head rotation with ipsilateral limb extension and contralateral limb flexion. This reflex emerges in utero, is fully observable in full-term infants, and typically diminishes by approximately six months of age as the central nervous system (CNS) matures (Coryell & Cardinali, 1979; Zafeiriou, 2004).

According to OpenEvidence-supported medical literature, ATNR is mediated by proprioceptors in the neck and processed in upper cervical spinal segments (American Academy of Neurology [AAN], 2009). While transient presence is expected in infancy, persistence beyond typical developmental windows may indicate neurological immaturity and is associated with several functional challenges in school-age children (Gieysztor et al., 2018; McPhillips & Jordan-Black, 2007).

This article reviews the developmental purpose of ATNR, its potential impact when retained, and its clinical relevance for children with ASD, ADHD, and related pediatric conditions.

Developmental Neurophysiology of ATNR

The ATNR plays an essential role in:

• establishing early eye–hand coordination
• promoting midline awareness
• facilitating early reaching and rolling
• shaping visuomotor pathways
• supporting transitions toward bilateral, symmetrical movement patterns

The reflex provides infants with sensorimotor experiences that link head position to limb activation. Through thousands of repetitions, ATNR contributes to the development of postural stability, visual tracking, early grasp, and proximal control needed for later handwriting and fine motor tasks.

ATNR typically reaches peak expression around six weeks of age before gradually diminishing as corticospinal pathways mature (Physical Therapy, 1979). CNS maturation, increased cerebellar involvement, and enhanced postural control support the natural inhibition of the reflex.

Persistence of ATNR and Neurodevelopmental Outcomes

Motor Coordination and Functional Skills

Persistence of ATNR is associated with:

• immature bilateral coordination
• poor crossing-midline ability
• gait asymmetries, including pelvic rotation changes during walking (Gieysztor et al., 2020)
• difficulties with fine motor tasks (e.g., handwriting, tool use)
• altered postural stability and trunk control

Children may turn their head when writing, lift their elbow, or compensate with whole-body movements due to involuntary coupling between head rotation and limb response.

Visual–Motor Integration and Reading

Retained ATNR may influence:

• oculomotor tracking
• smooth pursuit movements
• visual attention across midline
• reading fluency and endurance

McPhillips and Jordan-Black (2007) reported significant associations between persistent ATNR and early reading difficulties, including skipping lines and losing place on the page.

Emerging evidence also suggests that reflex persistence may correlate with changes in eye movement patterns observed during standardized oculomotor testing (Domingo-Sanz et al., 2024).

Associations With ADHD

Multiple studies demonstrate significant correlations between ATNR persistence and ADHD-related behaviors. A systematic review found a moderate positive correlation (r = .48, p < .05) between retained ATNR and ADHD symptoms (Wang et al., 2023). Additional studies show:

• stronger ATNR–ADHD associations in girls

• stronger STNR–ADHD associations in boys
  (Frontiers in Psychiatry, 2021)

These findings suggest sex-specific neurodevelopmental pathways associated with reflex disinhibition, attention regulation, and balance systems.

Associations With Autism Spectrum Disorder

Although fewer studies exist compared to ADHD, research indicates:

• increased persistence of primitive reflexes in infants with reduced motor repertoire
• greater prevalence of reflex retention in infants of parents with higher autistic traits
  (Chinello et al., 2018)

These results imply that reflex integration may serve as an early indicator of neurodevelopmental variability in ASD.

Persistence of ATNR in autism may contribute to:

• motor planning challenges
• atypical postural tone
• visuomotor differences
• sensory modulation difficulties
• Reflex status should never be used diagnostically but may provide insight into developmental trajectories.

Clinical Assessment of ATNR

Testing Procedures

ATNR is commonly assessed through passive or active head rotation while observing limb responses in the following positions:

• Supine
• Sitting
• Quadruped (hands-and-knees)

See video of ATNR screening test:

Clinicians observe:

• degree of limb extension and flexion
• asymmetrical muscle tone
• head–body dissociation
• balance disruptions
• compensatory motor patterns

Marked or obligatory responses beyond infancy, especially into school age, may indicate atypical integration and warrant further evaluation (Zemke & Draper, 1984).

Clinical Presentation in Autism, ADHD, and Sensory Processing Disorders

Families may observe functional signs such as:

• head turning during writing
• switching hands or inconsistent hand dominance
• clumsiness during bilateral motor tasks
• difficulty copying from the board
• sensory seeking or avoidance during postural tasks
• challenges with sustained attention during seated work
• visual fatigue or poor tracking

In sensory processing disorders, ATNR may heighten postural instability, affecting regulation and tolerance for movement-based activities.

Occupational Therapy Intervention Framework

OT intervention emphasizes functional goals rather than reflex suppression alone. Evidence-informed approaches include:

1.Sensorimotor and Postural Development

• core strengthening
• proximal stability
• bilateral integration exercises
• cross-lateral movement patterns (e.g., crawling, climbing, ball games)

2.Visual–Motor and Fine-Motor Integration

• tracking and scanning tasks
• saccadic movement training
• hand dominance development
• handwriting mechanics

3.Sensory Modulation and Self-Regulation

• proprioceptive input (heavy work)
• deep pressure strategies
• rhythmic movement-based preparatory activities
• self-regulation techniques supporting autonomic balance

While reflex integration strategies may be incorporated, current literature emphasizes functional, occupation-centered goals aligned with AOTA guidelines.

4.Implications for Families and Clinicians

Persistent ATNR is not a diagnosis but may provide valuable information about:

• motor development
• academic functioning
• sensory processing
• attention
• emotional regulation
• For children with ASD, ADHD, coordination difficulties, or sensory modulation challenges, ATNR screening can help guide individualized, developmentally grounded intervention plans.

Parents should seek an OT evaluation if concerns arise around handwriting, reading, coordination, attention, fatigue with desk work, or motor planning.

Conclusion

The Asymmetrical Tonic Neck Reflex is a critical developmental building block that supports early motor and sensory integration. When it persists beyond infancy, research indicates associations with functional challenges commonly observed in children with autism, ADHD, learning difficulties, and motor coordination delays. Understanding ATNR and its potential influence on developmental pathways allows clinicians and families to address underlying needs through targeted, evidence-informed occupational therapy intervention.

References

Bob, P., Konicarova, J., & Raboch, J. (2021). Disinhibition of primitive reflexes in attention deficit and hyperactivity disorder: Insight into specific mechanisms in girls and boys. Frontiers in Psychiatry, 12, 430685.

Chinello, A., Di Gangi, V., & Valenza, E. (2018). Persistent primary reflexes affect motor acts: Potential implications for autism spectrum disorder. Research in Developmental Disabilities, 83, 287–295.

Coryell, J., & Cardinali, N. (1979). The asymmetrical tonic neck reflex in normal full-term infants. Physical Therapy, 59(6), 747–753.

Domingo-Sanz, V. A., et al. (2024). Persistence of primitive reflexes associated with oculomotor function in children. BMC Ophthalmology, 24, 204.

Gieysztor, E. Z., Choińska, A .M., & Paprocka-Borowicz, M. (2018). Persistence of primitive reflexes and associated motor problems in healthy preschool children. Frontiers in Psychology, 9, 450.

Gieysztor, E., Pecuch, A., Kowal, M., Borowicz, W., & Paprocka-Borowicz, M. (2020). Pelvic symmetry is influenced by asymmetrical tonic neck reflex during young children's gait. International Journal of Environmental Research and Public Health, 17(13), 4759.

McPhillips, M., & Jordan-Black, J.-A. (2007). Primary reflex persistence and reading difficulties. Neuropsychologia, 45(4), 748–754.

Wang, M., Yu, J., Kim, H. D., & Cruz, A. (2023). Attention deficit hyperactivity disorder is associated with (a)symmetric tonic neck reflexes: A systematic review and meta-analysis. Frontiers in Psychiatry, 14, 1175974.

Zafeiriou, D. I. (2004). Primitive reflexes and postural reactions in the neurodevelopmental examination. Pediatric Neurology, 31(1), 1–8.

Zemke, R., & Draper, D. C. (1984). Notes on measurement of the magnitude of the asymmetrical tonic neck reflex response in normal preschool children. Journal of Motor Behavior, 16(3), 336–343.