Developmental milestones are observable behaviors and physical skills that infants and children achieve as they grow, covering movement, language, and social interaction. Parents often monitor these milestones closely, and delays in gross motor skills, such as walking, can raise concerns about a child’s overall development. A common query is whether a delay in learning to walk is linked to Autism Spectrum Disorder (ASD). This article explores the current scientific understanding of the relationship between the onset of independent walking and a later diagnosis of ASD.
Typical Motor Milestones
Gross motor development involves the large muscle groups used for movements like crawling, sitting, and walking. The age at which a child begins to walk independently varies widely, but it follows a general timeline. Most children walk unassisted between 9 and 18 months of age.
The median age for a child to begin walking is around 12 to 13 months. A developmental delay is commonly defined as the absence of independent walking by 18 months of age. Developmental timelines are not rigid, and factors like temperament and practice influence when a child begins to walk. Observing the full sequence of motor skill acquisition is more informative than focusing on any single milestone.
The Correlation Between Delayed Walking and Autism
Delayed walking is observed more often in children later diagnosed with ASD than in the general population, but it is not a direct diagnostic marker for the condition. Studies suggest that gross motor milestone delays, including later walking, are present in a subset of children with ASD. One study defined delayed walking as onset at or after 16 months, finding it to be a marker of atypical development.
Delayed walking is also strongly associated with other neurodevelopmental disorders and intellectual disability (ID). Research indicates that children with ID but without ASD are more likely to have a significant delay in walking compared to children with both ASD and ID. Rates of delayed walking were significantly lower in children with ASD and low nonverbal IQ compared to those with other diagnoses and low nonverbal IQ.
The link between walking delay and ASD may relate to underlying differences in brain development, specifically in networks involved in motor control and self-awareness. One hypothesis suggests that motor delays are a secondary effect of the neurological differences characteristic of ASD, rather than a primary symptom. Motor development is connected to socio-cognitive development, and the onset of walking is associated with changes in social interaction and language.
While delayed walking can be a feature in some children with ASD, it is often a subtle delay. The presence of delayed walking alone does not predict an ASD diagnosis. The core diagnostic criteria for ASD remain deficits in social communication and restricted or repetitive behaviors.
Broader Motor Skill Differences in Early Autism
Motor skill differences in children later diagnosed with ASD often extend beyond the timing of walking onset. These differences are diverse and can manifest as early as six months of age. Observed issues include delays in achieving earlier milestones, such as sitting or crawling, or atypical movement patterns.
Atypical gait patterns are common, with toe-walking reported in a significant percentage of autistic children, sometimes as high as 19 percent in studied cohorts. Other motor characteristics include poor coordination, difficulties with motor planning (praxis), and low muscle tone (hypotonia). Hypotonia has been reported in more than half of cases in some studies.
Fine motor skills, such as grasping and manipulating objects, can also be affected, making daily tasks like buttoning a coat or using cutlery more challenging. These motor differences are considered associated features of ASD; they are not required for diagnosis but are frequently present. These broader differences, affecting both gross and fine motor skills, are more consistently reported than an isolated delay in walking and can be important early indicators.
When to Seek Professional Guidance
Parents who have concerns about any developmental milestone should consult with their child’s pediatrician. Not walking independently by 18 months is a recognized sign that warrants further evaluation to determine the underlying cause. The pediatrician can perform a developmental screening and decide if a referral to a specialist is necessary.
Specialists, such as a physical therapist or an occupational therapist, can assess gross and fine motor skills and recommend early intervention services. Early intervention is beneficial for addressing both motor and social-communication delays, regardless of whether a formal diagnosis is made. Monitoring a child’s development should involve observing the full range of milestones, including social, language, and cognitive skills, not just movement. Open communication with healthcare providers about any observed delays or atypical behaviors is the most proactive step for parents.