Some children begin to show signs of autism spectrum disorder (ASD) in early infancy. These may include limited eye contact, not responding when their name is called, or seeming indifferent to caregivers. Others may initially develop typically but later regress—becoming withdrawn, displaying aggressive behavior, or losing previously acquired language skills. In most cases, signs of ASD become evident by the age of 2. 

Each individual with ASD exhibits a unique behavioral pattern and varies in symptom severity, ranging from low-functioning to high-functioning. 

While some children with ASD struggle with learning and may show signs of intellectual disability, others may possess average or above-average intelligence. These children may learn quickly yet face challenges in communication, applying their knowledge in practical settings, or adapting to social environments. 

Due to the diverse symptom presentation, determining the severity of ASD can be challenging. It is usually assessed based on the extent to which the symptoms impair daily functioning. 

Common Signs of Autism Spectrum Disorder 

Social Communication and Interaction Challenges 

A child with ASD may exhibit difficulties in social communication and interaction, including: 

• Not responding to their name or appearing not to hear at times 
• Resisting physical affection and preferring solitary play 
• Poor eye contact and limited facial expression 
• Delayed speech or complete lack of verbal communication; possible loss of previously learned language 
• Inability to initiate or sustain a conversation, except to make requests or label objects 
• Unusual speech patterns, such as a singsong tone or robotic rhythm 
• Repetition of words or phrases without comprehension 
• Difficulty understanding simple questions or directions 
• Limited emotional expression and lack of awareness of others' emotions 
• Not pointing at or showing objects to express interest 
• Approaching social interactions in passive, aggressive, or disruptive ways 
• Trouble interpreting nonverbal cues such as facial expressions, gestures, or tone of voice 

Repetitive Behaviors and Restricted Interests 

Individuals with ASD may also show repetitive behaviors and have restricted interests, such as: 

• Repetitive motions like rocking, spinning, or hand-flapping 
• Engaging in self-injurious behaviors, including biting or head-banging 
• Rigid adherence to routines and distress over minor changes 
• Poor coordination, unusual movement patterns (e.g., toe-walking), or stiff body language 
• Intense focus on specific parts of objects, like spinning wheels, without understanding their purpose 
• Hypersensitivity to sensory input (light, sound, touch), or conversely, a lack of response to pain or temperature 
• Lack of pretend or imitative play 
• Fixation on certain objects or activities with intense concentration 
• Limited food preferences or aversion to certain textures 

As children with ASD grow, some may show improved social engagement and fewer behavioral issues. Those with milder symptoms may eventually function independently. However, others may continue to struggle with language, social interaction, and may face increased behavioral or emotional challenges during adolescence. 

When to Consult a Doctor 

Development varies among children, and not all follow standard milestones. Still, signs of ASD often appear before age 2, especially in language and social development. 

If you have concerns about your child’s development or suspect autism, it’s important to speak with your doctor. Many symptoms overlap with other developmental conditions, so professional evaluation is key. 

Your doctor might recommend developmental assessments if your child: 

• Doesn’t smile or show joyful expressions by 6 months 
• Doesn’t mimic sounds or facial expressions by 9 months 
• Isn’t babbling or cooing by 12 months 
• Fails to gesture (e.g., pointing or waving) by 14 months 
• Doesn’t say single words by 16 months 
• Doesn’t engage in pretend play by 18 months 
• Fails to use two-word phrases by 24 months 
• Loses previously acquired language or social skills at any age