11.1.2: Disorders Related to Brain Development

Learning Objectives

1. Describe what Cerebral Palsy is and how it affects motor development.
2. Explain the characteristics, diagnostic criteria, and early signs of Autism Spectrum Disorder (ASD).

Disorders that affect brain development can impact many aspects of a child's growth, including motor skills, communication, behavior, and social interaction. In this section, we will explore two such disorders: Cerebral Palsy and Autism Spectrum Disorder (ASD).

Cerebral Palsy

Cerebral Palsy (CP) is a group of disorders that affect movement and muscle tone. It is caused by damage to the developing brain, most often before or during birth. CP affects a child's ability to control their muscles and can cause difficulties with motor skills such as walking, sitting, or reaching for objects. Symptoms of Cerebral Palsy can vary but typically include:

• Muscle stiffness (spasticity) or weakness
• Difficulty with coordination and balance
• Abnormal gait or difficulty walking
• Delayed motor skills, such as sitting or crawling
• Involuntary movements or tremors

There are different types of cerebral palsy, which are classified based on the type of movement problems they cause. These include spastic, dyskinetic, ataxic, and mixed types.

Figure \(\PageIndex{1}\). A young cerebral palsy client is receiving physical therapy services to improve mobility. Image by Martine Perret / UNMIT is licensed CC BY-NC 2.0

Diagnosis of CP is typically made after a child shows delays in reaching developmental milestones or displays unusual muscle tone. Medical professionals may use imaging techniques, such as MRIs and CT scans, in conjunction with developmental assessments, to confirm the diagnosis.

While genetic factors are not typically the cause of CP, certain genetic mutations may make a child more vulnerable to brain damage from events like lack of oxygen during birth. Additionally, brain injuries caused by infections or trauma during infancy can increase the risk.

Autism Spectrum Disorders

Autism Spectrum Disorder (ASD) is a developmental disorder that affects how a person thinks, interacts, and experiences the world. It is often referred to as a "spectrum" because it includes a wide range of symptoms and severity levels. Children with ASD may have difficulty with social interactions and communication and may engage in repetitive behaviors. The exact cause of ASD is not fully understood, but a combination of genetic and environmental factors likely plays a role. Symptoms of Autism Spectrum Disorder may include:

• Difficulty with social communication, such as not making eye contact, not responding to their name, or struggling to understand social cues
• Repetitive behaviors, like hand-flapping, lining up toys, or repeating the same phrases
• Restricted interests, such as an intense focus on one activity or subject
• Sensory sensitivities, where a child might be overly sensitive or under-sensitive to lights, sounds, or textures

Figure \(\PageIndex{2}\). A young boy with autism is experiencing sensory overload due to hearing stimuli. Image is in the public domain.

Diagnosis and Screening Recommendations

ASD is typically diagnosed based on behavioral assessments and developmental screenings, which help to identify delays or differences in social and communication skills. Early diagnosis is crucial for effective treatment and intervention. Symptoms usually appear before the age of 3 and are often noticed when a child fails to meet developmental milestones in communication, socialization, or behavior.

The American Academy of Pediatrics (AAP; 2020) strongly recommends that all children be screened for developmental delays, including autism, during regular pediatric checkups. According to the AAP, screening for autism should occur at 18 and 24 months of age, with a follow-up screen if a child shows any signs of developmental delays or if parents or caregivers raise concerns.

Early screening is crucial for early diagnosis and intervention. When autism is identified early, children can receive therapies and supports that can greatly improve outcomes in communication, social skills, and behavior. Common screening tools include the Ages and Stages Questionnaire - Social/Emotional, Communication and Symbolic Behavior Scales (CSBS), and Modified Checklist for Autism in Toddlers (M-CHAT), which help identify children at risk for ASD and ensure timely referral for further evaluation if necessary.

Research

Research suggests that there is a strong genetic component to autism. While no single gene is responsible, studies show that mutations in certain genes may increase the likelihood of developing ASD. Families with one child with ASD have an increased risk of having another child with the disorder.

Neurological research, via MRI scans, has shown that children with autism have differences in the structure and function of the brain. For example, the amygdala, which plays a central role in processing emotions, has been one of the most studied areas in relation to ASD. It is involved in recognizing emotions in others (such as fear or happiness) and generating appropriate emotional responses. Studies have shown that individuals with autism often have differences in the size and functioning of the amygdala. For some, the amygdala is enlarged in early childhood but may show abnormal growth patterns as the child ages. This altered development is thought to contribute to difficulties with social recognition and processing emotions, which are hallmark symptoms of ASD (Baron-Cohen et al., 2009).

Additionally, research has found that:

• the prefrontal cortex may show reduced activation,
• the temporal lobe may function atypically and contribute to the difficulty in recognizing and interpreting facial expressions or social cues (McPartland & Pelphrey, 2012),
• there is usually a smaller cerebellar volume (Belmonte & Yurgelun-Todd, 2003),
• and/or the somatosensory cortex (responsible for processing sensory information) might also function atypically, causing either hypersensitivity or hyposensitivity to stimuli (Kern & Trivedi, 2012).

References, Contributors and Attributions

American Academy of Pediatrics. (2020). Developmental surveillance and screening of infants and young children. Pediatrics, 145(1), e20193449. https://doi.org/10.1542/peds.2019-3449

Baron-Cohen, S., Ashwin, E., Ashwin, C., & others. (2009). The amygdala theory of autism. Neuropsychological Review, 19(3), 301-311. https://doi.org/10.1007/s11065-009-9074-5

Baio, J., Wiggins, L., Christensen, D., & others. (2020). Prevalence of autism spectrum disorder among children aged 8 years—Autism and developmental disabilities monitoring network, 11 sites, United States, 2016. Morbidity and Mortality Weekly Report, 69(4), 1–10. https://doi.org/10.15585/mmwr.mm6944a1

Belmonte, M. K., & Yurgelun-Todd, D. (2003). Functional anatomy of the autistic brain: A review of neuroimaging studies. Cognitive and Behavioral Neurology, 16(4), 179-186.

Kern, J. K., & Trivedi, M. H. (2012). The pathophysiology of autism: A review of the neurobiology of autism. Biological Psychiatry, 72(4), 293-302. https://doi.org/10.1016/j.biopsych.2012.04.012

McPartland, J. C., & Pelphrey, K. A. (2012). Autism spectrum disorders: Neural underpinnings and the importance of social context. Trends in Cognitive Sciences, 16(5), 204-213. https://doi.org/10.1016/j.tics.2012.03.001

Rosenbaum, P., & Stewart, D. (2014). Cerebral palsy: The lifelong effects of childhood disability. Mac Keith Press.

Smith, T., & Lovaas, O. I. (2016). The science and practice of autism: A developmental perspective. Springer.