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Head Circumference and Autism: 3 Key Points of Connection

Head Circumference and Autism: 3 Key Points of Connection

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What is the connection between macrocephaly and autism?

Are you familiar with the term “macrocephaly?” Although it may sound complex, it simply refers to a head size that is larger than usual. Doctors commonly monitor the growth of infants and children, including head size. However, numerous studies have found a link between head circumference and autism; children with Autism Spectrum Disorder (ASD) often experience an increase in skull and brain size, particularly during their early years, in contrast to their neurotypical peers.

Researchers extensively study autism, which is a multifaceted subject that includes various aspects, like early signs, causes, diagnosis, early intervention, and treatment options. Among these, the relationship between head circumference and autism is of significant interest. Head circumference may serve as a potential indicator of the disorder in some instances.

In this ABA Centers of Florida blog, we aim to address a question many parents might have: What is the connection between macrocephaly and autism? Continue reading to learn about the characteristics of autism and macrocephaly, the scientific evidence supporting this correlation, and the warning signs that, although macrocephaly generally is not a cause for concern, it could suggest a more severe underlying condition.

Defining Macrocephaly

Macrocephaly, which individuals also refer to as “large head” or “increased head circumference,” is a medical condition characterized by a child’s head size being more prominent than average compared to other children of the same age, sex, and race. This definition comes from Nicklaus Children’s Hospital. Often, children diagnosed with macrocephaly undergo a rapid growth spurt within the first few months after birth and may have a family history of the condition. 

Defining Macrocephaly

Physicians consider an infant to have macrocephaly when their head circumference is above the 97th percentile for children of the same age and gender.

Several conditions can lead to macrocephaly, including autism. In some instances, however, macrocephaly is simply a hereditary trait and poses no health risk.

While there isn’t a precise age pinpointed for the onset of macrocephaly in individuals with autism, research published by the Journal of the American Academy of Child and Adolescent Psychiatry indicates that the condition might appear a few months post-birth. Medical professionals have noted the occurrence of macrocephaly in both children and adults with autism, highlighting a significant link between head circumference and autism.

Head Circumference and Autism: What Does the Science Say?

Research published by the National Library of Medicine has observed that individuals with autism often exhibit a larger-than-average head circumference, although this is not universally the case. This increased head size frequently has a genetic basis and may correlate with a higher score on the ADI-R social algorithm, indicative of language difficulties. While an increased head circumference and the prevalence of macrocephaly can be indicators of autism, it’s essential to recognize that not everyone with ASD exhibits this characteristic, underscoring the clinical diversity of the disorder.

Another piece of research featured in Psychiatry Research: Neuroimaging established a connection between macrocephaly and brain overgrowth in autism. This study found that individuals with autism had a significantly larger head circumference compared to non-autistic controls, with 15.7% of individuals with autism displaying macrocephaly. Additionally, a significant correlation was identified between age and total brain volume, indicating that individuals with autism tend to have a larger head and brain size during early childhood. These findings offer definitive evidence of the link between head circumference and autism and support their consideration in multi-biomarker clinical diagnostic panels.

Conversely, research in the Journal of Autism and Developmental Disorders revealed that children with autism often follow an unusual trajectory of head circumference growth, which may signal a susceptibility to autism. This study investigated if younger siblings of children with ASD who exhibited an atypical head growth trajectory were more likely to develop symptoms of autism compared to those with a typical growth pattern. The findings showed that infants with a larger head circumference at 12 months and whose head growth decelerated more sharply between 12 and 24 months had a higher likelihood of demonstrating symptoms of autism. These results suggest that atypical growth patterns in head circumference could prompt pediatricians to perform further evaluations on younger siblings of children with autism, highlighting the critical connection between head circumference and autism.

Head Circumference and Autism: 3 Key Points of Connection

3 Points of Connection Between Autism and Macrocephaly

Although the relationship between head circumference and autism continues to be studied, we can examine three key aspects to understand this connection better:

  1. Accelerated Brain Development: Brain imaging studies have shown that macrocephaly in children with autism can indicate an increased brain volume rather than an accumulation of excess fluid or non-brain tissue. This finding indicates specific differences in brain structure and connectivity patterns in individuals with autism, potentially contributing to the increased head size. The connection between accelerated brain development and the observed increase in head circumference underscores a critical aspect of the relationship between head circumference and autism.
    2. Genetic Component: While the precise causes of autism remain undefined, a myriad of studies points to a significant genetic component in its development. Genetic mutations, such as PTEN and 22q11.2 deletion syndrome, have been associated with both autism and macrocephaly. These genetic variations could play a role in the increase in head size seen in some individuals with autism, highlighting the intricate interplay between genetics and the physical manifestations of autism.
    3. Neuroanatomical Variations: Autism is a complex disorder that impacts brain development, leading to alterations in its structure and function. The increase in head circumference observed in some individuals with autism may result from these specific neuroanatomical variations, including abnormalities in brain areas responsible for social communication, language, and sensory integration.

Grasping the relationship between head circumference and autism is critical for accurate diagnosis and effective intervention strategies. This understanding aids in identifying subgroups within the autism spectrum and tailoring personalized treatment approaches. However, it’s crucial to recognize that head size alone does not determine an autism diagnosis; a thorough assessment considering multiple factors is necessary.

Parents and caregivers should note that a larger head circumference might signal other conditions, emphasizing the importance of consulting specialized medical professionals for an accurate diagnosis and suitable treatment plan.

Warning Signs of Macrocephaly

While macrocephaly itself is not usually a problem, it is essential to recognize that there are causes other than autism and genetics that can lead to this condition. It is crucial to watch for the following symptoms to rule out any more severe problems related to your child’s larger head:

  • Vomiting
  • Poor feeding
  • Unusual eye movements
  • Abnormal limb movements
  • Tension in the head
  • Soft lumps on top of the head
  • Irritability
  • Excessive sleepiness
  • Persistent or high-pitched crying
  • Delayed cognitive development

These signs may indicate increased pressure in the head, which requires immediate specialized medical attention. Do not hesitate to consult a physician if you observe any of these symptoms in your child.

Transforming Lives Through Autism Treatment

While the relationship between head circumference and autism remains under study, there are a number of signs of autism, such as difficulties in communication, social interaction, repetitive behaviors, and sensory sensitivities, that parents can address with specialized behavioral help.

Applied Behavior Analysis (ABA) is a therapeutic methodology with over four decades of research. It has proven to be highly effective in helping individuals with autism learn essential skills and overcome behaviors that may limit their overall development and social integration.

At ABA Centers of Florida, we offer a full range of autism care services, including testing, diagnosis, early intervention, and ABA therapy in home, clinic, and school settings.

Our ABA therapy involves working one-on-one with a certified therapist to meet the personal goals of the individual and their family using methodologies specific to learning for individuals with autism. In addition, we seek to involve parents and caregivers in the therapeutic process to enhance each client’s support and skill acquisition.

In addition to therapy, we provide opportunities for socialization for children with autism through events designed to foster communication skills and interaction and for parents to continue learning from our certified professionals and other parents.

Join our family and give your child with autism the specialized support they need. Call us at (772) 773-1975 or contact us online to schedule a free consultation.

Discover how our autism treatment services can help you.

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