The nervous system is a highly adaptive, fault tolerant system.  Its primary purpose is to maintain homeostasis – balance

within the all the body’s systems.  When its threshold is lowered, its ability to adapt decreases, creating compensated responses.  These can be heightened, deferred, or regressive in nature.  The response varies but the underlying cause is the same – an impeded nervous system unable to respond to external stimuli affectively.

The acceptance of the growing number of children whose nervous systems are becoming more fragile, less adaptable, and compromised, as simply another statistic is troubling.  For example, in the 1980’s the autism rate in the United States was 1in 1,000, in 2023 it was estimated at 1 in 36. At the same time many children with autism, ADHD, or sensory processing issues exhibit symptoms of nervous system dysregulation due to difficulties in managing emotional or sensory input. Approximately 15–20% of children are neurodiverse, which often correlates with challenges in nervous system regulation.​ ⁽¹⁾ In addition stressful environments or early adverse childhood experiences can further exacerbate nervous system dysregulation. An estimated 10–20% of children may show chronic dysregulation symptoms due to ongoing stressors or lack of co-regulation support​. ⁽²⁾

Is it the increase in stressors or the lowered adaptability, due to genetics, environment, interference to function, that is the causative factor/s? This question needs to be addressed to stem the tide of the advancing numbers of children whose functional capacities are decreasing.  Acceptance of the growing numbers, societal compensations to adapt to their specific needs, finding ways to deal with or treat the symptoms of the problem, while not addressing the causative factors, is an unacceptable response.

Genetics, environment, lifestyle choices, and varying behavioral approaches should all be part of the conversation.  But the one thing all these children appear to have in common is a compensated nervous system, often coined as neurodiverse or dysregulated. While diversity in expression is expected, even fostered, when adaptability, functional capacity, and inclusion in active relationships is at risk, and these “glitches” in the nervous system become hinderances to growth, development and participation in life, we need to begin to address the underlying factors inherent in these children that are creating this dysfunction.

Is there a trajectory that is inherent in human nervous system development that needs to be followed to allow us to become functionally effective human beings, able to care for ourselves and contribute to society? Is there a specific pattern of brain development that sets us apart as human beings and allows us to adapt to the world in a cohesive, safe, and functionally effective manner? (Functionally affective manner refers to approaching a situation or performing a task with practical efficiency while remaining neutral about subjective opinions or preconceived notions of how things ought to be).

For this article I want to lay down a simplified model of the trajectory of brain development. The human brain follows a remarkable developmental trajectory from birth to age six, characterized by rapid growth and extensive neural network formation:

1. Birth to Age 2: At birth, the brain is about 25% of its adult size. By age 2, it grows to roughly 80% of its adult volume. This period is marked by the rapid creation of synapses (connections between neurons) and pruning, where unused connections are eliminated. The cerebellum, crucial for motor coordination, experiences significant growth in the first year, while the hippocampus (important for memory) grows more slowly. The cerebellum acts as the main processing center and grows 240% in this first year. ⁽³⁾
2. Age 2 to 5: This phase sees a peak in synaptic density, often referred to as the “preschool surge.” Language and social-emotional skills expand as regions associated with higher-order functions, like the prefrontal cortex, become increasingly active. The brain’s plasticity allows for adaptation and learning from environmental stimuli during this period​. ⁽⁴⁾
3. Age 5 to 6: While growth slows, the brain continues refining connections and neural networks. The development of the frontal and parietal lobes enhances problem-solving, attention, and reasoning skills. By this age, foundational neural pathways for motor, language, and emotional regulation are well established but remain modifiable​. ^(5)​

These early years are critical for cognitive, social, and emotional development. Underlying this developmental scenario are the development and integration of primary reflexes and linear developmental milestone acquisition. Primary reflexes and milestone development are foundational for brain growth and neural integration, ensuring that higher-level cognitive and motor skills can develop effectively.

Primary Reflexes and Their Role in Brain Development

• Definition: Primary reflexes (such as the Moro reflex, rooting reflex, and grasp reflex) are automatic, survival-based movements present at birth. They are controlled by the brainstem and facilitate essential functions like feeding and protection​.
• Neurological Impact:
  • Stimulate Brain Growth: Reflex movements activate sensory systems (e.g., touch, proprioception) that stimulate neural pathways and support the maturation of the brain’s motor and sensory regions.
  • Prepare for Voluntary Control: As the brain develops, primary reflexes are integrated or inhibited by higher brain centers (e.g., the cortex). This integration allows for voluntary movement and advanced motor skills​
• Persistence of Reflexes: If primary reflexes are not integrated (e.g., due to developmental delays or neurological issues), they may interfere with later milestones, such as balance, coordination, and focus as well as inhibit proper higher level brain function integration and can maintain a fight or flight response in the central nervous system.  This can cause the individual to react to “normal” stimuli in a dysregulated manner due to lack of higher brain center (prefrontal cortex) input.

Developmental Milestones and Brain Integration

• Sequential Milestone Achievement: Skills like rolling, crawling, walking, and talking emerge in predictable sequences. Each milestone builds on the previous, ensuring that neural circuits responsible for motor, sensory, and cognitive functions are interconnected properly​. Motor and sensory development are integrally related to emotional response mechanisms as well and their lack of integration or development can cause aberrant emotional responses in ‘normal” or challenging situations.
  • Motor Milestones: Activities like crawling enhance bilateral coordination and strengthen connections between the brain’s hemispheres (corpus callosum), crucial for reading and writing later on.
  • Sensory Integration: Milestones that involve sensory exploration (e.g., mouthing objects) refine sensory processing and help children understand their environment.
• Critical Windows: Early achievement of milestones corresponds with critical periods in brain development. For instance, the first year is essential for synaptic proliferation in motor and sensory regions​. The 2^nd – 3^rd years the integration between lower and higher brain centers. Leading to integrated development and nervous system function.

Higher Level Development

• Cognition and Emotional Regulation: Physical movement tied to milestones (e.g., crawling) is closely linked to problem-solving and emotional development. Physical activities provide input that strengthens neural pathways for emotional regulation and executive function.
• Preventing Dysfunction: Lack of reflex integration or milestone delays can result in challenges like poor coordination, learning disabilities, or emotional dysregulation.

Primary reflexes set the stage for milestone development, and these milestones, in turn, reinforce neural pathways and brain integration. Proper sequencing and achievement are essential for a well-regulated nervous system and overall cognitive, motor, and emotional health as well as and increased adaptability and functional capacity.

As chiropractors we focus on optimizing the function of the nervous system through chiropractic adjustments and, when necessary, ancillary support procedures. These protocols help the child create new, more systematic neural pathways and remove interference to already established aberrant processing systems. Our goal is to remove the interferences (subluxations) that can impede the optimal transmission of neural impulses through the entire nervous system, focusing on maintaining proper communication from the brain to the rest of the body. Interference to the transmission of neurological impulses has a global effect on all cells, organs and systems in the body.

A subluxation is a physical, emotional or chemical insult to the nervous system that creates a compensatory (less than optimal) reaction or adaptation. Removal and/or reduction of subluxations is the sole purview of chiropractors. Since our nervous systems are fault tolerance, able to adapt to stress, to a certain degree, these adaptations may at first go unnoticed, but if let uncorrected will create compensatory patterns (symptoms) further down the road as the individual will have to adapt to more and more environmental (physical, chemical or emotional) stimuli, with a lower threshold due to the compensatory adaptation that occurred earlier

In infancy, the nervous system is developing faster than it ever will again and it is also more sensitive to input, good and bad, than it will ever be in its lifetime. It is in these first 6 years that we are laying down the neurological foundation upon which we will depend for the rest of our lives. ⁽⁶⁾ As we can imagine, interference to the “normal” trajectory of nervous system development will have far reaching effects on the childhood development, functional capacity, emotional stability, processing ability, motor and sensory integration and cognitive capacity. Early detection and removal of this interference can often offset or repair these aberrant developmental patterns, restoring a more normal, balanced, functional nervous system.

Bibliography

1. Goally Apps & Tablets for Kids, Green Child Magazine
2. https://starr.org/2023/dysregulation-and-behavior-the-roots-of-teacher-burnout/
3. https://stories.uq.edu.au/the-brain/2022/timeline-of-brain-development/index.html
4. https://communities.springernature.com/posts/birth-to-two-charting-the-early-years-of-human-brain-development
5. https://communities.springernature.com/posts/birth-to-two-charting-the-early-years-of-human-brain-development
6. Rosen, M, Watson, N (2021). It’s All in the Head. Rosewat Publishing.