Understanding the exposome, neuroplasticity, neuroimmune interactions, and the ecological systems that influence brain development from pregnancy through adolescence.
Introduction: The Brain Does Not Develop in Isolation
Neurodevelopment cannot be adequately explained by studying the nervous system independently of the biological, psychological, social, and ecological systems within which it develops. So, what exactly determines how a child's brain develops?
Is neurological development primarily governed by genetics? Does the environment determine which neural pathways become stronger or weaker? Can immune activity influence the development of neural circuits? How do relationships, movement, sensory experiences, nutrition, sleep, and the broader physical environment contribute to cognitive and behavioral development?
For decades, developmental neuroscience has attempted to answer these questions by examining the individual components of human development. Geneticists have investigated inherited variations associated with neurological traits and conditions. Neuroscientists have studied neuronal differentiation, synaptic organization, myelination, and circuit plasticity. Psychologists have investigated learning, cognition, behavior, and social development. Immunologists have explored the relationship between immune signaling and central nervous system function.
Each discipline has contributed important discoveries. However, an increasingly compelling lesson is emerging from contemporary research: no single biological system, environmental exposure, or developmental experience adequately explains the extraordinary complexity of human neurodevelopment.
The developing brain exists within a larger system of interacting influences. Genes participate in the regulation of cellular activity, but gene expression is influenced by developmental context. Neural circuits are shaped by experience, but the effects of experience depend partly on the developmental stage and existing neural organization. Immune signaling contributes to normal brain development, yet certain inflammatory processes may interfere with aspects of neural function under particular conditions. Social relationships influence learning opportunities, while neighborhoods, institutions, economic resources, and physical environments influence the circumstances in which those relationships develop.
Four important publications provide complementary perspectives on these interactions.
In Nature Reviews Neurology, Owolabi and colleagues proposed a global framework for promoting brain health across the lifespan through coordinated surveillance, prevention, acute care, and rehabilitation.
In Neuropsychopharmacology, Robinson and colleagues examined the developmental exposome, emphasizing the combined influence of physical exposures, psychosocial experiences, and broader environmental circumstances on cognitive outcomes.
In Nature Human Behaviour, Cuartas and Morris-Perez proposed expanding Bronfenbrenner's bioecological model to recognize natural ecosystems as active contributors to human development.
Finally, Meltzer and Van de Water reviewed the relationship between immune function and autism spectrum disorder, exploring maternal immune activation, inflammatory signaling, and immune-related differences observed in subsets of autistic individuals.
Together, these publications support a broader perspective on neurodevelopment.
Human brain development emerges through ongoing interactions among biological organization, environmental conditions, lived experiences, and time. Understanding those interactions requires studying the developing person within the systems in which development occurs.
Neurodevelopment Is a Dynamic Biological Process
Neurodevelopment begins long before birth and continues through childhood, adolescence, and into adulthood.
During prenatal development, neural progenitor cells proliferate, differentiate, and contribute to the formation of the central nervous system. Neurons migrate toward developing brain regions, establish cellular identities, extend axons and dendrites, and begin forming functional connections.
As development proceeds, neural circuits become increasingly organized through processes including synaptogenesis, programmed cell elimination, synaptic remodeling, and myelination.
However, these processes do not occur uniformly throughout the nervous system.
Different neural structures follow different developmental trajectories. Sensory and motor systems generally establish many functional capacities earlier, whereas association networks involved in executive functioning and complex cognition undergo more prolonged maturation.
This phenomenon is known as heterochronous development: different biological structures and processes mature at different times and rates.
The developmental timetable also varies between individuals.
Consequently, chronological age is an important but incomplete indicator of neurological development.
Two children of the same age may demonstrate different patterns of motor coordination, language acquisition, attention, emotional regulation, or cognitive functioning without those differences necessarily indicating pathology.
Developmental assessment must therefore consider both the expected range of variation and the presence of clinically meaningful impairment.
Genetics Provides Biological Information, Not a Fixed Developmental Destiny
Genetic factors contribute substantially to neurological development.
Genes encode proteins involved in neuronal differentiation, axonal guidance, synaptic transmission, cellular metabolism, immune regulation, and many other biological processes.
Some genetic variants have substantial effects on neurodevelopment.
For example, certain pathogenic variants and chromosomal abnormalities are associated with recognizable neurodevelopmental syndromes.
Other neurological traits are influenced by numerous genetic variants, each contributing relatively small effects.
However, the relationship between genotype and phenotype is not always straightforward.
The expression of a genetic variant may depend on additional genetic factors, developmental timing, cellular conditions, and environmental influences.
This concept is consistent with the broader principles of biological relativity, in which causal influences operate across interacting levels of biological organization rather than exclusively from genes toward higher-level functions.
Nevertheless, acknowledging environmental regulation does not imply that genetic conditions can be reversed through lifestyle interventions.
Some genetic alterations produce profound developmental consequences that cannot be eliminated by changing environmental circumstances.
The more scientifically useful perspective is that genetics contributes to the developmental conditions under which biological systems operate, while the resulting phenotype emerges through complex developmental processes.
Understanding the Exposome: The Sum of Environmental Influences
One of the central papers informing this article is Robinson and colleagues' review, The Effect of the “Exposome” on Developmental Brain Health and Cognitive Outcomes.
The exposome concept was originally introduced to complement the genome.
Whereas the genome describes an individual's genetic information, the exposome represents the environmental exposures and experiences encountered throughout life.
However, the exposome is much broader than chemical exposure.
Robinson and colleagues describe three major domains relevant to developmental research: physical and chemical exposures, psychosocial experiences, and external environmental contexts.
Physical and chemical exposures include substances such as lead, air pollutants, tobacco smoke, and pesticides.
Psychosocial experiences include relationships, family interactions, adverse experiences, and other meaningful events.
External environmental contexts include socioeconomic resources, neighborhood conditions, cultural influences, and access to education or healthcare.
These domains are not independent.
For example, a child's neighborhood may influence air pollution exposure, access to recreational spaces, educational opportunities, and family stress.
The exposome framework seeks to understand how these influences accumulate and interact.
This represents an important departure from research designs that investigate one environmental variable at a time.
Why Studying One Exposure at a Time May Be Insufficient
Traditional epidemiological studies often examine the association between one exposure and one outcome.
For example, researchers might investigate whether exposure to a particular air pollutant is associated with differences in cognitive performance.
Although useful, this approach can overlook other factors associated with that exposure.
Children living in areas with elevated air pollution may also experience differences in housing conditions, traffic-related noise, access to green space, or socioeconomic resources.
These factors may be correlated.
They may also exert independent, additive, or interactive influences.
An association attributed to one exposure may therefore partly reflect another.
Exposomics attempts to address this complexity by integrating measurements across multiple environmental domains.
However, measuring more variables does not automatically establish causation.
Large environmental datasets can introduce statistical challenges involving correlated predictors, measurement errors, missing information, and model overfitting.
The most rigorous studies combine comprehensive exposure assessment with appropriate causal inference methods and independent validation.
A more comprehensive model of development is valuable only when greater complexity produces better understanding rather than additional speculation.
Sensitive Periods: Why Developmental Timing Matters
The developing nervous system does not respond identically to environmental influences at every age.
Certain developmental processes involve periods of heightened sensitivity to particular experiences or exposures.
These are often called sensitive periods.
During these periods, specific neural systems may demonstrate increased responsiveness to environmental input.
For example, early visual development depends on appropriate sensory information during particular stages of maturation.
Language development also involves age-related changes in learning sensitivity, although language learning remains possible beyond childhood.
Robinson and colleagues emphasize that developmental sensitivity is heterogeneous across the brain.
The timing of an environmental exposure may therefore influence its relationship with later cognitive or neurological outcomes.
A biological insult occurring during early neuronal migration may have different implications from a similar insult occurring after major neural structures have formed.
Likewise, the developmental effects of psychosocial experiences may depend on timing, duration, and the neural systems involved.
Importantly, sensitive periods should not be confused with universally irreversible critical windows.
Many neural systems retain some capacity for adaptation throughout life.
The presence of heightened plasticity during childhood does not mean meaningful learning, rehabilitation, or behavioral change becomes impossible in adulthood.
Neuroplasticity: How Experience Influences Neural Organization
Neuroplasticity refers to the capacity of the nervous system to change its structure, function, or connectivity in response to development, experience, injury, or other influences.
Plasticity occurs through several mechanisms.
Synaptic strength can change as a result of activity-dependent processes.
Neural circuits can undergo structural remodeling.
Myelination can be influenced by developmental and activity-related factors.
Learning can alter the organization of functional networks.
However, not every neurological change is necessarily beneficial.
Plasticity can contribute to adaptive learning and recovery, but it may also participate in maladaptive responses following injury or persistent abnormal activity.
Furthermore, neuroplasticity should not be treated as a guarantee that any intervention stimulating the nervous system will improve neurological outcomes.
An intervention must demonstrate clinically meaningful benefit through appropriate research.
The fact that a treatment engages neural circuitry does not establish its efficacy.
The appropriate question is whether a particular experience or intervention produces reliable improvements in a defined outcome for a particular population.
Bronfenbrenner's Bioecological Model: Development Within Nested Systems
Developmental psychologist Urie Bronfenbrenner proposed that human development occurs through interactions between individuals and their surrounding environments.
His ecological and later bioecological frameworks emphasized that development cannot be adequately understood without examining the systems in which individuals live.
The microsystem includes immediate environments such as family, school, and peer relationships.
The mesosystem involves connections among those immediate environments.
The exosystem includes broader circumstances that indirectly influence the individual, such as parental workplace policies.
The macrosystem encompasses cultural values, institutions, economic systems, and social policies.
The chronosystem introduces the dimension of time, recognizing that developmental contexts change across both individual lives and historical periods.
Later formulations emphasized proximal processes: recurring interactions between the developing individual and people, objects, and symbols in the immediate environment.
These processes are especially important because they provide recurring opportunities for learning, adaptation, and skill acquisition.
For example, language development occurs through repeated communication, attention, and interaction—not simply through the presence of language in the environment.
Bronfenbrenner's framework therefore helps explain why a child's developmental circumstances extend beyond individual biology.
The Geo-Bioecological Model: Bringing Nature Into Developmental Science
In their 2025 publication in Nature Human Behaviour, Cuartas and Morris-Perez argued that traditional bioecological models have not sufficiently emphasized natural ecosystems.
Although these models recognize social, cultural, and institutional environments, ecological processes such as climate, biodiversity, and environmental quality are often treated as background conditions.
The authors propose a geo-bioecological model that explicitly integrates natural ecosystems into the study of human development.
This framework recognizes that children develop within environments influenced by air quality, water quality, temperature, vegetation, and other ecological conditions.
These influences operate at multiple levels.
A child's immediate environment may include exposure to outdoor heat or neighborhood green space.
Broader policies may determine the availability of parks, pollution controls, and disaster preparedness.
Climate change may influence housing stability, food security, school participation, and patterns of infectious disease exposure.
Importantly, the model also emphasizes reciprocity.
Humans are not merely passive recipients of environmental conditions.
Collective human behavior modifies ecosystems, which subsequently influence the developmental environments of future generations.
The framework is a conceptual proposal intended to guide future research and policy. It should not be mistaken for a clinically validated diagnostic model.
Green Space, Outdoor Experience, and Cognitive Development
Access to natural environments has attracted increasing attention within developmental research.
Some observational studies associate greater exposure to green space with favorable cognitive, behavioral, or psychological outcomes in children.
Potential pathways include opportunities for physical activity, social interaction, play, and exposure to more restorative environments.
Green spaces may also influence heat exposure and local air quality.
However, these mechanisms are not necessarily independent.
Neighborhoods with greater access to green spaces may differ in income, educational resources, traffic patterns, and other conditions.
Consequently, an association between green space and cognition does not necessarily prove that vegetation itself caused the observed difference.
Research must distinguish direct environmental effects from correlated social and developmental opportunities.
Nevertheless, access to safe outdoor environments is a reasonable public health objective because it can support physical activity, recreation, and opportunities for meaningful interaction.
Environmental Neurotoxicants and Developing Neural Systems
Certain environmental exposures have established neurotoxic effects.
Lead is a particularly important example.
Lead exposure can interfere with neurological development and is associated with adverse cognitive and behavioral outcomes.
Children are especially vulnerable because the developing nervous system is sensitive to toxic exposures and because some childhood behaviors increase opportunities for environmental contact.
There is no known safe blood lead concentration in children.
Consequently, reducing lead exposure is an established public health priority.
Air pollution is another area of active developmental research.
Studies have reported associations between pollution exposure and differences in cognitive performance, brain structure, or neurodevelopmental outcomes.
However, the strength of evidence varies according to pollutant, exposure timing, outcome, and study design.
The environmental exposome framework encourages consideration of these exposures alongside other relevant influences.
It does not establish that every individual with a developmental disorder has experienced a harmful chemical exposure.
Nor does it justify broad, unvalidated toxin testing or detoxification treatments as routine neurodevelopmental care.
The Immune System Is an Active Participant in Brain Development
The relationship between the nervous and immune systems has become an important area of developmental research.
Historically, the central nervous system was sometimes described as relatively isolated from ordinary immune activity.
Contemporary research presents a more complex picture.
Immune-related cells and signaling molecules participate in normal nervous system development and maintenance.
Microglia, the resident immune cells of the central nervous system, contribute to tissue surveillance, responses to injury, and aspects of synaptic remodeling.
Complement proteins can participate in identifying synaptic elements for removal.
Cytokines and other signaling molecules may influence neural cells under certain physiological or pathological conditions.
These interactions demonstrate that immune activity is not inherently harmful to the brain.
Appropriate immune function contributes to normal biological regulation.
The important distinction is between physiological signaling and immune responses that may become excessive, mistimed, or otherwise dysregulated.
Microglia, Complement, and Synaptic Remodeling
During development, neural circuits undergo substantial reorganization.
Early synaptic connections are not necessarily maintained indefinitely.
Activity-dependent mechanisms contribute to the strengthening, weakening, or elimination of connections.
Microglia and complement signaling participate in aspects of these processes.
Research in experimental systems has demonstrated that complement components can help mark synaptic structures for removal by microglia.
However, translating these findings directly into explanations of human developmental disorders requires caution.
Microglial functions are diverse and depend on developmental stage, brain region, and local conditions.
Similarly, differences observed in postmortem tissue or experimental models do not necessarily identify the primary cause of a clinical condition.
It would be inaccurate to describe neurodevelopmental disorders generally as diseases of excessive synaptic pruning or chronic neuroinflammation.
These mechanisms may be relevant to particular research questions and biological subgroups, but their clinical significance requires further investigation.
Maternal Immune Activation and Prenatal Neurodevelopment
Meltzer and Van de Water's review examines evidence concerning maternal immune activation and autism.
Maternal immune activation refers to changes in immune signaling during pregnancy, often studied in the context of infection or experimental inflammatory stimulation.
Animal studies have demonstrated that certain maternal immune challenges can influence offspring neurodevelopment and behavior.
Researchers have investigated pathways involving cytokines, placental signaling, and developmental changes in neural circuits.
These experiments provide evidence that immune processes can influence neurological development under specific conditions.
However, experimental immune activation in animals is not equivalent to ordinary maternal immune responses during human pregnancy.
The type, intensity, timing, and duration of the immune challenge are critical.
Furthermore, behavioral findings in animal models cannot be directly equated with autism diagnoses in humans.
Animal research can establish biological plausibility, but human causal inference requires additional evidence.
Does Maternal Infection Cause Autism?
This question illustrates the importance of distinguishing association from causation.
Some earlier epidemiological studies found associations between maternal infections during pregnancy and increased autism diagnoses in offspring.
These observations contributed to growing interest in maternal immune activation.
However, more recent studies have used designs intended to account for family-related confounding.
A Swedish population-based study published in The Lancet Psychiatry in 2022 found that maternal infection during pregnancy was associated with autism in conventional analyses.
Yet the association was substantially attenuated in comparisons between siblings.
The sibling-comparison hazard ratio was 0.94, with a confidence interval spanning no association.
The investigators concluded that the association between maternal infection and autism was more likely explained by shared familial factors than by a direct causal effect of infection.
A large Taiwanese cohort study published in Molecular Psychiatry similarly found that associations between prenatal maternal infection and several neurodevelopmental diagnoses were attenuated toward the null in sibling analyses.
These findings do not exclude every possible immune-mediated developmental mechanism.
Specific infections, severe inflammatory responses, and uncommon biological circumstances may warrant additional investigation.
However, they demonstrate that maternal infection should not be presented as an established general cause of autism.
Pregnant individuals should not be blamed for a child's autism diagnosis because they experienced an infection or immune response.
Maternal Autoantibodies and Autism-Related Research
Another area reviewed by Meltzer and Van de Water involves maternally derived antibodies that recognize proteins expressed in the developing nervous system.
Researchers have identified certain maternal antibody patterns associated with autism in subsets of studied populations.
Experimental studies have investigated whether particular antibodies can influence neural development.
This has led to interest in the possibility of biologically distinct autism-associated subgroups.
However, important uncertainties remain.
An observed antibody pattern does not necessarily establish the cause of a child's developmental characteristics.
The sensitivity, specificity, predictive value, and clinical utility of proposed antibody tests must be evaluated carefully.
At present, maternal anti-brain antibody testing is not part of established routine screening for autism or general preconception care.
Similarly, findings from experimental research do not justify immune-suppressing treatments or other interventions intended to prevent autism in the absence of validated clinical indications.
This remains an important research area rather than a broadly established clinical application.
Autism Is Heterogeneous
Autism spectrum disorder encompasses a heterogeneous range of developmental characteristics involving social communication and restricted or repetitive patterns of behavior, interests, or activities.
Autistic individuals vary substantially in language development, cognitive functioning, sensory experiences, adaptive abilities, motor coordination, and support needs.
Some individuals have co-occurring intellectual disability or epilepsy.
Others demonstrate average or above-average cognitive abilities.
Medical and psychiatric conditions may coexist with autism, but their presence and significance vary.
This heterogeneity is relevant to immune research.
An immune-related finding identified in one subgroup should not automatically be generalized to all autistic individuals.
Likewise, associations between inflammatory markers and autism do not establish that autism itself is an inflammatory disease.
Autism is a neurodevelopmental condition with substantial genetic contributions and multiple possible developmental pathways.
Clinical care should focus on the individual's abilities, needs, preferences, and co-occurring medical concerns rather than assume one universal mechanism.
Immune Biomarkers: Promising Research Does Not Equal Validated Clinical Testing
Research studies have investigated circulating cytokines, lymphocyte populations, autoantibodies, and other immune markers in autism and related conditions.
However, immune biomarker findings often vary across studies.
Differences may reflect age, sex, medications, co-occurring conditions, sampling methods, recent infections, and other factors.
Peripheral blood measurements also do not directly reveal immune processes within the brain.
For example, an elevated circulating cytokine concentration does not establish that the same signaling molecule is causing pathological activity in a specific neural circuit.
Similarly, one measurement cannot necessarily distinguish normal immune variation from clinically meaningful dysfunction.
Immune testing may be appropriate when a child has symptoms suggesting an established immunological or inflammatory disease.
However, routine broad cytokine panels, lymphocyte phenotyping, or autoantibody screening have not been validated as general diagnostic tools for autism.
The distinction between clinical immunology and exploratory neuroimmune research is essential.
The Developing Brain as a System of Systems
The four source papers converge on a broader principle of systems biology.
Neurodevelopment occurs through interactions across multiple organizational levels.
At the molecular level, genes and signaling pathways regulate cellular functions.
At the cellular level, neurons, glial cells, and immune-related processes participate in tissue development and circuit organization.
At the network level, neural activity contributes to learning, perception, movement, and cognition.
At the behavioral level, individuals interact with their environments, acquire skills, and modify their experiences.
At the social level, relationships, education, and cultural practices shape opportunities for learning.
At the ecological level, environmental conditions influence health, resources, and daily experiences.
These levels are connected, but they should not be treated as interchangeable.
Evidence concerning a molecular pathway does not automatically establish a behavioral treatment.
Likewise, a social association does not identify the neural mechanism responsible for an observed outcome.
A systems approach is most useful when it helps researchers and clinicians connect well-supported findings while preserving the limitations of each level of evidence.
Neurodevelopment Is Both Experience-Dependent and Experience-Expectant
Developmental neuroscience distinguishes several ways experience contributes to brain organization.
Experience-expectant development refers to processes in which the nervous system anticipates forms of environmental input that are ordinarily available during development.
Normal visual experience is a classic example.
Experience-dependent development involves changes associated with an individual's particular experiences.
Learning a musical instrument, acquiring specialized motor skills, and developing expertise through practice involve experience-dependent processes.
These distinctions are useful because not all developmental experiences have the same biological significance.
Some inputs support fundamental developmental processes.
Others contribute to individual differences in learning and skill acquisition.
However, these categories should not be used to claim that children require unusually intensive stimulation to develop normally.
Appropriate opportunities for play, communication, movement, sleep, and social interaction are more defensible developmental priorities than maximizing the number of structured interventions.
Why Movement Matters in Neurodevelopment
Movement is one of the primary ways children explore and interact with their environments.
Motor development involves coordination among sensory systems, spinal pathways, brainstem structures, cerebellar networks, basal ganglia circuits, and cortical regions.
Through movement, children gather information about their bodies and surroundings.
They learn to regulate posture, coordinate actions, manipulate objects, and navigate physical environments.
Motor learning involves ongoing interactions between sensory feedback, action selection, prediction, and adaptation.
The cerebellum is particularly relevant to sensorimotor prediction and error-based learning, although its functions extend beyond motor coordination.
However, motor development is not simply a foundation that universally determines later cognition.
Relationships between motor and cognitive development are complex, and observed associations do not automatically establish causal dependency.
When a child demonstrates clinically meaningful motor delays or coordination difficulties, appropriate developmental assessment and evidence-based intervention may be useful.
The objective is to improve meaningful function rather than assume that correcting a motor pattern will automatically resolve unrelated developmental difficulties.
Social Relationships as Developmental Experiences
Children develop within relationships.
Caregiver interactions provide opportunities for communication, attention, emotional learning, and shared experiences.
Peer relationships contribute additional opportunities for social development.
Teachers and other adults influence educational experiences and skill acquisition.
Bronfenbrenner's model emphasizes that the quality and pattern of these interactions matter.
However, development should not be reduced to parenting quality.
Children differ in temperament, neurological characteristics, communication patterns, and support needs.
Caregivers also operate within broader social and economic circumstances.
For example, employment conditions, access to childcare, and housing stability may influence opportunities for consistent interaction.
A comprehensive developmental approach therefore considers family experiences without assuming that parents are responsible for the presence of a neurodevelopmental condition.
Adversity, Stress, and Developmental Outcomes
Psychosocial adversity is another important component of the developmental exposome.
Research has associated certain adverse experiences with differences in mental health, cognition, and brain development.
However, adversity is not a uniform biological exposure.
Different experiences involve different forms of threat, deprivation, unpredictability, and loss of control.
Their implications may vary according to timing, severity, duration, and available protective resources.
Some children experience substantial adversity without developing measurable neurological impairment.
Others may require additional psychological or developmental support.
Research examining adversity should also consider structural circumstances that influence exposure.
For example, poverty may be associated with housing instability, food insecurity, environmental hazards, and reduced access to healthcare.
These factors cannot be separated adequately by attributing every observed difference to psychological stress alone.
A more comprehensive approach investigates the actual developmental conditions involved.
The Importance of Protective Experiences
Although much neurodevelopmental research focuses on risk factors, protective factors are equally important.
Supportive relationships, adequate nutrition, appropriate healthcare, access to education, opportunities for movement, and safe environments may contribute to favorable developmental conditions.
However, protective influences should not be interpreted as guarantees against neurodevelopmental disorders.
For example, a child can receive excellent care and still have autism, ADHD, cerebral palsy, or an inherited neurological condition.
Likewise, developmental differences should not be interpreted as evidence that a child's environment was inadequate.
The purpose of identifying protective factors is to improve opportunities for health, participation, and learning.
It is not to establish unrealistic expectations of perfect development.
Brain Health Across the Lifespan
Owolabi and colleagues' Nature Reviews Neurology paper expands the discussion beyond individual developmental mechanisms.
The authors propose a global strategy for improving neurological health across the lifespan.
Their framework emphasizes four interconnected pillars: surveillance, prevention, acute care, and rehabilitation.
These domains address different but complementary needs.
Surveillance and research help identify neurological conditions, population trends, and service gaps.
Prevention focuses on reducing avoidable risks and supporting health.
Acute care emphasizes timely diagnosis and treatment.
Rehabilitation supports function, participation, and adaptation after neurological injury or in the context of ongoing disability.
The authors also emphasize the importance of social, psychological, and ecological contexts.
Although the paper is not specifically a neurodevelopmental treatment guideline, its broader framework is highly relevant to pediatric neurological care.
Children need access not only to diagnostic services but also to effective treatment, rehabilitation, education, and long-term support.
Why Neurological Health Is a Global Public Health Priority
The scale of neurological health needs is substantial.
A 2024 analysis published in The Lancet Neurology estimated that approximately 3.4 billion people worldwide experienced a condition affecting the nervous system in 2021.
The study examined 37 neurological conditions or categories.
Together, they accounted for approximately 443 million disability-adjusted life-years.
Importantly, the expanded analysis included neurodevelopmental and pediatric neurological conditions that were not fully represented in some earlier estimates.
This demonstrates why developmental neurological health deserves attention within broader healthcare systems.
However, the global burden of neurological conditions should not be conflated with the prevalence of neurodevelopmental disorders specifically.
The 3.4-billion estimate encompasses a broad range of nervous system conditions across the entire lifespan.
Its significance is the scale of neurological health needs and the importance of equitable services.
Developmental Assessment: Why One Test Cannot Describe the Entire Child
A meaningful neurodevelopmental assessment should begin with the child's actual developmental history and functional concerns.
Relevant domains may include communication, cognition, motor skills, sensory functioning, adaptive behavior, emotional regulation, and social participation.
However, no single assessment captures every dimension.
A neurological examination may identify motor abnormalities or signs suggesting a neurological disorder.
Standardized developmental measures can characterize particular abilities and delays.
Psychological assessment can provide additional information concerning cognition or behavior.
Hearing and vision assessments may be necessary when sensory impairment could influence developmental functioning.
Other investigations, including genetic testing, imaging, or laboratory studies, should be selected according to specific clinical indications.
Advanced technologies may contribute useful information in certain settings.
However, tools such as quantitative EEG, computerized posturography, or specialized ocular-motor assessments should not be presented as universal diagnostic tests for autism or other neurodevelopmental conditions.
Their value depends on the clinical question, validation, and relevance to treatment decisions.
What Personalized Neurodevelopmental Care Should Mean
Personalized developmental care should not be defined by the number of biomarkers collected or therapies offered.
It begins with understanding the child's developmental profile.
Two children with the same diagnosis may have substantially different needs.
One may require intensive communication support.
Another may have significant motor coordination difficulties.
A third may have epilepsy, sleep problems, or sensory impairments requiring separate evaluation.
A fourth may benefit primarily from educational accommodations and environmental modifications.
Effective care should reflect these differences.
The goal is to match evidence-based interventions to meaningful functional needs.
It should also recognize the perspectives and preferences of the child and family.
For autistic individuals, neurodiversity-informed care emphasizes dignity, communication access, autonomy, and support for participation rather than attempting to eliminate harmless differences merely because they depart from typical development.
The Limits of Multidisciplinary Intervention
A multidisciplinary approach may be appropriate when a child has needs involving several domains.
However, combining numerous therapies does not automatically improve outcomes.
Each intervention should have a clear clinical rationale and an appropriate evidence base.
For example, speech-language therapy may address communication needs.
Occupational therapy may help with specific functional activities.
Physical therapy may be indicated for certain movement limitations.
Medical treatment may be necessary for epilepsy or another established neurological condition.
Psychological or behavioral interventions may address clinically meaningful difficulties and support adaptive functioning.
However, emerging interventions should not be promoted as established treatments solely because they involve concepts such as neuroplasticity, immune regulation, sensory stimulation, or brain connectivity.
Photobiomodulation, neurofeedback, and other technologies require condition-specific evaluation of efficacy and safety.
A comprehensive care model should distinguish well-supported interventions from experimental approaches.
How This Research Informs Our Neurodevelopmental Care
We approach neurodevelopment through a multidisciplinary perspective that recognizes the relationships among neurological function, movement, behavior, health, and the environments in which children develop.
The four foundational papers offer an important scientific framework for this approach.
The exposome perspective encourages attention to relevant environmental exposures and developmental experiences.
The geo-bioecological model highlights the broader systems influencing the child's opportunities for health and learning.
Neuroimmune research underscores the importance of understanding interactions between biological systems while recognizing that many proposed mechanisms remain exploratory.
The neurological quadrangle emphasizes prevention, timely assessment, appropriate treatment, and rehabilitation across the lifespan.
Together, these perspectives encourage a more comprehensive understanding of developmental needs.
In practice, this may involve reviewing developmental history, identifying functional concerns, assessing clinically relevant neurological and sensorimotor findings, and considering appropriate referrals.
For children with established diagnoses, care should be coordinated with pediatricians, developmental-behavioral pediatricians, neurologists, psychologists, therapists, and other qualified professionals as indicated.
Our broader wellness services may support appropriate movement opportunities, nutrition education, sleep health, and family-centered health behaviors.
However, these services should not be represented as cures for autism, ADHD, or other neurodevelopmental conditions.
Likewise, complex laboratory testing should be reserved for situations in which results have established clinical utility.
Our objective is to help families understand their child's developmental profile, identify meaningful support needs, and make informed decisions using the best available evidence.
A personalized neurodevelopmental approach should recognize the complexity of the developing nervous system while keeping the child's functional abilities, quality of life, and individual needs at the center of care.
Conclusion: The Developing Brain Is Shaped by Biology, Experience, and Context
Human neurodevelopment is among the most complex processes in biology.
It involves the organization of billions of neural connections, the integration of multiple sensory systems, and the emergence of increasingly sophisticated cognitive, emotional, and behavioral abilities.
Genetics contributes to the biological organization of the nervous system.
Immune processes participate in normal development and may influence particular pathological mechanisms.
Environmental exposures can affect neurological health.
Experiences shape learning and neural adaptation.
Relationships influence developmental opportunities.
And broader ecological, social, and economic conditions help determine the environments in which these processes unfold.
Yet none of these influences operates in isolation.
The four research papers informing this article suggest that future advances will increasingly depend on interdisciplinary approaches capable of studying these interactions without oversimplifying them.
The challenge is not merely collecting more information.
It is determining which relationships are causal, which are clinically meaningful, and which can be modified through effective interventions.
For clinicians, this means avoiding explanations that reduce developmental differences to one gene, one exposure, one inflammatory marker, or one neural circuit.
For parents, it means recognizing that a child's development is neither entirely predetermined nor infinitely controllable.
And for healthcare systems, it means creating better opportunities for early identification, appropriate services, rehabilitation, and meaningful participation.
The developing brain is not an isolated organ following a predetermined sequence. It is a dynamic biological system developing through continuous interactions with the body, lived experience, and surrounding environment.
Understanding those interactions is essential to the future of developmental neuroscience.
More importantly, applying that knowledge responsibly may help us create healthier conditions in which children of different abilities and developmental trajectories can learn, adapt, participate, and thrive.
Research References
Foundational papers supplied for this article
Owolabi MO, Leonardi M, Bassetti C, et al. Global synergistic actions to improve brain health for human development. Nature Reviews Neurology. 2023;19:371–383. https://doi.org/10.1038/s41582-023-00808-z
Robinson H, Dave N, Barzilay R, Wagner A, Kells N, Keller AS. The effect of the “exposome” on developmental brain health and cognitive outcomes. Neuropsychopharmacology. 2026;51:169–184. Published online August 5, 2025. https://doi.org/10.1038/s41386-025-02180-6
Cuartas J, Morris-Perez P. Bringing natural ecosystems into the bioecological model of human development. Nature Human Behaviour. 2026;10:7–9. Published online October 29, 2025. https://doi.org/10.1038/s41562-025-02334-y
Meltzer A, Van de Water J. The role of the immune system in autism spectrum disorder. Neuropsychopharmacology. 2017;42:284–298. https://doi.org/10.1038/npp.2016.158
Additional supporting research
GBD 2021 Nervous System Disorders Collaborators. Global, regional, and national burden of disorders affecting the nervous system, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021. The Lancet Neurology. 2024;23:344–381. https://doi.org/10.1016/S1474-4422(24)00038-3
Maternal infection during pregnancy and likelihood of autism and intellectual disability in children in Sweden: a negative control and sibling comparison cohort study. The Lancet Psychiatry. 2022. https://pubmed.ncbi.nlm.nih.gov/36087610/
Prenatal and early childhood infections requiring hospitalization and risk of neurodevelopmental disorders in offspring: a population-based birth cohort study in Taiwan. Molecular Psychiatry. 2024. https://doi.org/10.1038/s41380-024-02787-z
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