Children Clinical Development

Neurodevelopmental Disorders in Children

Neurodevelopmental disorders are a group of disorders whose onset is in early childhood. They essentially impact and influence the development and functioning of the brain. These groups of disorders impact the child’s overall social interactions. They are associated with the impairment of growth and development of brain regions; they are complex in nature.

Essentially, they impair the cognitive or higher mental abilities of an individual. Neurodevelopmental Disorders are recognised in diagnostic manuals, but they co-occur with other disorders, often representing complex clinical presentations. The group of neurodevelopmental disorders include the following disorders: Attention-Deficit Hyperactivity Disorder (ADHD), Autism Spectrum Disorder(ASD), Communication Disorder (Speech Sound Disorder, Language Disorder, Stuttering, Social Communication Disorder), Intellectual Disability, Motor Disorders, and Specific Learning Disorders.

Neurodevelopmental Disorders are associated with parents feeling social exclusion in family interactions, neighbourhood, and children feeling excluded in classroom set – ups(American Psychiatric Association, n.d.; Pallanti et al., 2023).  This article aims to understand the classification of neurodevelopmental disorders, types, general causes and treatment approaches. 

Historical Underpinnings of Developmental Disorders

For the very first time, developmental disorders were introduced in DSM-III. They were introduced under Autistic Disorders. Finally, neurodevelopmental disorders were introduced in DSM – 5 as an independent group of clinical disorders because of their significant effects and influences on the individual. It was a replacement of the previous section, which was known as “ Disorders usually first diagnosed in infancy, childhood, or adolescence”. In ICD – 11, these disorders were given an important space in the chapter of: “Mental, behavioural or neurodevelopmental disorders”. Long before the establishment of NDDs, their symptoms were already described.

1. Early  descriptions of Attention Deficit and Hyperactivity Disorder

Attention Deficit and Hyperactivity Disorder was mentioned and discussed for the very first time by the work of German Physician Melchior Adam Weikard in 1775. He dedicated six pages in his book to describe Attention Deficit and Hyperactivity Disorder. His description of ADHD is noteworthy and is as follows: “He described that stimuli which are sensory in nature will capture the patient’s attention, and this will distract the patient from his thoughts. Furthermore, it is much simpler to perceive the information from sensory stimuli than to create ideas. Each sense is able to divert our thoughts and thinking, and eventually individuals divert their attention from their objects into something else. Most of the distraction happens from sight and hearing. It results in a lack of attention.”   

2. How were Autism Spectrum Disorder and Down Syndrome viewed?    

Behaviours consistent with ASD were described and mentioned way before Leo Kanner’s work on autism and the Refrigerator Mother Theory. Russian scholars also described the symptoms of autism as nonverbal, unable to interact socially, and those who were not comfortable with pain and cold. Considering the mentions of Down Syndrome, it was described by Dr J. Langdon Down.

He delivered a series of lectures before the Medical School of London. Furthermore, he also described 10 cases of individuals with exceptional abilities in narrow fields. Although these cases are not at all autistic, in the present day they would meet the criteria B of ASD in DSM-5.  After delivering the lecture series, Dr Down dedicated three decades to clinical research to propose a clear classification of Mental Retardation. He categorised it into three parts: congenital, accidental, and the third kind being developmental.

The third type that is developmental was proposed because some children were not showing the usual physical aspects of retardation. Some children grew normally until certain developmental periods but then regressed rapidly. These children lived in their own world, talked in third person, their movements consisted of rhythm and were automatic in nature(Morris et al., 2020). 

3. The Early Descriptions of Specific Learning Disorders

The early descriptions of SLDs date back to the 1800s. An ophthalmologist first noticed that there were children who found it difficult to read a string of words. The term Learning Difficulty was first used to include and broaden the scope. It was used to include all the specific school problems which were encountered by children without any cognitive retardation or behavioural disorders. Over the past 25 years, research has established relationships between schooling and cognitive abilities in order to develop efficient rehabilitative interventions(Cainelli et al., 2023). 

Types of Neurodevelopmental Disorders (NDDs)    

1. Attention – Deficit / Hyperactivity Disorders (ADHD)

ADHD is characterised by disruptive behaviour caused by inattention and hyperactivity among individuals. The inattention and hyperactivity is more than expected for a usual age group. It impacts family and social relationships, and academic and vocational achievements. Earlier in the 1980s, ADHD was named as “Attention Deficit Disorder’’ and later in 1987 it was revised and renamed as “Attention- Deficit/ Hyperactivity Disorder) by the American Psychiatric Association.

Most of the children with ADHD tend to display a combination of both hyperactive/impulsive behaviour, and some display inattentive behaviour. ADHD is comorbid in nature; it occurs with other disorders such as: Learning and Conduct disorders. To diagnose ADHD, the clinician should use judgment. Essentially, ADHD has good clinical validity, which means that children exhibit shared similarities and symptoms, respond to treatment and exhibit a general consistency. 

Research has been focused on the brain regions and abilities which get impacted due to ADHD. Children with ADHD often report problems with problem-solving, working memory, planning, responses and cognitive abilities. The causes behind ADHD remain uncertain, but research studies so far indicate that ADHD is caused by both genetic and environmental factors. Research places an emphasis on the fetal environment. Fetal environment such as smoking during pregnancy, preterm birth and low weight. Psychosocial adversity also plays an important role. Research also indicates that large amounts of lead in the blood of children also result in ADHD. 

2. Autism Spectrum Disorder (ASD)

The group of disabilities that impair social interactions, communication and behaviour is termed Autism Spectrum Disorder(ASD). Spectrum Disorder signifies that individuals with (ASDs) differ across symptoms, their severity and the impairment which is caused by ASD. Children with ASDs are not interested in others; they have difficulty expressing their emotions and tend to avoid physical contact.

Problems with communication are also noticed in children with ADHD because some children can speak efficiently while some cannot. Some of the important features of ASD are repetitive and similar patterns of behaviour. Children might continuously flap their hands, might line up their toys and spin in one direction continuously. Until now, no single causal factor has been identified; rather, ASD is caused by a combination of multiple genetic and environmental factors. 

There are some explanations for ASDs that are supported by research. The first proposition suggests that, due to chemical exposure, the neurological signalling systems are impaired. For instance, various pesticides tend to interfere with neurotransmission, chemical systems of  Acetylcholine (ACh) and gamma-aminobutyric acid (GABA). Some studies suggest that there are certain medicines which are consumed by pregnant women which then increase the risk of autism.

Other causes include: new forms of genetic mutation in the child, increasing maternal and paternal age, damage to DNA; studies have reported the potential presence of mercury in the blood, urine and teeth of children with autism when compared to the control group. Air pollutants are also contributors to ASDs. 

3. Communication Disorders

Communication disorders are characterised by children dealing with problems with communication such as: speech, language, stuttering, social communication disorder. Below is the description of these disorders : 

  • Speech Sound Disorder: Individuals with SSD have difficulty producing speech sounds. This creates problems in social interactions. Children who have difficulty with speech sound production may face problems in understanding or articulating. 
  • Language Disorder: Children with this disorder have problems with language such as learning, speaking, writing or sign language. Vocabulary and sentence structure are usually the main areas of areas. The language abilities are below the expected standards. 
  • Stuttering and Social Communication Disorder:  It is also known as childhood onset fluency disorder, where the flow and timing of speech are impaired. Its features include: repetition of syllables, dragging sounds of consonants and vowels. Social communication disorder simply explains that individuals cannot understand the rules of social communication, such as listening, turn-taking, etc.    

4. Intellectual Disability

When limitations in mental abilities impact intelligence, learning, and skills which are essential for day-to-day life, it is termed intellectual disability. The effects of intellectual disability vary widely; some individuals might have mild intellectual disability and they might also be able to independently work. On the other hand, some individuals might have severe intellectual disability and may be dependent on a caretaker for their entire life.

One of the misunderstandings which is associated with intellectual disability is having only low IQ but only low IQ cannot explain it. DSM-5 – TR names this condition as “intellectual developmental disorder.” It is widespread, and worldwide it affects 1 – 3 % of children. Symptoms of Intellectual Disability include: Markedly slow learning, reading, problems in reasoning and judgment, lack of problem-solving skills, difficulty focusing, slow in learning self-care activities, social development, dependence on a caregiver for day-to-day activities, trouble understanding important concepts of time and money, etc. 

There are several causes for intellectual disability, which include genetic inheritance or mutations in genes, disruption in fetal development due to infections such as toxoplasmosis, rubella, consumption of tobacco or alcohol during pregnancy, lack of oxygen during birth or hypoxia, premature birth. ADHD, ASD, Mood Disorders, and movement disorders are some of the disorders that co-occur with intellectual disability.

5. Motor Disorders

They consist of impaired motor abilities. When there are sudden, rapid, recurrent movements, they are termed Tic Disorders. Developmental Coordination Disorder is characterised by impaired motor skills and often manifests as clumsiness. It is also marked by inaccurate movements. There are three categories of motor disorders: Tic Disorder, Developmental Coordination Disorder and Stereotypic Movement Disorder. 

6. Specific Learning Disorder

Specific Learning Disorder affects school-going children. According to estimates, 5- 15% of children across cultures are affected by SLD. They are neurobiologically determined by multiple factors such as genetic and environmental factors. They are characterised by “reduction in the ability of the brain to efficiently and accurately understand the verbal and non – verbal information.” DSM-5 characterises Specific Learning Disorder (SLD) as difficulties in learning and academic skills; out of the following symptoms, one symptom should have been present for at least six months despite the provision targeting those difficulties. The symptoms are as follows- 

  • Inaccurate or slow and effortful word reading, 
  • Difficulty in the comprehension of the meaning of what is read, 
  • Difficulties with spelling, 
  • Difficulties with written expression,
  • Difficulties in mastering number sense, facts or calculations,
  • Difficulties with mathematical reasoning.

7. Dyslexia, Dysgraphia, Dyscalculia: What do they mean? 

Dyslexia is a pattern where individuals have impaired accuracy and fluency in word recognition and are poor in decoding and spelling abilities. They exhibit normal IQ and do not show any sensory deficit. Dysgraphia refers to the difficulty that individuals face when they are thoroughly instructed but cannot write well. They show distorted writing. Dyscalculia refers to when an individual struggles with processing numerical information, learning arithmetic facts, or performing calculations. Children with SLDs experience more emotional distress than their peers who do not experience it(American Psychiatric Association, n.d.; Cleveland Clinic, 2023; Chieffo et al., 2023; US Environmental Protection Agency, 2015).   

Prevalence of Neurodevelopmental Disorders

NDDs are seen to be more prevalent in males than in females. ASD is more prominent in males than in females, but the symptom representation is similar in both. NDDs are seen to have more comorbidities than they do with other mental health conditions. It is also common for an individual is diagnosed with more than one neurodevelopmental disorder. In a study conducted on 181 participants of ADHD, 40% did not report any comorbidity, 26% reported with anxiety disorders, there were 18 children with ASD; and 44% had Tic Disorder( Blain, 2026). 

Early Identification and Therapeutic Approaches

Early identification of NDDs is crucial and a cornerstone for planning interventions. Screening helps to understand the atypical developmental trajectories. Schools, Community should take small steps to psychoeducate teachers, students, and parents about neurodevelopmental disorders. This would also allow society to become free from stigma and develop the right understanding about NDDs.

To manage these disorders, various interventions are used. These various interventions include: behavioural therapy, speech and language therapy, physical and occupational therapy, and psychoeducation. These interventions are effective but compliance to them in the long term is difficult, economical resources may act as a barrier(Eun et al., 2026). 

Conclusion

Neurodevelopmental disorders are characterised by early onset and impact the cognitive abilities of an individual. Mentions of NDDs can be seen in scholarly work of German and Russian Physicians. Even before their systematic classification in DSM-5-TR, their symptoms were described by scholars in the field. There are various categories of NDDs: ADHD, ASD, Communication Disorder, Motor Disorder, Intellectual Disability and Specific Learning Disability. Studies indicate that genetic and environmental factors both play an important role in causing NDDs. They are more prevalent in males than in females. Children with NDDs experience emotional distress more often.     

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