Cognitive Learning Delay: Definition, Causes, and Treatment

Cognitive learning delay refers to a delay in an individual’s acquisition of cognitive and mental functioning skills. Cognitive skills, also known as thinking skills, encompass our ability to think, learn, and problem-solve. The assessment of these skills is based on age-appropriate milestones. The development of the fetal brain starts during the first trimester, more specifically in the fourth week of gestation, and continues throughout pregnancy with very rapid growth in early childhood but continuing actively through adolescence and into the middle of the third decade of life with ongoing development throughout the lifespan.

Cognitive delay can impact other areas of an individual’s development, including their social and communication skills and may also have a consequent impact on their behavior. For example, children who struggle to concentrate in school or complete set work may act out of frustration or boredom. In severe cases, this development delay in babies or development delay in toddlers may be considered permanent and be known as a cognitive disability or intellectual disability.

Understanding Developmental Delay

Delay in development occurs when the child fails to attain developmental milestones as compared to peers from the same population. It is caused by impairment in any of the following distinct domains, such as gross and fine motor, speech and language, cognitive and performance, social, psychological, sexual, and activities of daily living (ADL). It can be isolated (involving a single domain), multiple (involving two or more domains, or global (affecting most developmental areas). In order to avoid long term disability, early detection, and intervention is warranted.

Human development refers to the physical, cognitive, and psychosocial changes occurring throughout the lifespan. Many developmental lines progress sequentially and independently over time while also interacting with each other. Examples of the many developmental lines include:

Physiologic development and homeostasis
Structural and anatomic development
Motor development - both fine and gross motor
Development of language (the full spectrum of communications skills, including gesture and speech)
Cognitive development
Personality Development
Social development
Psychological development
Sexual development
Development of adaptive skill (Activities of daily living (ADL)

"Developmental delay" is a general descriptor of a broad phenotype that must then be specified by carefully determining one or more elements linked with the area of disrupted development. Developmental delay is not a diagnosis by itself rather a categorical, illustrative term used in the clinic. Further, the terms often used to specify a developmental delay may vary by country or area of practice. For example, the term "mental retardation is no longer in use with "learning disability" being used in the UK and Intellectual Disability being used in the US to define a group of individuals with a significant delay defined by "performance equal or greater than two standard deviations below the mean on age-appropriate standardized norm-referenced testing" (IQ or intelligent quotient testing).

Read also: Navigating the UCLA CogSci Minor

There are three types of developmental delay based on the number of domains involved:

Isolated developmental delay (involving single domain).
Developmental disability that mainly affects cognitive functioning.
Developmental disorders - are a very large group of syndromes in which the typical sequences or patterns of development are disrupted with delays in developmental steps and/or deviations in development processes.

Despite the American Academy of Pediatrics policy on early screening, a significant number of developmental disorders remain undiagnosed and untreated.

What is a Developmental Delay?

A developmental delay is when your child is slow to reach one or more developmental milestones compared to their peers. Developmental milestones include skills such as:

Smiling for the first time.
Rolling over.
Pulling up to stand.
Waving “bye-bye.”
Taking a first step.
Speaking a first word such as “dada.”

Children reach milestones in playing, learning, speaking, behaving, and moving. They develop and reach these milestones at different rates. There’s no strict timetable. So if your child is a little behind, that doesn’t mean they have a developmental delay. A developmental delay means your child is continually behind in developing skills expected by a certain age.

What is Child Development?

A child’s growth is more than just physical. Children grow, develop, and learn throughout their lives, starting at birth. You can learn about your child’s development by watching how they interact with their environment, including how they play, learn, speak, move, and behave.

Types of Developmental Delays

Developmental delays align with the areas of child development. These include:

Cognitive (thinking) skills: Cognitive skills include thinking, learning, and understanding information. A child with a cognitive delay may have trouble following directions or solving a problem.
Social and emotional skills: These skills include getting along with others, expressing feelings, and the ability to communicate needs. A child with social or emotional delays may struggle with understanding social cues, having a conversation, or dealing with changes to a routine.
Speech and language skills: Speech and language skills include using and understanding language. A child with speech and language delays may have difficulty speaking words or understanding what others say.
Fine and gross motor skills: These skills include the ability to coordinate small (fine) and large (gross) muscles. A child with a fine motor delay may have trouble holding an object in their hands or have trouble with coloring and writing. A child with a gross motor delay may have difficulty rolling over, sitting up, or walking.

What is Global Developmental Delay?

Developmental delay can be isolated, meaning a delay affects only one area of development. If a significant delay occurs in two or more of these developmental areas, your child may have what providers refer to as global developmental delay.

Developmental Delay vs. Autism

Developmental delay is different from developmental disabilities such as autism spectrum disorder.

A developmental delay is when your child doesn’t reach their developmental milestones as expected. It usually means your child is developing certain skills slower than their peers. But with early intervention and support, they’ll typically catch up.

Developmental disabilities such as autism don’t go away on their own - they’re usually lifelong conditions. Autism is a neurodevelopmental disorder present from early childhood. Children with autism have trouble interacting with others, forming relationships, and using language.

It can sometimes be difficult to determine if your child has a developmental delay or a developmental disability. However, it’s important to know there are treatment options for this diagnosis and it generally does not predict future intelligence.

Identifying Cognitive Delay

Cognitive delay may be identified in toddlers, or it may be something that is identified once a child starts school. Early signs of cognitive delay in toddlers would include delays or difficulties in learning how to count, identify colors and shapes, and to complete basic, age-appropriate puzzles or games.

Examples of Cognitive Delay

Speech and language delay, issues with vocabulary acquisition, and use of language, either spoken or written.
Learning difficulties, including diagnosable ones such as dyslexia, also including more general struggles and difficulties with learning. This might include issues with memory, information retention and processing, problem and puzzle-solving, as well as comprehension and reasoning skills.
Difficulties with everyday tasks that involve coordinating thought and action, such as getting dressed or following a morning routine to get ready for school. In a very young child, this might look like an inability to understand what basic objects are used for - for example, to not be able to understand what a toothbrush is for.
Is not able to follow simple instructions, as reasonably expected for their age.
Struggles to concentrate or focus for reasonable periods, according to age.

Causes of Cognitive Delay

Many factors may contribute to and cause cognitive delay. Sometimes cognitive development delay and cognitive disability are the symptoms of a rare disease or genetic syndrome. Down syndrome is one of the most well-known examples of this cause.

Genetic Factors: There is no known genetic substrate for developmental delay, per se. However, developmental patterns are often familial, including late walking and talking. Nonetheless, these developmental delays can also represent risks for syndromes or developmental disorders. There is a considerable variation in the genetics of developmental disorders, ranging from copy number variants (CNV's), insertions, deletions, and duplications. While most are rare variants, some represent common variants. The most common, known genetic factor for ID is Fragile X syndrome, a trinucleotide repeat disorder (CGG) targeting the Fragile Mental Retardation 1(FMR1) gene located on the X-chromosome. Fragile X appears to confer risk for ASD, as well. Imprinting can also be seen as is the case of Prader-Willi and Angelman syndrome, which vary with paternal (Prader-Willi) and maternal (Angelman) loss of function on chromosome 15q.
Neglect or Abuse: Cognitive delay may also be the result of neglect or abuse during the early years of a child’s life. A lack of stimulation and nurturing can contribute to cognitive development delay and mean a child does not have opportunities to develop their thinking and intellectual skills.
Neurological Disorders: Neurological disorders may also be one of the causes of cognitive delay. Autism spectrum disorder is one of the most well-known examples of this.
Environmental Factors: There is some research to suggest that environmental factors, including exposure to toxins (lead poisoning as one example) during pregnancy or after birth, may cause cognitive delay. Teratogens/toxins - such as lead, arsenic, mercury, etc.
Substance Abuse: Excessive exposure of a fetus to alcohol or other dangerous substances, due to substance abuse by the mother during pregnancy, may also cause cognitive delay. Fetal alcohol syndrome, as a result of alcohol use during pregnancy, is a known cause of cognitive delay.
Premature Birth or Oxygen Deprivation: In some cases, it is believed that a premature birth or oxygen deprivation during delivery and birth may contribute to and cause cognitive delay.
Metabolic disorders: Metabolic disorders like hypoglycemia, hyponatremia, or hypovolemia; Inborn errors of metabolism - PKU.
Trauma: Head trauma.
Infections: Infections (e.g., neonatal meningitis, encephalitis).
Maternal Factors: Maternal stress - such as depression, anxiety, etc.; Maltreatment, intimate partner, and/or domestic violence; Poverty; Malnutrition - especially multivitamins and minerals deficiency, such as iron, folate, Vitamin D, calcium, etc.
Idiopathic Causes: In other cases, there may be no known cause.

Pathophysiology of Developmental Delay

Except for specific syndromes that include developmental delay, the vast majority of developmental delay is idiopathic. Although the exact underlying pathophysiology is unknown, several mechanisms have been proposed by epidemiologic studies that lead to some sort of developmental delay and/or disabilities. Since some forms of developmental delay may run in families, genes have been assumed to play a significant role in developmental delay. A multitude of genes and mechanisms for genetic transmission have been proposed. While some causes of developmental delay such as Fragile X or Down syndrome have known genetic etiologies, for most others, it is unclear. Even for well-characterized disorders like autism spectrum disorder, there are over 100 risk alleles. Perinatal complications, profound deprivation, and poverty, among other environmental stressors, can play a role in causing developmental delays, but special causal links remain elusive.

The hypothalamic-pituitary axis (HPA) is responsible for the normal regulation of stress response in progenies. Psychosocial stressors during pregnancy, maternal immune activation (MIA), and modification of HPA may significantly affect fetal brain development, but there are no specific cause and effect relationships for most disorders. Boyce and his colleagues offered the concept of differential susceptibility. This suggests that the risk for developmental anomalies is increased by a variety of factors that create a biological vulnerability to environmental stressors but are only expressed when the environmental stresses occur. Furthermore, even vulnerable children can do well if environmental circumstances are highly favorable and foster resilience.

Epidemiology of Developmental Delay

Globally, in 2016, approximately 52.9 million children reportedly had identifiable developmental problems delay. Since 95% of the population resides in low and middle-income countries (LMICs), there is an increased risk for developmental delays and disorders. Although the exact prevalence of developmental delay is unknown, according to the World Health Organization (WHO), 10% of the population in each country population has a disability of one or another kind. In the United States, roughly 15% of children have been reported to have at least one developmental problem. In England, the prevalence of ID in children under age five and adults is 2.7% and 2.17%, respectively. Likewise, several other studies have also reported a slightly increased incidence in males, possibly due to genetic variability on the X-chromosome.

Evaluation and Assessment

If cognitive delay is suspected, then the first person to consult is a medical professional or doctor who can help place this delay in the context of age-appropriate cognitive skills development.

Assessment of developmental delays often requires the work of a team with experts in general and specific areas. This should start with primary care providers followed by pediatric subspecialists such as neurologists, child and adolescent psychiatrists, developmental and behavioral pediatricians, and other pediatric subspecialists as indicated. Besides, the skills from other disciplines may be necessary, for example, psychology, genetics, speech and language pathology, occupational therapy, physical therapy, nutritionists, etc. The United States Preventive Services Taskforce (USPSTF) offers specific recommendations for speech and language delays and autism but does not explicitly cover other developmental delays. Clinicians, particularly primary care providers, must have a sound understanding of developmental milestones and patterns, as well as up-to-date knowledge about screening tests and their strengths & limitations, to ensure proper screening for a referral if the clinical suspicion of developmental screening is high. During each well-child encounter, a PCP should encourage parents to express their concerns about their child's behavior or developmental milestones. Furthermore, since developmental delay can be due to normal variations or can be an indicator of a developmental disorder such as sensory or cognitive impairment, cerebral palsy, or autism, thorough evaluation and follow-up is warranted. Therefore, in addition to direct physical examination and observation, the use of validated screening instruments at every well-child visit can aid in the early detection of problematic developmental delays. Developmental screening should take place in response to parental concerns or clinicians' observations as well as during every well-child visit at 9, 18, and 30 months of age. An autism-specific screening test is recommended at 18 and 24 months.

History and Physical Examination

A comprehensive history and thorough physical examination are essential elements of the examination of children with developmental delays. Additional information can also be gathered by a play interaction with the child us age-appropriate toys (e.g., toy cars, blocks, crayons, and paper) as well as watching the child move around the clinic.

Collect comprehensive data on the entirety of the child's development from conception to the current age.
Collect a detailed family history of at least first, second, and third-degree relatives.
Growth parameters - such as occipitofrontal circumference, weight, height, and BMI.
General physical examination involving head-to-toe assessment.
Detailed neurologic exam, including hearing and vision evaluation.
Examination for dysmorphology.

Screening Instruments

Among many general developmental screening instruments, The Ages and Stages Questionnaire, Third Edition (ASQ-3), and the Parents' Evaluation of Developmental Status (PEDS) are commonly used parent-report tools for use during well-child encounters. Hamilton et al. 2016, cited by Vitrikas, reported the sensitivity and specificity of PEDS questionnaires for all ages 75% and 74%, respectively.

Diagnostic Tests

Blood Tests: Routine complete blood count (CBC), electrolytes, and lead screening are appropriate for most children, along with a lipid panel. If indicated, additional testing may include a metabolic chemistry panel(CMP), iron, calcium, phosphate, creatinine kinase (CK) enzyme.
Genetic Testing: In general, genetic testing is not indicated for developmental delay unless there is a specific indication or evidence of a discrete syndrome. If further genetic testing is indicated, this should begin with a chromosomal microarray (CMA). Since the most commonly known genetic cause of intellectual delay is Fragile X, FraX screening may be appropriate. As per Moeschler et al., CMA is required for Fragile X syndrome. The detection of significant copy number variants and approximated diagnostic yield of microarray tests are 15-20% and 12%, respectively. If further genetic testing is indicated, referral to a geneticist is indicated.
MRI of the Brain: In the absence of discrete family history, specific injury, or focal neurological finding, MRI is rarely indicated in the routine assessment of children with developmental delay. This is because children under the age of 7 or 8 will have difficulty being still, and so movement artifacts will make interpretation of the scans difficult to impossible. Examinations can be completed using anesthesia, but, in most cases, the risk of anesthesia outweighs the potential benefit of the MRI scan. MRI is used to evaluate for microcephaly, macrocephaly, seizures, abnormal neurologic signs and symptoms, and hydrocephalus. One prospective and observational study compared the MRI findings of eighty-one (n=81) pediatric patients. Among them, 68% of cases showed abnormal MRI findings compared to 32% normal MRI results.
(EEG): In the absence of discrete family history, specific injury, or focal neurological findings, EEG studies are rarely indicated in the routine assessment of children with developmental delay. EEG may be useful if there is a clear history of regression and/or directly observed seizure activity.

In summary, children with developmental delays are usually identified as a result of parental concern, school/daycare observation, or during the course of routine care in primary care settings. When there is information from parents and/or teachers, the primary care provider should take it seriously and carefully assess the developmental delay and its possible causes.

Treatment and Management

The management of developmental delay is a team effort that includes primary care providers as well as pediatric subspecialists such as neurologists, child and adolescent psychiatrists, developmental and behavioral pediatricians, and other pediatric subspecialists as indicated. Also, the skills from other disciplines may be necessary, for example, psychology, genetics, speech and language pathology, occupational therapy, physical therapy, nutritionists, etc. In short, treatment strategies are usually multi-modal.

Early intervention, through the form of targeted support and therapies, may help some individuals progress with their cognitive delay, allowing them to catch up with age-expected cognitive development milestones.

Treatment strategies require that the lead member of the team, often the primary care provider, establishes a therapeutic partnership with the pediatric care team, educating and providing parents/families with necessary information about the developmental delay and any evidence of an evolving syndrome, including the course of the disorder, diagnosis, prognosis, and complications. Additionally, psychosocial support and parental counseling/guidance are essential elements of care. Information should be provided at a level consistent with the ability of the parents to understand as this will enhance acceptance and adherence to care plans. For some families, social work support services may be necessary for coordination and transportation services, regular home visits, and other services essential to complete evaluations. If there is significant clinical concern that the developmental delay represents an evolving clinical syndrome and the parents appear to not understand or be in denial, then follow-up appointments with the primary care provider during the developmental evaluation will be helpful.

Recommendations for Early Interventions and Referrals:

Early childhood education
Early intervention programs
Early and periodic screening, diagnostic, and treatment (EPSDT)
Parenting problems - consider referral for parent training. This might include parent-child interaction therapy (PCIT) consisting of two phases, such as…

Additional Support and Resources

Although there is no exact “cure” for an intellectual disability, there is plenty of help available to help your child live a fulfilling life. Most children with cognitive developmental delays can learn to do many things. For example, The Warren Center offers Early Childhood Intervention (ECI) that helps infants and toddlers. In addition, a therapist might help design an Individualized Program to advise how you can help your child practice and learn adaptive skills at home.

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