Neurodevelopmental Function and Dysfunction in the School-Aged Child

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Chapter 29 Neurodevelopmental Function and Dysfunction in the School-Aged Child

A neurodevelopmental function is a basic brain process needed for learning and productivity. Neurodevelopmental variation refers to differences in neurodevelopmental functioning. Wide variations in these functions exist within and between individuals. These differences can change over time and need not represent pathology or abnormality. Neurodevelopmental dysfunctions reflect disruptions of neuroanatomic structure or psychophysiologic function that may be associated with problems related to cognition, academics, and/or behavioral, emotional, social, and adaptive functioning.

Terminology and Epidemiology

The primary manifestation of neurodevelopmental dysfunction is academic disability. Academic disorders have been diagnostically classified by the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR) and the International Classification of Diseases (ICD) of the World Health Organization. The DSM-IV-TR separates academic disorders into reading disorder, mathematics disorder, and disorder of written expression, and it differentiates these disorders from motor skills disorders and communication disorders. Other diagnostic terms such as dyslexia (reading), dyscalculia (mathematics), or dysgraphia (written expression) are used primarily in neurologic classifications.

Traditionally, the educational system has identified specific learning disabilities (SLD) through the process of psychoeducational testing. Through this process, students experiencing academic problems would be evaluated psychometrically. Typical testing batteries have usually included measures of overall intelligence, academic skills, and adaptive functioning. A student exhibiting a significant discrepancy between scores on tests of intelligence (aptitude) and tests of academic achievement could be classified as a student with an SLD and would subsequently be eligible for special education services (e.g., resource support). The degree of discrepancy required for such classification differs between states and even between school districts. The reauthorization in 2004 of the Individuals with Disabilities Education Act (IDEA) incorporated the Response to Intervention (RTI) model, which does not necessitate that education agencies use the discrepancy model for determining if a student has an SLD. Instead, schools may employ research-based intervention approaches and monitor a student’s response to that intervention before initiating psychoeducational testing. This major shift in educational policy will likely lead to future changes in epidemiologic rates.

Overall estimates of the prevalence of academic disabilities range from 3-10%, with more recent data indicating that approximately 8% of children 3-17 yr of age have, at one point, been identified as having an academic disability. The prevalence rate for disorders of attention (e.g., ADHD; Chapter 30) in this same age span is reported at 7.4%, with boys identified at a significantly higher rate than girls (9.5% and 5.9%, respectively). Prevalence estimates can vary owing to numerous factors, including differences in definitions and criteria used for classification and diagnosis and differences in methods of assessment.

Etiology

Multiple factors underlie neurodevelopmental dysfunctions. These include genetic, medical, psychologic, environmental, and sociocultural influences. Some of the genes that contribute to neurodevelopmental dysfunction have been identified. It is well established that reading disorders can be both familial and heritable; studies have linked some reading disabilities to specific gene loci on chromosomes 6 and 15. Chromosomal abnormalities can lead to unique patterns of dysfunction, such as visual-spatial deficits in girls with Turner’s syndrome or language deficits in persons with fragile X syndrome (Chapter 76). Gene-deletion syndromes such as velocardiofacial syndrome are associated with predictable patterns of neurodevelopmental dysfunction (attention and working memory deficits, with academic difficulties in reading comprehension and mathematics conceptualization).

Perinatal risk factors that have been associated with neurodevelopmental dysfunction include very low birth weight, severe intrauterine growth restriction, perinatal hypoxic-ischemia encephalopathy, and prenatal exposure to alcohol and other drugs (Chapter 90). Increased risk of academic and attention disorders is associated with environmental toxins, including lead (Chapter 702); drugs such as cocaine; infections, such as meningitis and HIV; and brain injury secondary to intraventricular hemorrhage or head trauma. There have been conflicting reports regarding the contribution of persistent otitis media with effusion and associated conductive hearing loss to subsequent language problems.

Psychological influences can also result in and/or exacerbate neurodevelopmental dysfunctions. Some research has postulated that early psychological trauma can result in both structural and neurochemical changes in the developing brain, which may contribute to neurodevelopmental dysfunction. Some findings suggest that the effects of exposure to trauma and/or abuse early in the developmental course can induce disruption of a brain regulatory system with connections in the orbitofrontal cortex and can influence right-hemisphere function with associated risk for problems with information processing, memory, development of academic skills, and overall functioning (e.g., attention and self-regulation). Environmental and sociocultural deprivation can lead to, or potentiate, neurodevelopmental dysfunction. In the child with an academic skills disorder (e.g., reading, written expression, or mathematics), often there are a combination of etiologic factors contributing, and a single cause is seldom ascertained.

Core Neurodevelopmental Functions

The neurodevelopmental processes that are critical for academic success fall within core neurodevelopmental domains.

Sensory and Motor Development

Sensory development (e.g., auditory, visual, tactile, proprioceptive) begins well before birth. This neurodevelopmental process is crucial in helping children experience, understand, and manipulate their environments and is a vital mechanism for basic survival. Through sensory experiences, children’s brains mature as new neuronal pathways are created and existing pathways are strengthened. Sensory development for the school-age child progresses in association with motor development, with the two processes having a symbiotic relationship. Motor movements can be separated into three categories: continuous, discrete, and procedural movements. Of these, procedural movements represent motor functions that are most relevant to daily life (e.g., manipulating utensils).

Motor development can also be broken down into three distinct, yet related, forms of neuromotor ability: fine motor, graphomotor, and gross motor coordination. In school, problems with fine motor function can affect a child’s ability to excel in artistic and crafts activities and can interfere with learning a musical instrument or mastering a computer keyboard. Eye-hand incoordination may be prominent because the child has trouble with the rapid and precise integration of visual inputs with specific motor plans. Some children have difficulty remembering fine motor sequences, such as those required for tying shoelaces. The term dyspraxia relates to difficulty in developing an ideomotor plan and activating coordinated and integrated visual-motor actions to complete a task or solve a motor problem, such as assembling a model.

Graphomotor function refers to the specific motor aspects of written output. Several subtypes of graphomotor dysfunction significantly impede writing. Some students harbor weaknesses of visualization during writing. They have trouble picturing the configurations of letters and words as they write (orthographics). Their written output tends to be poorly legible, with inconsistent spacing between words. Others have weaknesses in graphomotor memory, the ability to recall letter and number forms rapidly and accurately. They labor over individual letters and prefer printing (manuscript) to cursive writing. Some exhibit signs of finger agnosia or weak graphomotor feedback; they have trouble localizing their fingers while they write. As a result, they need to keep their eyes very close to the page and tend to apply excessive pressure to the pencil. Others struggle with graphomotor production deficits. Such students have trouble producing the highly coordinated motor sequences needed for writing and have difficulty assigning writing roles to specific muscle groups in their hands. This phenomenon has also been described as dyspraxic dysgraphia. It is important to emphasize that a child may show excellent fine motor dexterity (as revealed in mechanical or artistic domains) but very poor graphomotor fluency (with labored or poorly legible writing).

Some children exhibit gross motor incoordination. They have problems in processing “outer spatial” information to guide gross motor actions. Affected children are inept at catching or throwing a ball because they cannot form accurate judgments about trajectories in space. Others demonstrate diminished body position sense. They do not efficiently receive or interpret proprioceptive and kinesthetic feedback from peripheral joints and muscles. They are likely to be impaired when activities demand balance and ongoing tracking of body movement. Others are unable to satisfy the motor praxis demands of certain gross motor activities. It is hard for them to recall or plan complex motor procedures (such as those needed for dancing, gymnastics, or swimming). Children with gross motor problems can incur considerable embarrassment in physical education classes. Gross motor weaknesses can lead to social rejection, withdrawal, and generalized feelings of inadequacy.

Language

Language may be the most critical cognitive function humans develop. Brain imaging confirms areas of brain specialization for language development (e.g., for processing of phonological, orthographic, semantic, and syntactic information), along with increased connections and integration between language association areas, dominance of the left hemisphere in language processing, and the presence of “language control” regions. Language dysfunction has been linked to reduced cerebral volume and underactivation in the perisylvian areas, planum temporale, temporal lobes, and frontal lobes.

Disordered language occurs in many forms. Some children have particular problems with phonology (Chapter 32). They experience unclear reception of language sounds and have difficulty discriminating between, and forming associations with, the sounds of their native language. For the brain to process these language sounds, it must, for example, accommodate the very rapid transition (∼30 msec in duration) from the sound k to the uh in kuh. In some cases, affected students have trouble processing these acoustic signals within language sounds rapidly enough. Commonly, a weak phonologic sense has a negative effect on reading, as well as other academic skills. A student with a poor appreciation of language sounds is likely to form unstable associative linkages between those sounds and visual symbols (letter combinations). It can be hard for these students to conceptualize words as made up of language sound segments (phonemes); thus, their ability to break words down into their constituent sounds and then reblend them into pronounceable words is impeded. They can also have problems manipulating language sounds in their minds and blending them to form a word.

Children with semantic deficits have trouble learning the meaning of new words and using words appropriately. Other common language deficiencies include difficulty with syntax (word order), problems with discourse (paragraphs and passages), an underdeveloped sense of metalinguistics (how language works), and trouble with drawing appropriate inferences (supplying missing information) from language. Difficulty with pragmatic language skills, or the social applications of language, can be another significant impediment.

It is important to distinguish between receptive language dysfunctions (problems with auditory comprehension/understanding) and expressive language dysfunctions (problems with speech and language production and/or communication). Children with primarily receptive language problems may have difficulty understanding verbal information, following instructions and explanations, and interpreting what they hear. Expressive language weaknesses can result from problems with speech as well as language. Speech difficulties include oromotor problems affecting articulation, verbal fluency, and naming. Some students have trouble with sound sequencing within words. Others find it hard to regulate the rhythm or prosody of their verbal output. Their speech may be dysfluent, hesitant, and inappropriate in tone. Problems with word retrieval can also thwart expressive language fluency. Despite an adequate vocabulary, affected children have problems in finding exact words when they need them (as in a class discussion). They may show marked hesitation and keep substituting definitions for words (circumlocution). Children with expressive impediments have trouble formulating sentences, using grammar acceptably, and organizing spoken (and possibly written) narratives.

Language weaknesses can also manifest in content areas such as the sciences, which necessitate the processing of dense verbal material in textbooks and the rapid convergent recall of facts, and social studies courses that often entail the use of sophisticated language and verbal abstract concepts (e.g., democracy). Learning foreign languages can be a serious problem. In particular, those with even mild trouble with phonologic awareness, semantics, or syntax in their primary language can have serious problems adding a second language. In contrast, students who possess strong language abilities can make use of their linguistic facility to compensate for any academic problems; it may be possible to verbalize one’s way through a mathematics curriculum, thereby circumventing a tendency to be confused by predominantly nonverbal concepts (ratio, equation, diameter).

Some studies have linked expressive language dysfunction to delinquent behavior. This may be especially true when an expressive language disorder occurs in a context of environmental deprivation or turmoil. To one degree or another, all academic skills are taught largely through language, and thus it is not surprising that children who experience language dysfunction usually have troubled educational careers. Up to 80% of children with academic disabilities have problems that are language-based.

Visual-Spatial and Perceptual Functioning

Vision begins well before birth, with continued development and refinement throughout childhood (Chapter 613). Important structures involved in the development and function of the visual system, beyond the eyes themselves, include the retina, optic cells (e.g., rods and cones), the optic chiasm, the optic nerves, the brainstem (control of automatic responses like pupil dilation), the thalamus (e.g., lateral geniculate nucleus for form, motion, color), and the primary (visual space and orientation) and secondary (color perception) visual processing regions located in and around the occipital lobe. Other brain areas, considered to be outside of the primary visual system, are also important to visual function, helping to process what (temporal lobe) is seen and where it is (parietal lobe). It is now well documented that the left and right cerebral hemispheres interact considerably in visual processes, with each hemisphere possessing more specialized functions including processing of details, patterns, and linear information mediated by the left hemisphere and processing of the gestalt, form, and integrative functions mediated by the right hemisphere.

The function of vision has many components, ranging from basic sensory identification to visual acuity, identification of form, color, and location, perceptual impairments (e.g., depth perception), perception of relative size, foreground and background relationships, and form constancy, to integration of visual information with other functions, such as motor output and development of language and academic skills (e.g., reading, writing, and mathematics). Children with obvious visual impairments are easily identified; many children with more subtle or milder deficits (and even some with more pronounced impairments) are often misidentified and/or missed completely. Indications of visual processing deficits in the school-aged child may be difficulty learning to draw and write and problems with crafts activities. These children often have trouble discriminating between left and right. They might encounter problems recognizing letters and words, resulting in delayed reading, spelling, and writing.

Although many authors have argued that visual-spatial processing dysfunctions are not, in themselves, a common cause of chronic reading disorders, more recent investigations have established that deficits in both orthographic coding (visual-spatial analysis of character-based systems) and phonological processing can contribute to reading disorders. Spelling and writing can emerge as a weakness because children with visual processing problems commonly have trouble with the precise visual configurations of words. In mathematics, these children often have difficulty with visual-spatial orientation, with resultant difficulty aligning digits in columns when performing calculations and/or difficulty managing geometric material. In the social realm, intact visual processing allows a child to make use of nonverbal or physical cues when communicating and interpreting paralinguistics. These functions are also necessary to process proprioceptive and kinesthetic feedback and to coordinate movements during physical activities. Children with visual processing deficits are thus susceptible to problems such as social isolation and withdrawal and consequent behavioral and/or emotional difficulties.

Memory

Memory is a term used to describe the cognitive mechanism by which information is acquired, retained, and recalled. Structurally, some major brain areas involved in memory processing include the hippocampus, the fornix, the temporal lobes, and the cerebellum, with connections in and between most brain regions. The memory system can be partitioned into subsystems based on processing sequences; the form, time span, and method of recall; whether memories are conscious or unconsciously recalled; and the types of memory impairments that can occur.

Once information has been identified (through auditory, visual, tactile, and/or other sensory processes), it needs to be encoded and registered, a mental process that constructs a representation of the information into the memory system. The period of time (typically seconds) during which this information is being held and/or manipulated for registration, and ultimately encoded, consolidated, and retained, is sometimes referred to as working memory (WM). Other descriptors include short-term memory (STM) and immediate memory (IM). Consolidation and storage represent the process by which information in STM is transferred into long-term memory (LTM). Information in LTM can be available for hours or as long as a lifespan. LTMs are generally thought to be housed, in whole or in part, in various brain regions (e.g., the cortex, cerebellum). Ordinarily, consolidation in LTM is accomplished in one or more of four ways: pairing two bits of information (such as a group of letters and the English sound it represents); storing procedures (consolidating new skills, such as the steps in solving mathematics problems); classifying data in categories (filing all insects together in memory); and linking new information to established rules, patterns, or systems of organization (rule-based learning).

Once information finds its way into LTM, it must be accessed. In general, information can be retrieved spontaneously (a process known as free recall) or with the aid of cues (cued or recognition recall). Some other common descriptors of memory include anterograde memory (the capacity to learn from a single point in time forward), retrograde memory (the capacity to recall information that was already learned), and explicit memory (conscious awareness of recall), implicit memory (subconscious recall: no awareness that the memory system is being activated), procedural memory (memory for how to do things), and prospective memory or remembering to remember.

As children proceed through school, the demands for the efficient use of memory progressively increase. By secondary school, rapid and precise recall is heavily emphasized. Children can have trouble with one or more memory mechanism. They might struggle with the initial registration of information in STM. Others might have difficulty storing newly introduced information. Other children might have difficulty accessing (retrieving) information, despite having registered and stored it effectively. Children can experience frustration in their efforts at consolidating information into LTM and/or encounter difficulty with simultaneous recall (retrieval of several facts or procedures at once). Some students exhibit delayed automatization: Not enough of what they have learned in the past is accessible to them instantaneously and with no expenditure of effort. Such skills as forming letters, mastering mathematical facts, and decoding words must ultimately become automatic if students are to make good academic progress.

Weaknesses with memory processing can be highly specific and/or dependent on the material. Some children struggle to learn visual-spatial material, whereas others may be deficient in learning auditory information. Some have difficulty processing linear data or sequential information. Some can experience difficulty with rote data (e.g., word lists) yet have little or no difficulty registering information in context (e.g., a narrative). Although in-depth examination (e.g., neuropsychological testing) is often necessary to differentiate potential memory weaknesses and their impact on the child’s overall functioning, screening for memory problems should be part of any well-child examination.

Attention

Most brain processes are heavily dependent on functional arousal, alertness, and attention. Any malfunction within or across these systems will likely result in weaknesses in other areas. Functional attention subsumes intact neuroanatomic and neurochemical brain systems. Structurally, brain regions involved include subcortical, cortical, and association areas throughout the brain. Primary structures involved include brainstem regions (e.g., basal ganglia), the limbic system (e.g., amygdala and hippocampus), and the frontal lobes (e.g., prefrontal cortex). The neurotransmitter dopamine, along with its neuronal pathways, has been identified as a major chemical modulator of attention. From the perspective of development, attention begins very early, as infants regularly demonstrate attentional control. With increasing age, the external demands on the attention system increase exponentially. It is through the cognitive mechanisms of attention and executive functions (see next section) that the child’s brain acquires, organizes, and processes information and regulates, plans, and monitors behavior and thought. Children with attention dysfunction comprise a widely heterogeneous group who show various patterns of impairment of these systems (Chapter 30). The resulting symptoms not only affect behavior, learning, and academic skills development but also have an impact on the child emotionally and socially.

The process of attention is far from a unitary, independent, or specific function. This may be illustrated best through the phenotype associated with attention-deficit/hyperactivity disorder (ADHD). ADHD is not only a disorder of impaired focus but also includes a host of symptoms related to problems with vigilance, distractibility, impulsivity in thought and behavior, hyperactivity, and flexibility. Disordered attention can occur owing to faulty mechanisms in and/or across subdomains of attention. These subdomains include selective attention (the ability to focus attention to a particular stimulus and to discriminate relevant from irrelevant information), divided attention (the ability to orient to more than one stimulus at a given time), sustained attention (the ability to maintain one’s focus), and alternating attention (the capacity to shift focus between stimuli).

Attention problems in school-aged children can manifest at any point in the process, from arousal through output. Children with diminished alertness and arousal can exhibit signs of mental fatigue in a classroom or when engaged in any activity requiring sustained focus. They might yawn, stretch, fidget, and daydream. They can become overactive in an effort to attain or maintain a higher level of arousal. Their arousal problems might cause them to have difficulty falling asleep or waking on time. They are apt to have difficulty allocating and sustaining their concentration, and their efforts may be erratic and unpredictable, with extreme performance inconsistency. These children can also have difficulty discriminating between important and unimportant information. Such weaknesses of determining saliency often result in focusing on the wrong stimuli at home and in school and can result in the child’s missing important information and can impede their ability to take notes, to summarize information, or to recognize what to study for a test.

More overt forms of weak processing controls result in various types of distractibility, which can take the form of listening to extraneous noises instead of a teacher, staring out the window, or constantly thinking about the future. These children often show evidence of superficial concentration, where their level of focus is not of sufficient intensity to capture specific information. As a result, these children are often described as “forgetful” because directions and explanations need to be repeated and details, such as changes in operational signs in mathematics, may be missed. These children can also exhibit difficulties with cognitive activation and generalization, passively processing and not linking information with prior knowledge and experience, or over-relying on prior experience. Many of these children display insatiability and are often restless, bored easily, and require high levels of stimulation or excitement.

Attention dysfunction can affect the output of work, behavior, and/or social activity. These children have a tendency to perform or act without previewing a likely outcome or thinking through the potential consequences of what they are about to do or say. Their impulsivity can lead to careless mistakes in academic work and unintended misbehavior. It is important to appreciate that most children with attentional dysfunction also harbor other forms of neurodevelopmental dysfunction. Although ADHD is not classified as a specific academic disability, children with ADHD often have associated academic disorders (with some estimates suggesting up to 60% comorbidity). Other common comorbidities include oppositional defiant disorder (ODD), conduct disorder (CD), and other disruptive behavior disorders. Difficulties with mood, anxiety, depression, and socialization are also frequently reported.

Executive Functioning

There is considerable overlap between attention and executive function (EF). EF, like attention, is an umbrella term used to describe specific cognitive processes involved in regulating, guiding, organizing, and monitoring of one’s thoughts and actions to achieve a specific goal. More formally, EFs can be conceptualized as a collection of processes that guide, direct, and manage cognitive, behavioral, and emotional functions, especially during active and novel problem solving. Processes considered to be executive in nature include inhibition, flexibility (ability to shift between activities or thoughts), emotional control, initiation skills, planning, organization, WM, and self-monitoring.

Although EFs are of critical importance to the school-aged child, some have received more consideration. Organization skills, for instance, are often cited as a potential factor in academic underachievement. Many school-aged children harbor incapacitating organizational problems that adversely affect performance. Some fail to make use of effective techniques and strategies to facilitate task completion and work output. Others struggle because they are unable to maintain a systematized notebook, keep track of assignments, get to classes on time, meet deadlines, locate their belongings, organize a locker, and remember what books to take home from school. Many disorganized children also have trouble studying for tests. They do not seem to know how and what to study and for how long. They often lack self-testing skills.

Inhibition, or inhibitory control, refers to the ability to control a response, whether it be cognitive or behavioral. Disinhibition, then, is the inability to delay or control a response. Failure to “control the behavioral response” most often manifests as impulsivity in the school-aged child, typically resulting in a host of undesired outcomes. Clinically, impulsivity is a behavioral descriptor that suggests that the child’s behavior is disinhibited, resulting in their acting or thinking without regard to the consequences of their actions or thoughts. This concept is also described in detail in Chapter 30 (on ADHD).

The function of working memory (WM) has been the focus of much recent research as an important underlying cognitive process. WM can be defined as the ability to hold, manipulate, and store information for short periods. An example of a task requiring WM is multiplying 10 × 12, whereby one must store (hold) the information, process it (perform the calculations), and produce the answer. In its simplest form, WM involves the interaction of short-term verbal and visual processes (e.g., memory, phonologic, awareness and spatial skills) with a centralized control mechanism that is responsible for coordinating all of the cognitive processes involved (i.e., temporarily suspending information in memory while working with it). Developmentally, WM capacity can double or triple between the preschool years and adolescence. A student with WM dysfunction might carry a number and then forget what it was that he or she intended to do after carrying that number. WM is an equally important underlying function for reading, where it enables the child to remember the beginning of a paragraph when he or she arrives at the end of it. In writing, WM helps children remember what they intend to express in written form while they are performing another task, like placing a comma or working on spelling a word correctly. WM also enables the linkage between new incoming information in STM with prior knowledge or skills held in LTM. WM is an extremely important, complex, higher-order cognitive function that interacts with many other functions and is influenced by a number of factors (e.g., age of the child, demands of the activity or task), making it a challenging process to assess and rehabilitate.

Intellectual Function

The concept of intellectual function, or intelligence, has had many definitions and theoretical models and has been the topic of much debate. Well-known theories include Spearman’s unitary concept of “the g-factor,” the “verbal and nonverbal” theories (e.g., Binet, Thorndike), the two-factor theory from Catell (crystallized versus fluid intelligence), Luria’s simultaneous and successive processing model, and more recent models that view intelligence as a global construct composed of more-specific cognitive functions (e.g., auditory and visual-perceptual processing, spatial abilities, processing speed, and WM). For our purposes, intellectual function is defined as the capacity to think in the abstract, reason, problem solve, and comprehend.

The expression of intellect is mediated by many factors, including language development, sensory-motor abilities, genetics, heredity, environment, and neurodevelopmental dysfunction or neuropathology. In terms of classification systems based on psychometric testing, one’s intellectual level can fall within a range, from profoundly deficient (IQ standard score ≤25) to well above average (IQ standard score ≥130) and higher. Test results have proved useful in predicting future functionality (e.g., academic, occupational, and social). Notwithstanding, intelligence test scores (e.g., IQ) reflect only part of an individual’s ability profile. Functionally, there are some common cognitive characteristics that distinguish children with lower intellectual functioning from those with average or above abilities. Typically, those at the lowest end of the spectrum (e.g., profound or severe intellectual deficiencies) are incapable of independent function, and require a highly structured environment with constant aid and supervision and an individualized relationship with a caregiver (Chapter 33). At the other end of the spectrum are those with unusually well developed intellect (e.g., gifted). Although this level of intellectual functioning offers many opportunities, it can also be associated with functional challenges related to socialization, learning style, and communication and perceptual differences.

More common are observations of differences between those whose intellect falls in the borderline or low-average ranges (sometimes called slow learners) and those whose abilities lie in the average to above-average ranges. The former tend to experience greater difficulty processing and managing information that is abstract, making connections between concepts and ideas, and generalizing information (e.g., may be able to comprehend a concept but unable to apply it in different settings). Those functioning in the borderline or low-average ranges also tend to struggle with fluid reasoning. In general, those with borderline or low-average intellect tend to do better when information is presented in more concrete and explicit terms, and when working with rote information (e.g., memorizing specific material). Stronger intellect has been associated with better-developed concept formation, critical thinking, problem solving, understanding and formulation of rules, brainstorming and creativity, and metacognition (the ability to think about thinking).

Social Cognition

For the school-aged child, the development and effective use of social skills is of immeasurable importance. It is heavily dependent on secure social cognition, which is composed of mental processes that allow an individual to understand and interact with the social environment. Although some evidence has shown that social cognition exists as a discrete area of neurodevelopmental function, multiple cognitive processes are involved with social cognition. These include the ability to recognize, interpret, and make sense of the thoughts, communications (verbal and nonverbal), and actions of others, the ability to understand that others’ perceptions, perspectives, and intentions might differ from our own (commonly referred to as “theory of mind”), the ability to use language to communicate with others socially (pragmatic language), and the ability to make inferences about others and/or the environment based on contextual information. It can also be argued that social cognition involves processes associated with memory and EFs like flexibility.

Weaknesses in social cognition can have a pervasive influence on the school-aged child’s ability to enter smoothly into and maintain new and truly reciprocal (e.g., sharing) relationships with peers. They can have difficulty in perceiving and understanding the emotions of others, in timing and staging interactions appropriately, in interpreting nonverbal cues (e.g., facial expressions, gestures, and body language), and in figuring out how to resolve social conflicts appropriately (e.g., without aggression). Moreover, they might not be adept at overcoming their own egocentricity in order to praise or nurture others, might not understand how their actions affect others, and may be deficient at establishing their own self-concept and marketing themselves to peers and adults. Weak social cognition hampers a child’s overall social skills development, which in turn can exert an enduring negative effect on behavioral adjustment, mental health, and ultimately, life achievement.

Pathogenesis

Functional magnetic resonance imaging (fMRI) has indicated that children with a reading disorder (dyslexia), when compared to children with normal reading abilities, demonstrate decreased left temporoparietal cortical activation during a phonologic task of rhyming, and decreased occipitoparietal extrastriate activation during an orthographic task of letter matching. Biological underpinnings are also suggested by imaging studies of children with ADHD, which have identified structural changes involving the frontal/striatal system, and by near-infrared spectroscopy studies, which have indicated prefrontal cortical hypometabolism. Abnormal quantitative electroencephalograms (QEEGs) have been reported in 25-45% of children with academic disorders, further supporting the biological perspective of pathogenesis as one potential cause of dysfunction.

Two important considerations when analyzing the literature on pathogenesis of neurodevelopmental disabilities are that the heterogeneity of study populations warrants a cautious approach to generalization of findings and to clinical applications for the individual child and that although they might not, on their own, be causative, environmental influences (e.g., socioeconomic status) typically play a significant role in the expression of developmental dysfunction.

Clinical Manifestations

School-aged children with neurodevelopmental dysfunctions vary widely with regard to clinical presentations. Their specific patterns of academic performance and behavior represent final common pathways, the convergence of many forces, including interacting cognitive strengths and deficits; environmental, social, or cultural factors; temperament; educational experience; and intrinsic resilience.

Symptoms of academic disorders differ with age. Children in preschool or kindergarten might present with delayed language development, including problems with articulation, vocabulary development, word finding and rhyming. They often experience early challenges with learning colors, shapes, letters and numbers, the alphabet, and days of the week. Difficulty following instructions, overactivity, and distractibility may be early symptoms of emerging attention and inhibitory control weaknesses. Difficulties with fine motor development (e.g., grasping crayons and pencils, coloring or drawing) and social interaction are not uncommon. As these children enter elementary school, they can evidence problems integrating and associating letters and sounds and problems with semantic knowledge such as mixing up their words (like go and eat). While learning to read and spell, challenges with reversals (b/d), inversions (m/w), transpositions (felt/left), and substitutions (house/home) might persist. Reading comprehension may be weak.

Children with early signs of a mathematics weakness might have difficulty with concepts of quantity or with adding or subtracting without using concrete representation (e.g., their fingers when calculating). Difficulty learning time concepts and confusion with directions (right/left) might also be observed. Sequencing problems are noted in reading, spelling and writing, and mathematics. Poor fine motor control and coordination and poor planning can lead to spelling and writing problems. Attention and behavioral regulation weaknesses observed earlier can continue, and together with executive functioning weaknesses (e.g., organization, WM, initiation skills), further complicate the child’s ability to acquire and generalize new knowledge.

Middle school brings with it a significant shift in cognitive, academic, and regulatory demands, as children in this age group are expected to be increasingly independent, causing further difficulties for a child with existing attention, inhibitory, and/or executive challenges. In reading and writing, middle school children might present with transposition and sequencing errors; might struggle with root words, prefixes, and suffixes; might have difficulty with written expression; and might avoid reading and writing altogether. Challenges completing word problems in math are common. Difficulty with recall of information might also be experienced. Although observable in both lower and more advanced grades, behavioral, emotional, and/or social difficulties tend to become more salient in middle school children who experience cognitive and/or academic problems.

Many of these challenges continue well into high school students. In particular, high school students can present with deficient reading comprehension, written expression, and slower processing efficiency. Trouble answering open-ended questions, dealing with abstract information, and producing executive control (e.g., self-monitoring, organization, planning, and self-starting) is often reported.

Reading

Reading disorders (Chapter 31), also termed dyslexia, can stem from any number of neurodevelopmental dysfunctions as described earlier (Table 29-1). Most commonly, language and/or auditory processing weaknesses are present as evidenced by poor phonologic processing. Challenges with phonologic processing often result in deficiencies at the level of decoding individual words and, consequently, a delay in automaticity (e.g., acquiring a repertoire of words they can identify instantly) that causes reading to be slow, laborious, and frustrating. Without effective identification and intervention, reading comprehension, and ultimately the acquisition of knowledge may be seriously compromised.

Table 29-1 NEURODEVELOPMENTAL DYSFUNCTION UNDERLYING ACADEMIC DISORDERS

CADEMIC DISORDER	POTENTIAL UNDERLYING NEURODEVELOPMENTAL DYSFUNCTION
Reading	Language • Phonological processing • Verbal fluency • Syntactic and semantic skills Memory • Working memory Sequencing Visual-spatial Attention

Written expression, spelling

Language

• Phonological processing

• Syntactic and semantic skills

Mathematics

Isolated neurodevelopmental dysfunction can lead to a specific academic disorder, but more often there is a combination of factors underlying weak academic performance. In addition to the dysfunction in neurodevelopmental domains as listed in the table, the clinician must also consider the possibility of limitations of intellectual and cognitive abilities or associated social and emotional problems.

Deficits in other core neurodevelopmental domains might also be present. Weak WM might make it difficult for a child to hold sounds and/or symbols in mind while breaking down words into their component sounds or might cause reading comprehension problems. Some children experience temporal-ordering weaknesses and struggle with reblending phonemes into correct sequences. Memory dysfunction can cause problems with recall and summarization of what was read. Some children with higher-order cognitive deficiencies have trouble understanding what they read because they lack a strong grasp of the concepts in a text. Although relatively rare as a cause of reading difficulty, problems with visual-spatial functions (e.g., visual perception) can cause children difficulty in recognizing letters. It is not unusual for children with reading problems to avoid reading practice, and a delay in reading proficiency becomes increasingly pronounced and difficult to remediate.

Spelling and Writing

Spelling and writing impairments share many related underlying processing deficits with reading, so it is not surprising that the two disorders often occur simultaneously in school-aged children (see Table 29-1). Core neurodevelopmental weaknesses can include phonologic and decoding difficulties, orthographic problems (coding letters and words into memory), and morphologic deficits (use of suffixes, prefixes, and root words). Problems in these areas can manifest as phonetically poor, yet visually comparable approximations to the actual word (faght for fight), spelling that is phonetically correct but visually incorrect (fite for fight), and inadequate spelling patterns (played as plade). Children with memory disorders might misspell words because of coding weaknesses. Others misspell due to poor auditory WM that interferes with their ability to process letters. Sequencing weaknesses often result in transposition errors when spelling. Overall, the careful analysis of a child’s errors can provide valuable insights into the nature of their spelling problems. As children proceed through school, demands increase for large amounts of well-organized written output.

Writing difficulties have been classified as disorder of written expression, or dysgraphia (see Table 29-1). Although many of the same dysfunctions described for reading and spelling can contribute to problems with writing, written expression is the most complex of the language arts, requiring synthesis of many neurodevelopmental functions (e.g., auditory, visual-spatial, memory, executive). Deficits in any of these domains can be problematic. Even when a child’s phonologic and/or orthographic skills are functional, he or she can experience writing problems owing to weaknesses with language, attention, EFs, sequencing and/or fine motor development. These weaknesses can occur in written output that is difficult to comprehend, disjointed, and/or poorly organized. The child with WM challenges can lose track of what he or she intended to write. Attention deficits can make it hard for a child to mobilize and sustain the mental effort, pacing, and self-monitoring demands necessary for writing. In many cases, writing is laborious because of an underlying graphomotor dysfunction (e.g., fluency does not keep pace with ideation and language production). Thoughts may also be forgotten or underdeveloped during writing because the mechanical effort is so taxing.

Mathematics

Delays in mathematical ability, known as mathematics disorder or dyscalculia, can be especially refractory to correction, partly because math involves the assimilation of both procedural knowledge (e.g., calculations) and higher-order cognitive processes (e.g., WM) (see Table 29-1). In a school-based study, it was found that no student who was delayed >6 mo in mathematics in 6th grade ever caught up, and another study has shown persistence of severe arithmetic disorder in half of affected preteen children. Factors associated with persistence of difficulties included the disorder’s severity and heritability. Significant mathematical weaknesses can become virtually insurmountable because the subject is so cumulative in its structure.

Some children experience mathematics failure because of weaknesses in reasoning and problem solving (e.g., intellectual functioning). It may be hard for them to grasp and apply concepts effectively and/or systematically. Good mathematicians are able to use both verbal and perceptual conceptualization to understand such concepts as fractions, percentages, equations, and proportion. Children with language dysfunctions have difficulty in mathematics because they have trouble understanding their teachers’ verbal explanations of quantitative concepts and operations and are likely to experience frustration in solving word problems and in processing the vast network of technical vocabulary in math. Mathematics also relies on visualization. Children who have difficulty forming and recalling visual imagery may be at a disadvantage in acquiring mathematical skills. They might experience problems writing numbers correctly, placing value locations, and processing geometric shapes or fractions. Children with attention, inhibitory control, or executive deficits (e.g., WM) may be unable to focus on fine detail (such as operational signs), might take an impulsive approach to problem solving, engage in little or no self-monitoring, forget components of the same problem, or commit careless errors. When a child’s memory system is weak, he or she might have difficulty recalling appropriate procedures and automatizing mathematical facts (e.g., multiplication tables). Moreover, it is not unusual for children with mathematical disabilities to have superimposed mathematics phobias. Anxiety over mathematics can be especially debilitating.