Understanding Neurodevelopmental and Learning Disorders
Articulation, Speech, and Language Impairments
Articulation Disorder
- Refers to problems making speech sounds and with phonological processing skills.
- Seen mostly in young children (preschool age).
- Diagnosed if children do not outgrow common articulation errors (e.g., “wabbit” instead of “rabbit;” “nana” instead of “banana”).
- May be more common in developmental disorders (e.g., autism), genetic syndromes (e.g., Down syndrome), hearing loss, illness, or neurological disorders (e.g., cerebral palsy).
- Can impact intelligibility, conversational skills, and social skills.
Speech/Language Impairment
- Involves deficits in expressive and/or receptive language.
- Characterized by deficits in vocabulary, memory, naming, syntax (grammar), semantics (word meaning), and speech perception.
- May include impaired temporal sequencing of nonverbal auditory stimuli and poor discrimination of sounds.
- Speech articulation issues may also be present.
Neuropsychological Correlates
- Impaired temporal processing of auditory information.
- Involvement of the superior temporal lobes in decoding acoustic signals of speech.
- Involvement of the left frontal lobes in semantic operations.
- Less control over involuntary movements.
- Working memory and short-term memory deficits.
Psychosocial Correlates
- Higher rate of emotional and behavioral disorders.
- Communication and verbal intelligence are related to social adjustment.
- Difficulty expressing one’s wants and needs may lead to physical expressions of frustration or turning feelings inward.
DSM-5 Criteria for Autism Spectrum Disorder
Persistent Deficits in Social Communication
Persistent deficits in social communication and social interaction across multiple contexts, as manifested by the following:
- Deficits in social-emotional reciprocity, ranging from abnormal social approach and failure of normal back-and-forth conversation.
- Deficits in nonverbal communicative behaviors used for social interaction, ranging from poorly integrated verbal and nonverbal communication.
- Deficits in developing, maintaining, and understanding relationships, ranging from difficulties adjusting behavior to suit various social contexts.
Restricted, Repetitive Patterns of Behavior
Restricted, repetitive patterns of behavior, interests, or activities, as manifested by at least two of the following:
- Stereotyped or repetitive motor movements, use of objects, or speech (e.g., simple motor stereotypies, lining up toys, flipping objects, echolalia, idiosyncratic phrases).
- Insistence on sameness, inflexible adherence to routines, or ritualized patterns of verbal or nonverbal behavior.
- Highly restricted, fixated interests that are abnormal in intensity or focus.
- Hyper- or hypo-reactivity to sensory input or unusual interests in sensory aspects of the environment (e.g., apparent indifference to pain/temperature).
Executive Function Deficits in ADHD and ASD
EF Deficits for ADHD
- Affects attention, impulse control, activity level, and learning.
EF Deficits for ASD
Learning Disabilities: Definition, Etiology, and Risks
Definition
Problems in any one of the seven areas of learning, including listening comprehension, expressive language, basic reading skills (word identification, phonological coding), reading comprehension, written language, mathematics calculation, or mathematics reasoning.
Etiology
- Learning problems can arise from many sources, including genetic, neuropsychological, cognitive, psycho-social, and environmental factors.
- Many children may experience difficulty in more than one area.
- Children with learning disabilities are more susceptible to internalizing disorders such as anxiety, depression, low self-esteem, and withdrawal.
- Difficulties with adjustment may persist through adulthood.
- Children with reading difficulty often also experience math difficulty.
Risk Factors
Prenatal and postnatal factors influencing learning disabilities include:
- Premature birth
- Low birth weight
- Lack of environmental stimulation in infancy
- Frequent ear infections
- Other environmental factors
Neuropsychological Correlates
- Planum temporale: phonological processing.
- Occipital-temporal system: rapid recognition of words, orthographic route to reading and spelling.
- Frontal regions: reading.
- Dyslexia: hypoactivation in the left parietal region and hyperactivation in the left inferior regions, caudate, and thalamus; reduced gray matter volume.
Reading Disabilities: Sub-areas and Interventions
Reading Decoding
The ability to transform orthographic patterns of alphabetic letters into phonological patterns of a corresponding spoken word.
Word Recognition
The ability to identify words when reading, either through word decoding or sight word identification, without using strategies to decode.
Reading Fluency
The ability to recognize and read words accurately, smoothly, and quickly, usually in context.
Reading Comprehension
The ability to understand the meaning of written text.
Interventions and Programs
- Response to Intervention (RTI) (small group instruction, 1:1 instruction, specialized reading programs)
- Wilson Reading System
- Read 180
- Reading Recovery
- Orton-Gillingham
- Lindamood-Bell
Written Language Disorders and Interventions
Writing Process
The ability to plan (i.e., “pre-writing”), organize, draft, reflect on, revise, and edit written text.
Written Product
The end-product of the writing process; it can be examined at the word level (e.g., word choice and spelling), sentence level (e.g., grammar and complexity), and text level (e.g., discourse structure, use of cohesive devices, and coherence).
Spelling
Also known as encoding, spelling requires the ability to segment words into phonemes and map those phonemes onto graphemes (letters or letter combinations) in an acceptable sequence in written form.
Interventions
- Direct teaching of the ability to plan, revise, and edit a writing sample.
- Setting goals, developing outlines, and preparing a draft.
- Teaching self-regulation, self-monitoring, and self-reward.
- Using web-based programs to support writing skills.
- Small group or 1:1 instruction.
Mathematics Disabilities and Interventions
Subtypes of Math Disabilities
- Procedural: Developmental delays that improve with age. Individuals may make careless errors.
- Semantic: Often co-occurs with a reading disability and involves problems with memory and retrieval of math facts (left-hemispheric dysfunction).
- Visuospatial: Problems with spatial representations, aligning columns, etc. (right-hemisphere dysfunction).
Interventions
Interventions include the use of visual cues, manipulatives (e.g., counting rods), teaching self-monitoring strategies, and using charts to facilitate memorization.
Nonverbal Learning Disability: Features and Syndromes
Features of Nonverbal Learning Disability
- Tactile-perceptual deficits
- Visual-spatial and organizational deficits
- Problems adapting to novel and complex situations
- Difficulty with problem-solving and concept formation
- Distorted sense of time
- Difficulty with visual working memory
- Well-developed rote verbal memory
- Highly verbose
- Problems with math calculations but strengths in reading and spelling
- Problems with attention and executive functioning
- Problems with social judgment
Related Syndromes
Turner Syndrome
- Caused by the loss of an X chromosome.
- Occurs in females.
- Significant problems processing social information, visuospatial information, and severe math disabilities.
- Nonverbal IQ is approximately 15 points lower than verbal IQ.
- Smaller volumes in occipital and parietal lobes.
- The amygdala shows an abnormal response to fear and facial expressions (similar to ASD).
Velocardiofacial Syndrome
- Caused by a deletion on chromosome 22.
- Involves neurological, cognitive, and behavioral deficits.
- Deficits in visual-spatial skills, social processing, and math reasoning.
- Differences in white matter in the parietal regions.
Agenesis of the Corpus Callosum
- The corpus callosum forms incompletely or not at all.
- Cognitive ability ranges from intellectual disability to average.
- Difficulty with novel problem-solving and social understanding.
- Trouble understanding figurative language.
Traumatic Brain Injury (TBI): Types, Risks, and Profile
Types of Injuries
- Open injury: Involves an open wound and is caused by an object penetrating the skull and entering the brain.
- Closed injury: Occurs when the head strikes another surface or as a result of child abuse or shaken baby syndrome.
Etiology and Risk Factors
TBI can cause a decline in nonverbal intelligence, visual-motor impairment, attentional and memory deficits, decreases in oral fluency, comprehension, verbal association, and reading achievement, and increases in psychiatric disorders.
Neuropsychological Profile
- Nonverbal IQ is typically lower than Verbal IQ.
- Difficulties in language, reading, arithmetic, calculation, writing, and spelling.
- Motor speed and information processing are impaired.
- Memory deficits, particularly in verbal memory and working memory (visual-spatial memory may not be affected).
- Attentional and executive functioning difficulties.
- Disinhibition and impulsivity.
Dyslexia: Definition and Subtypes
The term refers to an inability to acquire functional reading skills despite the presence of normal intelligence and exposure to adequate educational opportunities.
Phonological Dyslexia
This subtype involves difficulty using the phonological route in reading, leading to the use of the visual route to the lexicon. There is little reliance on letter-to-sound conversion and an over-reliance on visual cues to determine meaning from print.
- Neuropsychological significance: Left superior temporal gyrus.
- Prevalence: Represents approximately two-thirds of all individuals with dyslexia.
Surface Dyslexia
Also referred to as visual-form dyslexia, this is characterized by an inability to visualize words in a fashion where the process of reading becomes automatic. Individuals over-rely on sound-symbol relationships because the process of reading never becomes automatic.
- Neuropsychological significance: Occipital/parietal junctures of the angular gyrus and corpus callosum deficiencies; role of the insular cortex.
- Prevalence: Approximately 14 percent of all individuals with dyslexia.
Mixed Dyslexia
This involves severely impaired readers with characteristics of both phonological deficits and visual/spatial deficits. These readers have no usable key to the reading and spelling code.
- Neuropsychological significance: Shifting difficulty via the corpus callosum.
- Structural Explanation: The genu of the corpus callosum is much smaller and the splenium is larger.
Deep Dyslexia
This is a rare form of reading comprehension disorder characterized by impairments in reading words with abstract meanings, while the ability to read more concrete, easily imagined words remains intact. Semantic errors are the hallmark of this disorder. This is a double-deficit type of reading disability, as the child has poor sound-symbol relationships coupled with a deficit in relying solely on the visual contour of letters.
- Neuropsychological significance: Difficulty activating the left hemisphere (right-hemisphere reading); damage to the supramarginal gyrus or angular gyrus; subcortical damage, such as to the thalamus.