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Developmental Learning Disorders

Michael A. Davis, MD  


A learning disorder is identified in 6-7% of all school-aged children, and twice as many boys as girls are diagnosed. The disorders may be identified as early as the preschool years. Learning disorders are not outgrown.

Clinical Definitions

Learning disability is defined as difficulty in the acquisition and use of basic reading skills, reading comprehension, oral expression, listening comprehension, mathematical reasoning, and mathematical comprehension. This definition requires a 2-year discrepancy between the child's expected level of achievement and the child’s level of performance.

Learning disorders include all disorders that cause a persistent deficit in function of the brain, including mental retardation, acquired disorders (eg, traumatic brain injury), and difficulties with fine motor coordination (dysgraphia, dyspraxia), modulation of sensory modalities (ie, tactile defensiveness, hyperacusis), social cognition (autism), and executive functioning. Attention deficit disorder is also included.

Disorders of Speech and Language


Dyslexia is a disorder of phonologic processing and decoding of words. It is the most common developmental language disorder. Dyslexia frequently is familial, occurring more often in sons (35-40% risk) than in daughters (17-18% risk).

Dyslexic children do not appreciate that speech is composed of sounds that join together to form words. When reading or writing, the child has difficulty in decoding or encoding words.

Preschool children who have dyslexia manifest delays in acquisition of speech, poor articulation, difficulty with learning the names of letters and colors, and persistent missequencing of syllables (eg, "aminals" for "animals").

These children have difficulty following multi-step directions. They are unable to express frustration by "using words" and, therefore, are prone to develop secondary behaviors such as hitting, kicking, or throwing tantrums.

Dyslexia can be diagnosed confidently by the end of the second grade. Children will be slow and halting in their oral reading and have difficulty in reading comprehension. They have poor word retrieval and frequently use more fillers ("um," "like," "you know") in their speech.

Attention-Deficit Hyperactivity Disorder (ADHD)

ADHD is a heritable disorder characterized by an inability to sustain attention, impulsivity, distractibility, and overactivity. Symptoms must be manifested in multiple settings (eg, in school and at home). ADHD affects 3-6% of school-aged children.

Preschool children may be hyperactive or disinhibited, judge danger poorly, and be physically aggressive with peers. They often move rapidly from toy to toy in a chaotic fashion, and play skills are delayed for their level of intelligence.

School-aged children who have ADHD fidget, wander, and have difficulty remaining seated. They are easily distracted and inattentive and have great difficulty in organizing themselves, completing tasks, and working independently.

Adulthood is often characterized by an inability to maintain employment, by substance abuse, and by social isolation.

Differential Diagnosis of ADHD and Learning Disorders

Overactivity and irritability may be caused by chaotic families, depression, or hyperthyroidism.

High lead levels, caffeine, antihistamines, or corticosteroids also may cause overactivity. Children who have autism or a pervasive developmental disorder may be very agitated.

Disorders of sleep (especially sleep apnea) and hearing loss may cause similar behaviors.

Acquired Memory Disorders

These children have difficulty restarting tasks after interruptions. They may be labile, impulsive, and inattentive.

This group of disorders is caused by trauma, recurrent seizures, central nervous system infection, stroke, tumor, or exposure to toxins.


This disorder is characterized by limitations in social cognition (lack of reciprocity, sensitivity to nonverbal cues, appreciation of humor). Their interests are constricted, and their repertoire of activities is restricted, and they have atypical development of play and language.

Patients also may be inattentive and hyperactive. Often, they experience anxiety or obsessive-compulsive symptoms that respond to tricyclic antidepressants.

Nonverbal Learning Disorder

These children develop language composed of rote expressions and fragments of ritualized dialogue. Major deficits lie in the areas of tactile and visual perception, concept formation, and problem solving.

These difficulties result in a reliance on rote routines that often appear stilted and inappropriate.

Clinical Evaluation of Suspected Developmental Learning Disorders

Neurodevelopmental History

Current difficulties in school and relationships with family and peers should be assessed, and gestational, developmental, medical, academic, and family histories should be evaluated.

Neurodevelopmental History

Current level of functioning: at school, at home, with peers



School and social history

Play and hobbies

Gestational history

Early developmental milestones

Medical disorders

Family history

Family functioning


Medical Conditions That Predispose to Disorders of Learning and Attention


Fetal alcohol syndrome

Fetal alcohol effects


Nutritional deprivation

Emotional deprivation

Traumatic brain injury

Lead poisoning

Familial dysfunction

Sequelae of Prematurity

Hypoxic ischemic encephalopathy

Periventricular leukomalacia

Intraventricular hemorrhage



Brain tumors


Radiation and chemotherapy effects



Human immunodeficiency virus encephalopathy

Congenital infection

Sydenham chorea


Chronic hypoxia

Chronic illness




Medication Effects





Ethanol and recreational drugs

Evaluation the child's sleep and eating patterns may reveal vegetative symptoms of depression and may give clues to underlying medical conditions that can exacerbate poor school performance.

A chaotic family life may result in agitated, unfocused behavior in the classroom. Anorexia or hyperphagia may suggest an affective disorder.

Physical Examination

Associated neurologic signs and the manner in which a given set of tasks is completed should be assessed. A general physical examination should include screening of vision and hearing, and measurement of head size.

If the head is unusually large or unusually small, the parents' heads should be measured for comparison. A small head size suggests acquired microcephaly, and macrocephaly suggests overgrowth syndromes such as arrested hydrocephalus.

Multiple minor dysmorphic features of the face, palate, teeth, hands, and feet suggest a dysmorphic syndrome (prognathism, big ears, and prominent forehead suggest fragile X syndrome).

Neurocutaneous stigmata may be diagnostic of an underlying CNS disorder (eg, café au lait spots found in neurofibromatosis.

Hepatosplenomegaly may be suggestive of a metabolic storage disease.

Neurologic examination may reveal motor or phonic tics. Motor impersistence (inability to keep arms extended above the head for 30 to 60 seconds), dysmetria, mirror motor movements, poorly coordinated rapid finger apposition, and motor impulsivity (eg, beginning maneuvers before instructions are given) all suggest CNS dysfunction. The positive "corridor sign" (inability to inhibit the impulse to wander into each open door along the way) suggests ADHD.

Oppositional behavior or difficulty in separating from the parent is often noted.

The child may be asked to read text of increasing difficulty out loud, answer questions based on the content of the text, and write a description of a picture. Asking adolescents to relay information about their recreational activities, recount the plot of their favorite movie, or discuss their taste in music may reveal difficulties with word retrieval.

Neuropsychometric testing may aid in detecting attention deficit disorders or subtle learning disorders

Treatment of Learning Disorders. A remedial program should be developed in consultation with speech and language therapists, neuropsychologists, education specialists, and occupational therapists. §