Dyslexic children require special instruction for word analysis and spelling from an early age. While there are fonts that may help people with dyslexia better understand writing, this might simply be due to the added spacing between words. The prognosis, generally speaking, is positive for individuals who are identified in childhood and receive support from friends and family.

Longitudinal studies indicate that problems are largely resolved by 5 years of age in around 40% of 4-year-olds with early language delays who have no other presenting risk factors. However, for children who still have significant language difficulties at school entry, reading problems are common, even for children who receive specialist help, and educational attainments are typically poor. Poor outcomes are most common in cases where comprehension as well as expressive language is affected. There is also evidence that scores on tests of nonverbal ability of children with DLD decrease over the course of development.

DLD is associated with an elevated risk of social, emotional and mental health concerns. For instance, in a UK survey, 64% of a sample of 11-year-olds with DLD scored above a clinical threshold on a questionnaire for psychiatric difficulties, and 36% were regularly bullied, compared with 12% of comparison children. In the longer-term, studies of adult outcomes of children with DLD have found elevated rates of unemployment, social isolation and psychiatric disorder among those with early comprehension difficulties. However, better outcomes are found for children who have milder difficulties and do not require special educational provision.

It is generally accepted that DLD is strongly influenced by genetic factors. The best evidence comes from the Twin study method. Two twins growing up together are exposed to the same home environment, yet may differ radically in their language skills. Such different outcomes are, however, much more common in fraternal (non-identical) twins, who are genetically different. Identical twins share the same genes and tend to be much more similar in language ability. There can be some variation in the severity and persistence of DLD in identical twins, indicating that non-genetic factors affect the course of disorder, but it is unusual to find a child with DLD who has an identical twin with typical language.

There was considerable excitement when a large, multigenerational family with a high rate of DLD were found to have a mutation of the FOXP2 gene just in the affected family members. However, subsequent studies have found that, though DLD runs in families, it is not usually caused by a mutation in FOXP2 or another specific gene. Current evidence suggests that there are many different genes that can influence language learning, and DLD results when a child inherits a particularly detrimental combination of risk factors, each of which may have only a small effect. Nevertheless, study of the mode of action of the FOXP2 gene has helped identify other common genetic variants involved in the same neural pathways that may play a part in causing DLD.

Language disorders are associated with aspects of home environment, and it is often assumed that this is a causal link, with poor language stimulation leading to weak language skills. Twin studies, however, show that two children in the same home environment can have very different language outcomes, suggesting we should consider other explanations for the link. Children with DLD often grow up into adults who have relatively low educational attainments, and their children may share a genetic risk for language disorder.

One non-genetic factor that is known to have a specific impact on language development is being a younger sibling in a large family.

Language delays are the most frequent developmental delays, and can occur for many reasons. A delay can be due to being a “late bloomer,” or a more serious problem. The most common causes of speech delay include

- Hearing loss

- Slow development

- Intellectual Disability

Such delays can occur in conjunction with a lack of mirroring of facial responses, unresponsiveness or unawareness of certain noises, a lack of interest in playing with other children or toys, or no pain response to stimuli.

Other causes include:

- Psychosocial deprivation - The child doesn't spend enough time talking with adults. Research on early brain development shows that babies and toddlers have a critical need for direct interactions with parents and other significant care givers for healthy brain growth and the development of appropriate social, emotional, and cognitive skills.

- Television viewing is associated with delayed language development. Children who watched television alone were 8.47 times more likely to have language delay when compared to children who interacted with their caregivers during television viewing. As recommended by the American Academy of Pediatrics (AAP), children under the age of 2 should watch no television at all, and after age 2 watch no more than one to two hours of quality programming a day. Therefore, exposing such young children to television programs should be discouraged. Parents should engage children in more conversational activities to avoid television-related delays to their children language development, which could impair their intellectual performance.

- Stress during pregnancy is associated with language delay.

- Being a twin

- Attention deficit hyperactivity disorder

- Autism (a developmental disorder) - There is strong evidence that autism is commonly associated with language delay. Asperger syndrome, which is on the autistic spectrum, however, is not associated with language delay.

- Selective mutism (the child just doesn't want to talk)

- Cerebral palsy (a movement disorder caused by brain damage)

- Genetic abnormalities - In 2005, researchers found a connection between expressive language delay and a genetic abnormality: a duplicate set of the same genes that are missing in sufferers of Williams-Beuren syndrome. Also so called XYY syndrome can often cause speech delay.

- Correlation with male sex, previous family history, and maternal education has been demonstrated.

The contribution of gene–environment interaction to reading disability has been intensely studied using twin studies, which estimate the proportion of variance associated with a person's environment and the proportion associated with their genes. Studies examining the influence of environmental factors such as parental education and teacher quality have determined that genetics have greater influence in supportive, rather than less optimal, environments. However, more optimal conditions may just allow those genetic risk factors to account for more of the variance in outcome because the environmental risk factors have been minimized. As environment plays a large role in learning and memory, it is likely that epigenetic modifications play an important role in reading ability. Animal experiments and measures of gene expression and methylation in the human periphery are used to study epigenetic processes; however, both types of study have many limitations in the extrapolation of results for application to the human brain.

Dysgraphia is a biologically based disorder with genetic and brain bases. More specifically, it is a working memory problem. In dysgraphia, individuals fail to develop normal connections among different brain regions needed for writing. People with dysgraphia have difficulty in automatically remembering and mastering the sequence of motor movements required to write letters or numbers. Dysgraphia is also in part due to underlying problems in orthographic coding, the orthographic loop, and graphmotor output (the movements that result in writing) by one’s hands, fingers and executive functions involved in letter writing. The orthographic loop is when written words are stored in the mind’s eye, connected through sequential finger movement for motor output through the hand with feedback from the eye.

Language-based learning disabilities or LBLD are "heterogeneous" neurological differences that can affect skills such as listening, reasoning, speaking, reading, writing, and maths calculations. It is also associated with movement, coordination, and direct attention. LBLD is not usually identified until the child reaches school age. Most people with this disability find it hard to communicate, to express ideas efficiently and what they say may be ambiguous and hard to understand

It is a neurological difference. It is often hereditary, and is frequently associated to specific language problems.

There are two types of learning disabilities: non-verbal, which includes disabilities from psychomotor difficulties to dyscalculia, and verbal, language based.

The causes for learning disabilities are not well understood, and sometimes there is no apparent cause for a learning disability. However, some causes of neurological impairments include:

- Heredity and genetics

- Problems during pregnancy and birth

- Accidents after birth

There are some common problems not related to dysgraphia but often associated with dysgraphia, the most common of which is stress. Often children (and adults) with dysgraphia will become extremely frustrated with the task of writing (and spelling); younger children may cry, pout, or refuse to complete written assignments. This frustration can cause the child (or adult) a great deal of stress and can lead to stress-related illnesses. This can be a result of any symptom of dysgraphia.

It is estimated that 25 to 50% of children diagnosed with Autism Spectrum Disorder (ASD) never develop spoken language beyond a few words or utterances. Despite the growing field of research on ASD, there is not much information available pertaining to individuals with autism who never develop functional language; that, in fact, individuals with nonverbal autism are considered to be underrepresented in all of autism research. Because of the limited research on nonverbal autism, there are not many validated measurements appropriate for this population. For example, while they may be appropriate for younger children, they lack the validity for grade-school aged children and adolescents and have continued to be a roadblock for nonverbal autism research. Often in autism research, individuals with nonverbal autism are sub-grouped with LFA, categorized by learning at most one word or having minimal verbal language.

Most of the existing body of research in nonverbal autism focuses on early interventions that predict successful language outcomes. Research suggests that most spoken language is inherited before the age of five, and the likelihood of acquiring functional language in the future past this age is minimal, that early language development is crucial to educational achievement, employment, independence during adulthood, and social relationships.

Studies have failed to find clear evidence that language delay can be prevented by training or educating health care professionals in the subject. Overall, some of the reviews show positive results regarding interventions in language delay, but are not curative. (Commentary - Early Identification of Language Delays, 2005)

Mixed receptive-expressive language disorder (DSM-IV 315.32) is a communication disorder in which both the receptive and expressive areas of communication may be affected in any degree, from mild to severe. Children with this disorder have difficulty understanding words and sentences. This impairment is classified by deficiencies in expressive and receptive language development that is not attributed to sensory deficits, nonverbal intellectual deficits, a neurological condition, environmental deprivation or psychiatric impairments. Research illustrates that 2% to 4% of 5 year olds have mixed receptive-expressive language disorder. This distinction is made when children have issues in expressive language skills, the production of language, and when children also have issues in receptive language skills, the understanding of language. Those with mixed receptive-language disorder have a normal left-right anatomical asymmetry of the planum temporale and parietale. This is attributed to a reduced left hemisphere functional specialization for language. Taken from a measure of cerebral blood flow (SPECT) in phonemic discrimination tasks, children with mixed receptive-expressive language disorder do not exhibit the expected predominant left hemisphere activation. Mixed receptive-expressive language disorder is also known as receptive-expressive language impairment (RELI) or receptive language disorder.

Nonverbal learning disorder (also known as nonverbal learning disability, NLD, or NVLD) is a learning disorder characterized by verbal strengths as well as visual-spatial, motor, and social skills difficulties. It is sometimes confused with Asperger Syndrome or high IQ. Nonverbal learning disorder has never been included in the American Psychiatric Association's "Diagnostic and Statistical Manual of Mental Disorders" or the World Health Organization's "International Classification of Diseases".

Nonverbal autism is a subset of autism where the subject is unable to speak. While most autistic children eventually begin to speak, there is a significant minority who will remain nonverbal.

Deficits in any area of information processing can manifest in a variety of specific learning disabilities. It is possible for an individual to have more than one of these difficulties. This is referred to as comorbidity or co-occurrence of learning disabilities. In the UK, the term "dual diagnosis" is often used to refer to co-occurrence of learning difficulties.

Pragmatic language impairment (PLI), or social (pragmatic) communication disorder (SCD), is an impairment in understanding pragmatic aspects of language. This type of impairment was previously called semantic-pragmatic disorder (SPD). People with these impairments have special challenges with the semantic aspect of language (the meaning of what is being said) and the pragmatics of language (using language appropriately in social situations). It is assumed that those with autism have difficulty with "the meaning of what is being said" due to different ways of responding to social situations.

PLI is now a diagnosis in DSM-5, and is called social (pragmatic) communication disorder. Communication problems are also part of the autism spectrum disorders (ASD); however, the latter also show a restricted pattern of behavior, according to behavioral psychology. The diagnosis SCD can only be given if ASD has been ruled out.

If assessed on the Wechsler Adult Intelligence Scale, for instance, symptoms of mixed receptive-expressive language disorder may show as relatively low scores for Information, Vocabulary and Comprehension (perhaps below the 25th percentile). If a person has difficulty with specific types of concepts, for example spatial terms, such as 'over', 'under', 'here' and 'there', they may also have difficulties with arithmetic, understanding word problems and instructions, or difficulties using words at all.

They may also have a more general problem with words or sentences, both comprehension and orally. Some children will have issues with pragmatics - the use of language in social contexts as well; and therefore, will have difficulty with inferring meaning. Furthermore, they have severe impairment of spontaneous language production and for this reason, they have difficulty in formulating questions. Generally, children will have trouble with morphosyntax, which is word inflections. These children have difficulty understanding and applying grammatical rules, such as endings that mark verb tenses (e.g. -"ed"), third-person singular verbs (e.g. I "think", he "thinks"), plurals (e.g. -"s"), auxiliary verbs that denote tenses (e.g. "was" running, "is" running), and with determiners ("the, a"). Moreover, children with mixed receptive-expressive language disorders have deficits in completing two cognitive operations at the same time and learning new words or morphemes under time pressure or when processing demands are high. These children also have auditory processing deficits in which they process auditory information at a slower rate and as a result, require more time for processing.

LBLD can be an enduring problem. Some people might experience overlapping learning disabilities that make improvement problematic. Others with single disabilities often show more improvement. Most subjects can achieve literacy via coping mechanisms and education.

A communication disorder is any disorder that affects an individual's ability to comprehend, detect, or apply language and speech to engage in discourse effectively with others. The delays and disorders can range from simple sound substitution to the inability to understand or use one's native language.

Although disorder for written expressions skills can be difficult and an enduring problem all throughout childhood into adulthood, different types of treatment and support can help individuals who have this disorder to employ strategies and skills in the home and school environment. This includes remedial education tailored to improve specific skills, providing special academic services in the learning environment, and addressing concurrent health and mental issues. It is sometimes necessary to foster motivational techniques to maintain motivation and minimize negative thoughts or feelings. Using whatever modifications are necessary to overcome fears of failure in the early stages of writing mediation is strongly encouraged because children with learning disabilities often experience low self-esteem and confidence, which may further interfere with learning and academic success.

Considered to be neurologically based, nonverbal learning disorder is characterized by verbal strengths as well as visual-spatial, motor, and social skills difficulties. People with this disorder may not at times comprehend nonverbal cues such as facial expression or tone of voice. Challenges with mathematics and handwriting are common.

While various nonverbal impairments were recognized since early studies in child neurology, there is ongoing debate as to whether/or the extent to which existing conceptions of NLD provide a valid diagnostic framework. As originally presented "nonverbal disabilities" (p. 44) or "disorders of nonverbal learning" (p. 272) was a category encompassing non-linguistic learning problems (Johnson and Myklebust, 1967). "Nonverbal learning disabilities" were further discussed by Myklebust in 1975 as representing a subtype of learning disability with a range of presentations involving "mainly visual cognitive processing," social imperception, a gap between higher verbal ability and lower performance IQ, as well as difficulty with handwriting. Later neuropsychologist Byron Rourke sought to develop consistent criteria with a theory and model of brain functioning that would establish NLD as a distinct syndrome (1989).

Questions remain about how best to frame the perceptual, cognitive and motor issues associated with NLD.

The DSM-5 (Diagnostic and Statistical Manual) and ICD-10 (International Classification of Diseases) do not include NLD as a diagnosis.

Assorted diagnoses have been discussed as sharing symptoms with NLD—these conditions include Right hemisphere brain damage and Developmental Right Hemisphere Syndrome, Developmental Coordination Disorder, Social-Emotional Processing Disorder, Asperger syndrome, Gerstmann syndrome and others.

Labels for specific associated issues include visual-spatial deficit, dyscalculia, dysgraphia, as well as dyspraxia.

In their 1967 book "Learning Disabilities; Educational Principles and Practices", Doris J. Johnson and Helmer R. Myklebust characterize how someone with these kinds of disabilities appears in a classroom: "An example is the child who fails to learn the meaning of the actions of others...We categorize this child as having a deficiency in social perception, meaning that he has an inability which precludes acquiring the significance of basic nonverbal aspects of daily living, though his verbal level of intelligence falls within or above the average." (p. 272). In their chapter "Nonverbal Disorders Of Learning" (p. 272-306) are sections titled "Learning Though Pictures," (274) "Gesture," (281) "Nonverbal Motor Learning," (282) "Body Image," (285) "Spatial Orientation," (290) "Right-Left Orientation," (292) "Social Imperception," (295) "Distractibility, Perseveration, and Disinhibition." (298)

Disorders and tendencies included and excluded under the category of communication disorders may vary by source. For example, the definitions offered by the American Speech–Language–Hearing Association differ from that of the Diagnostic Statistical Manual 4th edition (DSM-IV).

Gleanson (2001) defines a communication disorder as a speech and language disorder which refers to problems in communication and in related areas such as oral motor function. The delays and disorders can range from simple sound substitution to the inability to understand or use their native language.

In general, communications disorders commonly refer to problems in speech (comprehension and/or expression) that significantly interfere with an individual’s achievement and/or quality of life. Knowing the operational definition of the agency performing an assessment or giving a diagnosis may help.

Persons who speak more than one language or are considered to have an accent in their location of residence do not have speech disorders if they are speaking in a manner consistent with their home environment or a blending of their home and foreign environment.

At times, speech delay and impairment is caused by a physical disruption in the mouth such as a deformed frenulum, lips, or palate. If the motion or ability to form words and appropriate sounds is disrupted, the child may be slow to pick up words and lack the ability to shape their mouth and tongue in the formation of words.

Other more serious concerns are those that can be caused by oral-motor issues. Oral-motor dysfunction refers to a lack or delay in the area of the brain that speech is formed and created and communicated to the mouth and tongue. While speech may be the only concern, this disorder can be highlighted with feeding issues as well.

Children that are having speech delay disorders could have the following characteristics (Shriberg 1982):

- Speech mechanism in which speech is associated with hearing, motor speech and craniofacial malfunction

- Cognitive-linguistic aspects in which the impairment is associated with the child's intellectual, receptive, expressive and linguistic ability.

- Psychosocial issues in which the impairment is associated with caregiver, school environment, and the child's self behaviors such as aggression and maturity

The many other causes of speech delay include bilingual children with phonological disorders autism spectrum disorders, childhood apraxia, Auditory processing disorder, prematurity, cognitive impairment and hearing loss. Broomfield and Dodd's (2004a) found out after survey that 6.4% of children who are perfectly normal showed speech difficulty while they lacked these disorders will often show early signs and are at times identified as "at risk" when the speech delay is diagnosed.

Specific causes of this disorder are unknown. The interaction of physical, psychological, and environmental factors is thought to contribute to the disorder of written expression. In neuropsychological and neurobiological research, some studies show evidence that abnormally high testosterone levels and abnormalities in cognitive processes (visual-motor, linguistic, attentional, and memory) are thought to play a role in learning disorder cases. The impact of brain injuries in both children and adults can impair any of these cognitive processes.

Among children, the cause of intellectual disability is unknown for one-third to one-half of cases. About 5% of cases are inherited from a person's parents. Genetic defects that cause intellectual disability but are not inherited can be caused by accidents or mutations in genetic development. Examples of such accidents are development of an extra chromosome 18 (trisomy 18) and Down syndrome, which is the most common genetic cause. Velocariofacial syndrome and fetal alcohol spectrum disorders are the two next most common causes. However, doctors have found many other causes. The most common are:

- Genetic conditions. Sometimes disability is caused by abnormal genes inherited from parents, errors when genes combine, or other reasons. The most prevalent genetic conditions include Down syndrome, Klinefelter syndrome, Fragile X syndrome (common among boys), neurofibromatosis, congenital hypothyroidism, Williams syndrome, phenylketonuria (PKU), and Prader–Willi syndrome. Other genetic conditions include Phelan-McDermid syndrome (22q13del), Mowat–Wilson syndrome, genetic ciliopathy, and Siderius type X-linked intellectual disability () as caused by mutations in the "PHF8" gene (). In the rarest of cases, abnormalities with the X or Y chromosome may also cause disability. 48, XXXX and 49, XXXXX syndrome affect a small number of girls worldwide, while boys may be affected by 49, XXXXY, or 49, XYYYY. 47, XYY is not associated with significantly lowered IQ though affected individuals may have slightly lower IQs than non-affected siblings on average.

- Problems during pregnancy. Intellectual disability can result when the fetus does not develop properly. For example, there may be a problem with the way the fetus' cells divide as it grows. A pregnant person who drinks alcohol (see fetal alcohol spectrum disorder) or gets an infection like rubella during pregnancy may also have a baby with intellectual disability.

- Problems at birth. If a baby has problems during labor and birth, such as not getting enough oxygen, he or she may have developmental disability due to brain damage.

- Exposure to certain types of disease or toxins. Diseases like whooping cough, measles, or meningitis can cause intellectual disability if medical care is delayed or inadequate. Exposure to poisons like lead or mercury may also affect mental ability.

- Iodine deficiency, affecting approximately 2 billion people worldwide, is the leading preventable cause of intellectual disability in areas of the developing world where iodine deficiency is endemic. Iodine deficiency also causes goiter, an enlargement of the thyroid gland. More common than full-fledged cretinism, as intellectual disability caused by severe iodine deficiency is called, is mild impairment of intelligence. Certain areas of the world due to natural deficiency and governmental inaction are severely affected. India is the most outstanding, with 500 million suffering from deficiency, 54 million from goiter, and 2 million from cretinism. Among other nations affected by iodine deficiency, China and Kazakhstan have instituted widespread iodization programs, whereas, as of 2006, Russia had not.

- Malnutrition is a common cause of reduced intelligence in parts of the world affected by famine, such as Ethiopia.

- Absence of the arcuate fasciculus.