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.

Dyslexia is thought to have two types of cause, one related to language processing and another to visual processing. It is considered a cognitive disorder, not a problem with intelligence. However, emotional problems often arise because of it. Some published definitions are purely descriptive, whereas others propose causes. The latter usually cover a variety of reading skills and deficits, and difficulties with distinct causes rather than a single condition. The National Institute of Neurological Disorders and Stroke definition describes dyslexia as "difficulty with phonological processing (the manipulation of sounds), spelling, and/or rapid visual-verbal responding". The British Dyslexia Association definition describes dyslexia as "a learning difficulty that primarily affects the skills involved in accurate and fluent word reading and spelling" and is characterized by "difficulties in phonological awareness, verbal memory and verbal processing speed".

Acquired dyslexia or alexia may be caused by brain damage due to stroke or atrophy. Forms of alexia include pure alexia, surface dyslexia, semantic dyslexia, phonological dyslexia, and deep dyslexia.

Dyscalculia is thought to be present in 3–6% of the general population, but estimates by country and sample vary somewhat. Many studies have found prevalence rates by gender to be equivalent. Those that find gender difference in prevalence rates often find dyscalculia higher in females, but some few studies have found prevalence rates higher in males.

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.

It has long been noted that males are more affected by DLD than females, with a sex ratio of affected males: females around 3 or 4:1 However, the sex difference is much less striking in epidemiological samples, suggesting that similar problems may exist in females but are less likely to be detected. The reason for the sex difference is not well understood.

Poor motor skills are commonly found in children with DLD.

Brain scans do not usually reveal any obvious abnormalities in children with DLD, although quantitative comparisons have found differences in brain size or relative proportions of white or grey matter in specific regions. In some cases, unusual brain gyri are found. To date, no consistent 'neural signature' for DLD has been found, although some studies have noted evidence for involvement of subcortical systems. Differences in the brains of children with DLD vs typically developing children are subtle and may overlap with atypical patterns seen in other neurodevelopmental disorders.

Dyscalculia is difficulty in learning or comprehending arithmetic, such as difficulty in understanding numbers, learning how to manipulate numbers, and learning facts in mathematics. It is generally seen as a specific developmental disorder.

Dyscalculia can occur in people from across the whole IQ range – often higher than average – along with difficulties with time, measurement, and spatial reasoning. Estimates of the prevalence of dyscalculia range between 3 and 6% of the population. In 2004, it was reported that a quarter of children with dyscalculia had ADHD.

In 2015, it was established that 11% of children with dyscalculia also have ADHD. Dyscalculia has also been associated with people who have Turner syndrome and people who have spina bifida.

Mathematical disabilities can occur as the result of some types of brain injury, in which case the proper term, acalculia, is to distinguish it from dyscalculia which is of innate, genetic or developmental origin.

It is now generally accepted that SLI is a strongly genetic disorder. The best evidence comes from studies of twins. 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, seen almost exclusively 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 SLI in identical twins, indicating that environmental factors affect the course of disorder, but it is unusual to find a child with SLI who has an identical twin with normal language.

SLI is not usually caused by a mutation in a single gene. Current evidence suggests that there are many different genes that can influence language learning, and SLI results when a child inherits a particularly detrimental combination of risk factors, each of which may have only a small effect. It has been hypothesized, however, that a mutation of the FOXP2 gene may have an influence on the development on SLI to a certain degree, as it regulates genes pertinent to neural pathways related to language.

Only a handful of non-genetic factors have been found selectively to impact on language development in children. Later-born children in large families are at greater risk than earlier born.

Overall, genetic mutation, hereditary influences, and environmental factors may all have a role in the development and manifestation of SLI. It is important, therefore, to not associate the development to a single factor, but recognize that it is oftentimes the result of complex interactions between any or all of these factors.

Epidemiological surveys, in the US and Canada, estimated the prevalence of SLI in 5-year-olds at around 7 percent. However, neither study adopted the stringent 'discrepancy' criteria of the Diagnostic and Statistical Manual of Mental Disorders or ICD-10; SLI was diagnosed if the child scored below cut-off on standardized language tests, but had a nonverbal IQ of 90 or above and no other exclusionary criteria.

Surface dyslexia is a type of dyslexia, or reading disorder. According to Marshall & Newcombe's (1973) and McCarthy & Warrington's study (1990), patients with this kind of disorder cannot recognize a word as a whole due to the damage of the left parietal or temporal lobe. Individuals with surface dyslexia are unable to recognize a word as a whole word and retrieve its pronunciation from memory. Rather, individuals with surface dyslexia rely on pronunciation rules. Thus, patients with this particular type of reading disorder read non-words fluently, like "yatchet", but struggle with words that defy pronunciation rules (i.e. exception words). For example, a patient with surface dyslexia can correctly read regular words like "mint", but will err when presented a word that disobeys typical pronunciation rules, like "pint". Often, semantic knowledge is preserved in individuals with surface dyslexia.

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.

A reading disability is a condition in which a sufferer displays difficulty reading resulting primarily from neurological factors. Developmental Dyslexia, Alexia (acquired dyslexia), and Hyperlexia (word-reading ability well above normal for age and IQ).

National Institute of Neurological Disorders and Stroke defines reading disability or dyslexia as follows: "Dyslexia is a brain-based type of learning disability that specifically impairs a person's ability to read. These individuals typically read at levels significantly lower than expected despite having normal intelligence. Although the disorder varies from person to person, common characteristics among people with dyslexia are difficulty with spelling, phonological processing (the manipulation of sounds), and/or rapid visual-verbal responding. In adults, dyslexia usually occurs after a brain injury or in the context of dementia. It can also be inherited in some families, and recent studies have identified a number of genes that may predispose an individual to developing dyslexia."

The NINDS definition is not in keeping with the bulk of scientific studies that conclude that there is no evidence to suggest that dyslexia and intelligence are related. The Rose Review 2009 Definition is more in keeping with modern research and debunked discrepancy model of dyslexia diagnosis:

- Dyslexia is a learning difficulty that primarily affects the skills involved in accurate and fluent word reading and spelling.

- Characteristic features of dyslexia are difficulties in phonological awareness, verbal memory and verbal processing speed.

- Dyslexia occurs across the range of intellectual abilities.

- It is best thought of as a continuum, not a distinct category, and there are no clear cut-off points.

- Co-occurring difficulties may be seen in aspects of language, motor co-ordination, mental calculation, concentration and personal organisation, but these are not, by themselves, markers of dyslexia.

- A good indication of the severity and persistence of dyslexic difficulties can be gained by examining how the individual responds or has responded to well founded intervention.

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.

Deep dyslexia is a form of dyslexia that disrupts reading processes. Deep dyslexia may occur as a result of a head injury, stroke, disease, or operation. This injury results in the occurrence of semantic errors during reading and the impairment of nonword reading.

The term dyslexia comes from the Greek words 'dys' meaning 'impaired', and 'lexis' meaning 'word' and is used to describe disorders of language concerning reading and spelling.

Numerous models and hypotheses have been proposed in attempt to explain the broad range of symptoms experienced by deep dyslexics, but a definite consensus has yet to be reached. The proposed models and hypotheses have helped in treatment of some suffering patients, but only with certain specific symptoms. Additionally, the recovery seen is not experienced equally in all patients.

Learning disability is a classification that includes several areas of functioning in which a person has difficulty learning in a typical manner, usually caused by an unknown factor or factors. Given the "difficulty learning in a typical manner", this does not exclude the ability to learn in a different manner. Therefore, some people can be more accurately described as having a "Learning Difference", thus avoiding any misconception of being disabled with a lack of ability to learn and possible negative stereotyping.

In the UK, the term "learning disability" generally refers to an intellectual disability, while difficulties such as dyslexia and dyspraxia are usually referred to as "learning difficulties".

While "learning disability, learning disorder" and "learning difficulty" are often used interchangeably, they differ in many ways. Disorder refers to significant learning problems in an academic area. These problems, however, are not enough to warrant an official diagnosis. Learning disability, on the other hand, is an official clinical diagnosis, whereby the individual meets certain criteria, as determined by a professional (psychologist, pediatrician, etc.). The difference is in degree, frequency, and intensity of reported symptoms and problems, and thus the two should not be confused. When the term "learning disorder" is used, it describes a group of disorders characterized by inadequate development of specific academic, language, and speech skills. Types of learning disorders include reading (dyslexia), mathematics (dyscalculia) and writing (dysgraphia).

The unknown factor is the disorder that affects the brain's ability to receive and process information. This disorder can make it problematic for a person to learn as quickly or in the same way as someone who is not affected by a learning disability. People with a learning disability have trouble performing specific types of skills or completing tasks if left to figure things out by themselves or if taught in conventional ways.

Individuals with learning disabilities can face unique challenges that are often pervasive throughout the lifespan. Depending on the type and severity of the disability, interventions, and current technologies may be used to help the individual learn strategies that will foster future success. Some interventions can be quite simplistic, while others are intricate and complex. Current technologies may require student training to be effective classroom supports. Teachers, parents, and schools can create plans together that tailor intervention and accommodations to aid the individuals in successfully becoming independent learners. School psychologists and other qualified professionals quite often help design the intervention and coordinate the execution of the intervention with teachers and parents.

In 2006, the U.S. Department of Education indicated that more than 1.4 million students were served in the public schools' special education programs under the speech or language impairment category of IDEA 2004. This estimate does not include children who have speech/language problems secondary to other conditions such as deafness; this means that if all cases of speech or language impairments were included in the estimates, this category of impairment would be the largest. Another source has estimated that communication disorders—a larger category, which also includes hearing disorders—affect one of every 10 people in the United States.

ASHA has cited that 24.1% of children in school in the fall of 2003 received services for speech or language disorders—this amounts to a total of 1,460,583 children between 3 –21 years of age. Again, this estimate does not include children who have speech/language problems secondary to other conditions. Additional ASHA prevalence figures have suggested the following:

- Stuttering affects approximately 4% to 5% of children between the ages of 2 and 4.

- ASHA has indicated that in 2006:

- Almost 69% of SLPs served individuals with fluency problems.

- Almost 29% of SLPs served individuals with voice or resonance disorders.

- Approximately 61% of speech-language pathologists in schools indicated that they served individuals with SLI

- Almost 91% of SLPs in schools indicated that they servedindividuals with phonological/articulation disorder

- Estimates for language difficulty in preschool children range from 2% to 19%.

- Specific Language Impairment (SLI) is extremely common in children, and affects about 7% of the childhood population.

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.

Developmental coordination disorder is a lifelong neurological condition that is more common in males than in females, with a ratio of approximately four males to every female. The exact proportion of people with the disorder is unknown since the disorder can be difficult to detect due to a lack of specific laboratory tests, thus making diagnosis of the condition one of elimination of all other possible causes/diseases. Approximately 5–6% of children are affected by this condition.

Phonological dyslexia is a reading disability that is a form of alexia (acquired dyslexia), resulting from brain injury, stroke, or progressive illness and that affects previously acquired reading abilities. The major distinguishing symptom of acquired phonological dyslexia is that a selective impairment of the ability to read pronounceable non-words occurs although the ability to read familiar words is not affected. It has also been found that the ability to read non-words can be improved if the non-words belong to a family of pseudohomophones.

Intellectual disability affects about 2–3% of the general population. 75–90% of the affected people have mild intellectual disability. Non-syndromic or idiopathic ID accounts for 30–50% of cases. About a quarter of cases are caused by a genetic disorder. Cases of unknown cause affect about 95 million people as of 2013.

Semantic dyslexia is, as the name suggests, a subtype of the group of cognitive disorders known as alexia (acquired dyslexia). Those who suffer from semantic dyslexia are unable to properly attach words to their meanings in reading and/or speech. When confronted with the word "diamond", they may understand it as "sapphire", "shiny" or "diamonds"; when asking for a bus ticket, they may ask for some paper or simply "a thing".

Semantic dementia (SD) is a degenerative disease characterized by atrophy of anterior temporal regions (the primary auditory cortex; process auditory information) and progressive loss of semantic memory. SD patients often present with surface dyslexia, a relatively selective impairment in reading low-frequency words with exceptional or atypical spelling-to-sound correspondences.

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.

Hyperlexia is a syndrome characterized by a child's precocious ability to read. It was initially identified by Norman E. Silberberg and Margaret C. Silberberg (1967), who defined it as the precocious ability to read words without prior training in learning to read, typically before the age of 5. They indicated that children with hyperlexia have a significantly higher word-decoding ability than their reading comprehension levels. Children with hyperlexia also present with an intense fascination for written material at a very early age.

Hyperlexic children are characterized by having average or above-average IQs, and word-reading ability well above what would be expected given their age. First named and scientifically described in 1967 (Silverberg and Silverberg), it can be viewed as a superability in which word recognition ability goes far above expected levels of skill. Some hyperlexics, however, have trouble understanding speech. Some experts believe that most, or perhaps all children with hyperlexia, lie on the autism spectrum. However, one expert, Darold Treffert, proposes that hyperlexia has subtypes, only some of which overlap with autism. Between 5 and 20 percent of autistic children have been estimated to be hyperlexic.

Hyperlexic children are often fascinated by letters or numbers. They are extremely good at decoding language and thus often become very early readers. Some hyperlexic children learn to spell long words (such as "elephant") before they are two years old and learn to read whole sentences before they turn three.

An fMRI study of a single child showed that hyperlexia may be the neurological opposite of dyslexia.