Loss of language and skills related to social interaction and self-care are serious. The affected children face ongoing disabilities in certain areas and require long term care. Treatment of CDD involves both behavior therapy, environmental therapy and medications.

- Behavior therapy: The main aim of Applied Behavior Analysis (ABA) is to systematically teach the child to relearn language, self-care and social skills. The treatment programs designed in this respect "use a system of rewards to reinforce desirable behaviors and discourage problem behavior." ABA programs may be designed by a board-certified specialist in behavior analysis called a "BCBA" (Board Certified Behavior Analyst), but ABA is also widely used by a number of other health care personnel from different fields like psychologists, speech therapists, physical therapists and occupational therapists with differing levels of expertise. Parents, teachers and caregivers are instructed to use these behavior therapy methods at all times.

- Environmental Therapy: Sensory Enrichment Therapy uses enrichment of the sensory experience to improve symptoms in autism, many of which are common to CDD.

- Medications: There are no medications available to directly treat CDD. Antipsychotic medications are used to treat severe behavior problems like aggressive stance and repetitive behavior patterns. Anticonvulsant medications are used to control seizures.

No medications directly treat the core symptoms of AS. Although research into the efficacy of pharmaceutical intervention for AS is limited, it is essential to diagnose and treat comorbid conditions. Deficits in self-identifying emotions or in observing effects of one's behavior on others can make it difficult for individuals with AS to see why medication may be appropriate. Medication can be effective in combination with behavioral interventions and environmental accommodations in treating comorbid symptoms such as anxiety disorder, major depressive disorder, inattention and aggression. The atypical antipsychotic medications risperidone and olanzapine have been shown to reduce the associated symptoms of AS; risperidone can reduce repetitive and self-injurious behaviors, aggressive outbursts and impulsivity, and improve stereotypical patterns of behavior and social relatedness. The selective serotonin reuptake inhibitors (SSRIs) fluoxetine, fluvoxamine, and sertraline have been effective in treating restricted and repetitive interests and behaviors.

Care must be taken with medications, as side effects may be more common and harder to evaluate in individuals with AS, and tests of drugs' effectiveness against comorbid conditions routinely exclude individuals from the autism spectrum. Abnormalities in metabolism, cardiac conduction times, and an increased risk of type 2 diabetes have been raised as concerns with these medications, along with serious long-term neurological side effects. SSRIs can lead to manifestations of behavioral activation such as increased impulsivity, aggression, and sleep disturbance. Weight gain and fatigue are commonly reported side effects of risperidone, which may also lead to increased risk for extrapyramidal symptoms such as restlessness and dystonia and increased serum prolactin levels. Sedation and weight gain are more common with olanzapine, which has also been linked with diabetes. Sedative side-effects in school-age children have ramifications for classroom learning. Individuals with AS may be unable to identify and communicate their internal moods and emotions or to tolerate side effects that for most people would not be problematic.

There is no known cure for autism, although those with Asperger syndrome and those who have autism and require little-to-no support are more likely to experience a lessening of symptoms over time. The main goals of treatment are to lessen associated deficits and family distress, and to increase quality of life and functional independence. In general, higher IQs are correlated with greater responsiveness to treatment and improved treatment outcomes. Although evidence-based interventions for autistic children vary in their methods, many adopt a psychoeducational approach to enhancing cognitive, communication, and social skills while minimizing problem behaviors. It has been argued that no single treatment is best and treatment is typically tailored to the child's needs.

Intensive, sustained special education programs and behavior therapy early in life can help children acquire self-care, social, and job skills. Available approaches include applied behavior analysis, developmental models, structured teaching, speech and language therapy, social skills therapy, and occupational therapy. Among these approaches, interventions either treat autistic features comprehensively, or focus treatment on a specific area of deficit. Generally, when educating those with autism, specific tactics may be used to effectively relay information to these individuals. Using as much social interaction as possible is key in targeting the inhibition autistic individuals experience concerning person-to-person contact. Additionally, research has shown that employing semantic groupings, which involves assigning words to typical conceptual categories, can be benevficial in fostering learning.

There has been increasing attention to the development of evidence-based interventions for young children with ASD. Two theoretical frameworks outlined for early childhood intervention include applied behavioral analysis (ABA) and the developmental social-pragmatic model (DSP). Although ABA therapy has a strong evidence base, particularly in regard to early intensive home-based therapy. ABA's effectiveness may be limited by diagnostic severity and IQ of the person affected by ASD. The Journal of Clinical Child and Adolescent Psychology has deemed two early childhood interventions as “well-established”: individual comprehensive ABA, and focused teacher-implemented ABA combined with DSP.

Another evidence-based intervention that has demonstrated efficacy is a parent training model, which teaches parents how to implement various ABA and DSP techniques themselves. Various DSP programs have been developed to explicitly deliver intervention systems through at-home parent implementation.

A multitude of unresearched alternative therapies have also been implemented. Many have resulted in harm to autistic people and should not be employed unless proven to be safe.

In October 2015, the American Academy of Pediatrics (AAP) proposed new evidence-based recommendations for early interventions in ASD for children under 3. These recommendations emphasize early involvement with both developmental and behavioral methods, support by and for parents and caregivers, and a focus on both the core and associated symptoms of ASD.

There is no cure for ASD and proper treatment depends on the case and what is most struggled with. Autism spectrum disorder is like many other disorders where when diagnosed early, can be better treated. Different types of therapy are helpful such as music therapy and physical therapy. Other treatments include auditory training, discrete trial training, facilitated communication, and sensory integration therapy.

There is no known "cure" for PDD-NOS, but there are interventions that can have a positive influence. Early and intensive implementation of evidence-based practices and interventions are generally believed to improve outcomes. Most of these are individualized special education strategies rather than medical or pharmaceutical treatment; the best outcomes are achieved when a team approach among supporting individuals is utilized.

Some of the more common therapies and services include:

- Visual and environmental supports, visual schedules

- Applied behavior analysis

- Discrete trial instruction (part of applied behavior analysis)

- Social stories and comic strip conversations

- Physical and occupational therapy

The main goals when treating children with autism are to lessen associated deficits and family distress, and to increase quality of life and functional independence. In general, higher IQs are correlated with greater responsiveness to treatment and improved treatment outcomes. No single treatment is best and treatment is typically tailored to the child's needs. Families and the educational system are the main resources for treatment. Studies of interventions have methodological problems that prevent definitive conclusions about efficacy, however the development of evidence-based interventions has advanced in recent years. Although many psychosocial interventions have some positive evidence, suggesting that some form of treatment is preferable to no treatment, the methodological quality of systematic reviews of these studies has generally been poor, their clinical results are mostly tentative, and there is little evidence for the relative effectiveness of treatment options. Intensive, sustained special education programs and behavior therapy early in life can help children acquire self-care, social, and job skills, and often improve functioning and decrease symptom severity and maladaptive behaviors; claims that intervention by around age three years is crucial are not substantiated. Available approaches include applied behavior analysis (ABA), developmental models, structured teaching, speech and language therapy, social skills therapy, and occupational therapy. Among these approaches, interventions either treat autistic features comprehensively, or focalize treatment on a specific area of deficit. There is some evidence that early intensive behavioral intervention (EIBI), an early intervention model based on ABA for 20 to 40 hours a week for multiple years, is an effective treatment for some children with ASD. Two theoretical frameworks outlined for early childhood intervention include applied behavioral analysis (ABA) and developmental social pragmatic models (DSP). One interventional strategy utilizes a parent training model, which teaches parents how to implement various ABA and DSP techniques, allowing for parents to disseminate interventions themselves. Various DSP programs have been developed to explicitly deliver intervention systems through at-home parent implementation. Despite the recent development of parent training models, these interventions have demonstrated effectiveness in numerous studies, being evaluated as a probable efficacious mode of treatment.

Many medications are used to treat ASD symptoms that interfere with integrating a child into home or school when behavioral treatment fails. More than half of US children diagnosed with ASD are prescribed psychoactive drugs or anticonvulsants, with the most common drug classes being antidepressants, stimulants, and antipsychotics. Antipsychotics, such as risperidone and aripiprazole, have been found to be useful for treating irritability, repetitive behavior, and sleeplessness that often occurs with autism, however their side effects must be weighed against their potential benefits, and people with autism may respond atypically. There is scant reliable research about the effectiveness or safety of drug treatments for adolescents and adults with ASD. No known medication relieves autism's core symptoms of social and communication impairments. Experiments in mice have reversed or reduced some symptoms related to autism by replacing or modulating gene function, suggesting the possibility of targeting therapies to specific rare mutations known to cause autism.

The ideal treatment for AS coordinates therapies that address core symptoms of the disorder, including poor communication skills and obsessive or repetitive routines. While most professionals agree that the earlier the intervention, the better, there is no single best treatment package. AS treatment resembles that of other high-functioning ASDs, except that it takes into account the linguistic capabilities, verbal strengths, and nonverbal vulnerabilities of individuals with AS. A typical program generally includes:

- A positive behavior support procedure includes training and support of parents and school faculty in behavior management strategies to use in the home and school;

- An applied behavior analysis (ABA) technique called social skills training for more effective interpersonal interactions;

- Cognitive behavioral therapy to improve stress management relating to anxiety or explosive emotions and to cut back on obsessive interests and repetitive routines;

- Medication, for coexisting conditions such as major depressive disorder and anxiety disorder;

- Occupational or physical therapy to assist with poor sensory processing and motor coordination;

- Social communication intervention, which is specialized speech therapy to help with the pragmatics of the give and take of normal conversation.

Of the many studies on behavior-based early intervention programs, most are case reports of up to five participants and typically examine a few problem behaviors such as self-injury, aggression, noncompliance, stereotypies, or spontaneous language; unintended side effects are largely ignored. Despite the popularity of social skills training, its effectiveness is not firmly established. A randomized controlled study of a model for training parents in problem behaviors in their children with AS showed that parents attending a one-day workshop or six individual lessons reported fewer behavioral problems, while parents receiving the individual lessons reported less intense behavioral problems in their AS children. Vocational training is important to teach job interview etiquette and workplace behavior to older children and adults with AS, and organization software and personal data assistants can improve the work and life management of people with AS.

Treatments for HFA address individual symptoms, rather than the condition as a whole. For instance, to treat anxiety, which is often associated with HFA, the main treatment is cognitive behavior therapy. While this is the tested and approved treatment for anxiety, it does not quite meet the needs associated with the symptoms of HFA. There is very little discussion of the parent's role in anxiety intervention for children and teenagers. A revised version of cognitive behavior therapy has parents and teachers acting in a role as social coaches to help the children or young adults cope with the issues they are facing. There have been several trials proving that the involvement of parents in the lives of the children affected with anxiety associated with HFA is important.

No single intervention exists to aid individuals with high-functioning autism. However, there are proactive strategies, such as self care and self-management, designed to maintain or change behavior to make living with high functioning autism easier. Self-management strategies aim to provide skills necessary to self-regulate behavior, leading to greater levels of independence. Improving self-management skills allows the individual to be more self-reliant rather than having to rely on an external source for supervision or control. Self-monitoring is a framework, not a rigid structure, designed to encourage independence and self-control. Self-monitoring is not for everyone. It requires the attention and dedication of the individual with high-functioning autism as well as the individual overseeing the progress.

A framework for self-monitoring is provided below

- Identify positive target behaviors

- Establish an alternative behavior that is positive/constructive

- Establish a self-recording sheet

- Individuals can make sure to stay on track with intended goals

- Set goals and keep them

The goal of self-monitoring is to enforce self-monitoring independently without prompting.

Treatment of ADHD often includes a combination of psychological, behavioural, pharmaceutical and educational advice and interventions.

Medications commonly used in the treatment of ADHD are primarily stimulants such as methylphenidate and lisdexamphetamine and non-stimulants such as atomoxetine.

SSRI antidepressants may be unhelpful, and could worsen symptoms of ADHD.

However ADHD is often misdiagnosed as depression, particularly when no hyperactivity is present.

Treatment is usually carried out by speech and language therapists/pathologists, who use a wide range of techniques to stimulate language learning. In the past, there was a vogue for drilling children in grammatical exercises, using imitation and elicitation, but such methods fell into disuse when it became apparent that there was little generalisation to everyday situations. Contemporary approaches to enhancing development of language structure, for younger children at least, are more likely to adopt 'milieu' methods, in which the intervention is interwoven into natural episodes of communication, and the therapist builds on the child's utterances, rather than dictating what will be talked about. Interventions for older children, may be more explicit, telling the children what areas are being targeted and giving explanations regarding the rules and structures they are learning, often with visual supports.

In addition, there has been a move away from a focus solely on grammar and phonology toward interventions that develop children's social use of language, often working in small groups that may include typically developing as well as language-impaired peers.

Another way in contemporary remediation differ from the past is that parents are more likely to be directly involved, but this approach is largely used with preschool children, rather than those whose problems persist into school age.,

For school-aged children, teachers are increasingly involved in intervention, either in collaboration with speech and language therapists/pathologists, or as the main agents of delivery of the intervention. Evidence for the benefits of a collaborative approach is emerging, but the benefits of asking education staff to be the main deliverers of SLT intervention (the “consultative” approach) are unclear. When SLT intervention is delivered indirectly by trained SLT assistants, however, there are indications that this can be effective.

A radically different approach has been developed by Tallal and colleagues, who devised a computer-based intervention, FastForWord, that involves prolonged and intensive training on specific components of language and auditory processing. The theory underlying FastForword maintains that language difficulties are caused by a failure to make fine-grained auditory discriminations in the temporal dimension, and the computerised training materials are designed to sharpen perceptual acuity. However, a systematic review of clinical trials assessing FastForWord reported no significant gains relative to a control group.

In this field, Randomized controlled trial methodology has not been widely used, and this makes it difficult to assess clinical efficacy with confidence. Children's language will tend to improve over time, and without controlled studies, it can be hard to know how much of observed change is down to a specific treatment. There is, however, increasing evidence that direct 1:1 intervention with an SLT/P can be effective for improving vocabulary and expressive language. There have been few studies of interventions that target receptive language, though some positive outcomes have been reported.,

Medications are used to address certain behavioral problems; therapy for children with PDD should be specialized according to the child's specific needs.

Some children with PDD benefit from specialized classrooms in which the class size is small and instruction is given on a one-to-one basis. Others function well in standard special education classes or regular classes with support. Early intervention, including appropriate and specialized educational programs and support services, play a critical role in improving the outcome of individuals with PDD.

Cognitive-behavioural therapy (CBT) is a frequently suggested treatment for executive dysfunction, but has shown limited effectiveness. However, a study of CBT in a group rehabilitation setting showed a significant increase in positive treatment outcome compared with individual therapy. Patients' self-reported symptoms on 16 different ADHD/executive-related items were reduced following the treatment period.

Children who demonstrate deficiencies early in their speech and language development are at risk for continued speech and language issues throughout later childhood. Similarly, even if these speech and language problems have been resolved, children with early language delay are more at risk for difficulties in phonological awareness, reading, and writing throughout their lives. Children with mixed receptive-expressive language disorder are often likely to have long-term implications for language development, literacy, behavior, social development, and even mental health problems. If suspected of having a mixed receptive-expressive language disorder, treatment is available from a speech therapist or pathologist. Most treatments are short term, and rely upon accommodations made within the environment, in order to minimize interfering with work or school. Programs that involve intervention planning that link verbal short term memory with visual/non-verbal information may be helpful for these children. In addition, approaches such as parent training for language stimulation and monitoring language through the "watch and see" method are recommended. The watch-and-see technique advises children with mixed receptive-expressive language disorder who come from stable, middle-class homes without any other behavioral, medical, or hearing problems should be vigilantly monitored rather than receive intervention. It is often the case that children do not meet the eligibility criteria established through a comprehensive oral language evaluation; and as a result, are not best suited for early intervention programs and require a different approach besides the "one size fits all" model.

This therapy retains all of the above-mentioned four principles and adds:

- Intensity (person attends therapy daily for a prolonged period of time)

- Developmental approach (therapist adapts to the developmental age of the person, against actual age)

- Test-retest systematic evaluation (all clients are evaluated before and after)

- Process driven vs. activity driven (therapist focuses on the "Just right" emotional connection and the process that reinforces the relationship)

- Parent education (parent education sessions are scheduled into the therapy process)

- "joie de vivre" (happiness of life is therapy's main goal, attained through social participation, self-regulation, and self-esteem)

- Combination of best practice interventions (is often accompanied by integrated listening system therapy, floor time, and electronic media such as Xbox Kinect, Nintendo Wii, Makoto II machine training and others)

The main form of sensory integration therapy is a type of occupational therapy that places a child in a room specifically designed to stimulate and challenge all of the senses.

During the session, the therapist works closely with the child to provide a level of sensory stimulation that the child can cope with, and encourage movement within the room. Sensory integration therapy is driven by four main principles:

- Just right challenge (the child must be able to successfully meet the challenges that are presented through playful activities)

- Adaptive response (the child adapts his behavior with new and useful strategies in response to the challenges presented)

- Active engagement (the child will want to participate because the activities are fun)

- Child directed (the child's preferences are used to initiate therapeutic experiences within the session)

The most effective course of treatment for dysprosody has been speech therapy. The first step in therapy is practice drills which consist of repeating phrases using different prosodic contours, such as pitch, timing, and intonation. Typically a clinician will say either syllables, words, phrases, or nonsensical sentences with certain prosodic contours, and the patient repeats them with the same prosodic contours. Treatment following the lines of the principles of motor learning (PML) was found to improve the production of lexical stress contrasts. Once a patient is able to effectively complete this drill, they can start with more advanced forms of speech therapy. Upon completion of therapy, most people can identify prosodic cues in natural situations, such as normal conversation. Speech therapy has proven most effective for linguistic dysprosody because therapy for emotional dysprosody requires much more effort and is not always successful. One way that people learn to cope with emotional dysprosody is to explicitly state their emotions, rather than relying on prosodic cues.

Over time, there have also been cases of people suffering from dysprosody gaining their native accent back with no course of treatment. Since the part of the brain responsible for dysprosody has not definitely been discovered, nor has the mechanism for the brain processes which cause dysprosody been found, there has not been much treatment for the disease by means of medication.

Since 1997 there has been experimental and clinical practice of psychosocial treatment for adults with executive dysfunction, and particularly attention-deficit/hyperactivity disorder (ADHD). Psychosocial treatment addresses the many facets of executive difficulties, and as the name suggests, covers academic, occupational and social deficits. Fifty percent of medication-based treatments for adults with ADHD are ineffective, so psychosocial treatment—although complicated and difficult to apply—is a promising alternative. Psychosocial treatment facilitates marked improvements in major symptoms of executive dysfunction such as time management, organization and self-esteem.

Current trends in treating the disorder include medications for symptom-based treatments that aim to minimize the secondary characteristics associated with the disorder. If an individual is diagnosed with FXS, genetic counseling for testing family members at risk for carrying the full mutation or premutation is a critical first-step. Due to a higher prevalence of FXS in boys, the most commonly used medications are stimulants that target hyperactivity, impulsivity, and attentional problems. For co-morbid disorders with FXS, antidepressants such as selective serotonin reuptake inhibitors (SSRIs) are utilized to treat the underlying anxiety, obsessive-compulsive behaviors, and mood disorders. Following antidepressants, antipsychotics such as Risperdal and Seroquel are used to treat high rates of self-injurious, aggressive and aberrant behaviors in this population (Bailey Jr et al., 2012). Anticonvulsants are another set of pharmacological treatments used to control seizures as well as mood swings in 13%–18% of individuals suffering from FXS. Drugs targeting the mGluR5 (metabotropic glutamate receptors) that are linked with synaptic plasticity are especially beneficial for targeted symptoms of FXS. Lithium is also currently being used in clinical trials with humans, showing significant improvements in behavioral functioning, adaptive behavior, and verbal memory. Alongside pharmacological treatments, environmental influences such as home environment and parental abilities as well as behavioral interventions such as speech therapy, sensory integration, etc. all factor in together to promote adaptive functioning for individuals with FXS.

Current pharmacological treatment centers on managing problem behaviors and psychiatric symptoms associated with FXS. However, as there has been very little research done in this specific population, the evidence to support the use of these medications in individuals with FXS is poor.

ADHD, which affects the majority of boys and 30% of girls with FXS, is frequently treated using stimulants. However, the use of stimulants in the fragile X population is associated with a greater frequency of adverse events including increased anxiety, irritability and mood lability. Anxiety, as well as mood and obsessive-compulsive symptoms, may be treated using SSRIs, although these can also aggravate hyperactivity and cause disinhibited behavior. Atypical antipsychotics can be used to stabilise mood and control aggression, especially in those with comorbid ASD. However, monitoring is required for metabolic side effects including weight gain and diabetes, as well as movement disorders related to extrapyramidal side effects such as tardive dyskinesia. Individuals with coexisting seizure disorder may require treatment with anticonvulsants.

Intervention is usually carried out by speech and language therapists, who use a wide range of techniques to stimulate language learning. In the past, there was a vogue for drilling children in grammatical exercises, using imitation and elicitation methods, but such methods fell into disuse when it became apparent that there was little generalisation to everyday situations. Contemporary approaches to enhancing development of language structure are more likely to adopt 'milieu' methods, in which the intervention is interwoven into natural episodes of communication, and the therapist builds on the child's utterances, rather than dictating what will be talked about. In addition, there has been a move away from a focus solely on grammar and phonology toward interventions that develop children's social use of language, often working in small groups that may include typically developing as well as language-impaired peers.

Another way in which modern approaches to remediation differ from the past is that parents are more likely to be directly involved, particularly with preschool children.

A radically different approach has been developed by Tallal and colleagues, who have devised a computer-based intervention, Fast Forword, that involves prolonged and intensive training on specific components of language and auditory processing. The theory underlying this approach maintains that language difficulties are caused by a failure to make fine-grained auditory discriminations in the temporal dimension, and the computerised training materials are designed to sharpen perceptual acuity.

For all these types of intervention, there are few adequately controlled trials that allow one to assess clinical efficacy. In general, where studies have been done, results have been disappointing, though some more positive outcomes have been reported. In 2010, a systematic review of clinical trials assessing the FastForword approach was published, and reported no significant gains relative to a control group.

Speech and language therapy is typically the primary treatment for individuals with aphasia. The goal of speech and language therapy is to increase the person’s communication abilities to a level functional for daily life. Goals are chosen based on collaboration between speech language pathologists, patients, and their family/caregivers. Goals should be individualized based on the person’s aphasia symptoms and communicative needs. In 2016, Wallace et al. found the following outcomes were commonly prioritized in therapy: communication, life participation, physical and emotional well-being, normalcy, and health and support services. However, available research is inconclusive about which specific approach to speech and language therapy is most effective in treating global aphasia.

Therapy can be either group or individual. Group therapies that integrate the use of visual aids allow for enhanced social and communication-skill development. Group therapy sessions typically revolve around simple, preplanned activities or games, and aim to facilitate social communication.

One particular therapy designed specifically for treatment of aphasia is Visual Action Therapy (VAT). VAT is a non-verbal gestural output program with 3 phases and 30 total steps. The program teaches unilateral gestures as symbolic representations of real life objects. Research on the effectiveness of VAT is limited and inconclusive.

One important therapy technique includes teaching family members and caregivers strategies for more effectively communicating with their loved ones. Research offers such strategies including, simplifying sentences and using common words, gaining the person's attention before speaking, using pointing and visual cues, allowing for adequate response time, and creating a quiet environment free of distractions.

Another approach to speech and language treatment is constraint-induced language therapy (CILT). CILT involves teaching the patient to use speech in small segments but avoid using gestures and familiar words . The speech language pathologist provides positive feedback throughout and ignores any mistakes made by the patient. The intensity with which this treatment is provided has been debated in the literature. One study, performed in 2015, compared the outcomes of patients with aphasia who received CILT for either 30 hours total over 2 weeks or 30 hours distributed over 10 weeks. Results showed that both groups made significant speech and language improvements. Overall, CILT is an effective treatment at a variety of intensities.

Research supporting the efficacy of pharmacological treatments for aphasia is limited. To date, no large scale clinical trials have proven benefits of pharmacological treatment.

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".

There is currently no specific treatment for megalencephaly, however periodic head measurements may be assessed to determine the rate of brain growth.

Those individuals who develop neurological disorders may be prescribed anti-epileptic drugs for seizures. Studies have shown that reducing epilepsy can increase cell apoptosis and reduce the proliferation of neurons that ultimately leads to brain overgrowth.

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.

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.