Mast cell activation syndrome ( MCAS ) is a term referring to one of two types of mast cell activation disorder ( MCAD ); the other type is idiopathic MCAD. MCAS is an immunological condition in which mast cells inappropriately and excessively release chemical mediators, resulting in a range of chronic symptoms, sometimes including anaphylaxis or near-anaphylaxis attacks. Primary symptoms include cardiovascular, dermatological, gastrointestinal, neurological and respiratory problems.

MCAS is an umbrella term that describes a set of symptoms; it is not a specific diagnosis. Multiple diagnostic schemes for MCAS have been proposed. MCAS has often been misdiagnosed, especially as medical professionals and patients don’t understand that symptoms can wax or wane, and it can be a seemingly slow buildup with symptoms occurring in multiple organ systems before anaphylaxis type episodes; many healthcare providers are not trained to recognize its symptoms nor know much about what to do with it; after all, it was only in 2010 that diagnostic criteria was formalized. ( Full article... )

Echolalia is the unsolicited repetition of vocalizations made by another person (when repeated by the same person, it is called palilalia ). In its profound form it is automatic and effortless. It is one of the echophenomena , closely related to echopraxia , the automatic repetition of movements made by another person; both are "subsets of imitative behavior" whereby sounds or actions are imitated "without explicit awareness". Echolalia may be an immediate reaction to a stimulus or may be delayed.

Echolalia occurs in many cases of autism spectrum disorder and Tourette syndrome . It may also occur in several other neurological conditions such as some forms of dementia or stroke-related aphasia . ( Full article... )

Research in Developmental Disabilities is a bimonthly peer-reviewed medical journal covering developmental disabilities . It was formed in 1987 by the merger of Analysis and Intervention in Developmental Disabilities and Applied Research in Mental Retardation , which were established in 1981 and 1980, respectively. It is published by Elsevier and the editor-in-chief is Dagmara Dimitriou ( UCL Institute of Education ).

In early February of 2015, the journal's founding editor-in-chief Johnny Matson ( Louisiana State University ) was accused of excessively citing his own works and thereby inflating his citation counts . An investigation by Elsevier came to the conclusion that Matson had used his position to have papers published without proper peer review that used assessment batteries developed by himself and sold through a company registered in his wife's name, failing to report this conflict of interest . This eventually led to the retraction of 24 papers across Research in Developmental Disabilities and Research in Autism Spectrum Disorders , a second Elsevier journal edited by Matson . Matson was also criticized for publishing a large number of his own papers, citing his own work, in these journals. Effective March 2015 Elsevier appointed Dagmara Dimitriou as the new editor-in-chief and updated the journal's editorial policies. ( Full article... )

The Journal of Autism and Developmental Disorders is a monthly peer-reviewed medical journal covering research on all aspects of autism spectrum disorders and related developmental disabilities . The journal was established in 1971 as the Journal of Autism and Childhood Schizophrenia , obtaining its current title in 1979. It is published by Springer Science+Business Media and the editor-in-chief is Lynn Kern Koegel ( Stanford University ). ( Full article... )

The Journal of Autism and Developmental Disorders is a monthly peer-reviewed medical journal covering research on all aspects of autism spectrum disorders and related developmental disabilities . The journal was established in 1971 as the Journal of Autism and Childhood Schizophrenia , obtaining its current title in 1979. It is published by Springer Science+Business Media and the editor-in-chief is Lynn Kern Koegel ( Stanford University ). ( Full article... )

Special interests are highly focused interests common in autistic people.

Special interests are more intense than typical interests, such as hobbies, and may take up much of a person's free time. A person with a special interest will often hyperfocus on their special interest for hours, want to learn as much as possible on the topic, collect related items, and incorporate their special interest into play and art.
Some interests are more likely to be seen as special interests if they are particularly unusual, specific, or niche. Autism rights advocates and psychologists say this binary of acceptable "passions" and pathologised "obsessions" is unfair. Terms like circumscribed interests, obsessions, or restricted interests have historically been used to describe special interests, but these terms are discouraged by autism rights advocates. ( Full article... )

The basal ganglia ( BG ) or basal nuclei are a group of subcortical nuclei found in the brains of vertebrates . In humans and other primates , differences exist, primarily in the division of the globus pallidus into external and internal regions, and in the division of the striatum . Positioned at the base of the forebrain and the top of the midbrain , they have strong connections with the cerebral cortex , thalamus , brainstem and other brain areas. The basal ganglia are associated with a variety of functions, including regulating voluntary motor movements , procedural learning , habit formation , conditional learning , eye movements , cognition , and emotion .

The main functional components of the basal ganglia include the striatum , consisting of both the dorsal striatum ( caudate nucleus and putamen ) and the ventral striatum ( nucleus accumbens and olfactory tubercle ), the globus pallidus , the ventral pallidum , the substantia nigra , and the subthalamic nucleus . Each of these components has complex internal anatomical and neurochemical structures. The largest component, the striatum (dorsal and ventral), receives input from various brain areas but only sends output to other components of the basal ganglia. The globus pallidus receives input from the striatum and sends inhibitory output to a number of motor-related areas. The substantia nigra is the source of the striatal input of the neurotransmitter dopamine , which plays an important role in basal ganglia function. The subthalamic nucleus mainly receives input from the striatum and cerebral cortex and projects to the globus pallidus. ( Full article... )

Classic autism , also known as childhood autism , autistic disorder , (early) infantile autism , infantile psychosis , Kanner's autism , Kanner's syndrome , or (formerly) just autism , is a neurodevelopmental condition first described by Leo Kanner in 1943. It is characterized by atypical and impaired development in social interaction and communication as well as restricted, repetitive behaviors, activities, and interests. These symptoms first appear in early childhood and persist throughout life.


It was last recognized as a diagnosis in the DSM-IV and ICD-10 , and has been superseded by autism spectrum disorder in the DSM-5 (2013) and ICD-11 (2022). Globally, classic autism was estimated to affect 24.8 million people . ( Full article... )

Brain: A Journal of Neurology is a peer-reviewed scientific journal of neurology , founded in 1878 by John Charles Bucknill , David Ferrier , James Crichton-Browne and John Hughlings Jackson . It is published by Oxford University Press .

The journal was edited by John Newsom-Davis from 1997 to 2004, Alastair Compston ( Cambridge University ) until 2013, and Dimitri Kullmann (UCL) until 2021. The current editor-in-chief is Masud Husain ( University of Oxford ). ( Full article... )

Intellectual disability ( ID ), also known as general learning disability (in the United Kingdom) and mental retardation , is a generalized neurodevelopmental disorder characterized by significant impairment in intellectual and adaptive functioning that is first apparent during childhood. Children with intellectual disabilities typically have an intelligence quotient (IQ) below 70 and deficits in at least two adaptive behaviors that affect everyday, general living. According to the DSM-5 , intellectual functions include reasoning , problem solving, planning , abstract thinking , judgment, academic learning, and learning from experience. Deficits in these functions must be confirmed by clinical evaluation and individualized standard IQ testing. On the other hand, adaptive behaviors include the social, developmental, and practical skills people learn to perform tasks in their everyday lives. Deficits in adaptive functioning often compromises an individual's independence and ability to meet their social responsibility.

Intellectual disability is subdivided into syndromic intellectual disability, in which intellectual deficits associated with other medical and behavioral signs and symptoms are present, and non-syndromic intellectual disability, in which intellectual deficits appear without other abnormalities. Down syndrome and fragile X syndrome are examples of syndromic intellectual disabilities. ( Full article... )

Self-harm is intentional conduct that is considered harmful to oneself. This is most commonly regarded as direct injury of one's own skin tissues usually without a suicidal intention. Other terms such as cutting , self-injury , and self-mutilation have been used for any self-harming behavior regardless of suicidal intent. Common forms of self-harm include damaging the skin with a sharp object or by scratching, hitting , or burning . The exact bounds of self-harm are imprecise, but generally exclude tissue damage that occurs as an unintended side-effect of eating disorders or substance abuse , as well as societally acceptable body modification such as tattoos and piercings .

Although self-harm is by definition non-suicidal, it may still be life-threatening. People who do self-harm are more likely to die by suicide, and self-harm is found in 40?60% of suicides . Still, only a minority of those who self-harm are suicidal. ( Full article... )

Pathological demand avoidance ( PDA ) or extreme demand avoidance ( EDA ) is a proposed disorder, and proposed sub-type of autism spectrum disorder , defined by characteristics such as a demand avoidance?which is a greater-than-typical refusal to comply with requests or expectations?and extreme efforts to avoid social demands. Any expectation, even routine activities, such as brushing teeth, or highly desired activities, such as getting ready to leave home to visit a playground, can trigger avoidant behavior. If the demand cannot be avoided, a panic attack or a meltdown may ensue. ( Full article... )

Attention deficit hyperactivity disorder ( ADHD ) is a neurodevelopmental disorder characterised by executive dysfunction occasioning symptoms of inattention , hyperactivity, impulsivity and emotional dysregulation that are excessive and pervasive, impairing in multiple contexts, and otherwise age-inappropriate .

ADHD symptoms arise from executive dysfunction , and emotional dysregulation is often considered a core symptom. ADHD represents the extreme lower end of the continuous dimensional trait (bell curve) of executive functioning and self-regulation, which is supported by twin, brain imaging and molecular genetic studies. Difficulties with self-regulation such as time management, inhibition and sustained attention may result in poor professional performance, relationship difficulties and numerous health risks, collectively predisposing to a diminished quality of life and a direct average reduction in life expectancy of 13 years. Although people with ADHD struggle to persist on tasks with temporally delayed consequences, they may be able to maintain an unusually prolonged level of attention for tasks they do find intrinsically interesting or immediately rewarding; this is known as hyperfocus (more colloquially) or perseverative responding. ADHD is associated with other neurodevelopmental and mental disorders as well as some non-psychiatric disorders, which can cause additional impairment, especially in modern society. ( Full article... )

The Journal of Autism and Developmental Disorders is a monthly peer-reviewed medical journal covering research on all aspects of autism spectrum disorders and related developmental disabilities . The journal was established in 1971 as the Journal of Autism and Childhood Schizophrenia , obtaining its current title in 1979. It is published by Springer Science+Business Media and the editor-in-chief is Lynn Kern Koegel ( Stanford University ). ( Full article... )

Depression is a mental state of low mood and aversion to activity. It affects more than 280 million people of all ages (about 3.5% of the global population). Depression affects a person's thoughts, behavior, feelings, and sense of well-being . Depressed people often experience loss of motivation or interest in, or reduced pleasure or joy from, experiences that would normally bring them pleasure or joy.

Depressed mood is a symptom of some mood disorders such as major depressive disorder and dysthymia ; it is a normal temporary reaction to life events, such as the loss of a loved one; and it is also a symptom of some physical diseases and a side effect of some drugs and medical treatments.
It may feature sadness, difficulty in thinking and concentration and a significant increase or decrease in appetite and time spent sleeping. People experiencing depression may have feelings of dejection or hopelessness and may experience suicidal thoughts. It can either be short term or long term. ( Full article... )

Tuberous sclerosis complex ( TSC ) is a rare multisystem autosomal dominant genetic disease that causes non-cancerous tumours to grow in the brain and on other vital organs such as the kidneys , heart , liver , eyes , lungs and skin . A combination of symptoms may include seizures , intellectual disability , developmental delay , behavioral problems, skin abnormalities, lung disease, and kidney disease.

TSC is caused by a mutation of either of two genes , TSC1 and TSC2 , which code for the proteins hamartin and tuberin , respectively, with TSC2 mutations accounting for the majority and tending to cause more severe symptoms. These proteins act as tumor growth suppressors , agents that regulate cell proliferation and differentiation . ( Full article... )

Classification is usually understood to mean the allocation of objects to certain pre-existing classes or categories. This distinguishes it from clustering in which similar objects are grouped together, thereby creating new classes. Examples include a pregnancy test and identifying spam emails.

Classification is a part of many different kinds of activities and studied from many different points of view including philosophy , law , anthropology , biology , taxonomy , cognition , communications , knowledge organization , psychology , statistics , machine learning , librarianship and mathematics . ( Full article... )

The Journal of Autism and Developmental Disorders is a monthly peer-reviewed medical journal covering research on all aspects of autism spectrum disorders and related developmental disabilities . The journal was established in 1971 as the Journal of Autism and Childhood Schizophrenia , obtaining its current title in 1979. It is published by Springer Science+Business Media and the editor-in-chief is Lynn Kern Koegel ( Stanford University ). ( Full article... )

A genetic disorder is a health problem caused by one or more abnormalities in the genome . It can be caused by a mutation in a single gene (monogenic) or multiple genes (polygenic) or by a chromosomal abnormality . Although polygenic disorders are the most common, the term is mostly used when discussing disorders with a single genetic cause, either in a gene or chromosome . The mutation responsible can occur spontaneously before embryonic development (a de novo mutation), or it can be inherited from two parents who are carriers of a faulty gene ( autosomal recessive inheritance) or from a parent with the disorder ( autosomal dominant inheritance). When the genetic disorder is inherited from one or both parents, it is also classified as a hereditary disease . Some disorders are caused by a mutation on the X chromosome and have X-linked inheritance. Very few disorders are inherited on the Y chromosome or mitochondrial DNA (due to their size).

There are well over 6,000 known genetic disorders, and new genetic disorders are constantly being described in medical literature. More than 600 genetic disorders are treatable. Around 1 in 50 people are affected by a known single-gene disorder, while around 1 in 263 are affected by a chromosomal disorder . Around 65% of people have some kind of health problem as a result of congenital genetic mutations. Due to the significantly large number of genetic disorders, approximately 1 in 21 people are affected by a genetic disorder classified as " rare " (usually defined as affecting less than 1 in 2,000 people). Most genetic disorders are rare in themselves. ( Full article... )

Inborn errors of metabolism form a large class of genetic diseases involving congenital disorders of enzyme activities. The majority are due to defects of single genes that code for enzymes that facilitate conversion of various substances ( substrates ) into others ( products ). In most of the disorders, problems arise due to accumulation of substances which are toxic or interfere with normal function, or due to the effects of reduced ability to synthesize essential compounds. Inborn errors of metabolism are often referred to as congenital metabolic diseases or inherited metabolic disorders . Another term used to describe these disorders is "enzymopathies". This term was created following the study of biodynamic enzymology , a science based on the study of the enzymes and their products. Finally, inborn errors of metabolism were studied for the first time by British physician Archibald Garrod (1857?1936), in 1908. He is known for work that prefigured the "one gene-one enzyme" hypothesis , based on his studies on the nature and inheritance of alkaptonuria. His seminal text, Inborn Errors of Metabolism , was published in 1923. ( Full article... )

Insomnia , also known as sleeplessness , is a sleep disorder where people have trouble sleeping . They may have difficulty falling asleep, or staying asleep for as long as desired. Insomnia is typically followed by daytime sleepiness, low energy, irritability , and a depressed mood . It may result in an increased risk of accidents of all kinds as well as problems focusing and learning. Insomnia can be short term, lasting for days or weeks, or long term, lasting more than a month. The concept of the word insomnia has two possibilities: insomnia disorder (ID) and insomnia symptoms, and many abstracts of randomized controlled trials and systematic reviews often underreport on which of these two possibilities the word insomnia refers to.


Insomnia can occur independently or as a result of another problem. Conditions that can result in insomnia include ADHD , psychological stress , chronic pain , heart failure , hyperthyroidism , heartburn , restless leg syndrome , menopause , certain medications , and drugs such as caffeine , nicotine , and alcohol . Other risk factors include working night shifts and sleep apnea . Diagnosis is based on sleep habits and an examination to look for underlying causes. A sleep study may be done to look for underlying sleep disorders. Screening may be done with two questions: "do you experience difficulty sleeping?" and "do you have difficulty falling or staying asleep?" ( Full article... )

Learning disability , learning disorder , or learning difficulty (British English) is a condition in the brain that causes difficulties comprehending or processing information and can be caused by several different 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 possible lack of an ability to learn and possible negative stereotyping. In the United Kingdom, the term "learning disability" generally refers to an intellectual disability , while conditions such as dyslexia and dyspraxia are usually referred to as "learning difficulties".

While learning disability and learning disorder 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 (such as a psychologist, psychiatrist, speech-language pathologist, or paediatrician). The difference is in the 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 ), arithmetic ( dyscalculia ) and writing ( dysgraphia ). ( Full article... )

Schizophrenia is a mental disorder characterized by reoccurring episodes of psychosis that are correlated with a general misperception of reality. Other common signs include hallucinations (typically hearing voices ), delusions (i.e., paranoia ), disorganized thinking and behavior , social withdrawal , and flat or inappropriate affect . Symptoms develop gradually and typically begin during young adulthood and are never resolved. There is no objective diagnostic test; diagnosis is based on observed behavior, a psychiatric history that includes the person's reported experiences, and reports of others familiar with the person. For a diagnosis of schizophrenia, the described symptoms need to have been present for at least six months (according to the DSM-5 ) or one month (according to the ICD-11 ). Many people with schizophrenia have other mental disorders, especially substance use disorders , depressive disorders , anxiety disorders , and obsessive?compulsive disorder .


About 0.3% to 0.7% of people are diagnosed with schizophrenia during their lifetime. In 2017, there were an estimated 1.1 million new cases and in 2022 a total of 24 million cases globally. Males are more often affected and on average have an earlier onset than females. The causes of schizophrenia may include genetic and environmental factors. Genetic factors include a variety of common and rare genetic variants . Possible environmental factors include being raised in a city , childhood adversity, cannabis use during adolescence, infections, the age of a person's mother or father , and poor nutrition during pregnancy . ( Full article... )

Dysautonomia , autonomic failure , or autonomic dysfunction is a condition in which the autonomic nervous system (ANS) does not work properly. This may affect the functioning of the heart , bladder , intestines , sweat glands , pupils , and blood vessels. Dysautonomia has many causes, not all of which may be classified as neuropathic . A number of conditions can feature dysautonomia, such as Parkinson's disease , multiple system atrophy , dementia with Lewy bodies , Ehlers?Danlos syndromes , autoimmune autonomic ganglionopathy and autonomic neuropathy , HIV/AIDS , mitochondrial cytopathy , pure autonomic failure , autism , and postural orthostatic tachycardia syndrome .

Diagnosis is made by functional testing of the ANS, focusing on the affected organ system . Investigations may be performed to identify underlying disease processes that may have led to the development of symptoms or autonomic neuropathy. Symptomatic treatment is available for many symptoms associated with dysautonomia, and some disease processes can be directly treated. Depending on the severity of the dysfunction, dysautonomia can range from being nearly symptomless and transient to disabling and/or life-threatening. ( Full article... )