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Neurodevelopmental disorder | |
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Specialty | Psychiatry, neurology |
Neurodevelopmental disorders are a group of mental conditions affecting the development of the nervous system, which includes the brain and spinal cord. According to the American Psychiatric Association Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, (DSM-5) published in 2013, these conditions generally appear in early childhood, usually before children start school, and can persist into adulthood. [1] The key characteristic of all these disorders is that they negatively impact a person's functioning in one or more domains of life (personal, social, academic, occupational) depending on the disorder and deficits it has caused. All of these disorders and their levels of impairment exist on a spectrum, and affected individuals can experience varying degrees of symptoms and deficits, despite having the same diagnosis. [1] [2]
The DSM-5 classifies neurodevelopmental disorders into six overarching groups: intellectual, communication, autism, attention deficit hyperactivity, motor, and specific learning disorders. [1] Often one disorder is accompanied by another. [2]
Intellectual disability, also known as general learning disability is a disorder that affects the ability to learn, retain, or process information; to think critically or abstractly, and to solve problems. Adaptive behaviour is limited, affecting daily living activities. Global developmental delay is categorized under intellectual disability and is diagnosed when several areas of intellectual functioning are affected. [3]
A communication disorder is any disorder that affects an individual's ability to comprehend, detect, or apply language and speech to engage in dialogue effectively with others. [4] This also encompasses deficiencies in verbal and nonverbal communication styles. [5] The delays and disorders can range from simple sound substitution to the inability to understand or use one's native language. [6]
Autism, also called autism spectrum disorder (ASD) or autism spectrum condition (ASC), is a neurodevelopmental disorder characterized by symptoms of deficient reciprocal social communication and the presence of restricted, repetitive, and inflexible patterns of behavior. While its severity and specific manifestations vary widely across the spectrum, autism generally affects a person's ability to understand and connect with others, as well as their adaptability to everyday situations. Like most developmental disorders, autism exists along a dimension of symptom severity, subjective distress, and functional impairment. A consequence of this dimensionality is substantial variability in the nature and extent of support a person with ASD requires.
A formal diagnosis of ASD requires not merely the presence of ASD symptoms, but symptoms that cause significant impairment in multiple domains of functioning, in addition to being excessive or atypical enough to be developmentally and socioculturally inappropriate. [7] [8]
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 developmentally-inappropriate. [3] [9] [10] [11]
ADHD symptoms arise from executive dysfunction, [20] and emotional dysregulation is often considered a core symptom. [24] Difficulties in self-regulation such as time management, inhibition and sustained attention may cause poor professional performance, relationship difficulties and numerous health risks, [25] [26] collectively predisposing to a diminished quality of life [27] and a direct average reduction in life expectancy of 13 years. [28] [29] ADHD is associated with other neurodevelopmental and mental disorders as well as non-psychiatric disorders, which can cause additional impairment. [11]
Motor disorders including developmental coordination disorder, stereotypic movement disorder, and tic disorders (such as Tourette's syndrome), and apraxia of speech.
Deficits in any area of information processing can manifest in a variety of specific learning disabilities (SLD). 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. [30] In the UK, the term dual diagnosis is often used to refer to co-occurrence of learning difficulties.
There are neurodevelopmental research projects examining potential new classifications of disorders including:
The multitude of neurodevelopmental disorders span a wide range of associated symptoms and severity, resulting in different degrees of mental, emotional, physical, and economic consequences for individuals, and in turn families, social groups, and society. [2]
The development of the nervous system is tightly regulated and timed; it is influenced by both genetic programs and the prenatal environment. Any significant deviation from the normal developmental trajectory early in life can result in missing or abnormal neuronal architecture or connectivity. [36] Because of the temporal and spatial complexity of the developmental trajectory, there are many potential causes of neurodevelopmental disorders that may affect different areas of the nervous system at different times and ages. These range from social deprivation, genetic and metabolic diseases, immune disorders, infectious diseases, nutritional factors, physical trauma, and toxic and prenatal environmental factors. Some neurodevelopmental disorders, such as autism and other pervasive developmental disorders, are considered multifactorial syndromes which have many causes that converge to a more specific neurodevelopmental manifestation. [37] Some deficits may be predicted from observed deviations in the maturation patterns of the infant gut microbiome. [38]
Deprivation from social and emotional care causes severe delays in brain and cognitive development. [39] Studies with children growing up in Romanian orphanages during Nicolae Ceauşescu's regime reveal profound effects of social deprivation and language deprivation on the developing brain. These effects are time-dependent. The longer children stayed in negligent institutional care, the greater the consequences. By contrast, adoption at an early age mitigated some of the effects of earlier institutionalization. [40]
A prominent example of a genetically determined neurodevelopmental disorder is trisomy 21, also known as Down syndrome. This disorder usually results from an extra chromosome 21, [41] although in uncommon instances it is related to other chromosomal abnormalities such as translocation of the genetic material. It is characterized by short stature, epicanthal (eyelid) folds, abnormal fingerprints, and palm prints, heart defects, poor muscle tone (delay of neurological development), and intellectual disabilities (delay of intellectual development). [42]
Less commonly known genetically determined neurodevelopmental disorders include Fragile X syndrome. Fragile X syndrome was first described in 1943 by Martin and Bell, studying persons with family history of sex-linked "mental defects". [43] Rett syndrome, another X-linked disorder, produces severe functional limitations. [44] Williams syndrome is caused by small deletions of genetic material from chromosome 7. [45] The most common recurrent copy number variation disorder is DiGeorge syndrome (22q11.2 deletion syndrome), followed by Prader-Willi syndrome and Angelman syndrome. [46]
Immune reactions during pregnancy, both maternal and of the developing child, may produce neurodevelopmental disorders. One typical immune reaction in infants and children is PANDAS, [47] or Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infection. [48] Another disorder is Sydenham's chorea, which results in more abnormal movements of the body and fewer psychological sequellae. Both are immune reactions against brain tissue that follow infection by Streptococcus bacteria. Susceptibility to these immune diseases may be genetically determined, [49] so sometimes several family members may have one or both of them following an epidemic of Strep infection.[ citation needed ]
Systemic infections can result in neurodevelopmental consequences, when they occur in infancy and childhood of humans, but would not be called a primary neurodevelopmental disorder. For example HIV [50] Infections of the head and brain, like brain abscesses, meningitis or encephalitis have a high risk of causing neurodevelopmental problems and eventually a disorder. For example, measles can progress to subacute sclerosing panencephalitis.
A number of infectious diseases can be transmitted congenitally (either before or at birth), and can cause serious neurodevelopmental problems, as for example the viruses HSV, CMV, rubella (congenital rubella syndrome), Zika virus, or bacteria like Treponema pallidum in congenital syphilis, which may progress to neurosyphilis if it remains untreated. Protozoa like Plasmodium [50] or Toxoplasma which can cause congenital toxoplasmosis with multiple cysts in the brain and other organs, leading to a variety of neurological deficits.
Some cases of schizophrenia may be related to congenital infections, though the majority are of unknown causes. [51]
Metabolic disorders in either the mother or the child can cause neurodevelopmental disorders. Two examples are diabetes mellitus (a multifactorial disorder) and phenylketonuria (an inborn error of metabolism). Many such inherited diseases may directly affect the child's metabolism and neural development [52] but less commonly they can indirectly affect the child during gestation. (See also teratology).
In a child, type 1 diabetes can produce neurodevelopmental damage by the effects of excess or insufficient glucose. The problems continue and may worsen throughout childhood if the diabetes is not well controlled. [53] Type 2 diabetes may be preceded in its onset by impaired cognitive functioning. [54]
A non-diabetic fetus can also be subjected to glucose effects if its mother has undetected gestational diabetes. Maternal diabetes causes excessive birth size, making it harder for the infant to pass through the birth canal without injury or it can directly produce early neurodevelopmental deficits. Usually the neurodevelopmental symptoms will decrease in later childhood. [55]
Phenylketonuria, also known as PKU, can induce neurodevelopmental problems and children with PKU require a strict diet to prevent intellectual disability and other disorders. In the maternal form of PKU, excessive maternal phenylalanine can be absorbed by the fetus even if the fetus has not inherited the disease. This can produce intellectual disability and other disorders. [56] [57]
Nutrition disorders and nutritional deficits may cause neurodevelopmental disorders, such as spina bifida, and the rarely occurring anencephaly, both of which are neural tube defects with malformation and dysfunction of the nervous system and its supporting structures, leading to serious physical disability and emotional sequelae. The most common nutritional cause of neural tube defects is folic acid deficiency in the mother, a B vitamin usually found in fruits, vegetables, whole grains, and milk products. [58] [59] (Neural tube defects are also caused by medications and other environmental causes, many of which interfere with folate metabolism, thus they are considered to have multifactorial causes.) [60] [61] Another deficiency, iodine deficiency, produces a spectrum of neurodevelopmental disorders ranging from mild emotional disturbance to severe intellectual disability. (see also congenital iodine deficiency syndrome). [62]
Excesses in both maternal and infant diets may cause disorders as well, with foods or food supplements proving toxic in large amounts. For instance in 1973 K.L. Jones and D.W. Smith of the University of Washington Medical School in Seattle found a pattern of "craniofacial, limb, and cardiovascular defects associated with prenatal onset growth deficiency and developmental delay" in children of alcoholic mothers, now called fetal alcohol syndrome, It has significant symptom overlap with several other entirely unrelated neurodevelopmental disorders. [63]
Brain trauma in the developing human is a common cause (over 400,000 injuries per year in the US alone, without clear information as to how many produce developmental sequellae) [64] of neurodevelopmental syndromes. It may be subdivided into two major categories, congenital injury (including injury resulting from otherwise uncomplicated premature birth) [65] and injury occurring in infancy or childhood. Common causes of congenital injury are asphyxia (obstruction of the trachea), hypoxia (lack of oxygen to the brain), and the mechanical trauma of the birth process itself. [66]
Although it not clear yet as strong is the correlation between placenta and brain, a growing number of studies are linking placenta to fetal brain development. [67]
Neurodevelopmental disorders are diagnosed by evaluating the presence of characteristic symptoms or behaviors in a child, typically after a parent, guardian, teacher, or other responsible adult has raised concerns to a doctor. [68]
Neurodevelopmental disorders may also be confirmed by genetic testing. Traditionally, disease related genetic and genomic factors are detected by karyotype analysis, which detects clinically significant genetic abnormalities for 5% of children with a diagnosed disorder. As of 2017 [update] , chromosomal microarray analysis (CMA) was proposed to replace karyotyping because of its ability to detect smaller chromosome abnormalities and copy-number variants, leading to greater diagnostic yield in about 20% of cases. [46] The American College of Medical Genetics and Genomics and the American Academy of Pediatrics recommend CMA as standard of care in the US. [46]
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Fragile X syndrome (FXS) is a genetic neurodevelopmental disorder characterized by mild-to-moderate intellectual disability. The average IQ in males with FXS is under 55, while about two thirds of affected females are intellectually disabled. Physical features may include a long and narrow face, large ears, flexible fingers, and large testicles. About a third of those affected have features of autism such as problems with social interactions and delayed speech. Hyperactivity is common, and seizures occur in about 10%. Males are usually more affected than females.
Tourette syndrome or Tourette's syndrome is a common neurodevelopmental disorder that begins in childhood or adolescence. It is characterized by multiple movement (motor) tics and at least one vocal (phonic) tic. Common tics are blinking, coughing, throat clearing, sniffing, and facial movements. These are typically preceded by an unwanted urge or sensation in the affected muscles known as a premonitory urge, can sometimes be suppressed temporarily, and characteristically change in location, strength, and frequency. Tourette's is at the more severe end of a spectrum of tic disorders. The tics often go unnoticed by casual observers.
Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by executive dysfunction occasioning symptoms of inattention, hyperactivity, impulsivity and emotional dysregulation that are excessive and pervasive, impairing in multiple contexts, and developmentally-inappropriate.
Developmental disorders comprise a group of psychiatric conditions originating in childhood that involve serious impairment in different areas. There are several ways of using this term. The most narrow concept is used in the category "Specific Disorders of Psychological Development" in the ICD-10. These disorders comprise developmental language disorder, learning disorders, developmental coordination disorders, and autism spectrum disorders (ASD). In broader definitions, attention deficit hyperactivity disorder (ADHD) is included, and the term used is neurodevelopmental disorders. Yet others include antisocial behavior and schizophrenia that begins in childhood and continues through life. However, these two latter conditions are not as stable as the other developmental disorders, and there is not the same evidence of a shared genetic liability.
Autism spectrum disorder (ASD) is a neurodevelopmental disorder that begins in early childhood, persists throughout adulthood, and is characterized by difficulties in social communication and restricted, repetitive patterns of behavior. There are many conditions comorbid to autism spectrum disorder, such as attention deficit hyperactivity disorder, anxiety disorders, and epilepsy.
Adult Attention Deficit Hyperactivity Disorder is the persistence of attention deficit hyperactivity disorder (ADHD) into adulthood. It is a neurodevelopmental disorder, meaning impairing symptoms must have been present in childhood, except for when ADHD occurs after traumatic brain injury. Specifically, multiple symptoms must be present before the age of 12, according to DSM-5 diagnostic criteria. The cutoff age of 12 is a change from the previous requirement of symptom onset, which was before the age of 7 in the DSM-IV. This was done to add flexibility in the diagnosis of adults. ADHD was previously thought to be a childhood disorder that improved with age, but recent research has disproved this. Approximately two-thirds of childhood cases of ADHD continue into adulthood, with varying degrees of symptom severity that change over time and continue to affect individuals with symptoms ranging from minor inconveniences to impairments in daily functioning.
Neurofibromatosis type I (NF-1), or von Recklinghausen syndrome, is a complex multi-system human disorder caused by the mutation of neurofibromin 1 (NF-1). NF-1 is a gene on chromosome 17 that is responsible for production of a protein (neurofibromin) which is needed for normal function in many human cell types. NF-1 causes tumors along the nervous system that can grow anywhere on the body. NF-1 is one of the most common genetic disorders and is not limited to any person's race or sex. NF-1 is an autosomal dominant disorder, which means that mutation or deletion of one copy of the NF-1 gene is sufficient for the development of NF-1, although presentation varies widely and is often different even between relatives affected by NF-1.
Nonverbal learning disorder is a proposed category of neurodevelopmental disorder characterized by core deficits in non-verbal skills, especially visual-spatial processing. People with this condition have normal or advanced verbal intelligence and significantly lower nonverbal intelligence. A review of papers found that proposed diagnostic criteria were inconsistent. Proposed additional diagnostic criteria include intact verbal intelligence, and deficits in the following: visuoconstruction abilities, speech prosody, fine motor coordination, mathematical reasoning, visuospatial memory and social skills. NVLD is not recognised by the DSM-5 and is not clinically distinct from learning disorders.
Cognitive disengagement syndrome (CDS) is a syndrome characterized by developmentally-inappropriate, impairing and persistent levels of decoupled attentional processing from the ongoing external context and resultant hypoactivity. Symptoms often manifest in difficulties with staring, mind blanking, withdrawal, mental confusion and maladaptive mind wandering alongside delayed, sedentary or slow motor movements. To scientists in the field, it has reached the threshold of evidence and recognition as a distinct syndrome.
XXYY syndrome is a sex chromosome anomaly in which males have two extra chromosomes, one X and one Y chromosome. Human cells usually contain two sex chromosomes, one from the mother and one from the father. Usually, females have two X chromosomes (XX) and males have one X and one Y chromosome (XY). The appearance of at least one Y chromosome with a properly functioning SRY gene makes a male. Therefore, humans with XXYY are genotypically male. Males with XXYY syndrome have 48 chromosomes instead of the typical 46. This is why XXYY syndrome is sometimes written as 48, XXYY syndrome or 48, XXYY. It affects an estimated one in every 18,000–40,000 male births.
Developmental coordination disorder (DCD), also known as developmental motor coordination disorder, developmental dyspraxia or simply dyspraxia, is a neurodevelopmental disorder characterized by impaired coordination of physical movements as a result of brain messages not being accurately transmitted to the body. Deficits in fine or gross motor skills movements interfere with activities of daily living. It is often described as disorder in skill acquisition, where the learning and execution of coordinated motor skills is substantially below that expected given the individual's chronological age. Difficulties may present as clumsiness, slowness and inaccuracy of performance of motor skills. It is often accompanied by difficulty with organisation and/or problems with attention, working memory and time management.
Central nervous system diseases or central nervous system disorders are a group of neurological disorders that affect the structure or function of the brain or spinal cord, which collectively form the central nervous system (CNS). These disorders may be caused by such things as infection, injury, blood clots, age related degeneration, cancer, autoimmune disfunction, and birth defects. The symptoms vary widely, as do the treatments.
In psychology and neuroscience, executive dysfunction, or executive function deficit is a disruption to the efficacy of the executive functions, which is a group of cognitive processes that regulate, control, and manage other cognitive processes. Executive dysfunction can refer to both neurocognitive deficits and behavioural symptoms. It is implicated in numerous psychopathologies and mental disorders, as well as short-term and long-term changes in non-clinical executive control. Executive dysfunction is the mechanism underlying ADHD paralysis, and in a broader context, it can encompass other cognitive difficulties like planning, organizing, initiating tasks and regulating emotions. It is a core characteristic of ADHD and can elucidate numerous other recognized symptoms.
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.
Mental disorders diagnosed in childhood can be neurodevelopmental, emotional, or behavioral disorders. These disorders negatively impact the mental and social wellbeing of a child, and children with these disorders require support from their families and schools. Childhood mental disorders often persist into adulthood. These disorders are usually first diagnosed in infancy, childhood, or adolescence, as laid out in the DSM-5 and in the ICD-11.
Autism or autism spectrum disorder (ASD), is a neurodevelopmental disorder characterized by repetitive, restricted, and inflexible patterns of behavior, interests, and activities, as well as persistent difficulties in social communication and interaction. Autism generally affects a person's ability to understand and connect with others, as well as their adaptability to everyday situations, with its severity and support needs varying widely across the underlying spectrum. For example, some are nonverbal, while others have proficient spoken language.
The RASopathies are a group of developmental syndromes caused by germline mutations in genes belonging to the Ras/MAPK pathway. Common features include intellectual disability, congenital heart defects, skin abnormalities, and craniofacial abnormalities.
Metadoxine, also known as pyridoxine-pyrrolidone carboxylate, is a drug used to treat chronic and acute alcohol intoxication. Metadoxine accelerates alcohol clearance from the blood.
Deaf and hard of hearing individuals with additional disabilities are referred to as "Deaf Plus" or "Deaf+". Deaf children with one or more co-occurring disabilities could also be referred to as hearing loss plus additional disabilities or Deafness and Diversity (D.A.D.). About 40–50% of deaf children experience one or more additional disabilities, with learning disabilities, intellectual disabilities, autism spectrum disorder (ASD), and visual impairments being the four most concomitant disabilities. Approximately 7–8% of deaf children have a learning disability. Deaf plus individuals utilize various language modalities to best fit their communication needs.
Fetal valproate spectrum disorder (FVSD), previously known as fetal valproate syndrome (FVS), is a rare disease caused by prenatal exposure to valproic acid (VPA), a medication commonly used to treat epilepsy, bipolar disorder, and migraines. This exposure can lead to a range of neurodevelopmental and physical symptoms, including cognitive impairments, developmental delays, autism spectrum disorder (ASD), attention deficit hyperactivity disorder (ADHD), and congenital malformations.
Early results with structural MRI show thinning of the cerebral cortex in ADHD subjects compared with age-matched controls in prefrontal cortex and posterior parietal cortex, areas involved in working memory and attention.
EFs and prefrontal cortex are the first to suffer, and suffer disproportionately, if something is not right in your life. They suffer first, and most, if you are stressed (Arnsten 1998, Liston et al. 2009, Oaten & Cheng 2005), sad (Hirt et al. 2008, von Hecker & Meiser 2005), lonely (Baumeister et al. 2002, Cacioppo & Patrick 2008, Campbell et al. 2006, Tun et al. 2012), sleep deprived (Barnes et al. 2012, Huang et al. 2007), or not physically fit (Best 2010, Chaddock et al. 2011, Hillman et al. 2008). Any of these can cause you to appear to have a disorder of EFs, such as ADHD, when you do not.
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