Neurodevelopmental disorder

Neurodevelopmental disorders are a group of disorders which affect the development of the nervous system, leading to abnormal brain function which may affect emotion, learning ability, self-control, and memory. The effects of neurodevelopmental disorders tend to last for a person's entire lifetime. Neurodevelopmental disorders are a group of disorders which affect the development of the nervous system, leading to abnormal brain function which may affect emotion, learning ability, self-control, and memory. The effects of neurodevelopmental disorders tend to last for a person's entire lifetime. Neurodevelopmental disorders are impairments of the growth and development of the brain and/or central nervous system. A narrower use of the term refers to a disorder of brain function that affects emotion, learning ability, self-control and memory which unfolds as an individual develops and grows. Disorders which are currently considered to be neurodevelopmental include the following: According to the DSM-5, ADHD and related disorders are also considered neurodevelopmental disorders. The term is sometimes erroneously used as an exclusive synonym for autism spectrum disorders. Development of the nervous system is tightly regulated and timed; it is influenced by both genetic programs and the environment. Any significant deviation from the normal developmental trajectory early in life can result in missing or abnormal neuronal architecture or connectivity. 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 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. Deprivation from social and emotional care causes severe delays in brain and cognitive development. 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 (abnormal psychology). 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, 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 mental retardation (delay of intellectual development). Less commonly known genetically determined neurodevelopmental disorders include Fragile X syndrome. Fragile X syndrome was first described in 1943 by J.P. Martin and J. Bell, studying persons with family history of sex-linked 'mental defects'. Rett syndrome, another X-linked disorder, produces severe functional limitations. Williams syndrome is caused by small deletions of genetic material from chromosome 7.The most common recurrent Copy Number Variannt disorder is 22q11.2 deletion syndrome (formerly DiGeorge or velocardiofacial syndrome), followed by Prader-Willi syndrome and Angelman syndrome. 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, or Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infection. 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, so sometimes several family members may suffer from one or both of them following an epidemic of Strep infection.