Neurodevelopmental disorders are a group of neurological disorders that 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 lifetime.
Types
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.
According to the DSM-5, the neurodevelopmental disorders include the following: Attention deficit hyperactivity disorder (ADHD) DLD - Developmental language disorder (formerly known as SLI- Specific Language Impairment) Communication, speech, or language disorders, expressive language disorder, fluency disorder, social (pragmatic) communication disorder, and speech sound disorder. Autism spectrum disorder (ASD) Intellectual disabilities (IDs) or intellectual development disorder (IDD, previously called mental retardation) and global developmental delay (GDD) Motor disorders including developmental coordination disorder, stereotypic movement disorder, and tic disorders (such as Tourette's syndrome), and CAS - Apraxia of speech Neurogenetic disorders, such as Fragile X syndrome, Down syndrome, Rett syndrome, hypogonadotropic hypogonadal syndromes Specific learning disorders, like dyslexia or dyscalculia. Traumatic brain injury (including congenital injuries such as those that cause cerebral palsy) and disorders due to neurotoxicants including Minamata disease caused by mercury, behavioral disorders including conduct disorder etc. caused by other heavy metals, such as lead, chromium, platinum etc., hydrocarbons like dioxin, PBDEs and PCBs, medications and illegal drugs, like cocaine, radioactive metals like Po210(which is found in cigarettes), and others. Fetal Alcohol Spectrum Disorders (FASD) can exhibit a combination of the above, most commonly ADHD, because of this, FASD is usually under-diagnosed, yet it is estimated that about 1 in 20 people may be affected.
Currently being researched
There are neurodevelopmental research projects examining potential new classifications of disorders including: Nonverbal learning disorder (NLD or NVLD), a neurodevelopmental disorder thought to be linked to white matter in the right hemisphere of the brain and generally considered to include (a) low visuospatial intelligence; (b) discrepancy between verbal and visuospatial intelligence; (c) visuoconstructive and fine-motor coordination skills; (d) visuospatial memory tasks; (e) reading better than mathematical achievement; and (f) socioemotional skills. While Nonverbal learning disorder is not categorized in the ICD or DSM as an discrete classification, "the majority of researchers and clinicians agree that the profile of NLD clearly exists (but see Spreen, 2011, for an exception), but they disagree on the need for a specific clinical category and on the criteria for its identification."
Presentation
Consequences
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.
Causes
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. 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.