mental retardation

Mental retardation (MR) is a generalized disorder appearing before adulthood, characterized by significantly impaired cognitive functioning and deficits in two or more adaptive behaviors. It has historically been defined as an Intelligence Quotient score under 70.^[1] Once focused almost entirely on cognition, the definition now includes both a component relating to mental functioning and one relating to individuals' functional skills in their environment. As a result, a person with a below-average intelligence quotient (BAIQ) may not be considered mentally retarded. Syndromic mental retardation is intellectual deficits associated with other medical and behavioral signs and symptoms. Non-syndromic mental retardation refers to intellectual deficits that appear without other abnormalities.

The terms used to describe this condition are subject to a process called the euphemism treadmill. This means that whatever term is chosen for this condition, it eventually becomes perceived as an insult. The terms mental retardation and mentally retarded were invented in the middle of the 20th century to replace the previous set of terms, which were deemed to have become offensive. By the end of the 20th century, these terms themselves have come to be widely seen as disparaging and politically incorrect and in need of replacement.^[2] The term intellectual disability or intellectually challenged is now preferred by most advocates in most English-speaking countries. Clinically, however, mental retardation is a subtype of intellectual disability, which is a broader concept and includes intellectual deficits that are too mild to properly qualify as mental retardation, too specific (as in specific learning disability), or acquired later in life, through acquired brain injuries or neurodegenerative diseases likedementia. Intellectual disabilities may appear at any age. Developmental disability is any disability that is due to problems with growth and development. This term encompasses many congenital medical conditions that have no mental or intellectual components, although it, too, is sometimes used as a euphemism for MR.^[3] Because of its specificity and lack of confusion with other conditions,mental retardation is still the term most widely used and recommended for use in professional medical settings, such as formal scientific research and health insurance paperwork.^[4]

ADHD

Attention deficit hyperactivity disorder (ADHD) is a developmental disorder.^[1] It is characterized primarily by "the co-existence of attentional problems and hyperactivity, with each behavior occurring infrequently alone" and symptoms starting before seven years of age.^[2]

ADHD is the most commonly studied and diagnosed psychiatric disorder in children, affecting about 3 to 5 percent of children globally^[3][4] and diagnosed in about 2 to 16 percent of school aged children.^[5] It is a chronic disorder^[6] with 30 to 50 percent of those individuals diagnosed in childhood continuing to have symptoms into adulthood.^[7][8] Adolescents and adults with ADHD tend to develop coping mechanisms to compensate for some or all of their impairments.^[9] It is estimated that 4.7 percent of American adults live with ADHD.^[10] Standardized rating scales such as the World Health Organization'sAdult ADHD Self-Report Scale can be used for ADHD screening and assessment of the disorder's symptoms' severity.^[11]

ADHD is diagnosed two to four times more frequently in boys than in girls,^[12][13] though studies suggest this discrepancy may be partially due to subjective bias of referring teachers.^[14] ADHD management usually involves some combination of medications, behavior modifications, lifestyle changes, and counseling. Its symptoms can be difficult to differentiate from other disorders, increasing the likelihood that the diagnosis of ADHD will be missed.^[15] In addition, most clinicians have not received formal training in the assessment and treatment of ADHD, in particular in adult patients.^[15]

ADHD and its diagnosis and treatment have been considered controversial since the 1970s.^[16] The controversies have involved clinicians, teachers, policymakers, parents and the media. Topics include ADHD's causes, and the use of stimulant medications in its treatment.^[17][18][19] Most healthcare providers accept that ADHD is a genuine disorder with debate in the scientific community centering mainly around how it is diagnosed and treated.^[20][21][22]The American Medical Association concluded in 1998 that the diagnostic criteria for ADHD are based on extensive research and, if applied appropriately, lead to the diagnosis with high reliability.^[23]

dyslexia

Dyslexia is a very broad term defining a learning disability that impairs a person's fluency or comprehension accuracy in being able to read,^[1] and which can manifest itself as a difficulty with phonological awareness, phonological decoding, orthographic coding, auditory short-term memory, or rapid naming.^[2][3] Dyslexia is separate and distinct from reading difficulties resulting from other causes, such as a non-neurological deficiency with vision or hearing, or from poor or inadequate reading instruction.^[4][5] It is believed that dyslexia can affect between 5 and 10 percent of a given population although there have been no studies to indicate an accurate percentage.^[6][7][8]

There are three proposed cognitive subtypes of dyslexia: auditory, visual and attentional.^{[7][9][10][11][12][13]} Reading disabilities, or dyslexia, is the most common learning disability, although in research literature it is considered to be a receptive language-based learning disability.^[14] Researchers at MIT found that people with dyslexia exhibited impaired voice-recognition abilities.^[15]

Accomplished adult dyslexics may be able to read with good comprehension, but they tend to read more slowly than non-dyslexics and may perform more poorly at nonsense word reading (a measure of phonological awareness) and spelling.^[16] Dyslexia is not an intellectual disability, since dyslexia and IQ are not interrelated, as a result of cognition developing independently.^[17]

autism

Autism is a disorder of neural development characterized by impaired social interaction and communication, and by restricted and repetitive behavior. These signs all begin before a child is three years old.^[2] Autism affects information processing in the brain by altering how nerve cells and their synapses connect and organize; how this occurs is not well understood.^[3] It is one of three recognized disorders in the autism spectrum (ASDs), the other two being Asperger syndrome, which lacks delays in cognitive development and language, and Pervasive Developmental Disorder-Not Otherwise Specified (commonly abbreviated as PDD-NOS), which is diagnosed when the full set of criteria for autism or Asperger syndrome are not met.^[4]

Autism has a strong genetic basis, although the genetics of autism are complex and it is unclear whether ASD is explained more by rare mutations, or by rare combinations of common genetic variants.^[5] In rare cases, autism is strongly associated with agents that cause birth defects.^[6] Controversiessurround other proposed environmental causes, such as heavy metals, pesticides or childhood vaccines;^[7] the vaccine hypotheses are biologically implausible and lack convincing scientific evidence.^[8] The prevalence of autism is about 1–2 per 1,000 people worldwide; however, the Centers for Disease Control and Prevention (CDC) reports approximately 9 per 1,000 children in the United States are diagnosed with ASD.^[9][10] The number of people diagnosed with autism has increased dramatically since the 1980s, partly due to changes in diagnostic practice; the question of whether actual prevalence has increased is unresolved.^[11]

Parents usually notice signs in the first two years of their child's life.^[12] The signs usually develop gradually, but some autistic children first develop more normally and then regress.^[13] Early behavioral or cognitive intervention can help autistic children gain self-care, social, and communication skills.^[12]Although there is no known cure,^[12] there have been reported cases of children who recovered.^[14] Not many children with autism live independently after reaching adulthood, though some become successful.^[15] An autistic culture has developed, with some individuals seeking a cure and others believing autism should be accepted as a difference and not treated as a disorder.^[16]