Cell division
Frank J. Dye in Human Life Before Birth, 2019
Because meiosis reduces the number of chromosomes from the diploid number to the haploid number, the fusion of cells during sexual reproduction is manageable. If, on the other hand, the chromosome number increased with each generation, developmental problems would result. We know this because occasionally humans are conceived with a tetraploid number (4n) of chromosomes. This genetic makeup is not compatible with human life, and the situation leads to spontaneous abortions (miscarriages) or stillbirths. As a species, we do not tolerate chromosomal abnormalities very well, and almost invariably such developmental chromosomal abnormalities carry with them intellectual disability. Perhaps chromosomal abnormalities almost always cause intellectual disability because our brains are so complex that all of our chromosomes carry genes that are vital for normal brain development. Therefore, if any chromosome is abnormal, some gene involved in brain development is damaged.
Intellectual and Developmental Disabilities
Christopher J. Nicholls in Neurodevelopmental Disorders in Children and Adolescents, 2018
So how does one provide therapeutic intervention for an individual with an intellectual disability? Many professionals assume that because the patient has limited cognitive abilities, they will not be responsive to our typical arsenal of psychological and other treatments. This assumption may be valid if one thinks only of treatment approaches such as existential psychotherapy or wanting to train an individual to gain insight into the causes of their particular distress. There has nevertheless been clear responsiveness of ID patients to more structured interventions that are administered in a more concrete manner. Indeed, the entire field of Applied Behavior Analysis (ABA) emerged as we learned that through the systematic assessment of the antecedents, purposes and consequences of individual behaviors, we could engineer the environment of the individual so as to modify the frequency of those behaviors. This way of thinking was originally considered to be “behavior modification;” however, this seemed to emphasize changes in the environment only, and it soon became clear that there is a two-way interaction of the individual within his or her environment.
The Child With Developmental Delay
Michael B O’Neill, Michelle Mary Mcevoy, Alf J Nicholson, Terence Stephenson, Stephanie Ryan in Diagnosing and Treating Common Problems in Paediatrics, 2017
Global developmental delay (GDD) has been defined by the American Academy of Neurology and the Child Neurology Society as performance at least two standard deviations below the mean, using standardised norm-referenced age-appropriate and developmentally appropriate criteria, in at least two domains. It is one of the commonest reasons for referral to paediatric neurologists. Global developmental delay (GDD) is the preferred term for significant deficits in learning skills and adaptation in children age five years or younger. The term ‘intellectual disability’ is applied to children older than 5 years of age, when IQ testing is more reliable and is characterised by significant limitations both in intellectual functioning (reasoning, learning, problem-solving) and in adaptive behaviour, which covers a range of everyday social and practical skills, with onset before 18 years of age. The terms ‘global developmental delay’ and ‘intellectual disability’ are not interchangeable. A child with GDD will not necessarily test in the intellectually disabled range when older. Global developmental delay affects 1%–3% of children under 5 years of age.
Do parent-mediated interventions improve communication and language development in children with Down syndrome? – A Cochrane Review summary with commentary
Published in Developmental Neurorehabilitation, 2020
Irene Ferrario
Down syndrome is a genetic disorder caused by the presence of all or part of a third copy of chromosome 21; the incidence of Down syndrome has been estimated to range from 1 per 1000 to 1100 live births worldwide.2 It is the most common genetic cause of intellectual disability, and is associated with abnormalities in various organ systems and developmental difficulties, such as congenital heart disease and hearing and vision disorders. Language is especially impaired and contributes to difficulties in achieving independent living.3 Children with Down syndrome generally present a language profile characterized by poorer expressive than receptive skills, particularly in terms of vocabulary, and difficulties with both receptive and expressive grammar.4 Interactions with caregivers have been shown to have a beneficial impact on a child’s language development.5 Thus, for young children with Down syndrome, it is thought that training their parents on the importance of the quality and quantity of their language input, interaction, and responsivity could promote language development in these children. Parent-mediated interventions are designed to foster and increase adult–child interactions and facilitate adequate language modeling and prompting from adult in an ecologically valid and family-centered way.6 A Cochrane Review synthetized evidence regarding the effects of parent-mediated interventions on communication and language development in children with Down syndrome.1
Developmental Functioning of Infants and Toddlers with Neurodevelopmental Disorders
Published in Developmental Neurorehabilitation, 2023
Megan Callahan, Johnny L Matson, Celeste Tevis
Intellectual disability is highly comorbid with other neurodevelopmental disorders. Current estimates suggest ID occurs in approximately 40% of individuals with ASD.36 Further, research suggests ID influences the sex ratio of ASD, as it increases to 2:1 male-to-female for individuals with comorbid ASD and ID.37 Similarly, approximately 45% of individuals with CP were found to have comorbid ID.21,38 Comorbid ID is implicated in later walking, non-ambulation, hypotonic and dyskinetic CP subtypes, and epilepsy.38 On the other hand, 16% of individuals with epilepsy have comorbid ID,39 which is related to higher rates of ASD, behavioral problems, postictal psychosis, and both psychotic and nonpsychotic disorders.40 Comorbid disorders have implications in both diagnostic procedures as well as treatment plans. Assessments need to be robust in order to provide differential diagnoses, while dual diagnoses play a significant role in how to formulate treatment plans and setting realistic expectations.
Accuracy of WISC-III and WAIS-IV short forms in patients with neurological disorders
Published in Developmental Neurorehabilitation, 2018
Jans S. van Ool, Petra P.M. Hurks, Francesca M. Snoeijen-Schouwenaars, In Y. Tan, Helenius J. Schelhaas, Sylvia Klinkenberg, Albert P. Aldenkamp, Jos G.M. Hendriksen
The Wechsler intelligence scales are widely used for assessing the intellectual abilities of children and adults, and are often incorporated as standard components in diagnostic batteries for neuropsychological evaluations.1 The most recent versions available in the Dutch language are the Wechsler Intelligence Scale for Children-Third Edition, published in 2002 (WISC-III2,3), and the Wechsler Adult Intelligence Scale-Fourth Edition, published in 2012 (WAIS-IV4,5). The assessment of intellectual abilities is believed to be fundamental for, for example, the diagnosis of intellectual disability (ID), along with a measure of adaptive functioning,6 or the evaluation of cognitive abilities associated with neurological disorders. Periodic re-evaluation of these abilities is recommended,7 which is especially relevant for individuals with co-morbid neurological disorders, such as epilepsy, who are at risk of possible deterioration.8
Related Knowledge Centers
- Activities of Daily Living
- Down Syndrome
- Heredity
- Fragile X Syndrome
- Neurodevelopmental Disorder
- Intellect
- Adaptive Behavior
- Signs & Symptoms
- Idiopathic Disease
- Genetic Disorder
- Activities of Daily Living