Intellectual Disability: Etiology, Diagnosis, and Management

Intellectual Disabilities Definition/description A disorder with onset during the developmental period that includes both intellectual and adaptive functioning deficits in conceptual, social and practical domains. Causes • • • Genetic: - Down syndrome - Fragile X syndrome Medical: - After meningitis, whooping cough or measles - Head injury during childhood - Brain malformations - Maternal diseases - Labour and delivery related events - Infections during pregnancy - Issues at birth e.g. not receiving enough oxygen - Inborn errors of metabolism - Demyelinating diseases - Severe and chronic social deprivation - Toxic metabolic syndromes Environmental: - Toxin exposure such as lead or mercury - Alcohol Pathophysiology • • • • • The end result of many disorders of CNS function Most have no discernible structure abnormalities of the brain - Including those with a severe intellectual impairment Dysfunction is mainly localised to the cortical structures - Hippocampus - Medical temporal cortex Most common malformations include: - Neural tube defects - Hydranencephaly - Microcephaly Less common CNS malformations: - Disorders of migrations (lissencehaphies) - Agenesis of the corpus callosum Key facts • • Most do not have other neurologic complications, CNS malformations or dysmorphisms. Are more likely to be born into families with low SES, low IQ and limited education. - Contribution of poverty is unclear Clinical Features • • • • • • • • • Cognitive skills delay - Memory issues - Problem solving difficulties - Logical reasoning issues - Difficulty following directions Language delay - One of first signs - Includes both expressive and receptive speech - Red flags: ➔No mama, dada, babbling by 12 months ➔No two word phrases by age 2 ➔Parents reporting concerns that the child is deaf Adaptive skills delay Development delays - Vary depending on cause and severity Fine motor/adaptive delays - Significant delays in activities such as: ➔Self-feeding ➔Toileting ➔Dressing ➔Prolonged messy finger feeding and dropping Social delays - Lack of interest in age-appropriate toys - Delays in imaginative - Reciprocal play with age-matched peers Gross motor delays - Infrequency accompanies the cognitive, language and fine/adaptive delays associated with intellectual disabilities, unless the underlying condition results in both ID and cerebral palsy. Behavioural disturbances - More likely to have difficult temperaments, hyperactivity, disordered sleep and colic - Aggression - Self-injury - Defiance - Inattention - Hyperactivity - Stereotypic behaviours Neurologic and physical abnormalities - Increased incidence of seizures, microcephaly, prematurity and congenital anomalies Diagnosis • • • Lab studies - Genetic testing Imaging - Brain MRI - Head CT scan - Skeletal films Histology DSM-V criteria All of the following criteria must be met: A. Deficits in intellectual functions such as reasoning, problem solving, planning, abstract thinking, judgement, academic leaning and learning from experience conformed by both clinical assessment and individualised intelligence testing. B. Deficits in adaptive functioning that result in failure to meet developmental and sociocultural standards for personal independence and social responsibility. Without ongoing support, the adaptive deficits limit functioning in one or more activities of daily life, such as communication, social participation and independent living, across multiple environments such as home, school, work and community. C. Onset of intellectual and adaptive deficits during development Treatment and Management • • Consultations: - Developmental paediatrician or psychologist - Child neurologist - Geneticist and counsellor - Psychiatrist - Densit - Podiatrist - Social education/educational therapist - Occupational, speech and/or physical therapist - Behaviourist - Pharmacist - Durable medical equipment providers - Social services/social workers Long term monitoring: - Treatment of associated impairments - Pharmacotherapy - Behaviour management - Educational services - Recreational needs - Family counselling • Medications - No specific pharmacological treatment is present for cognitive impairment in the developing child or adult with intellectual disability. - Development of nootropic drugs that may alter cognitive processes is of current interest research. - Vitamin and mineral therapies are popular, but their efficacy is not established in clinical trials. - CNS stimulants ➔Ritalin, Metadate ER, Dexedrine and Adderall ➔Most common prescribed drug class - Alpha-adrenergic agonists ➔Commonly used to modulate hyperactivity, aggression, tics and dyssomnias ➔Catapres, Tenex - Neuroleptic drugs/anti-psychotics ➔Most commonly prescribed drug class for targeting behaviours such as aggression, self-injury and hyperactivity. ➔Risperdal, Abilify