Scoring of severity is a complex task – it depends a lot on age and the presentation varies in the individual ages CAUSES OF ID: BIOLOGICAL CAUSES: CHROMOSOMAL ABNORMALITIES: Down Syndrome: Extra 21stchromosome (trisomy 21) Biological causes of ID are not usually inherited but some cases of down syndrome have been inherited This happens when there is an error that occurs during meiosis or there is a mutation Distinct Physical Features oSmall heads and small stature oSlanted eyes oModerate to severe range of ID oThey can develop an Alzheimer’s like pathology oThey are at risk for many medical conditions like…Shorter life span Skeletal abnormalities GENETIC INHERITED DISORDERS: Fragile-X Syndrome:There is a weak leg of the x chromosome Mild ID rangeMales are more severely effected than females This can look a lot like autism oTend to be socially anxious and have some of the repeated behaviors Often have a distinct type of physical appearance oLarge jawoElongated foreheads oLarge and underdeveloped ears Phenylketonuria (PKU):Unable to metabolize phenylaline (an amino acid) in food Thus, it builds up causing an ID Inheritance of two recessive forms of a gene that results in the inability to metabolize an amino acid We can test for PKU when children are born oAll babies in the US are tested for this when they are born They way to prevent ID is to control the person’s diet – be very careful of what they don’t consumeENVIORNMENTAL RISK FACTORS: (before, during and after birth)Infections oRubella oHIV infection oMeningitis oViral and bacterial Exposure to Toxins oIntrauterine exposure to drugs (cocaine, alcohol, and heroine) oLead/mercury after birth Trauma oInfant head injury oFetal hypoxia oBrain hemorrhage Environmental Deprivation oFrom less stimulation to extremely deprived/abusive environments oCan never recover to the point where they are functioning at a normal level Malnutrition Maternal Age oFor down syndrome, after the age of 35 Under 30: 1 in 1000
Over 40: 1 in 100NORMAL GENETIC VARIATION: Cultural- Familial Mental Retardation oID that is due to a combination of genetic and psychosocial factors oSome percent of the population (about 2%) that we expect to have ID just because among humans the genes that determine IQ distribute themselves oThe ID is determined by the normal genetic variation on top of psychosocial factors like reduced access to resources Clusters in low socioeconomic groups due to shared environmental factors Clusters in families due to genetic factors oREACTION RANGEoGenetics determine the range of IQ scores you are going to hit in your life oBut environmental factors determine to what extent the individual fulfills genetic potential **Still have about half the cases of ID that we don’t know the causes of**ISSUES IN ID RESEARCHHeterogeneity oThe ID deficits are a piece of a complex set of problems oThere is much variability in the symptoms and the causes o
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- Spring '14
- Abnormal Psychology, Mental retardation, IQ score, IQ scores, Autism Spectrum Disorders, adaptive functioning deficits