CHAPTER 13

1. CHAPTER 13 Intelligence And Cognitive Functioning Deficiencies and Disorders of Intelligence

2. Developmental disabiliteis and mental retardation • The criteria for retardation =arbitrary, and based on judgments about the abilities required to get along in our complex world. • In 1978, then 1994 the American Psychiatric Association set the criteria for retardation as a combination of an IQ below 70 points and difficulty meeting routine needs like self-care. • Prior to that, cut off was 85 • “cured” thousands of individuals • Not only is any definition arbitrary, but it is situational and cultural as well. • A person considered retarded in our society might fare reasonably well in a simpler environment. • 6-hour retarded child

3. Developmental disabiliteis and mental retardation • MANY causes of retardation • Retardation can be inherited or due to improper cell division • Fragile X • Tay Sachs • Williams Syndrome • Prader Willy • Down Syndrome • Retardation can be caused by diseases contracted during infancy • Meningitis; infection, etc. • prenatal exposure to viruses such as rubella (measles).

4. Developmental disabiliteis and mental retardation • Can be due to teratogen exposure • Maternal alcoholism is now the leading cause of mental retardation • Other drugs • Can be caused by prematurity • 50% of preterm infants have significant disability • Two most common: Cerebral palsy and mental retardation • What about autism? • Used to be generically called retardation • Now identify it as separate disorder • Many of individual who would have been diagnosed as retarded are now labeled autistic

5. Down syndrome • Down syndrome usually caused by • the presence of an extra 21st chromosome, • Mosaicism: chromosome splits into many small parts • Trisomy 21: chromosonal split resembles presence of 3 21st chromosomes • Related to maternal age, but not necessarily caused by age • Typically results in individuals with IQs in the 40 to 55 range. • Early intervention critical • Early that begin intervention, typically higher the IQ • Amyloid precursor protein gene that involved in early-onset Alzheimer’s disease is located on chromosome 21 • was discovered because Down syndrome individuals also develop amyloid plaques. • 95% of people with Down syndrome have the entire extra chromosome • In a few cases: only an end portion is present, and attached to another chromosome.

6. Phenylketonuria • Phenylketonuria or PKU • due to an inherited inability to metabolize the amino acid phenylalanine. • excess phenylalanine interferes with myelination during development. • Without dietary treatment • the individual is severely or profoundly retarded • an adult IQ of around 20 points. • Much more rare today: Postnatal blood tests and routine hospital screenings followed by dietary changes has greatly reduced incidence in this country.

7. Other causes of retardation • Hydrocephalus • Water on the brain • occurs when cerebrospinal fluid builds up in the cerebral ventricles. • The increased fluid volume crowds out neural tissue, usually causing retardation. • Hydrocephalus can be relatively easily treated if caught early • installing a shunt that prevents the accumulation of the excess cerebrospinal fluid. • Eliminate or greatly reduce likelihood of long term brain damage

8. autism • Autism is a disorder that typically includes • compulsive, ritualistic behavior • impaired sociability • Language deficits • Often to usually: mental retardation. • Autism is one of 5 autism spectrum disorders • Autism, classic autism, high functioning autism • Autistic Disorder • Asperger Syndrome or Asperger's Disorder • Pervasive Developmental Disorder (PDD), • Autism Spectrum Disorder (ASD).

9. autism • Autism diagnosis given based on • Number and particular kinds of symptoms • Severity - mild to severe • Age of onset • Levels of functioning • Challenges with social interactions • Autism is the most common neurological disorder affecting children and one of the most common developmental disabilities • http://www.youtube.com/watch?v=FDMMwG7RrFQ

10. autism • Asperger’s syndrome • is the most similar to autism • most likely to share common causes. • People with Asperger’s syndrome are • socially impaired • display repetitive movements • preoccupations with narrow interests like autistic individuals, • But language and cognitive development and self help skills are more normal.

11. Autism: Common core of impairment • Whether retarded or not, autistic individuals share a common core of impairment in • Communication: often difficulty with communication • Imagination: very literal • Socialization: poor social skills • May be mute or show delayed language development • have trouble understanding verbal and nonverbal communication. • Again, very literal and concrete • Much of social behavior problem may be because autistic person lacks a theory of mind • ability to attribute mental states to oneself and to others. • An individual with autism cannot infer what other people are thinking.

12. Theory of mind • Two hypotheses as to how we develop a theory of mind. • “theory theory:” We build hypotheses over time based on our experience. • Simulation theory: We gain insight into people’s thoughts and intentions by mentally mimicking the behavior of others. • Data tends to support simulation view: • Existence of mirror neurons • Poor imitation skills in individuals with autism • Very different from Williams syndrome

13. How does poor mirror function affect intelligence? • Impaired mirror functions reduces the autistic person’s ability to • Empathize • learn language through imitation. • For example, some individuals with autism show no mirror neuron activity while • imitating facial expressions • or when observing a model’s hand movements. • Other studies show reduced activation in the inferior frontal cortex and motor cortex, • Suggests weakness in the dorsal stream connections • Provide important input to those areas containing mirror neurons.

14. Superior abilities? • Savant • person with exceptional intellectual skills • beyond the level of “ordinary” genius, like Leonardo da Vinci or Albert Einstein. • term is more frequently used to describe individuals who have one or more remarkable skills but whose overall functioning is below normal. • http://www.youtube.com/watch?v=lkDMaJ-wZmQ • Half of these individuals with islands of exceptional capabilities are autistic savants.

15. How can you be retarded and superior? • The source of the autistic savant’s enhanced ability is unknown. • Dehaene (1997): • may be due to intensely concentrated practice, • more typically the skill appears without either practice or instruction • Suggests innate ability. • Ramachandran and Blakeslee (1998): specialized area of the brain becomes enlarged at the expense of others. • Snyder and Mitchell (1999): • savant capabilities within us all, • are released when brain centers that control executive or integrative functions are compromised. • Brain damage studies lend support this hypothesis

16. Brain areas affected in autism • Subtle but widespread brain anomalies have been found, • Especially in the • brain stem, • the cerebellum, • temporal lobes. • The location of damage is inconsistent, which may mean only that there are various pathways to autism. • What causes these brain defects? • is uncertain, • at least we know they occur early, during brain development • So: know where and when to look for the answer. • NOT caused by parental rejection!

17. Autism and environmental influence • Environmental influence: Teratogens? • received the most public attention • generated the greatest controversy is vaccines, • either the MMR vaccine (for measles, mumps, and rubella) • Or mercury as a vaccine preservative. • Research does not support this hypothesis. • Another possibility: Brain damage = autoimmune reaction. • A likely source for such an autoimmunity is viral diseases like measles. • Immune system attacks brain • Could easily be genetic/familial

18. What DO we know? • Elevated serotonin levels • biological or biochemical abnormality most consistently found in autistics • One of the genes suspected of playing a role in autism = responsible for the mechanism involved in serotonin reuptake. • Serotonin drugs improve functioning in autism • Supports 5HT model • Changes in serotonin activity suggests that SSRI therapeutic effect is in producing compensatory changes in receptor activity.

19. What DO we know? • Oxytocin referred to as “sociability molecule” • Affects social behavior and bonding in lower animals. • Autistic children were found to have lower levels of oxytocin than normal controls, • this difference pronounced in the autistic children who were described as aloof. • Thus, may be that low levels of oxytocin are involved • Interestingly, Williams syndrome kids have HIGHER levels than normal • http://video.nytimes.com/video/2007/07/06/magazine/1194817106646/my-life-with-williams.html • http://www.williams-syndrome.org/forparents/whatiswilliams.html • May be in the eyes: • Interest in eyes related to oxytocin levels • Individuals with autism avoid eye contact • Individuals with Williams syndrome seek out eye contact

20. Is autism “genetic’ or inherited? • Siblings of autistics are 40 to 60 times more likely to be diagnosed with autism than other children. • The number would be even higher, but parents tend to stop having children after the first autistic diagnosis. • Suggests strong familial, if not genetic, link • Autism occurs two to four times more frequently in males than in females, • suggests that the genes for autism might be on the X chromosome • Currently: at least four areas on the X chromosome that are potential sites for autism genes.