1 Causes of Mental Retardation Genetic, environmental, and psychosocial causes

2 Key vocabulary ► Perinatal causes ► Postnatal causes ► Social correlates ► Psychological correlates ► Preventative measures

3 Key vocabulary ► Roles of genes and chromosomes in heredity ► Autosomal genetic disorders ► Sex linked genetic disorders ► Disorders related to the number of chromosomes ► Disorders with multiple or unknown causes ► Genetic testing and genetic counseling

4 Causes ► Direct cause is more frequently not known than known ► Many persons with a label of mental retardation are considered to have had the potential of developing in a typical sequence or rate ► Implication of preventable ► No estimate of numbers

5 Prenatal causes ► Teratogens: agents causing a defect in a developing embryo or fetus  Infections  Radiation  Maternal nutrition  Low birth weight  Chromosomal disorders  Developmental disorders of brain formation  Environmental influences

6 Infections ► Toxoplasmosis ► Rubella ► Cytomegalovirus ► Syphilis ► HIV ► UTI

7 Radiation ► Noted with survivors of the A-bomb on Hiroshima and Nagasaki ► Radiation has effects depending on the time of exposure and intensity (dose)

8 Maternal Nutrition ► Malnutrition may have effects both pre- and post-natally ► Major concern in developing countries ► Low weight gain in pregnancy has differential effects for different populations ► Low birth weight—may result in as much as 40 to 60% reduction in brain cells

9 Maternal age ► Over 36 and under 16 at risk for low birth weight ► Younger mothers prone to giving birth early (LBW) ► Reasons for mental retardation from younger mothers or LBW not known

10 Lack of Pre-natal Care ► Sometimes racial differential ► Increased risk of premature rupture of amniotic membranes ► Maternal health problems ► Drug abuse and other substance abuse  LBW  FAS  FAE  Nicotine  Other drugs

11 Maternal health problems ► Endocrine disorders; e.g., diabetes ► Cardiovascular disorders ► Anemia ► Treatments for disorders affects fetus

12 Drug and alcohol abuse ► Drug use increasing ► Alcohol use during pregnancy  LBW  Microcephaly  Heart defects  Facial abnormalities  Poor growth developmental delay  Behavioral difficulties  Attention problems

13 ► Nicotine use  Increased probability of miscarriage  Developmental delay ► Cocaine, heroine, methadone  LBW  Withdrawal  Small head circumference  Developmental delay  Language problems

14 Perinatal causes ► Anoxia and asphyxia ► Prematurity- prior to 37 weeks ► Low birth weight –under 5 ½ pounds ► Hemorrhages ► Metabolic problems ► Seizures ► Birthing problems  Multiple births  Abnormal presentation  prolaspe of umbilical cord

15 ► Respiratory distress syndrome  lack of sulfactant (coats the alveoli)  Can result in collapsed alveoli ► Jaundice ► Rh incompatibility

16 Postnatal causes ► Quality of attachment ► Illnesses  Encephalitis  Meningitis  Poisoning  Malnutrition  Injuries

17 Psychosocial factors ► Social correlates  Low SES  Nutrition  Poverty  Family size  Low maternal intelligence  Low maternal educational level  Absence of parents  Language environment ► Psychological correlates  Child rearing practices  Abuse and neglect

Buck v Bell “We have seen more than once that the public welfare may call upon the best citizens

19 ► Young child with Down Syndrome

20 ► Karyotype of typically developing female

21 ► Turner’s syndrome ► Affects females ► Incomplete x chromosome ► Short stature ► Webbed neck ► Low hairline in back ► Skeletal deformities

22 Fragile X Syndrome ► Mental retardation Hyperactivity Short attention span *Tactilely defensive Hand-flapping Hand-biting Poor eye contact *Perseverative speech *Hyperextensible MP joints Large or prominent ears Large testicles *Simian crease or Sydney line Family history of mental retardation Mental retardationHyperactivityspeech*Hyperextensibleprominent earsLarge testiclesMental retardationHyperactivityspeech*Hyperextensibleprominent earsLarge testicles

23 Fragile X Syndrome ► In males, generally see a decrease in IQs over time ► Concrete thinking ► Facial features:  Long face  High arched palate  Long ears ► In females, less like to have a label of retardation; less severe features

24 ► Fragile X syndrome ► Boys  distractible and impulsive, with symptoms of attention deficit hyperactivity disorder (ADHD)  short attention spans and difficulty staying on task.  short attention spans and difficulty staying on task.  stereotypic behaviors, such as hand flapping and chewing on skin, clothing, or objects,  Sensory processing problems may manifest themselves as tactile defensiveness, or sensory defensiveness. ► Anxiety in both boys and girls manifests itself in various ways  Girls may show less hyperactivity, but still have many symptoms of ADHD.

25 Microcephaly ► Failure of the brain to grow at a normal rate ► infections, genetic disorders, and severe malnutrition. ► Primary causes  Down's syndrome Down's syndrome Down's syndrome  cri du chat syndrome cri du chat syndrome cri du chat syndrome  Seckel's syndrome  Rubinstein-Taybi syndrome Rubinstein-Taybi syndrome Rubinstein-Taybi syndrome  trisomy 13 trisomy 13 trisomy 13  trisomy 18 trisomy 18 trisomy 18  Smith-Lemli-Opitz syndrome  Cornelia de Lange syndrome

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27 CRI DU CHAT Syndrome ► missing a piece of chromosome number 5. ► high-pitched cry sounds like a cat (for which the syndrome was named) ► Low birth weight and slow growth ► small head ► wide-set eyes ► downward slant to the eyes ► small jaw ► low set ears (may be malformed) ► skin tags just in front of the ear ► partial webbing or fusing of fingers or toes ► single line in the palm of the hand (simian crease) simian creasesimian crease ► mental retardation ► slow or incomplete development of motor skills

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