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Lecture 12

Abnormal Psychology -- lecture 12.docx

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York University
PSYC 3140
James Alcock

April 1 , 2013 Tahreem Mahmood Lecture 12 Abnormal Psychology -Psych 3230 Mental Retardation  Involves a broad delay in cognitive and social functioning  Course is variable o Many children improve considerably over time o Especially in enriched environments – encouragement, support, stimulation  Impoverished environments may lead to deterioration  Training programs to develop community and social skills help many live independently or in group homes  Three criteria for diagnosis, according to DSM-IV: o IQ score of 70 or below on a standard IQ test such as WISC or Stanford-Binet o Evidence of impairment functioning in two or more areas of adaptive behaviour – e.g. self-care, school, work, social skills  Assessed in terms of level severity: o Mild mental retardation : IQ 50-70 (85% of mentally retarded) o Moderate mental retardation: IQ 35-49 (10%) o Severe mental retardation: IQ 20 – 34 (4-4%) o Profound mental retardation: IQ<20 (1-2%)  Famous people players have mentally and physically challenged actors – it is the first theater company in the world dedicated to people with special needs Causes of Retardation  Biological roots o Chromosomal and genetic diseases o Infectious diseases o Brain damage due to environmental toxins o Anoxia during birth, etc.  Impoverished home environment can combine with biological factors to produce more serious disorder Down syndrome  One of the most common causes of mental retardation  Down symptoms, along with retardation, include: o Flat face, small nose, eyes that appear to slant forward because of small folds of skin at inside corners (“mongoloids”), small ears, small short hands with curved fifth finger April 1 , 2013 Tahreem Mahmood Lecture 12 Abnormal Psychology -Psych 3230 o Likely to be obese in childhood and adolescence o Tend to have congenital heart abnormalities o Tend to show a form of senility as they age  Most die by middle age  Due to chromosomal abnormalities o Each parent contributes one of each 23 pairs of chromosomes in the zygote o Down syndrome occurs when there are three instead of two chromosomes at position 21 o Can occur in two ways; [95% of Down Syndrome traced to mother] 1. Nondisjunction: one pair of chromosomes in formation of egg or sperm did not separate – accounts for 80 to 90% of cases (also referred to as “trisomy”) a. Risk of nondisjunction rises dramatically in women over 40 (<1 per thousand for women in the 20s; 18 per 1000 for women over 40) 2. Translocation: sometimes material from a chromosome at 21 breaks off in the formation of an egg and fuses with another, so that during cell division, it is carried to the zygote  Karyotype: photograph of all the chromosomes in the human body o Trisomy 21 – you have three pairs of chromosome 21 Phenylketonuria (PKU)  Inherited metabolic disorder caused by a recessive gene carries by one person in 60 o Occurs in 1 out of every 12, 000 births in North America o Prevents child from metabolizing the amino acid phenylalanine, found in many foods o Can be avoided if the mother takes part in a phenylalanine-free diet o Both parents may have a recessive gene and the child who receives both recessive genes has the disease  Left untreated during infancy, leads to severe, irreversible mental retardation  May also experience neurobehavioral symptoms o Seizures, tremors, and psychotic episodes  Routine screening began in the mid 1960s;  Now healthy phenylketonuric women bear children Fragile X syndrome  Most common cause of inherited mental retardation o Related to genes on X chromosome (from mother) April 1 , 2013 Tahreem Mahmood Lecture 12 Abnormal Psychology -Psych 3230 o “fragile” spot on chromosome shows up when the chromosome is cultured in a laboratory o The gene that is responsible has been identified o Can produce other problems such as specific learning disorders, ADHD, instead of retardation  Fragile X syndrome is a spectrum of mental impairment – from learning disabilities to severe retardation, both combines with delayed speech and language development  X-linked recessive o 1 in 1,200 males is affected o 1 in 300 women carries the Fragile X mutation  Expression is variable  Moderate to severe mental retardation is most common symptom  “large penises”  Karyotypes of individuals with Fragile X Syndrome missing a small piece of X chromosome near the end. Fetal Alcohol Syndrome  Due to alcohol intake during pregnancy o Causes mental retardation and various physical disorders – e.g., flat faces, tissues obscuring inner corner of the eyes, short nose and low nasal bridge, undeveloped groove between nose and upper lip Tay-Sachs disease  Caused by recessive gene found mostly in Jewish people of eastern European origin (1 in 25 Jews in North America is a carrier) o Causes loss of muscle control, retardation, deafness, blindness, paralysis, and death usually before age 5 Other Causes of Retardation  Despite these biological roots, about 75% of people diagnosed as having a developmental handicap have no known organic cause or brain dysfunction!  Most of these are in the mild range o Not clear what the cause is – “inherited low intelligence” combines with an impoverished environment? Autism April 1 , 2013 Tahreem Mahmood Lecture 12 Abnormal Psychology -Psych 3230  If one looks at textbooks from thirty years ago, autism was considered to be “…a subgroup of psychotic disorder…”  In DSM-IV, autism is considered to be a pervasive developmental disorder.  Symptoms are usually present within the first year and a half of a child’s life. In some children the symptoms may show up early on, within the baby’s first few months of life  Other babies may appear normal for a while and suddenly exhibit an alarming regression at 18 to 24 months  Occasionally, the onset is a year and a half  In the beginning the child may: o Show a reduced level of activity o Cry less o Appear to be happier playing alone than with other children o Not show much interest in to
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