More than 2% of our children are considered to be mentally retarded. In order to understand retardation, we need to look a little at the concept of intelligence. We define intelligence as "general cognitive ability," meaning how well a person can solve problems, how easily they learn new things, and how quickly they can see relationships among things.
Intelligence Quotient (IQ) is the score you get on an intelligence test. Originally, it was a quotient (a ratio): IQ= MA/CA x 100, where MA is mental age and CA is chronological age. So a child who is 10 and has the same level of intellectual ability as most 10 year olds has an IQ of 10/10 x 100 = 100. If that 10 year old has the same ability as a 15 year old, his IQ will be 15/10 x 100 = 150 -- very smart indeed. If the 10 year old has the ability of a 5 year old, his IQ would be 5/10 x 100 = 50, which is considered mentally retarded.
Nowadays, IQ is a matter of comparing a person with many others of the same age, and assigning a score based on their place on a normal curve:
Here you get to see several important points about not only IQ but about descriptive statistics.
1. The normal curve, also called the bell-shaped curve, is an idealized version of what happens in many large sets of measurements: Most measurements fall in the middle, and fewer fall at points farther away from the middle. Here, most people score near 100 (the average), and much fewer people score very high or very low.
2. The mean is just the average of all scores. The sum of everyone’s IQ scores, divided by the number of scores, is the mean, which was originally set at 100. That has become the tradition.
3. The standard deviation (sd). The standard deviation is like the average degree to which scores deviate from the mean. For our purposes, just know that 1 standard deviation above and below the mean contains (in an ideal normal curve!) 68% of all the scores, 2 standard deviations contain 95.6%, and 3 standard deviations contain 99.7%. Or, you could say that there are only 2.2% above 130 and 2.2% below 70, and so on. By tradition, one standard deviation is 15 points. The percentages you see in the normal curve above are based on 10 point spreads: 10 points above or below the mean (90 to 110) contains 50% of all the scores.
The names for various "smart" people are of relatively little importance to us. But the differences among retarded people can be very significant. Please understand that the ranges are approximations, and labeling people is always a difficult and dangerous thing!
- 0 - 20: profound mental retardation -- these folks will likely need nursing care their entire lives.
- 20 - 35: severe mental retardation -- these people can learn to talk and develop basic hygiene habits.
- 35 - 50: moderate mental retardation -- they can achieve as much as a second grade education (e.g. learning to read and count change, etc.), but will likely need sheltered care.
- 50 - 70: mild mental retardation -- these people can achieve the equivalent of a sixth grade education, be self-supporting and have a partially independent life.
Basically, mental retardation is believed to be a matter of some sort of damage to the brain. There are many factors that can lead to that kind of damage:
- heredity (eg Downs syndrome)
- embryonic problems (eg fetal alcohol syndrome, rubella...)
- birth complications (anoxia, infection)
- childhood medical conditions (infections, traumas, lead poisoning)
- neglect and abuse
- other psychological disorders that involve neurological impairment (eg autism)
An interesting question to ask is: If being below, say, 50 is due to "brain damage," what do we say about people above, say, 150? Are they "brain enhanced?" Or do they have a different, more beneficial sort of "brain damage?"
Autism, the most common of the pervasive developmental disorders (with a prevalence of 10 to 12 children per 10,000 [Bryson & Smith, 1998]), is characterized by severely compromised ability to engage in, and by a lack of interest in, social interactions. It has roots in both structural brain abnormalities and genetic predispositions, according to family studies and studies of brain anatomy. The search for genes that predispose to autism is considered an extremely high research priority for the National Institute of Mental Health (NIMH, 1998). Although the reported association between autism and obstetrical hazard may be due to genetic factors (Bailey et al., 1995), there is evidence that several different causes of toxic or infectious damage to the central nervous system during early development also may contribute to autism. Autism has been reported in children with fetal alcohol syndrome (Aronson et al., 1997), in children who were infected with rubella during pregnancy (Chess et al., 1978), and in children whose mothers took a variety of medications that are known to damage the fetus (Williams & Hersh, 1997)
The causes of autism are still not known. It is believed by most researchers that it involves problems with neural circuits, and twin studies suggest that genetic influences are likely. For a long time, it was assumed incorrectly that autism resulted from parental neglect.
Because autism is a severe, chronic developmental disorder, which results in significant lifelong disability, the goal of treatment is to promote the child’s social and language development and minimize behaviors that interfere with the child’s functioning and learning. Intensive, sustained special education programs and behavior therapy early in life can increase the ability of the child with autism to acquire language and ability to learn. Special education programs in highly structured environments appear to help the child acquire self-care, social, and job skills.
There has been some limited success with antipsychotic drugs and with antidepressants.
In the last 20 years or so, a number of finer differentiations have evolved regarding what is now seen as an autistic spectrum. First, we have something called Asperger's Syndrome. These children (and adults) are generally of normal (and sometimes high) intelligence, but have difficulty in social interaction. They seem exceptionally shy and have a hard time making eye contact. They have trouble learning what is called pragmatics -- the part of communication between people that involves recognizing turn-taking, facial expressions, gestures, and other non-verbal cues. They tend to focus intensely on one thing at a time, don't like abrupt changes, and develop obsessive routines. As adults, they usually adapt, but are seen as being socially inept, absent minded, and eccentric. Of course, that begs the question a little: Is this truly a separate disorder, or just a little out there on the continuum of normal behavior?
There are other syndromes that focus more on language: The semantic-pragmatic disorder is sometimes used to label certain children who are similar to Asperger's children but more sociable. The focus of their problem is more on the communications side.
Hyperlexia is more a symptom than a disorder. It is a matter of being rather precocious in reading words, and being fascinated by letters and numbers. On the other hand, children with hyperlexia don't communicate well, nor do they socialize well.
Non-verbal learning disability is a matter of having a hard time with visual, spatial, and motor skills. They have a hard time picking out, say, one house out of a row of them, tying their shoes, getting dressed, kicking a ball, reading facial expressions, and recognizing the tone of someone's voice. One of the notable symptoms is the tendency to stare, especially when visually over-stimulated.
A related problem that is close to my heart (because I have a mild version of this) is prosopagnosia or face blindness. This affects about 2 1/2 % of the population, and people with this problem have a difficult time recognizing faces. It can be so severe that a man can walk past his own mother and not recognize her! Generally, people with this problem develop other ways of recognizing people, such as clothing or hair styles. I recognize people I have known for a long time, but cannot place less familiar people out of the context of, say, a specific classroom or circumstance. It makes one seem rude, but it is unintentional. Interestingly, people with prosopagnosia often also have a hard time identifying some other things, such as dogs and cars! It is believed to be a problem involving the fusiform gyrus, which is involved in facial recognition.
We say a child has a learning disorder when his or her performance is significantly below his or her IQ, i.e. they are not learning "up to their potential." We estimate that about 5% of students in US public schools have a learning disorder, most commonly reading disorder. Learning disorders are often found accompanying other medical problems such as lead poisoning, fetal alcohol syndrome, and so on.
Reading disorder -- better known as dyslexia -- is the most common learning disorder. Here, the child's reading scores are significantly below IQ, expected age level, or their general abilities. These kids seem to have trouble with the usual lleft to right scanning of words, which lead them to reverse letters and jumble the spelling. It could be compared to trying to read a newspaper in a language you have little familiarity with.
It is estimated that about 4% of US school kids have dyslexia. 60 to 80% of those diagnosed are boys, but this may be a matter of identification: boys with reading disorder act up more, drawing attention to their problems, while the girls tend to be quieter and less trouble. This is, of course, a problem for the girls in that their dyslexia is less often caught early.
Helping children with learning disorders has become a big part of educational research. Basically the help involves slow, careful teaching that gives the child an opportunity to work without the pressures of competition and frustration that exist in the ordinary classroom setting. In England, they take a different attitude towards dyslexia, seeing it as more a maturational problem rather than a more permanent neurological condition.
It should also be noted that dyslexia is a far greater problem for children who speak English than other languages: Of all languages written with a western alphabet, English has the most inconsistent spelling. Spelling is not even a subject in most western languages, because words are spelled pretty much as they sound! Unfortunately, there are few signs that English-speaking people will ever change their spelling system.
ADHD is really two different problems -- inattentiveness and hyperactivity -- that nevertheless tend to go together. It has been the focus of a great deal of controversy. Opinions range from considering ADHD to be a purely physical, highly genetic, medical problem to the belief that it is nothing more than the differences between children's maturation rates. Here are the opinions offered by the Surgeon General’s report:
Inattention or attention deficit may not become apparent until a child enters the challenging environment of elementary school. Such children then have difficulty paying attention to details and are easily distracted by other events that are occurring at the same time; they find it difficult and unpleasant to finish their schoolwork; they put off anything that requires a sustained mental effort; they are prone to make careless mistakes, and are disorganized, losing their school books and assignments; they appear not to listen when spoken to and often fail to follow through on tasks (DSM-IV; Waslick & Greenhill, 1997).
The symptoms of hyperactivity may be apparent in very young preschoolers and are nearly always present before the age of 7 (Halperin et al., 1993; Waslick & Greenhill, 1997). Such symptoms include fidgeting, squirming around when seated, and having to get up frequently to walk or run around. Hyperactive children have difficulty playing quietly, and they may talk excessively. They often behave in an inappropriate and uninhibited way, blurting out answers in class before the teacher’s question has been completed, not waiting their turn, and interrupting often or intruding on others’ conversations or games (Waslick & Greenhill, 1997).
Many of these symptoms occur from time to time in normal children. However, in children with ADHD they occur very frequently and in several settings, at home and at school, or when visiting with friends, and they interfere with the child’s functioning. Children suffering from ADHD may perform poorly at school; they may be unpopular with their peers, if other children perceive them as being unusual or a nuisance; and their behavior can present significant challenges for parents, leading some to be overly harsh (DSM-IV).
Inattention tends to persist through childhood and adolescence into adulthood, while the symptoms of motor hyperactivity and impulsivity tend to diminish with age. Many children with ADHD develop learning difficulties that may not improve with treatment (Mannuzza et al., 1993). Hyperactive behavior is often associated with the development of other disruptive disorders, particularly conduct and oppositional-defiant disorder (see Disruptive Disorders). The reason for the relationship is not known. Some believe that the impulsivity and heedlessness associated with ADHD interfere with social learning or with close social bonds with parents in a way that predisposes to the development of behavior disorders (Barkley, 1998).
Even though a great many children with this disorder ultimately adjust (Mannuzza et al., 1998), some—especially those with an associated conduct or oppositional-defiant disorder—are more likely to drop out of school and fare more poorly in their later careers than children without ADHD. As they grow older, some teens who have had severe ADHD since middle childhood experience periods of anxiety or depression. This seems to be especially common in children whose predominant symptom is inattention (Morgan et al., 1996)....
ADHD, which is the most commonly diagnosed behavioral disorder of childhood, occurs in 3 to 5 percent of school-age children in a 6-month period (Anderson et al., 1987; Bird et al., 1988; Esser et al., 1990; Pelham et al., 1992; Shaffer et al., 1996c; Wolraich et al., 1996).
We don’t have any solid knowledge about the origins of ADHD, but it is believed to include some very basic genetic, prenatal, and neurotransmitter problems. It is thought that children with ADHD do not have enough dopamine -- a neurotransmitter that has a lot to do with controlling behavior -- in their nervous system. It does seem to run in families, so a genetic factor is likely. And ADHD occurs more often in children from mothers who smoked while pregnant, in children exposed to lead, and in children who suffered from anoxia (low oxygen) before or during birth. (Whittaker et al., 1997).
Treatment of children with ADHD usually involves two approaches: Medication and behavioral training. The behaviorial training involves the parents as much as the child, and usually includes finding the appropriate ways of rewarding and punishing the child, including rewarding with attention and the famous “time-out” approach.
Medication takes the form of amphetamines and amphetamine-like stimulants such as the well-known ritalin. Research shows that stimulants are effective in 75 to 90% of all ADHD children (Spencer et al., 1995; Greenhill, 1998a, 1998b; Greenhill et al., 1998). Many peple have expressed some concern that we are overdiagnosing and overmedicating children, and that ritalin is just a way teachers and parents get rid of annoying kids. But there is, in fact, little evidence of this (Goldman et al., 1998; Jensen et al., 1999).
All this said, it should nevertheless be noted that some researchers see ADHD as a false category, and the use of stimulants akin to the way in which cocaine (or coffee) makes the average person temporarily more creative and productive. In fact, coffee has been used with some success in helping ADHD kids!
Stuttering, Tics, and Tourette's Syndrome
There are a number of problems kids face that involve neuromotor dysfunction. One of the most common is stuttering, which is found in about 1% of all children. It is found 3 times more commonly in boys. The good new is that 60% of stutterers recover on their own, usually by the age of 16. With the help of speech therapists, another 20% recover as well. Stuttering is strongly connected to anxiety, and it often disappears when the child is relaxed or, for example, when they are singing!
Somewhat more problematic are tics, which are repetitive abnormal movements that cannot be controlled. Most of us think of facial tics -- a repetitive squint or upward jerk of the cheek and so on. But some tics are far more dramatic. fFor example, their are various twisting movements, where the person's arm moves out like a snake, or dancing movements involving the whole body, even such tics as sudden deep knee bends. Like stuttering, tics are strongly associated with anxiety and therapy often concentrates on developing a relaxed attitude that diminishes the severity of the tics.
The most severe tics are found in people with Tourette's Syndrome. This is usually a life-long problem involving many different kinds of tics. Fortunately, it is very rare -- about 5 in 10,000 people. They may have tics involving complex movements, such as touching things or full body motions. Most characteristics of Tourette's are vocal tics, including a variety of clicks, grunts, barks, snorts, and coughs. About 10% of Tourette's sufferers have what is called coprolalia, which is the involuntary shouting of obscenities. Often the obscenities are situational, so that when the person is dealing with a woman, they may be unable to restrain themselves from shouting "bitch!" or when dealing with an African American, they may shout "nigger!" That might seem amusing, until you put yourself in their shoes.
Separation anxiety is a very common problem among children, especially younger ones. It is found in about 4% of kids. The problem is excessive anxiety about separation from the child's parents, other family members, or even their home. When separated, they become withdrawn and depressed and may have difficulty concentrating. They often develop other fears, anxiety about death, and nightmares. Of course, some separation anxiety is a normal part of childhood, so this can be a bit of a subjective call.
Separation anxiety usually occurs in tight, loving families. It often begins with some kind of life stress, such as moving to a new home or town, starting at a new school, or the death of a pet or relative. fortunately, for most children, it ends sometime in adolescence if not earlier.
Children or adolescents with conduct disorder behave aggressively by fighting, bullying, intimidating, physically assaulting, sexually coercing, and/or being cruel to people or animals. Vandalism with deliberate destruction of property, for example, setting fires or smashing windows, is common, as are theft; truancy; and early tobacco, alcohol, and substance use and abuse; and precocious sexual activity. Girls with a conduct disorder are prone to running away from home and may become involved in prostitution. The behavior interferes with performance at school or work, so that individuals with this disorder rarely perform at the level predicted by their IQ or age. Their relationships with peers and adults are often poor. They have higher injury rates and are prone to school expulsion and problems with the law. Sexually transmitted diseases are common. If they have been removed from home, they may have difficulty staying in an adoptive or foster family or group home, and this may further complicate their development. Rates of depression, suicidal thoughts, suicide attempts, and suicide itself are all higher in children diagnosed with a conduct disorder (Shaffer et al., 1996b).
The etiology of conduct disorder is not fully known. Studies of twins and adopted children suggest that conduct disorder has both biological (including genetic) and psychosocial components (Hendren & Mullen, 1997). Social risk factors for conduct disorder include early maternal rejection, separation from parents with no adequate alternative caregiver available, early institutionalization, family neglect, abuse or violence, parents’ psychiatric illness, parental marital discord, large family size, crowding, and poverty (Loeber & Stouthamer-Loeber, 1986).... Physical risk factors for conduct disorder include neurological damage caused by birth complications or low birthweight, attention-deficit/hyperactivity disorder, fearlessness and stimulation-seeking behavior, learning impairments, autonomic underarousal, and insensitivity to physical pain and punishment. A child with both social deprivation and any of these neurological conditions is most susceptible to conduct disorder (Raine et al., 1998)....
Studies have shown a correlation between the behavior and attributes of 3-year-olds and the aggressive behavior of these children at ages 11 to 13 (Raine et al., 1998).
Among children from 9 to 17, we find between 1 and 4 percent showing evidence of conduct disorder, and the problem being worse in the cities. Between 25 and 50% of these children are believed to develop into antisocial adults.
Treatment of children with conduct disorder tends to focus on making their family lives happier and more consistent. If the parents or other caretakers are responsive, there are programs that teach them how to use rewards and punishments more effectively. For many of these kids, it is a matter of trying to find a home for them at all! Medications have not been found to help.