Lesson 1: Predisposition, Biological Factors, and the Brain

Section/Lesson Objectives

     The student will ...

• Understand and describe how predisposition, biological factors, and the brain interact to cause abnormal behaviour [This lesson]
• Determine the genetic syndrome a person has from evaluating his or her karyotype [This lesson]
• Describe what constitutional liabilities are and how they relate to mental illnesses [This lesson]
• Explain how nutrition affects mental health [This lesson]
• State how physical deprivation can negatively affect mental health [This lesson]
   • Give examples of how psychosocial factors affect behaviour
   • Describe the Johari window and apply it to different scenarios
   • Discuss the effects of bullying
   • Differentiate between the way various cultures view abnormalityy
   • Understand and describe how sociocultural factors affect mental health

Introduction

In the lesson content you will come across some terms in maroon color that are bolded. Look them up in the course Glossary.

Terminology

For a person to go to bed one night as “normal” and then wake up the next morning with some form of mental illness would be unusual. Mental illness rarely resembles a light switch – normal one minute, then, with a flick of the switch, abnormal the next. To some degree everyone has vulnerabilities with respect to behaviour. Whether these vulnerabilities affect our behaviour in a negative way depends on the nature, number, and degree of the vulnerabilities we have, combined with the stressors we face in our lives.

In psychology, the term predisposition is often used when discussing abnormal behaviour. Predisposition is the tendency of a person with vulnerabilities to develop a psychological disorder given the appropriate environmental circumstances. These circumstances, or stressors, need not be the same for each person. Vulnerabilities also vary widely. For example, one can have biological or genetic vulnerabilities, experiential vulnerabilities (traumatic events in childhood), or skill deficit vulnerabilities (poor or non-existent coping mechanisms).

In addition to predisposition and vulnerability, the concepts of primary cause and precipitating cause are important when discussing reasons for abnormal behaviour. Although not always obvious to an observer, all mental illnesses have primary causes. For a person with hoplophobia (a fear of guns), the primary cause could be that he or she witnessed a gun-related murder as a child. Precipitating causes are like a collection of children’s building blocks being stacked one upon the other until a point at which, if even the smallest block is added, the entire pile falls to the ground. In this example, the last block is the precipitating cause of the fall of the structure. When comparing building blocks with human stressors, the size and number of total blocks before the collapse differs for each person.

Biological Causal Factors in Abnormal Behaviour

All behaviour, abnormal or not, is controlled by biochemical processes. Biological factors affect all aspects of behaviour including intellectual capabilities, temperament, stress tolerance, and more. The act of reading this paragraph is activating numerous sensory processes (feeling the paper, having your retinas receive electromagnetic radiation or light), motor processes (moving your eyes, changing the amount of light allowed into your eye), and neuronal processes (the conduction of nerve messages), all of which are mediated by chemical transmissions. Understanding these processes, however, does not account for your motivation to read the information and then think about or understand what is written. To understand these (motivation, thinking, and understanding), one must address the psychological processes driving the behaviour. Biological factors can be categorized into four main areas. Please refer to Figure 5.1 for a graphical overview.

Genetics

Each of the four main categories of biological factors encompass a number of conditions that affect the quality and function of our bodies. They are not always independent of each other, and they occur in various combinations throughout the general population. The first category, genetics, reminds us that no two people have exactly the same genes - the exception being identical twins. Genes are the long molecules of deoxyribonucleic acid (DNA) that occur at various locations on chromosomes. Each individual has 23 pairs of chromosomes, and each chromosome usually contains over 60 000 genes that contribute to the physical and psychological distinctiveness of individuals. When a baby is conceived, he or she receives 23 chromosomes from the mother and 23 chromosomes from the father. This means, for each characteristic or trait an individual has, there are two sets of instructions. These individual sets of instructions for the same trait are called alleles.

The instructions in the alleles from each parent can be the same or different. For example, one parent may have straight hair and the other parent may have curly hair. The expression of these competing genes is determined by whether the genes or alleles are dominant or recessive. Some genes, like those for curly hair, are described as dominant. When linked with other instructions, they are expressed and the recessive genes are suppressed. A recessive gene (e.g., straight hair) is expressed only when matched with another recessive gene with identical instructions. Biologically speaking, the development of most mental illnesses is associated with recessive genes. If mental illness were the result of dominant genes, the expression in each generation would be practically guaranteed, resulting in a continuing disadvantage.

Many disorders are thought to be the result of a combination of genes instead of a single one. Problems may also arise if a gene is absent rather than present. An important point is that having a gene that has been linked to an illness this does not mean you will certainly acquire the illness. The opposite is also true. If a person does not possess the gene that has been linked to an illness, that person may not be safe from getting the disease. Mental illness is often far too complicated for simple links and associations! Behaviour, unlike physical characteristics (e.g., straight hair versus curly hair), is the result of the interaction among genes, hormones, and the environment.

Problems with entire chromosomes can also result in abnormalities. Humans have 46 chromosomes in all cells except the reproductive (sex) cells. These 46 chromosomes are divided into 23 pairs. Twenty-two of these pairs are called autosomes; they determine general structural and physiological characteristics. The remaining pair of chromosomes are the sex chromosomes. In human females, both of the sex chromosomes are designated X, while in the male, one chromosome is an X and the other is a Y. With each gender, male or female, the mother donates an X to her offspring. The other chromosome comes from the father. It can be either an X or a Y. If it is an X, the offspring is female. If the chromosome is a Y, the offspring is a male. In humans, the male determines the gender of the offspring.

Chromosomal Abnormalities

Major difficulties arise if not exactly 23 pairs are present in the offspring. Down syndrome, for example, results when a trisomy (three not two) of chromosome pair 21 occurs. Problems also occur if one chromosome from a pair is missing. Turner syndrome, for instance, is a condition in the sex chromosomes where a female has only one X (monosomy). When a scientist takes a sample of a person’s chromosomes and arranges them into pairs, the arrangement is called a karyotype. In a karyotype, any chromosomal anomalies may then be seen. Please see Figure 3-1 for an example of a karyotype.

Please click on the web site below to learn more about chromosome abnormalities and Down syndrome.

https://www.stanfordchildrens.org/en/topic/default?id=types-of-chromosome-abnormalities-90-P02158

The following karyotype shows the 23 sets of chromosomes. Notice the trisomy in pair 18. This trisomy is called Edwards syndrome, which results in severe heart malformations. Also notice the monosomy of chromosome 23. This female has Turner syndrome. Extreme chromosomal abnormalities often result in spontaneous abortions or stillbirths.

Figure 3-1:  Karyotype for Turner and Edwards Syndrome

Learn more about Turner's syndrome by watching this short video:

Edwards Syndrome:

 Klinefelter Syndrome

For characteristics of various chromosomal anomalies, please see Table 3.2.

Table 3.2: Chromosomal Anomalies

Table 5.2: The Gene Pool (Jeff Holubitsky, 1996)

• Children inherit 50 percent of their genes from each immediate biological parent, 25 percent from each grandparent and so on down the line.

• In the long run, siblings are likely to share about half of this genetic information, but it could be more or it could be less.

• Twin studies have shown that although twins are called identical, they rarely are.

• Most experts in behaviour genetics believe that most human characteristics are determined by both the genetic inheritance and the life experience of the individual.

• There are about 30,000 genes that are distinct proteins in the brain and 20,000 are specific to the brain.

• Because of all the combinations and cross-overs in the chromosomes, parents could theoretically produce thousands of children and no two would be genetically identical.

• Many conditions such as cystic fibrosis, Huntington’s Chorea, and Tourette syndrome appear to have genetic links. Once a disease is determined to have a genetic cause, that information can lead to treatment. Currently, the genes can’t be changed, but the genes aren’t causing the consequences – proteins, enzymes and cells do, and they can be altered.

• Researchers also suspect some broader conditions such as dyslexia may have a genetic origin. If that’s the case, early diagnosis could lead to more effective teaching methods for these children.

• Genetic researchers are examining schizophrenia and depression, but these conditions are difficult to clinically define, unlike specific physical ailments.

• A minority of Alzheimer’s cases appear to be associated with a defective gene, however, most cases don’t appear to have a genetic cause.

Misunderstood condition marked by sudden rage

A last example for this section is Fragile X syndrome. This syndrome is a rare genetically linked disorder that affects the mental ability of its sufferers and may make individuals overly aggressive. It is caused by a mutation of a gene on the X chromosome, the symptoms of which often resemble those of autism, hyperactivity, and attention deficit disorder. Please review the following article that describes the experiences of one family dealing with Fragile X syndrome. (Susan Ruttan, Edmo)

Aggressive, autistic, and affectionate are just a few ways to describe the Smiths’ three children.

When strangers glare at her often-unruly children, Jane Smith has a ready response. She’s given it so often that she’s had it printed up on a business card to hand out.

“Things can happen right out of the blue,” said mom Jane in an interview in the family home”.

To have a child with fragile X syndrome, say parents, is to face endless ignorance and misunderstanding about the genetically inherited condition that so severely affects their child.

Raising three children with fragile X, as Jane and John Smith have, is a burden to daunt all but the most dedicated parents. The Smiths’ three children, nine-year-old identical twins Bill and Ted and their little sister Joan, six, look like blond, bubbly angels.

Watching the kids at home after school, with Bill and Ted drawing pictures in the living room and Joan playing with her Barbies in her bedroom, they appear unexceptional.

Only the frantic, exhausting pace of their play, the twins’ limited speech, and the scratches on Joan’s arm hint at the challenges they pose.

Fragile X syndrome causes mental retardation and a variety of behavioral problems that may include autism and aggression. The mix of problems in each fragile X child is different; what unites them is a genetic test that proves they have the syndrome.

In the Smith’s family, all three of their children can burst into sudden rages, especially Bill and Joan.

Each of them may attack their siblings, destroy the furniture or hurt themselves. And of course, one raging child sets off the others. Three siblings with fragile X are more than the sum of their parts.

Constitutional Liabilities

Behavioural difficulties that appear to be genetic but are not the result of gene or chromosome abnormalities can often be attributed to constitutional liabilities. The word constitutional describes those characteristics that were acquired during development in the uterus and not through heredity. A liability refers to something that is a disadvantage to an individual. In short, a constitutional liability is a characteristic acquired in utero that is a disadvantage to the individual.

The first of three main types of constitutional liabilities relates to the physique or the form and structure of the human body. Attractive people, generally speaking, have advantages in life not shared by less attractive people. One need only look at the rich and famous to see that the majority of people in this category are attractive. Studies have shown that even incorrect impressions that a person is unattractive may enhance the risk of disorder (Noles, Cash, & Winstead, 1985). In extreme cases, some individuals undergo cosmetic surgery time and time again to correct perceived physical liabilities.

The second type of constitutional liability is physical handicaps. The results of embryologic problems (e.g., cleft palate, spina bifida), or drug-related effects (e.g., fetal alcohol spectrum disorder, central nervous system defects) are obvious, but the causes of many of the handicaps are not known.

This video provides some interesting information on fetal alcohol spectrum disorder, which is caused by the mother drinking alcohol while pregnant.  This disorder is 100% preventable and leaves the baby with a life long struggle, as many of the neurons in their brain are destroyed before they are even born.

Although it may be heartbreaking for parents to see their newborn with any deformity, cosmetic surgery for cleft palates can be quite effective. See Table 4.1 for “cleft facts” (Gordon Wilkes, 2004) and Figure 4.2 for a picture of a child with a cleft lip.

Table 4.1: Cleft Facts

Figure 4.2: A cleft lip is a separation of the upper lip that can extend into the nose.

The last type of liability refers to primary reaction tendencies. Babies differ in how they react to various stimuli. Some babies are easily startled while others are quite placid. The differences in reactions are examples of primary reaction tendencies. The way the babies react appears to have been established before birth, some of which may be related to early hormonal influences in utero. Current studies suggest the mix of hormones before birth relate to gender preferences. The power of hormones!

Brain Dysfunction

Effective brain functioning relies on the way nerve cells (neurons) transmit their messages across synapses (junction points) to the next neurons. Neurons are specialized in their shape and position. The neurons do not touch each other. Small gaps, called synapses, lie between neurons. To get a message across a synapse, neurons release chemicals called neurotransmitters. An electrical impulse travels along a neuron, but when it reaches the end of the neuron, instead of the electrical impulse travelling into the next cell, neurotransmitters are released. These neurotransmitters then travel into the synapse between the two neurons, seeking a specialized receptor where they can fit onto the next neuron. We have many types of neurotransmitters, and they are all shaped differently. To have an effect on another neuron, the neurotransmitter must fit into a site specifically designed for them. To visualize this process, think of the way that your house key can open only the door to your own house.

Different neurotransmitters have different effects in the body, but all neurotransmitters must be working properly for a person to be able to sleep, move, and even maintain a positive outlook on life. The following are some of the neurotransmitters found in the human body.

Acetycholine - functions in the parasympathetic division of the nervous system and helps to return increased heart rate to normal.

Dopamine - found in areas of the brain that manage movement, emotional arousal, learning, and memory.

Epinephrine - (both a hormone and neurotransmitter) increases heart rate and blood pressure

Serotonin - produced in the central nervous system and has a role in sleep and emotional arousal. Lack of serotonin production or availability in the synapses is thought to be responsible for severe depression in some individuals. People suffering from depression find difficulty experiencing any uplifting emotions or happiness. They may also have a very difficult time sleeping. Antidepressants, drugs that are chemically designed to keep serotonin in the synapse long enough to attach to another neuron and have its proper effect, have been used with great success in alleviating severe depression.

Neuron	Synapse with Neurotransmitters

Examples of disorders relating to brain dysfunction include Alzheimer’s, Parkinson’s, epilepsy, and Creutzfeldt-Jakob disease. The Internet provides the most current information on Creutzfeldt-Jakob disease.

Epilepsy

Epilepsy is a neurological disorder that occurs when abnormal electrical impulses occur in the brain. The impulses may involve the body seizing or convulsing. Seizures may occur randomly, and most are accompanied by a loss of consciousness. Some people may experience seizures many times per day while others may have years go by between seizures. Doctors believe that some epileptic seizures are caused by high fevers or infection, but other seizures seem to occur randomly with no specific detectable causes. Epilepsy is thought to have genetic links because it is more likely to appear in families. Treatment may involve medication that prevents convulsions. In severe circumstances, brain surgery may be an option. If the aberrant impulses are specific to certain areas of the brain, the brain surgery may involve cutting certain neural connections, thereby preventing the abnormal electrical impulses from affecting areas they should not.

Parkinson’s Disease

Parkinson’s disease occurs when a specific part of the brain starts to degenerate. This section, called the Substantia Nigra, contains cells that release the neurotransmitter dopamine that is thought to have some role in controlling movement. The symptoms of Parkinson’s disease include shaking, muscle rigidity while at rest, involuntary movements, inability to maintain a body position, difficulty moving, and problems producing speech.

The main challenge researchers face in developing a cure for Parkinson’s is finding some way to stop the degeneration of the Substantia Nigra. Until a cure for the degeneration can be discovered, doctors must treat this disease with medication that enables the body to keep dopamine in its system.

Physical Deprivation

People require food, air, water, sleep, and other fundamental components to survive. These are the basic needs of all humanity. If such essential components are interfered with for a prolonged period of time, the ability to deal with stress drops dramatically. Prisoners have sometimes been “broken” by nothing more persuasive than the systematic prevention of sleep or deprivation of food over several days (Carson, Butcher, Coleman, 1988). Experimental studies where volunteers deprived themselves of sleep for over three days (up to 98 hours) showed that the subjects became disoriented, irritable, anxious, paranoid, and unable to concentrate. Another study on semi-starvation (Keys, 1950) is illustrated.

Besides the example of hunger, one can also think of trying to carry out a normal workload or schedule when very ill with a flu. Both our ability to cope and our behaviour are negatively affected.

The second component of physical deprivation is stimulation – or rather, the lack thereof. The importance of stimulation received by an infant is crucial to healthy development. Since the 1940s, researchers have known that a child who receives inadequate stimulation is at risk for emotional difficulties. In fact, some institutionalized infants (orphans) who did not receive attention and human contact, wasted away and died. The consequence of infant death due to lack of stimulation was termed hospitalization syndrome. A study, performed by Harry Harlow in 1966, involved rhesus monkeys. This study showed the importance of love and attention in the development of offspring. The experiment was, unfortunately, cruel and unethical; for humane reasons it would not be performed by scientists in North America today.

The Brain and Nutrition

Our biological health requires basic nutrition; one of our fundamental needs is food. Food and drink, however, can be healthy or unhealthy. A child raised on hot dogs and soft drinks would be lacking in complete and balanced nutrition. The body (especially the brain) needs special materials for it to operate effectively. Like a car that needs oil, gas, and antifreeze to operate, our bodies need vitamins, minerals, and glucose. Our bodies are more particular, however. Too much or too little of a vitamin, for instance, can result in problems with our development. Some vitamins are water-soluble (e.g., vitamin C); if we ingest too much, we excrete what we do not use (usually in our urine). Other vitamins are fat-soluble (e.g., vitamin D). If we ingest too much, we gradually build up toxic levels of the compound in our fat cells.  See Table 6.1 for specific examples. 

                                                                                                                www.glasbergen.com

TABLE 6.1

Some vitamins and minerals required by our bodies are not naturally produced by our bodies. Using the food we eat, the body must manufacture these substances that include proteins and fats. The body does this by digesting the proteins and fats in food to make special proteins and fats for our brains to use. Not all fats are created equal, however. The “good” fats or lipids include the omega-3 and omega-6 fats. Low levels of such fats can cause visual problems as well as problems in motivation and motor co-ordination.

As referred to previously, neurotransmitters are an important part of brain functioning. Certain foods contain essential components responsible for the functioning of neurotransmitters. If a person’s diet is lacking in the required foods, neurological and emotional disorders may occur. See Table 5.5 for examples of some essential components.

TABLE 6.2.

The nutrition of a pregnant woman is important to the development of her fetus. Proper nutrition during the first two years of life is also important. Malnutrition during either of these periods of rapid brain growth may result in developmental difficulties, some of which are not reversible. In addition to proper nutrition, people need to avoid non-nutritive substances that may lead to addiction. The addicted brain is a complicated subject – neurobiologists have known for a long time that certain substances (alcohol, cocaine, even sugar) induce the activity of the brain’s reward system so much so that individuals may do anything to get a “fix” or “hit” of a drug, even at the expense of eating and sleeping! Addiction is discussed further in subsequent lessons.

The importance of nutritional health to mental health

The following two articles connect the importance of nutritional health to mental health. The first article (Robert Boyd, 1997) indicates that the “brain’s wiring begins in the womb”.

The second article (Shankar Vedantam, 1997) encourages people to keep their brains active!

Hemispherectomy

The brain is the organ that makes us unique from other people. It is the organ that orchestrates our behaviour and houses our personalities. The consequences of brain damage can be irreversible. It is possible, however, to improve behaviour and functioning with the removal of a part of the brain. People born with Sturge-Weber syndrome (a disorder of blood vessels in the brain), often suffer from epileptic seizures and may be given medication to control the outbursts. The medication, however, may result in unwanted side-effects. In one case, a boy on medication for epilepsy related to Sturge-Weber had the side-effect of not being able to speak. The boy’s mother, after doing some research, determined with the help of doctors, that the best course of action was to have one half of her son’s brain removed as that half was very badly damaged.

The boy underwent surgery to have half his brain removed - a hemispherectomy. After a speedy physical recovery, the boy was weaned off his medication and soon after said his first words. He no longer had epilepsy nor any of the accompanying behaviour problems. In some cases a hemispherectomy does nothing to improve the life of the affected individual, but many times it does. Sometimes IQ can also improve dramatically. Why this happens and how a person with half a brain can be better off than before is still a mystery.

Lesson Review

The brain is a fascinating subject, don't you think?

Assignment

Complete the following:

1.  S2L1Quiz -  You may refer to your lesson while you complete this assignment).