Origin of mental illnesses
History of theories about mental illness
Mental illness in the ancient world
Over the history of the healing arts, there has been an evolution of theories regarding the root causes of mental illness. Early writings from such ancient civilizations as those of Greece, Rome, India, and Egypt focused on demonic possession as the cause. This concept eventually disappeared only to resurface again in the Middle Ages in Europe, along with inadequate treatment of the mentally ill. Demons or "foul spirits" were believed to attach themselves to individuals and make them depressed ("poor-spirited") or "mad." The word mad became an early synonym for psychosis . Unfortunately, the "possessed" included people with seizure disorders as well as others suffering from what are now known to be medical disorders. Few genuinely helpful treatments were available to relieve the suffering of the mentally ill.
The Hippocratic tradition
Hippocrates, a Greek physician who lived around 400 B.C. and is regarded as the source of the Hippocratic Oath taken by modern physicians, first introduced the concept of disturbed physiology (organic processes or functions) as the basis for all illnesses, mental or otherwise. Hippocrates did not describe disturbances of the nervous system as we do today, in terms of a chemical imbalance or a low level of neurotransmitters (neurotransmitters are the chemical messengers sent between brain cells). Instead, he used the notion of an imbalance of "humors." Humors were defined as bodily fluids, and were believed to be influenced by the environment, the weather, foods, and so on, producing various imbalances in a person's state of health. Hippocrates' theory was an early version of the idea that physiological disturbances or body chemistry might play a role in the development of mental illness. Most importantly, perhaps, Hippocrates' concept placed mental illness on the same footing as other medical disorders by highlighting the belief that the mentally ill are genuinely suffering, and therefore to be treated like other sick persons rather than as moral degenerates. Sadly, modern society has not fully overcome the tendency to stigmatize persons with mental disorders. Hippocrates' more "enlightened" perspective, however, meant that someone with depression or schizophrenia could be viewed as being in a state of "dis-ease," just like a diabetic or someone with high blood pressure.
The nineteenth century
Toward the end of the nineteenth century, several European neurologists began actively investigating the causes of mental illness. Chief among them, and destined to change forever the understanding of mental illness, was Sigmund Freud. Although psychology and psychiatry have advanced considerably since Freud (as have other fields of medicine), his explorations were revolutionary. Freud introduced the concepts of the unconscious and the ego to modern thought, and reintroduced the ancient art of dream interpretation, but from a psychological standpoint. Freud also regarded human psychological states as an energy system in which blockages in the flow of thought (repression or suppression, for example) would result in disease or illness, expressed as mental or emotional loss of balance. He introduced the notion of a "talking cure"; through the use of talk therapy alone, many patients would improve. This method of treatment is still used today, although the technique of talk therapy itself has undergone further development. Freud's early advances in understanding the mind, however, awaited further anatomical and biochemical discoveries of the structures and functions of the human brain. As a result, early psychiatry (from two Greek words, psyche , meaning "soul" or "mind," and iatros , meaning "physician") split into two competing traditions, one that followed Freud in emphasizing thoughts, emotions and dreams as keys to the healing of mental disorders, and another that looked for clues to these disorders in the tissues of the brain.
In the first half of the twentieth century, psychiatry was advanced by the discovery of medications that helped to alleviate depression, mania, and psychosis. As often occurs in the history of medicine, physicians stumbled upon solutions before they understood the mechanisms that made the treatment work. Later studies began to reveal that certain patients responded to medications that increased certain neurotransmitters. Drugs that increased the levels of the neurotransmitters norepinephrine and serotonin seemed to help depressed patients. Similarly, medications that blocked the transmission of dopamine, another neurotransmitter, provided relief for patients suffering from hallucinations and paranoia . These insights have led to the present emphasis on the biochemistry of the human brain. If, however, the biochemical model becomes the only view of mental health, modern psychiatry risks becoming "mindless." Clearly, a unified theory is needed to understand all the factors that contribute to mental disorders, and to do justice to the complexity of each human being. Understanding all the factors that lead to a disease state has much to do with an adequate treatment response.
Nature and nurture
One attempt to unify the varied theories regarding the origin of mental illness is called simply the "nature versus nurture" theory. It is really the "nature and nurture" theory, however, as it establishes the importance of two forces in the development of mental illness. For example, "nature" refers to biological factors that produce a tendency or predisposition to develop certain diseases. For instance, parents who have high blood pressure have offspring who have a higher probability of developing the same condition. If, on the other hand, these offspring learn to eat properly, exercise, and live in a relatively peaceful home, for instance, they may be able to avoid the expression of high blood pressure that runs in their family. This example illustrates the impact that a person's environment may have on the development of physical disease. Researchers believe the same holds true for mental illnesses. For example, researchers know that patients with schizophrenia who return to a family environment in which there is a high level of expressed emotion, such as critical and angry remarks, have more frequent psychotic episodes that require hospitalization . Thus, it appears that the interaction between the biological and psychological dimensions of a person and his or her environment determines the likelihood of expressing a mental illness, or perhaps any illness whatsoever. There is, however, no accurate prediction or test that will determine whether or not a specific person will develop a certain mental illness, even if many members of his or her are positive for that disease.
Conversely, a child with minimal genetic predisposition to mental illness may develop mental illness if he or she is traumatized in any number of ways, such as being raised in a non-nurturing or a physically, mentally, or emotionally abusive household. As of 2002, scientists do not know why some people become mentally ill while others do not. Much research remains to be done; although theories abound, the precise etiology or origin of all mental illnesses remains uncertain.
Current theories about the origin of mental disorders
GENETICS. Genetics is at this time an important area of research for psychiatric disorders. For example, a specific gene has been associated with bipolar disorder (also known as manic-depressive disorder), but unfortunately, the °switch" that controls the expression of the disorder is still unknown. It is presently thought that many genes go into the expression or nonexpression of any human characteristic, such as a facial feature or a certain aspect of mental health. Research done on identical twins has provided strong support for a genetic component in the development of schizophrenia. For instance, the average person in the United States has a 1% chance of developing schizophrenia, while the identical twin of a person diagnosed with schizophrenia has a 50% chance, even if he or she has been reared by adoptive parents. Other researchers who are studying schizophrenia have found that during embryonic development, there are nerve cells that do not migrate to their proper position in the brain. On the other hand, none of the genetic or embryological findings can account for the rare but occasional recoveries from schizophrenia, indicating that biology alone does not determine the occurrence of mental disorders.
Dementias are also noted to run in families, but most of these disorders cannot be predicted with any certainty for the following generation. Only one disorder, Huntington's chorea, which is really a movement disorder with a psychiatric component, appears to be determined by a single gene. Dementia of the Alzheimer's type does seem to have familial pattern, but again, the expression of the disease in any specific individual is not predictable at this time. Scientists believe that similar statements can be made for many mental disorders that run in families, such as obsessive-compulsive disorder (OCD), depression, anxiety, and panic disorder . The roles of the environment and learning behavior in the ultimate expression of genetically predisposed individuals are, however, undisputed.
NEUROTRANSMITTER-RELATED CHEMICAL IMBALANCES. This theory regarding the origin of mental disorders has become the foundation of most psychiatric treatment today. It has legitimized psychiatry by returning it to the world of biological medicine. Diabetes may offer a helpful analogy. In diabetes, a chemical necessary to health (insulin) is missing and can be replaced, essentially restoring the patient's health. In mental illness, the neurotransmitters in the brain may be present in insufficient amounts. These chemicals or transmitters allow communication between nerve cells; as a result, they coordinate information processing throughout the brain. As a person reads, for example, chemical levels rise and fall in response to the letters; the meaning they have; the reader's eye movements, thoughts, reflections and associations; and to the feelings the reader may have while reading. Thus, a person's brain chemistry is changed by everything that influences him or her, whether internally or externally. While the discovery of certain neurotransmitters and their roles in mental disorders has led in turn to the discovery of effective medications to treat these disorders, it has also resulted in the unfortunate notion that medication is the only method of treatment that is helpful.
Major neurotransmitters identified thus far include acetylcholine, dopamine, epinephrine, norepinephrine, histamine, and serotonin. Serotonin and norepinephrine are most highly implicated in depression, panic disorder and anxiety, as well as OCD. Most of the medications found effective for these disorders are drugs that increase the availability of serotonin and norepinephrine (such as selective serotonin re-uptake inhibitors, or SSRIs). In particular, depression, panic disorder, anxiety disorders, and OCD have responded strongly to medications that increase serotonin levels. On the other hand, medications that block the effects of dopamine in certain parts of the brain are effective in controlling auditory and visual hallucinations as well as paranoia in patients with psychotic disorders.
STRESS-RELATED FACTORS. Stress is something everyone in modern society seems to understand. There are two basic kinds of stress: inner stress from previous traumas or wounds that affect one's present life; and outer stress, or the environmental issues that complicate life on a daily basis, such as work or family problems. The interplay of these two forms of stress affects brain chemistry just as it can affect physical health. Numerous studies have shown that when people are chronically stressed in life, they are vulnerable to depression, anxiety, and other disorders. Interestingly, 70% of the adults in one recent European war situation were found to have depression, which is a normal human response to relentless stress. Researchers presently think that the mechanism that triggers this depression is the depletion of certain neurotransmitters, particularly serotonin and norepinephrine, which may lead to other biochemical imbalances. For instance, most people diagnosed with schizophrenia have their first psychotic episode during such stressful situations as leaving home for college or military service.
Genetic factors may add to a person's susceptibility to mental illness by lowering the body's production of neurotransmitters during difficult life transitions. The same combination of circumstances might affect the development of high blood pressure, diabetes, or ulcers in some families.
MEDICAL CONDITIONS. It is important to note that bacterial and viral infections, metabolic illnesses, medications and street drugs can all affect a person's mental status. Insults (injuries) to the brain can cause a person to be disoriented, speak incoherently, have difficulty concentrating, hallucinate, or even act out violently. When clinicians see disorientation and an abrupt change in a person's level of alertness, they refer to the altered mental state as delirium . Delirium is considered a medical emergency because the underlying cause must be identified and treated as quickly as possible. The exact way in which infectious disease and chemical agents change human mental function is unclear, and thus may not be visible on imaging studies .
The elderly are particularly vulnerable to changes in mental status resulting from apparently minor changes in body chemistry. Fever, dehydration, electrolyte imbalances, and even aspirin or antibiotics can all have an abrupt effect on the mental status of the elderly. Older people are susceptible simply because older brain tissue is more sensitive to the slightest change in metabolism or the presence of toxins.
Certain diseases have severe effects on the brain. An example is HIV/AIDS, in which approximately 70% of patients suffering from full-blown AIDS develop dementia, depression, or delirium. Similarly, at least 50% of patients with multiple sclerosis develop depression from the effects of the disease on brain tissues—not simply as a reaction to knowing that they have MS. Any infectious disease that causes inflammation inside the skull, such as meningitis or encephalitis, will usually result in some change in mental status; fortunately, these changes are usually completely reversible.
Recently, there has been an exciting development involving infectious disease and OCD as exemplified by "PANDAS," the acronym for Pediatric Autoimmune Neuropsychiatric Disorder Associated with Group A Streptococcus. Group A Streptococcus is an autoimmune disorder thought to cause OCD symptoms (neuropsychiatric symptoms) in children with streptococcal infection of the tonsils and pharynx (more commonly known as strep throat). The OCD symptoms resolve when the infection is treated with antibiotics. The neuropsychiatric symptoms are believed to result from an autoimmune reaction, meaning that antibodies made to fight the bacteria mistakenly attack part of the brain, resulting in symptoms of OCD. The discovery of this connection between a streptococcal infection and an autoimmune reaction may have great importance for treating certain mental illnesses in the future, since links between the onset of psychiatric disorders and physical infections have been observed from time to time.
Disorders of metabolism can certainly mimic depression, anxiety and sometimes, even psychosis. Overproduction of thyroid hormone (thyrotoxicosis) can cause agitation, anxiety, mania and even psychosis; while a lack of thyroid hormone produces symptoms of depression and is routinely checked in patients with depression of recent onset. Imbalances in glucose (sugar) management can result in mood swings and should always be evaluated. Less commonly, malfunctions of the adrenal glands can profoundly affect a person's energy level and mental activity. The role of estrogen in postmenopausal depression has been intensively studied in recent years, but the findings remain inconclusive.
NEUROPATHOLOGY. Neuropathology refers to damage to the brain tissue itself that results in mental illness. Dementias are placed in this category, since the brains of persons diagnosed with dementia exhibit microscopic changes in tissue structure when viewed under a microscope. These changes may ultimately appear on tests such as a CAT scan of the brain. Larger changes are seen with strokes, which result when the blood supply is cut off to a specific area of the brain and causes localized damage. In these instances, a person may have altered speech patterns but retain the ability to think clearly, or vice versa. The losses are somewhat predictable and specific, based on the area of the brain that was affected and the extent of oxygen starvation of the tissue in that region.
Brain tumors and accidental injuries are random in their effects, and the deficits are usually less predictable. Each case must be examined individually. As with strokes, however, the location of the injury or tumor will determine the resulting mental status changes or deficits.
Pancreatic and certain colon cancers are particularly interesting for psychiatrists. For reasons that are unknown as of 2002, these tumors are frequently accompanied by depression even though they are located in organs that are far removed from the brain. More research is needed on the relationship between mood disorders and certain illnesses; it is possible that the tumor releases compounds into the bloodstream that have depressive effects.
NUTRITIONAL FACTORS. There is no doubt that poor nutrition leads to mental imbalances. While few people in the United States are truly starving or completely depleted nutritionally, instances of mental disorders related to malnutrition still occur in this country. The B vitamins are essential for mental clarity and stability. Insufficient amounts of the B vitamins, which include thiamin, nicotinamide, pyridoxine, and B, can result in confusion, irritability, insomnia , depression, and in extreme cases, psychosis. The body does not store these vitamins, so one should monitor one's daily intake to ensure a sufficient supply. Tryptophan is an amino acid and supplement that is a building block for serotonin, the neurotransmitter that has been found to be essential in treating depression, anxiety, panic, and OCD, among others. Tryptophan is so important nutritionally that studies have shown that its absence in the diet will result in depression even when the person is taking a prescription antidepressant to increase the availability of serotonin.
PSYCHODYNAMIC THEORIES. Freud certainly opened the doors for humans to understand themselves in terms of psychology, or the notion that how one thinks and feels affects one's view of the world. Freud also found that simple conversation could help some very sick people out of depressions and other mental disorders. His work essentially demonstrated that extreme inner conflicts can become a source of mental illness. These extreme internal conflicts can occur, for instance, when one loves another deeply but also feels that that person is hurting them or limiting their development in some way. If the person who is causing pain or hindering growth is a parent or other powerful figure, these intense feelings can be hidden away or repressed. Also, a lack of honesty about reality can lead to any number of illnesses. For instance, feelings of anger and powerlessness, if unrecognized, may place the person at risk for developing aggressive behaviors or depression if insights and appropriate coping skills are not gained. These psychological dis-harmonies, if ignored, can lead to dis-ease if they are sufficiently intense or associated with central relationships in the person's life.
Freud's view of psychological conflicts as rooted in sexual repression was questioned by Jung, a psychiatrist and protégé of Freud, who felt that people's lives were affected by deep spiritual forces. Jung's work centered on psychological imbalances stemming from spiritual distress. There were other theorists after Freud, such as Adler, who regarded power as the central motivating force of human personality, or Melanie Klein, who emphasized the significance of envy.
Since the Second World War, behavioral and cognitive theories have emphasized the role of learning in the development of mental disorders. Children growing up in an abusive home, for example, may be "rewarded" by not getting beaten if they learn to be quiet and internalize everything. This internalized state may be a precursor of full-blown depression in later years. Unconscious assumptions based on early experiences may spill over into other situations later in life. As another example, children may learn to be "good" for their parents or society by taking on careers they don't like or belief systems that don't fit them, all for approval by the perceived higher authority.
Cognitive approaches to therapy maintain that people construct their view of the world from beliefs and feelings based on deeper assumptions about their own competencies. Depression, for instance, would be seen as a spiral downward into negative "self-talk" and feelings of inadequacy. Re-examining these negative assumptions then breaks the cycle based on erroneous thinking (cognition) which is causing the depression, anxiety, or aberrant behavior. Studies have shown that three months of cognitive therapy is as effective as medication in the treatment of depression. This finding shows clearly that talk therapy does change the chemistry of the brain.
TRAUMA-RELATED FACTORS. Psychological traumas refer to events that are outside the experience of everyday life, although the exact definition of a traumatic experience may vary from person to person, country to country, and century to century. Traumas in early life, such as sexual or physical abuse , can lead to mood disorders and contribute to the development of personality disorders . Horrendous early traumas involving torture of a child, other people, or animals, may result in dissociative identity disorder , formerly called multiple personality disorder. Dissociation is a self-protective mechanism for separating conscious awareness from repeated traumas. It has sometimes been described as self-hypnosis, but most clinicians believe that it is not under the patient's control, at least initially.
In later life, such severe traumas as war, rape, natural disasters, or any similar event, can lead to psychiatric difficulties. Post-traumatic stress disorder (PTSD) is a well-known disorder that affects war veterans. Extreme trauma causes the brain to record impressions in a way that is different from ordinary formation of memories. These disjointed impressions may re-emerge as flashbacks months or years after the traumatic experience. Chronic and repetitive trauma, exemplified by intermittent abuse or hostage situations, can lead to a chronic form of PTSD as well.
A subcategory of psychiatric disorders that occur in response to traumatic shock are termed fugue states. Fugue states are poorly understood, but can be described as conditions of total memory loss after witnessing an overwhelmingly horrible accident or atrocity. These states of memory loss can last from minutes to years.
SOCIOCULTURAL FACTORS. Some mental disorders are influenced by social values and social interactions shaped by those values. Anorexia nervosa , bulimia nervosa , and body dysmorphic disorder are the most commonly used examples of mental illnesses in this category. With the increased visibility of unnaturally slender women in modern society (as seen everywhere in advertising, television shows, movies, and celebrity fan magazines) doctors have seen a tremendous rise in the occurrence eating disorders. "You can never be too thin or too rich," a saying attributed to the Duchess of Windsor, is a phrase that has many women, and some men, monitoring their every ounce of food intake. The core of the illness is a lack of self-esteem combined with feelings that one's world is out of control. Some clinicians add fear of sexual maturation to this list of psychological causes of eating disorders. The common denominator is that these patients apparently believe they can control their world by controlling their food intake. Although neurotransmitter deficits have been found in patients with bulimia, whose vomiting may actually change their body chemistry, the desire to be thin is the conscious motivating force.
Modern society also values activity over rest, doing over being, thinking over feeling, resulting in many people becoming slaves to work and productivity, and having little respect for their inner life. Many cases of mild stress-related disorders run the risk of developing into full-blown generalized anxiety, panic, and depressive disorders. Mental health requires a reasonable balance between work and activity on the one hand and periods of rest and relaxation on the other.
ALCOHOL AND SUBSTANCE ABUSE. Alcohol is a central nervous system depressant. It plays a prominent role in the development of at least depression and is often involved in other mental disorders. In addition, people who abuse alcohol are at increased risk of mental disorders related to nutritional deficiencies. A lack of thiamin, a B-vitamin, can result in permanent brain damage in the form of severe dementia even at an early age. People in withdrawal from alcohol are also at risk for delirium tremens, a serious condition that can result in cardiovascular shock and death.
Street drugs are well known for their effects on young people's mood and behavior. Permanent brain damage may result from the use of some "designer" drugs. One example is "Ecstasy," which can cause permanent memory loss and severe depression that responds only slowly to treatment. Street drugs must always be considered as a possible factor in the sudden onset of a mental illness in a young person. Moreover, drugs may precipitate a first psychotic episode in a person with a genetic predisposition to schizophrenia. In this case, the drug is the stressor that reveals the person's dormant susceptibility to the disorder.
Current theory and future directions
The biopsychosocial model of mental illness
All of the above factors are most succinctly summarized in terms of the biopsychosocial model of mental illness. Biological contributions, thoughts and perceptions, social pressures, and environmental stressors, the presence or absence of nurturing and consistency of love, core values, and self-worth are just a few of the things that contribute to making up the psychological uniqueness of every human being on the planet. In addition to the above, researchers are actively examining the role of spirituality in mental health and recovery. No one factor can be said to be the sole cause of mental illness; rather, disorders result from a complex set of forces that act upon each person as an individual. Finding the various elements that contributed to the onset of an illness requires considerable patience from the patient, his or her family, and health workers. Identifying all factors, if possible, provides the best road map for the healing process.
In the future, scientists will certainly modify and expand our thought-models about the mind and brain. For example, a new treatment called transcranial magnetic stimulation (TMS) is being evaluated as an alternative to electric shock therapy. TMS uses powerful magnets instead of electricity, and is delivered to specific areas of the brain. Hence, in the future scientists must integrate some of the electromagnetic aspects of nature into the mind-brain puzzle. In addition, the National Institute of Mental Health (NIMH) is researching alternative healing modalities. Prominent among them is acupuncture , which has been used to treat depression, anxiety and panic disorder. Other alternative treatments being studied include the effects of prayer, meditation , creative writing, and yoga .
Deeper exploration of the human condition is both inevitable and desirable. Perhaps researchers will find better answers by asking the question, "What makes people healthy?" instead of simply looking at what makes us sick. In the end, researchers may find proof of some of the ancient truths taught by spiritual teachers from all traditions; and that the physical changes seen with human eyes or under a microscope are really just the symptoms of and not the causes of imbalances.
American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. 4th edition, text revised. Washington DC: American Psychiatric Association, 2000.
Kaplan, Harold I., and Benjamin J. Sadock. Kaplan and Sadock's Synopsis of Psychiatry: Behavioral Sciences–Clinical Psychiatry. Eighth edition. Philadelphia: Lippincott Williams and Wilkins, 1998.
Beth A. Bollinger, M.D.