Epidemiology and methodology of suicide

# Overview
It is probable that the incidence of suicide is widely under-reported due to both religious and social pressures, and possibly completely unreported in some areas. Nevertheless, from the known suicides, certain trends are apparent. However, since the data is skewed, attempts to compare suicide rates between nations is statistically unwise. The trends themselves are not the cause, but may be indicative of a root cause.

# Epidemiology
A recent report by the World Health Organisation (WHO) states that nearly a million people take their own lives every year, more than those murdered or killed in war. WHO figures show a suicide takes place somewhere in the world every 40 seconds. Suicide rates are highest in Europe's Baltic states, where around 40 people per 100,000 die by suicide each year, second in line is in the Sub-Saharan Africa where 32 people per 100,000 die by suicide each year. The lowest rates are found mainly in Latin America and a few countries in Asia.
In 1998, the World Health Organization ranked suicide as the twelfth leading cause of death worldwide.
Worldwide, the incidence of suicides is higher than the incidence of intentional homicides, except in Latin America and among certain minority groups such as African-Americans.
According to the National Institute of Mental Health, suicide contagion is a serious problem, especially for young people. Suicide can be facilitated in vulnerable teens by exposure to real or fictional accounts of suicide, including media coverage of suicide, such as intensive reporting of the suicide of a celebrity or idol.

## Gender and suicide
In the United States, males are four times more likely to die by suicide than females. Male suicide rates are higher than females in all age groups (the ratio varies from 3:1 to 10:1). In other western countries, males are also much more likely to die by suicide than females (usually by a factor of 34:1). It was the 8th leading cause of death for males, and 19th leading cause of death for females.
Excess male mortality from suicide is also evident from data from non-Western countries. In 1979-81, out of 74 countries with a non-zero suicide rate, two reported equal rates for the sexes (Seychelles and Kenya), three reported female rates exceeding male rates (Papua-New Guinea, Macao, and French Guiana), while the remaining 69 countries had male suicide rates greater than female suicide rates.
While there are more completed male suicides than female, females are more likely to attempt suicide. One possible explanation of this statistical phenomenon, supported by a study by Rich, Ricketts, Fowler, and Young, is that males tend to use more "violent, immediately lethal methods of suicide" than females. Another explanation is that females are more likely to use self-harm as a cry for help or an extreme grab for attention, while suicidal males would be more likely to genuinely want to end their lives.

## Race and suicide
By race, in the United States, non-Hispanic whites are nearly 2.5 times more likely to kill themselves than are blacks or Hispanics. There is a marked divergence by age as seen in the chart below. Suicide rates for younger blacks and whites are approximately equal, but older whites, elderly white men especially, commit suicide far more often than older blacks. However, of all ethnic groups in the United States, Native Americans, people of mixed race, and Filipino Americans have the highest risk of suicide.

## Age and suicide
Children of either sex are 1020 times less likely to die by suicide, and teenagers 1.52 times less likely than adults of the same sex. The incidence of suicide among males over 75 years old is roughly twice that of other adult males.

## Social factors and suicide
Higher levels of social and national cohesion reduce suicide rates. Suicide levels are highest among the retired, unemployed, impoverished, divorced, the childless, urbanites, empty nesters, and other people who live alone. Suicide rates also rise during times of economic uncertainty (although poverty is not a direct cause, it can contribute to the risk of suicide). Epidemiological studies generally show a relationship between suicide or suicidal behaviors and socio-economic disadvantage, including limited educational achievement, homelessness, unemployment, economic dependence and contact with the police or justice system. War is always associated with a steep fall in suicides; for example, during World War I and World War II the rate fell markedly, even in neutral countries.

## Health and suicide
Mental disorders (particularly depression and substance abuse) are associated with more than 90% of all cases of suicide.
Depression, either unipolar or as part of bipolar disorder, is an especially common cause. Substance abuse, severe physical disease or infirmity are also recognized causes.
An unknown amount of suicide fatalities are misdiagnosed as consequences of severe illness.

## Season and suicide
The idea that suicide is more common during the winter holidays (including Christmas in the northern hemisphere) is actually a myth, generally reinforced by media coverage associating suicide with the holiday season. The National Center for Health Statistics found that suicides drop during the winter months, and peak during spring and early summer. Considering that there is a correlation between the winter season and rates of depression, there are theories that this might be accounted for by capability to commit suicide  and relative cheerfulness.  Suicide has also been linked to other seasonal factors.

## Suicide trends
Certain time trends can be related to the type of death. In the United Kingdom, for example, the steady rise in suicides from 1945 to 1965 was curtailed following the removal of carbon monoxide from domestic gas supplies which occurred with the change from coal gas to natural gas. Methods vary across cultures, and the easy availability of lethal agents and materials plays a role.
It is estimated that global annual suicide fatalities could rise to 1.5 million by 2020.
Worldwide, suicide ranks among the three leading causes of death among those aged 15-44 years. Suicide attempts are up to 20 times more frequent than completed suicides.

# High-risk groups
Several groups have a greater than average incidence of suicide. These high-risk groups usually are indicative of a larger problem leading to their decision.
These groups include:
- Males 65 and older.
- People who have lost a spouse, especially empty-nesters.
- People in poor health, especially those with chronic pain and/or with a terminal illness.
- Males who have recently divorced.
- Ethnic minorities
- Criminals on the run.
- Victims of spousal abuse.
- People who live in metropolitan areas.
- POWs, refugees, and internally displaced persons.
- The economically disadvantaged, usually those who are living in poverty and those who are homeless.
- Closeted homosexuals and bisexuals.
- Transsexuals, especially male-to-females.
- Youth aged 15-24 are, as a whole, not a high-risk group.  However, some of them are:
Gay and lesbian youth.
Native American youth.
Alaska Native youth.
Incarcerated youth.
Youth with access to firearms.
Youth engaging in high-risk sexual or drug related behavior.
Low income youth.
- Gay and lesbian youth.
- Native American youth.
- Alaska Native youth.
- Incarcerated youth.
- Youth with access to firearms.
- Youth engaging in high-risk sexual or drug related behavior.
- Low income youth.
- People who suffer from mental illness, especially bipolar disorder, major depression, borderline personality disorder, and schizophrenia.
- People who are disabled, such as blind, deaf, and/or paralyzed; those who were born with such disabilites are at high-risk.
- People who have previously attempted suicide.
- Victims of childhood sexual abuse or rape.
- People with no one to depend on emotionally (no friends or parents to talk to).

# Possible warning signs
The warning signs listed are not necessarily risk factors for suicide and may include common behaviors among distressed persons. Many people experience occasional mood swings and behavior changes that may not be due to depressive or suicidal thoughts.
- Giving away prized possessions
- Abrupt and extreme changes in eating and sleeping habits
- Loss of interests in activities normally enjoyed
- Negative comments about oneself
- Talking about attempting suicide
- Self harm
- Extreme lack of concern for personal safety
- Extreme interest in suicide.
- Preoccupation with death or tragedy.

# Causes
There is no single cause for which suicide can be directly attributed. Environmental factors, childhood upbringing, and mental illness each play a large role. Sociologists today consider external circumstances, such as a traumatic event, as a trigger instead of an actual independent cause. Suicides are more likely to occur during periods of socioeconomic, family and individual crisis. Most people with suicidal tendencies tend to suffer from some mental illness such as depression, bipolar disorder, or some degree of anxiety disorder. These diagnosable mental disorders are associated with more than 90% of suicide victims. As a result, many researchers study the causes of depression to understand the causes of suicide.
Many theories have been developed to explain the causes of suicide. Psychiatric theories emphasize mental illness. Psychological theories emphasise personality and poor coping skills, while sociological theories stress the influence of social and environmental pressures.

## Socio-Cultural Influences
Today, most social scientists believe that a society's unity can influence suicide deaths. Emile Durkheim claimed that greater social integration translates to fewer suicides. Suicide rates among adults are lower for married people than for divorced, widowed, or single people, a statistic confirming Durkheim's argument.
Although people with suicidal tendencies do not necessarily have greater life stress, they have a more difficulty coping with the stress that results. Suicide attempts usually follow a traumatic event.
Social influences such as economic cycles with high unemployment rates, influence of religion, acceptance, and peer pressure all play a factor. For example, suicide rates were abnormally high during the Great Depression in America.

## Biological Causes
Genetic and biological factors play a large role in suicide likelihood. Research has shown that suicidal behaviour runs in families. A notable example are the suicides of the Hemingway family in which five members committed suicide. In 1985, the American Journal of Medical Genetics studied an Amish community in Pennsylvania. The studies revealed that four families, representing only 16 percent of the total Amish population, accounted for 73 percent of all Amish suicides. Some scientists claim 10 to 15 genes account for triggering suicide attempts. Similarly how depression is linked genetically, family ties may also have a large effect on one's suicide risk.

## Psychological Theories
In the early 1900s Austrian psychoanalyst Sigmund Freud developed some of the first psychological theories of suicide. Karl Menninger followed up on this principle theory and suggested that all suicides have three interrelated emotions: revenge, depression, and guilt. Edwin Shneidman argues victims of suicide show a sense of unbearable psychological pain, a sense of isolation, and the perception that death is the only solution to their problems.

# Motivations
Those who have ended their lives throughout history have done so for a variety of reasons, both conscious and unconscious (particularly among those suffering psychological distress). Suicide is often seen as a means to end suffering, pain, or shame.
- Altruism/heroism. This is when someone voluntarily dies for the good of another or others. Examples include the Greek (Spartan) military at Thermopylae, Japanese kamikaze pilots, Buddhist monks and others who, starting in 1963, protested the persecution of Buddhists in South Vietnam by burning themselves to death as well as after the Fall of Saigon to protest the Communist regime(self-immolation), and elderly people, who, feeling themselves to be a burden on their families, no longer wish to bring such strain upon them.
- Tactical. Terrorists and guerilla factions often use suicide bombings and attacks to fight against a more powerful faction, as it prevents more casualties and is much more surprising and cost-effective than a normal attack.
- Philosophy. Certain philosophical groups (e.g., existentialists and stoics) have advocated suicide under some circumstances.
- Religion. Often, this takes the form of martyrdom. It was common in Norse believers and in early Christianity. However, it may be argued that martyrs are not suicides since martyrs are usually put to death by authorities opposed to the religion in question.
- In order to escape from an unbearable situation. Examples are numerous, and "unbearable" is defined according to the person who must experience it (such as a criminal proceeding or torture by one or more enemies). If one commits suicide to prevent oneself from betraying information to one's torturers, it could be classified under the Altruism motive.
- Psychiatric conditions, such as clinical depression or schizophrenia. On the other hand, a person who has committed suicide is more likely to be classified as such, for the sole reason that they committed the act, a "chicken or the egg" scenario.
- Romantic love or attraction (e.g., death or unattainability of the loved one). Although perhaps most celebrated among the young, as in Shakespeare's Romeo and Juliet, it is more common among elderly couples who have lived together for many years, after one of them dies. It also occurs among men frustrated at their repeated inability to form relationships with women. According to Dr. Brian Gilmartin, 36% of the love-shy men he interviewed contemplated suicide, but none of the non-shy men (see love-shyness and The Sorrows of Young Werther).
Theories of the effects of age on suicide have changed over time. Initially, it was believed that across all demographic populations, suicides increased with age. However, new research indicates that while this is true for men, suicide rates in women rate peak around the age of 35, plateau and only decline past the age of 85.
Theories about the effects of social status on suicide rates are diverse. This is partly due to difficulty in quantifying social status. Some theorists believe that suicide rates increase in direct proportion to social status. Others believe that the inverse is true.
Socio-economic factors such as unemployment, poverty, homelessness, and even discrimination trigger such suicidal thoughts. It's also noted that poverty may not be a direct cause but it can increase the risk of suicide, as it is a major risk group for depression. Discrimination and bullying is another major factor in suicides, as bullying and discrimination can lower self-esteem which could lead to depression and then suicide.
Suicide is more common among alcoholics, especially after loss of intimate relationships, such as the death of a spouse, divorce, loss of a friend and parental alienation. However, it is difficult to ascertain whether suicide and experience of loss by an alcoholic are causally related, since no data regarding causal relationships between alcoholism itself and suicide exists.
Terminal illness has not been shown to be directly linked to higher suicide rates. Despite this, physical illness is found in nearly half of suicides.
Divorced or separated men commit suicide 400% more than women. This may be due to a combination of legal and cultural tendencies that favor women in these situations. For example, 85% of protection orders are awarded to females, and only 7% of these petitions are denied. Since 1994, only 15% of American men are granted custody of their children in divorce settlements. Furthermore, when the father lives outside the home, 40% of children have no contact with them; the other 60% average just 69 days a year. These factors may help explain why divorce situations are higher risk.
On an individual level, the driving forces behind suicide vary across a range of themes. Common intentions behind suicidal actions include those of guilt, remorse, escapism and the provoking of guilt in those left behind. Media reports or local knowledge of a suicide can trigger copycat suicides in vulnerable people.

## Honor suicide
Various cultures have promoted the moral value and psycho-sociological conception that it is better for the individual to commit suicide than to "lose" honor. Examples can be seen in Japanese seppuku as well as in the classical Mediterranean cultures of Greece, Rome, and even among the ancient Hebrews.

# Evolutionary explanations
Evolutionary psychologists have developed several models to explain the apparent contradiction of suicide and evolutionary theory. Denys de Catanzaro has conducted a lot of research into this field. Others, such as Donald H. Rubinstein, and Anne Campbell have also done work in this field. The major difficulty for evolutionary psychologists is to explain why an organism would so deliberately harm its own potential reproductive capacity. Suicide seems to be perhaps the ultimate maladaptive trait, other than, perhaps, infanticide of one's own children.
De Catanzaro begins to explain suicide by saying that differential reproduction is in fact much more important to evolution than is "survival of the fittest". That is to say, that mere survival is not particularly important to passing on genes. Even if someone is short lived, but reproduces a lot, they are likely to have more descendants than someone who lives a long time but does not reproduce very much. The other factor in explaining from the evolutionary perspective is inclusive fitness. Since an individual will share many genes with their relatives, it is in their evolutionary interest to ensure their relatives' survival and reproduction. More of their genes will be present in subsequent generations.
De Catanzaro believes that a general theory of suicide can be formed based on a calculation of the "costs of an individual's immediate death to the propagation of his or her genes". He developed a very complex equation that takes the various factors of the subject's potential reproduction, such as dependency of children, remaining reproductive potential, dependence on kin, and others, into account and is able to predict the subject's risk for suicide. Current research has been conducted mostly in the United States, with a large portion of the sample being young, educated, and religious.
According to de Catanzaro's variables, those at greatest risk of suicide include the elderly, especially those who are a burden on their family, anyone who is ostracized by their kin, someone unable to provide for their kin, dependent on their reproductively capable kin, or anyone who has difficulty relating with the opposite sex. All of these conditions will lead to emotional and psychological conditions that will make suicide more likely. De Catanzaro cites studies that show that emotions have a physiological basis to show that the self destructive response may be a natural, evolved response to their situation to ensure the continued propagation of one's genes.
According to this theory, those mostly likely to kill themselves would be the elderly dependent on financially pressed children, or someone with little hope of reproducing who is also dependent of kin. Dr. de Catanzaro's theory can also be applied to general self preservation. It can be used to predict how likely a mother or father is to sacrifice herself or himself to save their children, or other situations of that sort. De Catanzaro takes pains to recognize that his formula is only a base on which to predict likelihood of suicide or self sacrifice. He freely acknowledges that suicide is partially a learned behaviour, as is evidenced by the phenomenon of groupings of suicides occurring in short periods of time. He believes that there are many cultural phenomena that will affect any given individual. De Catanzaro also places strong emphasis on the fact that modern expressions of suicide may sometimes be unpredictable because we are in a different environment from that which we evolved in. He believes that there are many more suicides today than there would be in our "natural" environment due to stress and our confrontation with many situations that we have not been selected to deal with.
Another approach explains the differences between the sexes. One theory argues that men die of suicide more often than women because they do not value their lives as much as women. Since men are not essential to the survival of their offspring, and their potential for reproduction is much more varied, men have evolved to be less fearful of taking risks than women have. If a woman under natural conditions were to die, her children would most likely die as well. Therefore women have evolved to be more fearful of death and physical risk than men, and are therefore less likely to die of suicide. Under this theory suicide is just an expression of males' general willingness to take risks. This may be disclaimed by the fact that while men are 400% more likely to successfully commit suicide, the WHO reports that women attempt suicide more often than men.

# Suicide methods
The means of achieving suicide varies and is greatly influenced by availability, perceived effectiveness and final bodily state. For example, in the United States, firearms are relatively easy to obtain and suicide by this method is four times more common than the next method. However, one must take into account how Japan bans all firearms yet suffers from an extremely high suicide rate.
The common means of suicide, roughly in order of use (U.S.), are by gunshot (the so-called "Hemingway solution"), asphyxia, hanging (there is often considerable overlap between hanging and asphyxia due to lack of expertise), drug overdose, carbon monoxide poisoning, jumping from height, stabbing or exsanguination, and drowning.
Physician-assisted suicide (see euthanasia) is typically by a lethal dosage of a prescription drug supplied by the physician. It may be taken orally, by intravenous drip, or infusion pump with a switch operated by the patient.