Predatory death anxiety arises from the fear of being harmed. It is the most basic and oldest form of death anxiety, with its origins in the first unicellular organisms’ set of adaptive resources. Unicellular organisms have receptors that have evolved to react to external dangers, along with self-protective, responsive mechanisms made to guarantee survival in the face of chemical and physical forms of attack or danger. In humans, predatory death anxiety is evoked by a variety of danger situations that put one at risk or threaten one's survival. These traumas may be physical, psychological, or both. Predatory death anxiety mobilizes an individual’s adaptive resources and leads to a fight-or-flight response: active efforts to combat the danger or attempts to escape the threatening situation.

Specific phobias have a one-year prevalence of 8.7% in the USA with 21.9% of the cases being severe, 30.0% moderate and 48.1% mild. The usual age of onset is childhood to adolescence. Women are twice as likely to suffer from specific phobias as men.

Evolutionary psychology argues that infants or children develop specific phobias to things that could possibly harm them, so their phobias alert them to the danger.

The most common co-occurring disorder for children with a specific phobia is another anxiety disorder. Although comorbidity is frequent for children with specific phobias, it tends to be lower than for other anxiety disorders.

Onset is typically between 7 and 9 years of age. Specific phobias can occur at any age but seem to peak between 10 and 13 years of age.

It is during the years of young adulthood (20 to 40 years of age) that death anxiety most often begins to become prevalent. However, during the next phase of life, the middle age adult years (40–64 years of age), death anxiety peaks at its highest levels when in comparison to all other age ranges throughout the lifespan. Surprisingly, levels of death anxiety then slump off in the old age years of adulthood (65 years of age and older). This is in contrast with most people’s expectations, especially regarding all of the negative connotations younger adults have about the elderly and the aging process (Kurlychek & Trenner, 1982).

Agoraphobia occurs about twice as commonly among women as it does in men. The gender difference may be attributable to several factors: sociocultural traditions that encourage, or permit, the greater expression of avoidance coping strategies by women (including dependent and helpless behaviors), women perhaps being more likely to seek help and therefore be diagnosed, and men being more likely to abuse alcohol in reaction to anxiety and be diagnosed as an alcoholic. Research has not yet produced a single clear explanation for the gender difference in agoraphobia.

Panic disorder with or without agoraphobia affects roughly 5.1% of Americans, and about 1/3 of this population with panic disorder have comorbid agoraphobia. It is uncommon to have agoraphobia without panic attacks, with only 0.17% of people with agorophobia not presenting panic disorders as well.

Factors that can cause reluctance to attend school can be divided into four categories. These categories have been developed based on studies in the United States under the leadership of Professor Christopher Kearney. Some students may be affected by several factors at once.

- The child might want to be free.

- The child possibly wants to avoid school-related issues and situations that cause them to experience unpleasant feelings, such as anxiety, depression, or psychosomatic symptoms. The reluctance to attend school is one symptom that can indicate the presence of a larger issue, such as anxiety disorder, depression, learning disability, sleep disorder, separation anxiety or panic disorder.

- The child may want to avoid tests, presentations, group work, specific lessons, or interaction with other children. The child should be assessed for learning disabilities if academic performance is average or low.

- The child may want attention from significant people outside of school, such as parents or older acquaintances.

- The child possibly wants to do something more enjoyable outside of school, like practice hobbies, play computer games, watch movies, play with friends such as riding bikes, etc., or learn autodidactictally.

Other factors can be:

- Anxiety about academic achievement and being tested can arise on the basis of inflated claims by teachers and/or parents, but also unrealistic ambitions of the upset child themselves.

- School refusal may arise as a response to bullying or peer rejection.

- Shyness or a social phobia can contribute to school refusal.

- The child might worry about parents or siblings, for instance, a parent with substance abuse, or a parent who physically abuses other family members.

- Some students may refuse to go to school due to anxiety or fears of emergency drills, such as fire, lockdown, and tornado drills.

Several studies aim to understand the long-term mental health consequences of SAD. SAD contributed to vulnerability and acted as a strong risk factor for developing other mental disorders in people aged 19–30. Specifically disorders including panic disorder and depressive disorders were more likely to occur. Other sources also support the increased likelihood of displaying either of the two psychopathologies with previous history of childhood SAD.

Autophobia can be derived from social anxiety. When people with this phobia are left alone, they will often experience panic attacks, which is a common reaction in those suffering from social anxiety. This disease can also stem from depression because when people become seriously autophobic, they start to find certain tasks and activities almost impossible to complete. This usually occurs when autophobes are faced with a possibility of going into a public place where there are lots of people or simply a place that is uncomfortable or unfamiliar to them. This phobia can also be closely related to agoraphobia, which leads to lowered self-confidence and uncertainty of their ability to finish certain activities that need to be done alone. People suffering from this phobia tend to imagine the worst possible scenario. For example, they might have a panic attack and then think that they are going to die from this event.

Another experience that doctors believe leads individuals to develop this phobia is children being abandoned, usually by their parents, when they are very young. This first causes childhood trauma that then persists to effect them as they grow up. This turns into autophobia because they are now afraid that all of the important people in their lives are going to leave or abandon them. Therefore, this particular phobia can come from behavior and experiences that these people have had when they were growing up. However, abandonment does not necessarily mean being left alone physically, this also includes being isolated financially or emotionally. Having drastic, life-altering experiences, particularly causes more trauma which makes this phobia worse. People that have very high anxiety and in this case are more “high strung,” are more susceptible to this phobia.

Although this phobia is often developed at a young age, it can develop later in life as well. Individuals sometimes develop this fear with the death of a loved one or the ending of an important relationship. Autophobia can also be described as the fear of being without a specific person. Tragic events in a person's life may create this fear of being without one specific person, but this often will eventually progress into a fear of being secluded in general.

Discomfort from separations in children from ages 8 to 14 months is normal. Children oftentimes get nervous or afraid of unfamiliar people and places but if the behavior still occurs after the age of 6 and if it lasts longer than four weeks, the child might have Separation Anxiety Disorder.

About 4% of children have the disorder. Separation Anxiety Disorder is very treatable especially when caught early on with medication and behavioral therapies. Helping children with separation anxiety to identify the circumstances that elicit their anxiety (upcoming separation events) is important. A child's ability to tolerate separations should gradually increase over time when he or she is gradually exposed to the feared events. Encouraging a child with separation anxiety disorder to feel competent and empowered, as well as to discuss feelings associated with anxiety-provoking events promotes recovery.

Children with separation anxiety disorder often respond negatively to perceived anxiety in their caretakers, in that parents and caregivers who also have anxiety disorders may unwittingly confirm a child's unrealistic fears that something terrible may happen if they are separated from each other. Thus, it is critical that parents and caretakers become aware of their own feelings and communicate a sense of safety and confidence about separation.

Autophobia is a form of anxiety that can cause a minor to extreme feeling of danger or fear when alone. There is not a specific treatment to cure autophobia as it affects each person differently. Most sufferers are treated with psychotherapy in which the amount of time that they are alone is slowly increased. There are no conclusive studies currently that support any medications being used as treatment. If the anxiety is too intense medications have been used to aid the patient in a continuation of the therapy.

It is not uncommon for sufferers to be unaware that they have this anxiety and to dismiss the idea of seeking help. Much like substance abuse, autophobia is mental and physical and requires assistance from a medical professional. Medication can be used to stabilize symptoms and inhibit further substance abuse. Group and individual therapy is used to help ease symptoms and treat the phobia.

In mild cases of autophobia, treatment can sometimes be very simple. Therapists recommend many different remedies to make patients feel as though they are not alone even when that is the case, such as listening to music when running errands alone or turning on the television when at home, even if it is just for background noise. Using noise to interrupt the silence of isolated situations can often be a great help for people suffering from autophobia.

However, it is important to remember that just because a person may feel alone at times does not mean that they have autophobia. Most people feel alone and secluded at times; this is not an unusual phenomenon. Only when the fear of being alone beings to interrupt how a person lives their daily life does the idea of being autophobic become a possibility.

Hypochondria is currently considered a psychosomatic disorder, as in a mental illness with physical symptoms. Cyberchondria is a colloquial term for hypochondria in individuals who have researched medical conditions on the Internet. The media and the Internet often contribute to hypochondria, as articles, TV shows and advertisements regarding serious illnesses such as cancer and multiple sclerosis often portray these diseases as being random, obscure and somewhat inevitable. Inaccurate portrayal of risk and the identification of non-specific symptoms as signs of serious illness contribute to exacerbating the hypochondriac’s fear that they actually have that illness.

Major disease outbreaks or predicted pandemics can also contribute to hypochondria. Statistics regarding certain illnesses, such as cancer, will give hypochondriacs the illusion that they are more likely to develop the disease.

Overly protective caregivers and an excessive focus on minor health concerns have been implicated as a potential cause of hypochondriasis development.

It is common for serious illnesses or deaths of family members or friends to trigger hypochondria in certain individuals. Similarly, when approaching the age of a parent's premature death from disease, many otherwise healthy, happy individuals fall prey to hypochondria. These individuals believe they are suffering from the same disease that caused their parent's death, sometimes causing panic attacks with corresponding symptoms.

Family studies of hypochondriasis do not show a genetic transmission of the disorder. Among relatives of people suffering from hypochondriasis only somatization disorder and generalized anxiety disorder were more common than in average families. Other studies have shown that the first degree relatives of patients with OCD have a higher than expected frequency of a somatoform disorder (either hypochondriasis or body dysmorphic disorder).

Chronic use of tranquilizers and sleeping pills such as benzodiazepines has been linked to onset of agoraphobia. In 10 patients who had developed agoraphobia during benzodiazepine dependence, symptoms abated within the first year of assisted withdrawal. Similarly, alcohol use disorders are associated with panic with or without agoraphobia; this association may be due to the long-term effects of alcohol misuse causing a distortion in brain chemistry.

Tobacco smoking has also been associated with the development and emergence of agoraphobia, often with panic disorder; it is uncertain how tobacco smoking results in anxiety-panic with or without agoraphobia symptoms, but the direct effects of nicotine dependence or the effects of tobacco smoke on breathing have been suggested as possible causes. Self-medication or a combination of factors may also explain the association between tobacco smoking and agoraphobia and panic.

Approximately 1 to 5% of school-aged children have school refusal, though it is most common in 5- and 6-year olds and in 10- and 11-year olds, it occurs more frequently during major changes in a child’s life, such as entrance to kindergarten, changing from elementary to middle school, or changing from middle to high school. The problem may start following vacations, school holidays, summer vacation, or brief illness, after the child has been home for some time, and usually ends prior to vacations, school holidays, or summer vacation, before the child will be out of school for some time. School refusal can also occur after a stressful event, such as moving to a new house, or the death of a pet or relative.

The rate is similar within both genders, and although it is significantly more prevalent in some urban areas, there are no known socioeconomic differences.

Social anxiety disorder is known to appear at an early age in most cases. Fifty percent of those who develop this disorder have developed it by the age of 11, and 80% have developed it by age 20. This early age of onset may lead to people with social anxiety disorder being particularly vulnerable to depressive illnesses, drug abuse and other psychological conflicts.

When prevalence estimates were based on the examination of psychiatric clinic samples, social anxiety disorder was thought to be a relatively rare disorder. The opposite was found to be true; social anxiety was common, but many were afraid to seek psychiatric help, leading to an underrecognition of the problem.

The National Comorbidity Survey of over 8,000 American correspondents in 1994 revealed 12-month and lifetime prevalence rates of 7.9 percent and 13.3 percent, respectively; this makes it the third most prevalent psychiatric disorder after depression and alcohol dependence, and the most common of the anxiety disorders. According to U.S. epidemiological data from the National Institute of Mental Health, social phobia affects 15 million adult Americans in any given year. Estimates vary within 2 percent and 7 percent of the U.S. adult population.

The mean onset of social phobia is 10 to 13 years. Onset after age 25 is rare and is typically preceded by panic disorder or major depression. Social anxiety disorder occurs more often in females than males. The prevalence of social phobia appears to be increasing among white, married, and well-educated individuals. As a group, those with generalized social phobia are less likely to graduate from high school and are more likely to rely on government financial assistance or have poverty-level salaries. Surveys carried out in 2002 show the youth of England, Scotland, and Wales have a prevalence rate of 0.4 percent, 1.8 percent, and 0.6 percent, respectively. In Canada, the prevalence of self-reported social anxiety for Nova Scotians older than 14 years was 4.2 percent in June 2004 with women (4.6 percent) reporting more than men (3.8 percent). In Australia, social phobia is the 8th and 5th leading disease or illness for males and females between 15–24 years of age as of 2003. Because of the difficulty in separating social phobia from poor social skills or shyness, some studies have a large range of prevalence. The table also shows higher prevalence in Sweden.

The causes of PTSD are: Natural or human disasters, war, serious accident, witness of violent death of others, violent attack, being the victim of sexual abuse, rape, torture, terrorism or hostage taking.

Predisposing factors

The predisposing factors are: Personality traits and Previous history of Psychiatric illness.

Fear of intimacy is generally a social phobia and anxiety disorder resulting in difficulty forming close relationships with another person. The term can also refer to a scale on a psychometric test, or a type of adult in attachment theory psychology.

The fear of intimacy is the fear of being emotionally and/or physically close to another individual. This fear is also defined as “the inhibited capacity of an individual, because of anxiety, to exchange thought and feelings of personal significance with another individual who is highly valued”. Fear of intimacy is the expression of existential views in that to love and to be loved makes life seem precious and death more inevitable. It often results from past traumas such as rape or childhood sexual abuse. Fear of intimacy is also related to the fear of being touched .

People with this fear are anxious about or afraid of intimate relationships. They believe that they do not deserve love or support from others. Fear of intimacy has three defining features: content which represents the ability to communicate personal information, emotional valence which refers to the feelings about personal information exchanged, and vulnerability signifying their regard for the person they are intimate with. Bartholomew and Horowitz go further and determine four different adult attachment types: “(1) Secure individuals have a sense of worthiness or lovability and are comfortable with intimacy and autonomy; (2) preoccupied persons lack this sense of self-worthiness yet view others positively and seek their love and acceptance; (3) fearful people lack a sense of lovability and are avoidant of others in anticipation of rejection; (4) dismissing persons feel worthy of love yet detach from others whom they generally regard as untrustworthy”.

In Europe about 3% of the population has a panic attack in a given year while in the United States they affect about 11%. They are more common in females than males. They often begin during puberty or early adulthood. Children and older people are less commonly affected.

Risk factors (constructs which increase the likelihood or intensity of homesickness) and protective factors (constructs that decrease the likelihood or intensity of homesickness) vary by population. For example, a seafarers on board, the environmental stressors associated with a hospital, a military boot camp or a foreign country may exacerbate homesickness and complicate treatment. Generally speaking, however, risk and protective factors transcend age and environment.

It has been shown that there is a two to threefold greater risk of having social phobia if a first-degree relative also has the disorder. This could be due to genetics and/or due to children acquiring social fears and avoidance through processes of observational learning or parental psychosocial education. Studies of identical twins brought up (via adoption) in different families have indicated that, if one twin developed social anxiety disorder, then the other was between 30 percent and 50 percent more likely than average to also develop the disorder. To some extent this 'heritability' may not be specific – for example, studies have found that if a parent has any kind of anxiety disorder or clinical depression, then a child is somewhat more likely to develop an anxiety disorder or social phobia. Studies suggest that parents of those with social anxiety disorder tend to be more socially isolated themselves (Bruch and Heimberg, 1994; Caster et al., 1999), and shyness in adoptive parents is significantly correlated with shyness in adopted children (Daniels and Plomin, 1985).

Growing up with overprotective and hypercritical parents has also been associated with social anxiety disorder. Adolescents who were rated as having an insecure (anxious-ambivalent) attachment with their mother as infants were twice as likely to develop anxiety disorders by late adolescence, including social phobia.

A related line of research has investigated 'behavioural inhibition' in infants – early signs of an inhibited and introspective or fearful nature. Studies have shown that around 10–15 percent of individuals show this early temperament, which appears to be partly due to genetics. Some continue to show this trait into adolescence and adulthood, and appear to be more likely to develop social anxiety disorder.

Many people report stress-induced speech disorders which are only present during public speech. Some individuals with glossophobia have been able to dance, perform in public, or even to speak (such as in a play), or sing if they cannot see the audience, or if they feel that they are presenting a character or stage persona other than themselves. Being able to blend in a group (as in a choir or band) has been reported to also alleviate some anxiety caused by glossophobia.

It has been estimated that 75% of all people experience some degree of anxiety/nervousness when it comes to public speaking. In fact, surveys have shown that most people fear public speaking more than they fear death. If untreated, public speaking anxiety can lead to serious detrimental effects on one's quality of life, career goals and other areas. For example, educational goals requiring public speaking might be left unaccomplished. However, not all persons with public speaking anxiety are necessarily unable to achieve work goals, though this disorder becomes problematic when it prevents an individual from attaining or pursuing a goal they might otherwise have - were it not for their anxiety.

A recent study conducted by Garcia-Lopez, Diez-Bedmar, and Almansa-Moreno (2013) has reported that previously trained students could act as trainers to other students and help them to improve their public speaking skills.

The risk factors for homesickness fall into five categories: experience, personality, family, attitude and environment. More is known about some of these factors in adults—especially personality factors—because more homesickness research has been performed with older populations. However, a growing body of research is elucidating the etiology of homesickness in younger populations, including children at summer camp, hospitalized children and students.

- Experience factors: Younger age; little previous experience away from home (for which age can be a proxy); little or no previous experience in the novel environment; little or no previous experience venturing out without primary caregivers.

- Attitude factors: The belief that homesickness will be strong; negative first impressions and low expectations for the new environment; perceived absence of social support; high perceived demands (e.g., on academic, vocational or sports performance); great perceived distance from home

- Personality factors: Insecure attachment relationship with primary caregivers; low perceived control over the timing and nature of the separation from home; anxious or depressed feelings in the months prior to the separation; low self-directedness; high harm avoidance; rigidity; a wishful-thinking coping style.

- Family factors: Low decision control (e.g., caregivers forcing a young child to spend time away from home against her wishes); governments forcing a person to be in a novel environment (e.g., being drafted into military service away from home or being sentenced to prison); unsupportive caregiving; caregivers who express anxiety or ambivalence about the separation (e.g., "Have a great time away. I don't know what I'll do without you.")

- Environmental factors: High cultural contrast (e.g., different language, customs, food); threats to physical and emotional safety; dramatic alternations in daily schedule; lack of information about the new place; perceived discrimination

Finally, research has provided no support for a few factors that conventional wisdom had once held to be risk factors. These include: recent separation or divorce of primary caregivers; geographic distance from home; or recent geographic move. Most likely, it is not a change in family structure, distance or dwelling that predicts homesickness, but whether these changes have left unanswered (potentially preoccupying) questions in the person's mind.

The fear of trains is anxiety and fear associated with trains, railways, and railway travel.

The cause of dog separation anxiety is unknown, but may be triggered by:

- a traumatic event

- a change in routine

- major life change (e.g., new home, new baby, death of a family member, abandonment to a shelter)

- extreme attachment or dependency on the owner

A study on comorbidity of GAD and other depressive disorders has shown that treatment is not more or less effective when there is some sort of comorbidity of another disorder. The severity of symptoms did not affect the outcome of the treatment process in these cases.

Fear of the dark is a common fear or phobia among children and, to a varying degree, adults.