From Wikipedia, the free encyclopedia - View original article
In clinical psychology, a phobia is a type of anxiety disorder, usually defined as a persistent fear of an object or situation in which the sufferer commits to great lengths in avoiding, typically disproportional to the actual danger posed, often being recognized as irrational. In the event the phobia cannot be avoided entirely, the sufferer will endure the situation or object with marked distress and significant interference in social or occupational activities.
The terms distress and impairment as defined by the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV-TR) should also take into account the context of the sufferer's environment if attempting a diagnosis. The DSM-IV-TR states that if a phobic stimulus, whether it be an object or a social situation, is absent entirely in an environment — a diagnosis cannot be made. An example of this situation would be an individual who has a fear of mice (Suriphobia) but lives in an area devoid of mice. Even though the concept of mice causes marked distress and impairment within the individual, because the individual does not encounter mice in the environment no actual distress or impairment is ever experienced. Proximity and the degree to which escape from the phobic stimulus is impossible should also be considered. As the sufferer approaches a phobic stimulus, anxiety levels increase (e.g. as one gets closer to a snake, fear increases in ophidiophobia), and the degree to which escape of the phobic stimulus is limited has the effect of varying the intensity of fear in instances such as riding an elevator (e.g. anxiety increases at the midway point between floors and decreases when the floor is reached and the doors open).
The term phobia is encompassing and usually discussed in the contexts of specific phobias and social phobias. Specific phobias are nouns, such as arachnophobia or acrophobia, which are specific, and social phobias are phobias within social situations, such as public speaking and crowded areas. Some phobias, such as xenophobia, overlap with many other phobias.
Most phobias are classified into three categories and, according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), such phobias are considered to be sub-types of anxiety disorder. The three categories are:
1. Social phobia: fear of other people or social situations such as performance anxiety or fears of embarrassment by scrutiny of others. Overcoming social phobia is often very difficult without the help of therapy or support groups. Social phobia may be further subdivided into
2. Specific phobias: fear of a double specific panic trigger such as spiders, snakes, dogs, wind, water, heights, flying, catching a specific illness, etc. Many people have these fears but to a lesser degree than those who suffer from specific phobias. People with the phobias specifically avoid the entity they fear.
3. Agoraphobia: a generalized fear of leaving home or a small familiar 'safe' area, and of possible panic attacks that might follow. It may also be caused by various specific phobias such as fear of open spaces, social embarrassment (social agoraphobia), fear of contamination (fear of germs, possibly complicated by obsessive-compulsive disorder) or PTSD (post traumatic stress disorder) related to a trauma that occurred out of doors.
Phobias vary in severity among individuals. Some individuals can simply avoid the subject of their fear and suffer relatively mild anxiety over that fear. Others suffer full-fledged panic attacks with all the associated disabling symptoms. Most individuals understand that they are suffering from an irrational fear, but are powerless to override their panic reaction.
A specific phobia is a marked and persistent fear of an object or situation which brings about an excessive or unreasonable fear when in the presence of, or anticipating, a specific object; the specific phobias may also include concerns with losing control, panicking, and fainting which is the direct result of an encounter with the phobia. Specific phobias are defined in relation to objects or situations whereas social phobias emphasize social fear and the evaluations that might accompany them.
The DSM breaks specific phobias into five subtypes: animal, natural environment, blood-injection-injury, situational, and other. In children, phobias involving animals, natural environment (darkness), and blood-injection-injury usually develop between the ages of 7 and 9, and these are reflective of normal development. Additionally, specific phobias are most prevalent in children between ages 10 and 13.
Unlike specific phobias, social phobias include fear of public situations and scrutiny which leads to embarrassment or humiliation in the diagnostic criteria. People with social phobia have extreme feelings of self-consciousness built into powerful fear. In social phobias, there is also a generalized category. Unlike specific phobias which may develop before the age of 10, social phobias are typically not present until pubertal transition. After this transition, the prevalence of social phobia increases with age. Many adolescents who develop a social phobia consequently become rejected by their peers. As interpersonal dysfunction is a risk factor for depression, there are some negative outcomes for adolescents with social phobia. For example, about 20% of adolescents diagnosed with a social anxiety disorder also suffer from depression and use alcohol or other substances.
Rachman proposed three pathways to acquiring fear conditioning: classical conditioning, vicarious acquisition and informational/instructional acquisition:
A conditioned fear response to an object or situation is not always a phobia. To meet the criteria for a phobia there must also be symptoms of impairment and avoidance. Impairment is defined as being unable to complete routine tasks whether occupational, academic or social. In acrophobia an impairment of occupation could result from not taking a job solely because of its location at the top floor of a building, or socially not participating in a social event at a theme park. The avoidance aspect is defined as behavior that results in the omission of an aversive event that would otherwise occur with the goal of the preventing anxiety.
Beneath the lateral fissure in the cerebral cortex, the insula, or insular cortex, of the brain has been identified as part of the limbic system, along with cingulated gyrus, hippocampus, corpus callosum, and other nearby cortices. This system has been found to play a role in emotion processing and the insula, in particular, may contribute through its role in maintaining autonomic functions. Studies by Critchley et al. indicate the insula as being involved in the experience of emotion by detecting and interpreting threatening stimuli. Similar studies involved in monitoring the activity of the insula show a correlation between increased insular activation and anxiety.
In the frontal lobes, other cortices involved with phobia and fear are the anterior cingulate cortex and the medial prefrontal cortex. In the processing of emotional stimuli, studies on phobic reactions to facial expressions have indicated these areas to be involved in processing and responding to negative stimuli. The ventromedial prefrontal cortex has been said to influence the amygdala by monitoring its reaction to emotional stimuli or even fearful memories. Most specifically, the medial prefrontal cortex is active during extinction of fear and is responsible for long term extinction. Stimulation of this area decreases conditioned fear responses and so its role may be in inhibiting the amygdala and its reaction to fearful stimuli.
The hippocampus is a horseshoe shaped structure that plays an important part in the brain’s limbic system because of its role in forming memories and connecting them with emotions and the senses. When dealing with fear, the hippocampus receives impulses from the amygdala that allows it to connect the fear with a certain sense, such as a smell or sound.
The amygdala is an "almond shaped" mass of nuclei that is located deep in the brain’s medial temporal lobe. It processes the events associated with fear and is being linked to anxiety disorders and social phobias. The amygdala's ability to respond to fearful stimuli occurs through the process of fear conditioning. Similar to classical conditioning, the amygdala learns to associate a conditioned stimulus with a negative or avoidant stimulus, creating a conditioned fear response that is often seen in phobic individuals. In this way the amygdala is responsible for not only recognizing certain stimuli or cues as dangerous, but plays a role in the storage of threatening stimuli to memory. The basolateral nuclei (or basolateral amygdala) and the hippocampus interact with the amygdala in the storage of memory, which suggests why memories are often remembered more vividly if they have emotional significance.
In addition to memory, the amygdala also triggers the secretion of hormones that affect fear and aggression. When the fear or aggression response is initiated, the amygdala releases hormones into the body to put the human body into an "alert" state, which prepares the individual to move, run, fight, etc. This defensive "alert" state and response is generally referred to in psychology as the fight-or-flight response.
Inside the brain, however, this stress response can be observed in the hypothalamic-pituitary-adrenal axis (HPA).This circuit incorporates the process of receiving stimuli, interpreting it, and releasing certain hormones into the blood stream. The parvocellular neurosecretary neurons of the hypothalamus release corticotropin-releasing hormone(CRH) which is sent to the anterior pituitary. Here the pituitary releases adrenocorticotropic hormone (ACTH) which ultimately stimulates the release of cortisol. In relation to anxiety, the amygdala is responsible for activating this circuit, while the hippocampus is responsible for suppressing it. Glucocorticoid receptors in the hippocampus monitor the amount of cortisol in the system and through negative feedback can tell the hypothalamus to stop releasing CRH.
Studies on mice engineered to have high concentrations of CRH showed higher levels of anxiety, while those engineered to have no or low amounts of CRH receptors were less anxious. In phobic patients, therefore, high amounts of cortisol may be present, or alternatively, there may be low levels of glucocorticoid receptors or even serotonin (5-HT).
For the areas in the brain involved in emotion—most specifically fear— the processing and response to emotional stimuli can be significantly altered when one of these regions becomes lesioned or damaged. Damage to the cortical areas involved in the limbic system such as the cingulate cortex or frontal lobes have resulted in extreme changes in emotion. Other types of damage include Klüver-Bucy Syndrome and Urbach-Wiethe disease. In Klüver-Bucy syndrome, a temporal lobectomy, or removal of the temporal lobes results in changes involving fear and aggression. Specifically, the removal of these lobes results in decreased fear, confirming its role in fear recognition and response. Bilateral damage to the medial temporal lobes, which is known as Urbach-Wiethe disease exhibits similar symptoms of decreased fear and aggression, but also an inability to recognize emotional expressions, especially angry or fearful faces.
The amygdala’s role in learned fear includes interactions with other brain regions in the neural circuit of fear. While lesions in the amygdala can inhibit its ability to recognize fearful stimuli, other areas such as the ventromedial prefrontal cortex and the basolateral nuclei of the amygdala can affect the region's ability to not only become conditioned to fearful stimuli, but to eventually extinguish them. The basolateral nuclei, through receiving stimulus info, undergo synaptic changes which allow the amygdala to develop a conditioned response to fearful stimuli. Lesions in this area, therefore, have been shown to disrupt the acquisition of learned responses to fear. Likewise, lesions in the ventromedial prefrontal cortex (the area responsible for monitoring the amygdala) have been shown to not only slow down the speed of extinguishing a learned fear response, but also how effective or strong the extinction is. This suggests there is a pathway or circuit among the amygdala and nearby cortical areas that process emotional stimuli and influence emotional expression, all of which can be disrupted when an area becomes damaged.
Various methods are claimed to treat phobias. Some therapists use virtual reality or imagery exercise to desensitize patients to the feared entity. These are parts of systematic desensitization therapy.
Cognitive behavioral therapy (CBT) can be beneficial. Cognitive behavioral therapy allows the patient to challenge dysfunctional thoughts or beliefs by being mindful of their own feelings with the aim that the patient will realize their fear is irrational. CBT may be conducted in a group setting. Gradual desensitisation treatment and CBT are often successful, provided the patient is willing to endure some discomfort. In one clinical trial, 90% of patients were observed to no longer have a phobic reaction after successful CBT treatment.
CBT is also an effective treatment for phobias in children and adolescents, and it has been adapted to be appropriate for use with this age. One example of a CBT program targeted towards children is the Coping Cat. This treatment program can be used with children between the ages of 7 and 13 to treat social phobia. This program works to decrease negative thinking, increase problem solving, and to provide a functional coping outlook in the child. Another CBT program was developed by Ann Marie Albano to treat social phobia in adolescents. This program has five stages: Psychoeducation, Skill Building, Problem Solving, Exposure, and Generalization and Maintenance. Psycho education focuses on identifying and understanding symptoms. Skill Building focuses on learning cognitive restructuring, social skills, and problem solving skills. Problem Solving focuses on identifying problems and using a proactive approach to solving them. Exposure involves exposing the adolescent to social situations in a hierarchical approach. Finally, Generalization and Maintenance involves practicing the skills learned.
Eye Movement Desensitization and Reprocessing (EMDR) has been demonstrated in peer-reviewed clinical trials to be effective in treating some phobias. Mainly used to treat Post-traumatic stress disorder, EMDR has been demonstrated as effective in easing phobia symptoms following a specific trauma, such as a fear of dogs following a dog bite.
Another method psychologists and psychiatrists use to treat patients with extreme phobias is prolonged exposure. Prolonged exposure is used in psychotherapy when the person with the phobia is exposed to the object of their fear over a long period of time. This technique is only tested[clarification needed] when a person has overcome avoidance of or escape from the phobic object or situation. People with slight distress from their phobias usually do not need prolonged exposure to their fear.
For children and adolescents, one of the most effective treatments for specific phobias is participant modeling and reinforced practice. In this treatment method, the therapist models for the child how they should respond to their fears and then encourages the child to practice this behavior and reinforces their efforts.
Antidepressant medications such as SSRIs or MAOIs may be helpful in some cases of phobia. Benzodiazepines may be useful in acute treatment of severe symptoms, but the risk-benefit ratio is against their long-term use in phobic disorders.
Phobias are a common form of anxiety disorders and distributions are heterogeneous by age and gender. An American study by the National Institute of Mental Health (NIMH) found that between 8.7 percent and 18.1 percent of Americans suffer from phobias, making it the most common mental illness among women in all age groups and the second most common illness among men older than 25. Between 4 percent and 10 percent of all children experience specific phobias during their lives, and social phobias occur in one percent to three percent of children and adolescents.
A Swedish study found that females have a higher incidence than males (26.5 percent for females and 12.4 percent for males). Among adults, 21.2 percent of women and 10.9 percent of men have a single specific phobia, while multiple phobias occur in 5.4 percent of females and 1.5 percent of males. Women are nearly four times as likely as men to have a fear of animals (12.1 percent in women and 3.3 percent in men) — a higher dimorphic than with all specific or generalized phobias or social phobias. Social phobias are more common in girls than in boys, while situational phobia occurs in 17.4 percent of women and 8.5 percent of men.
The word phobia comes from the Greek: φόβος (phóbos), meaning "aversion", "fear", or "morbid fear". In popular culture, it is common for specific phobias to be given a name based on a Greek word for the object of the fear, plus the suffix -phobia. Creating these terms is something of a word game. Few of these terms are found in medical literature.
The word phobia may also refer to conditions other than true phobias. For example, the term hydrophobia is an old name for rabies, since an aversion to water is one of that disease's symptoms. A specific phobia to water is called aquaphobia instead. A hydrophobe is a chemical compound which repels water. Similarly, the term photophobia usually refers to a physical complaint (aversion to light due to inflamed eyes or excessively dilated pupils), rather than an irrational fear of light.
A number of terms with the suffix -phobia are used non-clinically. Such terms are primarily understood as negative attitudes towards certain categories of people or other things, used in an analogy with the medical usage of the term. Usually these kinds of "phobias" are described as fear, dislike, disapproval, prejudice, hatred, discrimination, or hostility towards the object of the "phobia". Often this attitude is based on prejudices and is a particular case of most xenophobia.
Below are some examples:
|Wikiquote has quotations related to: Anxiety|
|Look up anxiety in Wiktionary, the free dictionary.|