Specific Phobia

Etiology

The etiology of most psychiatric conditions involves various degrees and types of biological, psychological, and social contributors. Although psychological factors particularly impact the development of anxiety disorders, there are multiple biological components to pathological anxiety. The study of inheritance patterns has revealed a general familial aggregation among major anxiety disorders.[10] Twin studies have demonstrated stronger inheritance patterns for monozygotic twins compared to dizygotic twins, suggesting a genetic component to the development of pathological anxiety.[11] Although the study of anxiety and gene-environment interactions is limited, it is known that epigenetic mechanisms, particularly DNA methylation, contribute to mediating transcription factors for stress-related genes, which may underlie the development of pathological anxiety.[12]

Behavioral scientists have contributed significantly to uncovering the psychological mechanisms contributing to anxiety. Conditioned responses of learned fear are more significant among anxiety-disordered individuals compared to controls, with an explanation of 2 likely mechanisms: first, there is greater excitatory conditioning to danger cues, and second, there is impaired inhibitory conditioning to safety signals.[13] 

Parenting behaviors implicate cross-generational influences on the development of childhood anxiety. These parenting behavioral systems include vicarious learning, social referencing, and modeling of parental anxiety. Furthermore, overly protective and overly critical parenting styles, parental response to child anxiety, and family accommodation of a child's anxiety all contribute to the conditioning and development of childhood anxiety.[14] Children of parents with depression and anxiety disorders are at a higher risk of developing a depressive or anxiety disorder.[15] Another mechanism for developing a specific phobia is through modeling, in which a person observes a reaction in another person and internalizes that other person's fears or warnings about the dangers of a specific object or situation.[16]

Epidemiology

Anxiety disorders are among the most common mental health disorders, with an estimated prevalence of 5% to 34% worldwide, affecting both children and adults.[17][18][19] Lifetime 12-month prevalence estimates for specific phobia range from 7.7% to 12.5%; these estimates are maintained through different surveyed populations around the world.[20][21][22][23][24][25] The incidence rates for specific phobia are estimated to be 26.9% for individuals between 20 and 50 years.[25][26] Prevalence rates are higher in females compared to males,[27] and they decrease with age.[28][29] Sequentially, the most frequent types of specific phobias are those with stimuli related to animals, the natural environment, and then blood-injection-injury–related stimuli.[30]

Pathophysiology

Neuroanatomically, the amygdala is classically associated with provoking a fear response when stimulated. The amygdala and other fear-related neurocircuitry may share a similar neuroanatomy to anxiety neurocircuitry.[31] The amygdala and its connections to the frontal cortex (perirhinal cortex, ventrolateral prefrontal cortex, anterior insula) have received the most attention.[32] As the amygdala is part of the limbic system, other limbic system structures likely contribute to the development of anxiety, with a specific interest in the hippocampus, as it plays an integral role in fear learning and extinction.[33] Functional magnetic resonance imaging (fMRI) studies have found that hypofunction of the prefrontal cortex and anterior cingulate cortex is associated with emotional dysregulation and cognitive dysfunction in those with anxiety.[34]

The activation of fear neurocircuitry, with presumed anxiety neurocircuitry overlap, involves the release of various neurochemicals that lead to sympathetic stimulation. Classically characterized as a "fight-or-flight" reaction, this sympathetic response evolved to be adaptive and for a prompt behavioral response to avoid actual or perceived danger.[1] However, this response can be conditioned to over-activate, leading to pathological anxiety even when exposure to threat is low or should be low.[13] The neurochemicals involved in producing a fight-or-flight response are numerous and include norepinephrine, epinephrine, cortisol, neurosteroids, and vasopressin.[35] Dopamine likely has a modulatory role in producing anxiety-like behavior.[36] Low activity of postsynaptic serotonin 5-HT1A receptors contributes to pathological anxiety, which has led to the development of pharmacotherapy attempting to modulate these receptors to reduce anxiety.[37]

History and Physical

The presentation of specific phobia is variable. The chief complaint may be related to anxiety or impaired functioning in their social responsibilities due to symptoms of their illness. The chief complaint will likely be related to significant fear or anxiety in the presence of a specific situation or object, known as the phobic stimulus. It is essential to investigate if there is a single phobic stimulus or multiple. The anxiety reaction to the phobic stimulus must be greater than the expected reaction for the general population. In presence of the phobic stimuli, the anxiety must be severe, and it can produce panic attacks in certain cases. Anticipation of exposure to phobic stimuli may also induce anxiety. The anxiety reaction is anticipated to evoke nearly every time there is exposure to the phobic stimulus. Children may express fear or anxiety by crying, tantrums, freezing, or clinging.

In specific phobia, the individual actively avoids the phobic stimulus, and this is termed active avoidance. Examples of active avoidance include taking a longer driving route to avoid a bridge, avoiding grass and gardens due to concern for spiders or insects, and refusing to visit a doctor due to fear of needles or medical procedures. Some active avoidance may be obvious, but certain behaviors are subtle, such as refusing to look at certain movies or books that may potentially have a phobic stimulus. Active avoidance may impact regular functioning, including social relationships and occupational responsibilities. 

The mental status examination is completed in psychiatric evaluations and has a variable presentation in specific phobia; however, the following areas should be carefully considered:

• Behavior: When discussing the phobic stimulus, does the patient have anxious behaviors, such as constant movement, shaking, and small tremors? 
• Speech: Is the patient's tone frightened when speaking about the phobic stimulus? Does the patient actively try and change the conversation away from the topic of the phobic stimulus?
• Affect: Is the patient always anxious or only in the context of the phobic stimulus?
• Thought process: Is the patient's thought process logical when thinking and discussing the phobic stimulus?  
• Insight: What is the patient's understanding of their exaggerated response to the phobic stimulus?

Evaluation

Individuals with suspected specific phobia should be referred for a psychiatric evaluation.[38] The initial goals are to develop rapport with the patient, obtain historical information in detail from the patient, and conduct a mental status examination. Evaluation for applicable DSM-5-TR diagnostic criteria should be performed to make a formal diagnosis. 

DSM-5-TR Criteria for Specific Phobia

1. Marked fear or anxiety about a specific object or situation (flying, heights, animals, seeing blood, or other). In children the fear or anxiety may be expressed by crying, tantrums, freezing, or clinging.
2. The phobic object or situation almost always provokes immediate fear or anxiety.
3. The phobic object or situation is actively avoided or endured with intense fear or anxiety.
4. The fear or anxiety is out of proportion to the actual danger posed by the specific object or situation and to the sociocultural context.
5. The fear, anxiety, or avoidance is persistent, typically lasting for 6 months or more.
6. The fear, anxiety, or avoidance causes clinically significant distress or impairment in social, occupational, or other important areas of functioning.
7. The disturbances are not better explained by the symptoms of another mental disorder, including fear, anxiety, and avoidance of situations associated with panic-like symptoms; objects or situations related to obsessions; reminders of traumatic events; separation anxiety; or social situations

Specify if:

1. Animal (spiders, insects, dogs, etc)
2. Natural environment (heights, storms, water, etc)
3. Blood-injection-injury (needles, invasive medical procedures)
4. Situational (airplanes, elevators, enclosed places)
5. Other (situations that may lead to choking or vomiting, loud sounds, costumed characters)

Screening Tools

Multiple screening tools for anxiety disorders exist and have wide availability and validation. Generalized anxiety disorder screeners are common and widely available for adult screening, however most broader anxiety disorder screeners were designed to screen for anxiety disorders in children. When there is difficulty in obtaining the full diagnostic criteria from the interview alone, implementing a validated screening tool can be helpful in the diagnosis of specific phobia and in identifying possible comorbid conditions. 

Screen for Child Anxiety–Related Emotional Disorders 

Screen for Child Anxiety–Related Emotional Disorders (SCARED) is one of the most commonly used assessment tools for diagnosing anxiety disorders in children. SCARED is a child and parent self-report measure evaluated in numerous settings worldwide.[39] Various versions and revisions of the questionnaire have been developed. The most commonly used version consists of 41 questions. The total score is based on 5 subscale scores for the most common pediatric anxiety disorders:

1. Generalized anxiety disorder
2. Social phobia
3. Social anxiety disorder (SAD)
4. Somatic symptoms or panic disorder
5. School phobia.

Each response is scored between 0 and 2, with a total score of 25 or higher having high sensitivity and specificity for discriminating between anxiety and nonanxiety disorders.[39] A 55% or higher reduction in the total score with treatment best predicts treatment response and a 60% or higher reduction in parent SCARED scores predicts remission.[39] There is a modified version of SCARED, the Screen for Adult Anxiety Related Disorders (SCAARED), available to screen adults for similar anxiety disorders as children. 

The SCARED assessment tool can be used free of charge with an acceptable time burden on clinicians and families, making it an excellent tool for diagnosing and managing anxiety disorders in children. SCARED cutoffs can also be used to guide treatment. For example, an insufficient reduction in the SCARED score after an adequate trial of behavioral therapy may indicate the need for pharmacotherapy.[39] Studies have shown some discordance in the information provided by the child and parent on this questionnaire without apparent contributory factors.[38] More research is warranted to understand the cause of "low informant agreement" and what factors contribute to this discrepancy. Still, the SCARED assessment tool is considered a stable, reliable, valid, and sensitive measure of anxiety, despite the informant discrepancy, which interestingly also stays stable over time. The SCARED screening tool has shown strict measurement invariance and solid test-retest reliability.

Youth Anxiety Measure

Youth Anxiety Measure (YAM) is a new parent-child questionnaire developed to assess anxiety disorder symptoms in children and adolescents according to the DSM-5. The scale consists of 2 parts: part I consists of 28 items and measures the major anxiety disorders; part II contains 22 items relating to specific phobias and agoraphobia.[40] The validation study for this questionnaire reports acceptable "face validity" with items successfully linked to the intended anxiety disorders and phobias. The authors report good internal consistency and reliability of the new measure with the parent-child agreement and concurrent, convergent, divergent, and discriminant validity.[40] An analysis of the psychometric qualities of the scale with the collection of normative data in nonclinical and clinical populations is still needed.

Anxiety Disorder Interview Schedule 

Anxiety Disorder Interview Schedule (ADIS) is a well-validated diagnostic interview suitable for measuring all anxiety disorders, mood disorders, and attention-deficit or attention-deficit hyperactivity disorder in children. The ADIS is a semistructured diagnostic interview that primarily assesses child anxiety disorders, and the diagnoses are derived from interviews with both the child and the parent.[41] The interviews cover the entire range of anxiety-related disorders outlined by the DSM-5. Each diagnosis is assigned a clinician severity rating (CSR), a symptoms severity rating, and a functional impairment rating.

A CSR of 4 or higher is required to provide a particular diagnosis. If the child and parent interviews yield different diagnoses and CSRs, the interviewer makes a composite diagnosis using recommended guidelines in the clinician manual. The ADIS's parent and child versions possess high inter-rater and test-retest reliability. One study reported almost perfect agreement on both the child and parent interview for diagnosing an anxiety disorder using ADIS. They also report almost perfect agreement regarding the severity of the primary diagnosis.[40] The ADIS is considered the gold-standard diagnostic evaluation for anxiety disorders. 

Pediatric Anxiety Rating Scale 

Pediatric Anxiety Rating Scale (PARS) is a clinician-rated scale of anxiety severity using the frequency of distress symptoms, avoidance behaviors, and interference in daily functioning.[40] In a multisite study evaluating 128 children aged 6 to 17, PARS was shown to have high inter-rater reliability, adequate test-retest reliability, and fair internal consistency. PARS scores are sensitive to treatment and parallel change in other measures of anxiety symptoms. This assessment tool has been validated in various populations and is frequently used worldwide in clinical and research settings.[42]

Treatment / Management

The optimal treatment strategy for specific phobia is cognitive behavioral therapy. However, cognitive behavioral therapy can be a challenging treatment modality for some patients to tolerate. Therefore, it is important to consider, if treatment is indicated in each individual case of specific phobia. Assessment of the impact that specific phobia has on quality of life, levels of distress, and social and occupational functioning, can help determine the individualized level of necessity to intervene or not.[9] Medication interventions can be considered alternative treatments for specific phobia; however, no medications have been cleared by the FDA for this purpose. 

Cognitive behavioral therapy in specific phobia is generally limited to exposure therapy, which can be emotionally taxing and challenging for patients to complete a full course of treatment. Exposure therapy utilizes systematic desensitization. This implements the principles of classical conditioning and can be enhanced in combination with operant conditioning approaches such as adding reinforcement or punishment that leads to extinction. In methodical desensitization, the patient is exposed to a list of stimuli ranking from the least to the most anxiety-provoking. With this method, patients are taught various techniques to deal with anxiety, such as relaxation, breathing control, and alternative cognitive approaches.

The cognitive-behavioral approach includes reinforcing the realization that the phobic stimulus is safe. As the patient masters these techniques, they are taught to use them in the face of anxiety-provoking stimuli and induce relaxation. As the patients become desensitized to each stimulus on the scale, they keep moving up until the most anxiety-provoking stimuli no longer elicit any fear or anxiety.[43][44] 

Flooding, also known as implosion, is another behavioral technique that can be used to treat specific phobias. This technique involves increasing exposure to the stimulus to induce habituation and decrease anxiety. To be successful, behavioral therapy requires that the patient be committed to the treatment, there are distinctly identified problems and objectives, and there are alternative strategies for dealing with the patient’s feelings.[9]

Patients with a blood-injection-injury phobia are advised to tense their bodies and remain seated during the exposure to avoid the possibility of fainting from a vasovagal reaction. Also, beta-blockers and benzodiazepines can be used in patients when the phobia is associated with panic attacks.[9]

Other forms of treatment that may also be considered include virtual therapy, in which the patient is exposed to or interacts with the phobic stimulus on a computer screen. This field of treatment is relatively novel and requires more research. Other treatment modalities include hypnosis, supportive therapy, and family therapy. The goal of all forms of therapy is to help the patient recognize that the feared stimulus is not dangerous and to provide emotional support.[45][46](A1)

Differential Diagnosis

Differential diagnoses for specific phobia include:

Agoraphobia

Specific phobia may resemble agoraphobia. However, in specific phobia, the phobic stimulus is specific to a particular situation rather than a general fear of difficulty escaping. 

Panic Disorder

Panic attacks can occur in specific phobia. Panic disorder is another anxiety disorder, in which panic attacks occur uncued or unexpected. This is in contrast to specific phobia, when panic attacks can occur after exposure to the phobic stimulus. 

Social Anxiety Disorder

Social anxiety disorder describes a general fear of being publicly scrutinized, embarrassed, or judged negatively by others in a variety of contexts. 

Posttraumatic Stress Disorder 

Avoidance is a key feature of Posttraumatic Stress Disorder (PTSD). However, in PTSD, the avoidance is related to situations associated with the trauma. To distinguish these disorders, the panel of symptoms needs to be taken into consideration. PTSD is expected to have persisting affective symptoms, while specific phobia (outside of the phobic stimulus) is not. 

Separation Anxiety Disorder

Separation anxiety is primarily a disorder of childhood, however, it can occur in adults as well. Separation anxiety disorder describes the fear of being separated from an attachment figure, while specific phobia results in anxiety when exposed to a phobic stimulus.  

Prognosis

Patients who are able to complete a course of cognitive behavioral therapy (exposure therapy) have a promising prognosis, but it is improved when there is maintenance therapy to ensure remission of symptoms.[9] Treatment response with benzodiazepines has been more limited to the duration treated with medication, and the treatment gains do not persist after discontinuation of the medication.[9] For those with limited response or difficulty tolerating cognitive behavioral therapy, utilizing a step-wise approach of pharmacotherapy to control severe anxiety and then proceeding to cognitive behavioral therapy may be appropriate. 

Complications

Uncontrolled specific phobia increases the risk of other comorbid psychiatric illnesses, specifically depression. Specific phobias can have significant impairment to social and occupational functioning, which can worsen psychological stress. Anxiety disorders are a risk factor for suicidality, even after controlling for co-occurring mental health disorders and life stress.[47] Estimates of population-attributable risk suggested a 7% to 10% risk of suicidality in adolescent patients with anxiety disorders.[47]