Panic Disorder

Background

Panic disorder is an anxiety disorder whose essential feature is the presence of recurrent, unexpected panic attacks. Panic attacks are discrete, sudden-onset episodes of intense fear or apprehension accompanied by specific somatic or psychiatric symptoms (e.g., palpitations, shortness of breath, fear of losing control). A patient is diagnosed as having panic disorder when he or she has experienced such attacks, and at least one of the attacks has been followed by ≥1 month of persistent concern about additional attacks, worry about the implications or consequences of the attack, or a significant change in behavior related to the attack.

The symptoms of panic disorder usually begin in late adolescence to the mid-30s and may coincide with the presentation of major depressive disorder, social phobia, or generalized anxiety disorder. Panic disorder can interfere with the ability to conduct activities of daily living. Patients with panic disorder have an increased incidence of suicide.

Symptoms may mimic those of various physical illnesses or be caused by other medical conditions (e.g., hyperthyroidism, brain tumors, adrenal tumors, heart arrhythmias, hypoglycemia, anemia). Substance or alcohol intoxication or withdrawal also may cause panic symptoms. Patients with panic symptoms should be evaluated for other causative conditions.

Major depressive disorder occurs in 50-65% of people with panic disorder. Major depression may precede or follow the onset of panic disorder. Patients with panic disorder therefore should be screened for depression initially and periodically thereafter (see chapter Major Depression and Other Depressive Disorders). Anxiety also commonly is experienced by persons with panic disorder; see chapter Anxiety Disorders for further information about this condition.

S:Subjective

The patient complains of discrete periods of intense fear or discomfort in which four or more of the following symptoms developed abruptly and reached a peak within 10 minutes:

  • Shortness of breath or smothering sensation
  • Sweating
  • Trembling or shaking
  • Dizziness, lightheadedness, faintness, or feeling of unsteadiness
  • Numbness or tingling sensations
  • Chest pain or discomfort
  • Palpitations or accelerated heart rate
  • Hot flashes or chills
  • Sensation of choking
  • Depersonalization or derealization
  • Fear of dying
  • Fear of going crazy or losing control
  • Nausea or abdominal distress

Other subjective complaints may include the following:

  • Apprehension about the outcome of routine activities and experiences
  • Anticipation of a catastrophic outcome from a mild physical symptom or from medication side effects
  • Discouragement and demoralization

Panic attacks are, by definition, self-limited and they peak quickly. Symptoms that persist continuously for longer periods suggest other causes.

Ask about the symptoms indicated above and about the following:

  • Frequency, duration, and onset of panic episodes
  • Possible precipitants, (e.g., settings in which attacks occur), situations (e.g., being alone outdoors), relationship to food or hunger
  • Current medications, herbal products, and supplements; recent medication changes
  • Multiple visits to health care providers with complaints suggesting panic attacks
  • Family history of mood and psychiatric illnesses, particularly anxiety and panic
  • Use of recreational drugs (especially stimulants such as cocaine or amphetamines), alcohol (current and recent), and caffeine
  • Sleep disturbances
  • Concomitant illnesses (e.g., endocrine, cardiac, pulmonary)
  • Any associated or concurrent symptoms that could suggest a medical etiology
  • Screen for depression (see chapter Major Depression and Other Depressive Disorders)

O:Objective

Measure vital signs, with particular attention to heart rate (tachycardia) and respiratory rate (shortness of breath, hyperventilation). Perform a complete physical examination, including thyroid, cardiac, pulmonary, and neurologic evaluation.

During actual panic attacks, patients may have increases in heart rate, respiratory rate, or systolic blood pressure.

A:Assessment

A differential diagnosis may include the following conditions:

  • Congestive heart failure, myocardial ischemia, arrhythmias
  • Hyperthyroidism
  • Intoxication with or withdrawal from psychoactive substances (e.g., amphetamines, cocaine, hallucinogens, caffeine, medications)
  • Hypoglycemia
  • Hypoxia
  • Hyperparathyroidism
  • Medication side effects
  • Pheochromocytoma
  • Adrenal disorders, Cushing syndrome, electrolyte abnormalities
  • Respiratory infection
  • Seizure disorder
  • Vestibular dysfunction
  • Allergic reactions
  • Posttraumatic stress disorder
  • Social phobia or specific phobia (specific phobia is a response to a specific stimulus, whereas a patient with panic attacks is unsure when they will recur and what will trigger them)
  • Agoraphobia
  • Obsessive-compulsive disorder
  • Separation anxiety disorder

P:Plan

Diagnostic Evaluation

Perform the following tests:

  • Electrolytes, blood glucose
  • Thyroid function tests (thyroid stimulating hormone [TSH], T4)
  • Arterial blood gases if the patient has persistent shortness of breath
  • Electrocardiogram if chest pain or other cardiac symptoms are present
  • Other tests as indicated by symptoms and physical examination

Treatment

Once other diagnoses have been ruled out, consider the following treatments:

Psychotherapy

Options include cognitive-behavioral therapy, interpersonal therapy, exposure therapy, a stress-management group, relaxation therapy, visualization, guided imagery, supportive psychotherapy, and psychodynamic psychotherapy. Long-term psychotherapy may be indicated if experienced professionals are available and the patient is capable of forming an ongoing relationship. If possible, refer to an HIV-experienced therapist. The type of psychotherapy selected often will depend on the skills and training of the practitioners available in a given health care system or region. In addition, refer the patient to available community-based support. Emergency referrals may be needed for the most anxious patients and those with comorbid depression.

Pharmacotherapy

Patients with advanced HIV disease and geriatric patients may be more vulnerable to the central nervous system (CNS) effects of certain medications. Medications that affect the CNS should be started at low dosage and titrated slowly. Similar precautions should apply to patients with liver dysfunction.

Options

A number of medications have an approved indication by the U.S. Food and Drug Administration (FDA) for panic disorder. These include the serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitor (SNRI) venlafaxine extended-release, and benzodiazepines listed below. For most patients, SSRIs are preferable to benzodiazepines for the treatment of panic disorder because they do not have the potential for addiction and they do not pose the same level of risk if drug interactions cause an elevation of their levels. Other medications used to treat anxiety disorders, such as SNRIs may be considered, and some of them are less likely to interact with ARV medications. See chapter Anxiety Disorders for descriptions of these medications.

SSRI antidepressants approved for panic disorder include the following:

  • Fluoxetine (Prozac), recommended dosage 20 mg PO QD (usual starting dosage 10 mg daily)
  • Paroxetine (Paxil), recommended dosage 40 mg PO QD (usual starting dosage 10 mg daily)
  • Sertraline (Zoloft), recommended dosage 50-200 mg PO QD (usual starting dosage 25 mg daily)

SNRI antidepressant approved for panic disorder:

  • Venlafaxine (Effexor XR), recommended dosage 75-225 mg PO QD (usual starting dosage 37.5 mg daily)

Benzodiazepines approved for panic disorder include the following:

  • Clonazepam (Klonopin), recommended dosage 0.5-2 mg PO BID
  • Alprazolam (Xanax), recommended dosage 0.5-3 mg PO TID or Xanax XR at a recommended dosage of 3-6 mg PO QD; start at low dosage, may increase every 3-4 days in increments of ≤ 1 mg/day if tolerated

Potential ARV Interactions

Interactions may occur between certain ARVs and agents used to treat panic. Some combinations may be contraindicated and others may require dosage adjustment. Refer to medication interaction resources or consult with an HIV expert or clinical pharmacist before prescribing.

Some ARV medications (particularly protease inhibitors [PIs]) and the pharmacokinetic booster cobicistat may affect the metabolism of some SSRIs via cytochrome P450 interactions. These generally are not clinically significant, but SSRIs used concomitantly with PIs or cobicistat should be started at low dosages and titrated cautiously to prevent antidepressant adverse effects and toxicity. On the other hand, some PIs may decrease levels of paroxetine and sertraline, and efavirenz also lowers sertraline levels; these antidepressants may require upward titration if used concurrently with interacting ARVs.

PIs and cobicistat can significantly elevate the levels of clonazepam and alprazolam, resulting in the potential for severe sedation or respiratory depression. For patients receiving clonazepam or alprazolam, it is recommended that these medications be used at the lowest dosages for the shortest duration possible.

Patient Education

  • Inform patients that behavioral interventions can help to reduce the frequency and severity of panic attacks.
  • Some antidepressants and antianxiety medications can prevent or reduce the severity of panic attacks.
  • Advise patients that they may develop problems with sexual function because of the medications. Patients should report any problems to their prescribers. (Note: Providers should let the patient know that sexual well-being is fundamental to quality of life and can be talked about and addressed in the clinical setting.)

References