Panic Disorder

The DSM-V [1] defines panic disorder (PD) as the recurrent onset of sudden fear accompanied by somatic symptoms like palpitations, excessive sweating, and dyspnea. Other criteria include persistent anxiety about recurrence and its consequences or inappropriate behavioral changes. In order to diagnose PD, it is important to exclude medical illnesses, substance abuse, and other psychiatric disorders as the cause of the panic attacks.

The clinical presentation of panic attacks and PD can mimic the symptoms of coronary heart disease [2] and cardiomyopathies [2], making it difficult to differentiate between the conditions clinically [3]. For example, symptoms like chest pain, palpitations, sweating, discomfort, and dyspnea are common to PD as well as myocardial infarction (MI), angina pectoris and pulmonary embolism. Other somatic symptoms of PD include cold clammy hands, headache, diarrhea, insomnia, weakness, intrusive thoughts, and ruminations. The attacks in PD are often related to certain places or situations. Patients develop anxiety about the recurrence of the attack and start avoiding these situations and places resulting in agoraphobia [4]. This can further lead to the development of safety behaviors like dependence on anxiolytic medications and avoiding being alone [4].

Although no gender differences have been observed in the expression of PD symptoms in children and adolescents, a higher incidence of PD has been observed amongst girls. Children and adolescents experience somatic symptoms similar to those seen in adults and these include palpitations, dyspnea, sweating, chest pain, nausea, abdominal discomfort, dizziness, restlessness and a sense of losing control [5] [6] [7].

Diagnosis of PD can be challenging as its clinical presentation resembles that of several serious acute conditions. Therefore the diagnosis is often based on the exclusion. History, physical examination and mental status examination are the pillars of PD diagnosis. An electrocardiography (ECG) should be obtained early during the workup to rule out myocardial ischemia and conduction abnormalities in all patients presenting with palpitations, chest pain, dyspnea, and sweating. Pulse oximetry will usually show either normal or slightly higher oxygen levels. Arterial blood gas analysis is performed to exclude metabolic acidosis and hypoxemia. In patients with a history of a syncopal event, ambulatory Holter monitoring should be considered. A D-dimer test, spiral computed tomography (CT scan), lower limb Doppler or ventilation-perfusion (V/Q) scanning is indicated to exclude pulmonary embolism especially in those at risk. Electroencephalography may be required to differentiate PD from partial complex seizures.

Laboratory studies should be performed to exclude substance abuse and other medical conditions. These include complete blood count, hemoglobin, urine toxicology, serum electrolytes, serum glucose, cardiac enzymes and, thyroid-stimulating hormone.

Orexin or hypocretin has been shown to play a role in the pathogenesis of panic in rats [8] and elevated levels have been observed in the cerebrospinal fluid of individuals with panic attacks.

Functional magnetic resonance imaging is not routinely recommended in the workup of PD although increased flow in the right parahippocampal region with decreased serotonin type 1A receptor binding in the anterior and posterior cingulate and raphe of patients with panic disorder has been noticed on positron emission tomography (PET) scanning [9]. Patients with PD have also been observed to have smaller temporal lobe volume on magnetic resonance imaging [10].

1. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders. Fifth Edition. Arlington, VA: American Psychiatric Association; 2013.
2. Tully PJ. A good time to panic? Premorbid and postmorbid panic disorder in heart failure affects cardiac and psychiatric cause admissions. Australas Psychiatry. 2015;23:124 –7.
3. Tully PJ, Cosh SM, Baumeister H. The anxious heart in whose mind? A systematic review and meta-regression of factors associated with anxiety disorder diagnosis, treatment and morbidity risk in coronary heart disease.J Psychosom Rese. 2014;77:439 –48.
4. Roy-Byrne PP, Craske MG, Stein MB. Panic disorder. Lancet. 2006;16:1023-32
5. Masi G, Favilla L, Mucci M, Millepiedi S. Panic disorder in clinically referred children and adolescents. Child Psychiatry Hum Dev. 2000;31:139-51.
6. Ehlers A. Somatic symptoms and panic attacks: a retrospective study of learning experiences. Behav Res Ther. 1993;31:269-78.
7. Diler RS, Birmaher B, Brent DA, et al. Phenomenology of panic disorder in youth. Depress Anxiety. 2004;20:39-43.
8. Johnson PL, Truitt W, Fitz SD, et al. A key role for orexin in panic anxiety. Nat Med. Jan 2010; 16(1):111-5.
9. Neumeister A, Bain E, Nugent AC, et al. Reduced serotonin type 1A receptor binding in panic disorder. J Neurosci. Jan 21 2004; 24(3):589-91.
10. Vythilingam M, Anderson ER, Goddard A, et al. Temporal lobe volume in panic disorder--a quantitative magnetic resonance imaging study. Psychiatry Res. Aug 28 2000; 99(2):75-82