According to the DSM-IV, panic disorder is classified as an anxiety disorder consisting of repeated and unexpected panic attacks. Panic attacks are defined as discrete events characterized by the sudden onset of cardiorespiratory symptoms and physiological arousal, accompanied by catastrophic fears and the urge to flee. Typically, these symptoms include shortness of breath, tachycardia, nausea, sweating, and fears that the individual is losing control or going crazy. Such spontaneous panic attacks typically reach an apex of intensity within 10 minutes.
Data from large scale epidemiological surveys suggest that panic disorder is more common in women than in men (Joyce et al., 1989; Katerndahl and Realini, 1993; Reed and Witchen, 1998). The National Comorbidity Survey (NCS) examined the presence of psychiatric morbidity, including depression, panic disorder and general anxiety, in a large national sample (Kessler et al., 1994).
Based on NCS data, Eaton et al. (1994) found that panic disorder is 2.5 times more prevalent among women than men. In addition, the gender difference appears to increase according to age. For example, the prevalence rate of panic disorder for women ages 15 to 24 was 2.5%, compared to 1.3% of same-age men. For older women and men, the overall rates drop, but the difference between genders appears to grow. Among women ages 35 to 44, the rate of panic disorder was 2.1%, compared to the 0.6% rate among same-age men.
In addition to higher prevalence rates, women may suffer more debilitating forms of panic disorder. Yonkers and colleagues (1998) conducted a longitudinal study of 412 women and men diagnosed with panic disorder with and without agoraphobia for five years. This study found that after remission, panic symptoms reoccurred at twice the rate for women than men. Still other studies have shown that females suffer a significantly greater frequency of panic attacks than men (Maier and Buller, 1988).
We examined gender differences of specific panic-related symptoms using empirical data drawn from the NCS (Sheikh et al., 2002). Specifically, the frequency of 18 panic symptoms was examined according to the gender of patients with panic disorder (n=274) and patients with panic attacks only, but without meeting criteria for panic disorder (n=335).
Findings from this study suggested that heart pounding was the most frequently endorsed panic symptom for both genders and both diagnostic groups. However, in the panic disorder group, a significantly greater proportion of women than men endorsed shortness of breath (72% versus 50%), feeling faint (59% versus 45%) and feeling smothered (60% versus 43%). In the panic attack only group, women were more likely to complain of shortness of breath (65% versus 50%), choking or difficulty swallowing (37% versus 25%), and feeling smothered (50% versus 38%).
Using logistical regression, three symptoms predicted female gender: shortness of breath, nausea and feeling smothered. Two symptoms predicted male gender: sweating and pain in the stomach (Table).
Overall, the results of our study indicated that some gender differences do exist at the symptom level for panic disorder and panic attacks. Specifically, a significantly greater proportion of females appear to suffer respiration-related symptoms (difficulty breathing, feeling faint and smothered). Several theories are described here that show how adaptive physiological monitors for breathing and modulation of pain, coupled with fluctuations in the sex hormone cycle, may lead to panic.
Premenstrual hormonal fluctuations may partially explain the increased incidence of panic disorder in women. Seeman (1997) suggested that progesterone metabolites have anxiolytic effects due to their agonistic effect on g-aminobutyric acid (GABA)/benzodiazepine receptors. However, Stein et al. (1989) were unable to demonstrate increased anxiety ratings in normally menstruating females with panic disorder across two menstrual cycles. Nevertheless, other studies point to greater panic response in females suffering from premenstrual dysphoric disorder, indicating that a possible concurrent dysregulation of the GABA/benzodiazepine receptor complex may underlie aspects of both the panic response and disorders related to the female reproductive cycle.
Premenstrual hormonal fluctuations may also explain the increased frequency of respiratory-related symptoms in women with panic disorder (Klein, 1993). According to the suffocation false alarm theory, there is a suffocation alarm system that becomes unduly hypersensitive. Therefore, ordinary physiological fluctuations in blood carbon dioxide levels and brain lactate may be interpreted as impending asphyxiation. Such overreactions on the part of the suffocation alarm system initially release a sense of breathlessness or dyspnea, followed by hyperventilation, panic and the urge to flee. Another indication that female physiology may have a particular relationship to panic disorder came from challenge studies with CO2 and lactate. Although panic responses to such challenges only occur in panic disorder, women with premenstrual syndrome show similar respiratory difficulties as patients with panic disorder (Harrison et al., 1989; Sandberg et al., 1993).
Eaton WW, Kessler RC, Wittchen HU, Magee WJ (1994), Panic and panic disorder in the United States. Am J Psychiatry 151(3):413-420.
George DT, Nutt DJ, Walker WV et al. (1989), Lactate and hyperventilation substantially attenuate vagal tone in normal volunteers. A possible mechanism of panic provocation? Arch Gen Psychiatry 46(2):153-156.
Gittelman R, Klein DF (1984), Relationship between separation anxiety and panic and agoraphobic disorders. Psychopathology 17(suppl 1):56-65.
Harrison WM, Sandberg D, Gorman JM et al. (1989), Provocation of panic with carbon dioxide inhalation in patients with premenstrual dysphoria. Psychiatry Res 27(2):183-192.
Joyce PR, Bushnell JA, Oakley-Browne MA et al. (1989), The epidemiology of panic symptomatology and agoraphobic avoidance. Compr Psychiatry 30(4):303-312.
Katerndahl DA, Realini JP (1993), Lifetime prevalence of panic states. Am J Psychiatry 150(2):246-249.
Kessler RC, McGonagle KA, Zhao S et al. (1994), Lifetime and 12-month prevalence of DSM-III-R psychiatric disorders in the United States. Results from the National Comorbidity Survey. Arch Gen Psychiatry 51(1):8-19.
Klein DF (1993), False suffocation alarms, spontaneous panics, and related conditions. An integrative hypothesis. Arch Gen Psychiatry 50(4):306-317 [see comments].
Lipsitz JD, Martin LY, Mannuzza S et al. (1994), Childhood separation anxiety disorder in patients with adult anxiety disorders. Am J Psychiatry 151(6):927-929.
Maier W, Buller R (1988), One-year follow-up of panic disorder. Outcome and prognostic factors. Eur Arch Psychiatry Neurol Sci 238(2):105-109.
Panksepp J (1998), Affective Neuroscience: The Foundations of Human and Animal Emotions. New York: Oxford University Press.
Papp LA, Martinez JM, Klein DF et al. (1997), Respiratory psychophysiology of panicdisorder: three respiratory challenges in 98 subjects. Am J Psychiatry 154(11):1557-1565[see comment].
Porges SW (1998), Love: an emergent property of the mammalian autonomic nervous system. Psychoneuroendocrinology 23(8):837-861.
Reed V, Wittchen HU (1998), DSM-IV panic attacks and panic disorder in a community sample of adolescents and young adults: how specific are panic attacks? J Psychiatr Res 32(6):335-345.
Sandberg D, Endicott J, Harrison W et al. (1993), Sodium lactate infusion in late luteal phase dysphoric disorder. Psychiatry Res 46(1):79-88.
Seeman MV (1997), Psychopathology in women and men: focus on female hormones. Am J Psychiatry 154(12):1641-1647 [see comment].
Sheikh JI, Leskin GA, Klein DF (2002), Gender differences in panic disorder: findings from the National Comorbidity Survey. Am J Psychiatry 159(1):55-58 [see comment].
Stein MB, Schmidt PJ, Rubinow DR, Uhde TW (1989), Panic disorder and the menstrual cycle: panic disorder patients, health control subjects, and patients with premenstrual syndrome. Am J Psychiatry 146(10):1299-1303.
Yonkers KA, Zlotnick C, Allsworth J et al. (1998), Is the course of panic disorder the same in women and men? Am J Psychiatry 155(5):596-602.