The prevalence of<unk>  is unknown. One study estimated a minimal rate of 170<unk>  cases per 100,000 individuals, but the true prevalence is likely higher due to underdiagnosis. Another study estimated that there are at least 500,000 cases in the United States.<unk>  is more common in women than men, with a female-to-male ratio of 4:1. Most people with<unk>  are aged between 20 and 40, with an average onset of 21. Diagnoses of<unk>  beyond age 40 are rare, perhaps because symptoms improve with age.
Postural orthostatic tachycardia syndrome
Da Costa's syndrome  Da Costa's syndrome  1
Heat syncope
Laughter-induced syncope
Vasoplegic syndrome
Reflex syncope
Permissive hypotension
Postanesthetic shivering