比较流行病学家一再注意到，这些疾病存在显著特征：只有西方国家（或者更准确地说，有一神论传统的社会 ） ， 特别是繁荣的西方国家，存在如此程度的精神病普遍程度。
Comparative epidemiologists have repeatedly noticed something remarkable about these illnesses: only Western countries (or, more precisely, societies with monotheistic traditions) – particularly prosperous Western countries – are subject to prevalence rates of this magnitude.