Trance possession occurs across cultures but is rarely studied, and no consensus exists on its causes. This case study of five individuals proposes four distinct categories: pathological, religious, curative, and entertainment possession. Pathological possession involved acute psychological pain and chaotic-disengaged family histories. Religious possession (being overcome by the Holy Spirit) brought intense spiritual ecstasy and joy. Entertainment possession was triggered by music and ritual, attributed to supernatural beings. The findings support a holistic perspective: possession is a dynamic interaction between repressed psychological needs, frustrations, desires, and socioreligious beliefs. A single theoretical or physiological lens risks 'medical materialism,' as William James warned.
Mass psychogenic illness in Indonesia, occurring mainly in schools and factories, is classified differently by two diagnostic manuals: the DSM-5 categorizes it as a dissociative disorder, while the Indonesian PPDGJ classifies it as a conversion disorder. This inconsistency may lead to less effective and humane interventions. An assessment of 55 individuals using the Dissociative Disorder Interview Schedule found that most fit criteria for somatization disorder (98.18%), with many also meeting criteria for major depression (49%), trance (69%), childhood physical abuse (35%), and borderline personality disorder (47.2%). Few met criteria for dissociative disorders such as dissociative amnesia (14.54%) or dissociative identity disorder (5%). The findings suggest mass psychogenic illness is likely a manifestation of distinct mental disorders—particularly somatization, trance, borderline personality disorder, and major depression—rather than dissociative disorders exclusively.