Carlos S. Alvarado, PhD, Research Fellow, Parapsychology Foundation

“Post-Bereavement Hallucinatory Experiences: A Critical Overview of Population and Clinical Studies,” by Anna Castelnovo, Simone Cavallotti, Orsola Gambini, and Armando D’Agostino (Journal of Affective Disorders, 2015,186, 266–274).

Abstract

Background: Removal of the “bereavement exclusion” criterion for major depression and proposed research criteria for persistent complex bereavement disorder in DSM-V pose new compelling issues regarding the adequacy of current nosographical boundaries. Post-bereavement hallucinatory experiences (PBHE) are abnormal sensory experiences that are frequentlyreported by bereaved individuals without a history of mental disorder. Given current uncertainty over the continuum of psychotic experiences in the general population, whether or not they should be considered pathological remains unclear. Methods: In order to systemize available knowledge, we reviewed the literature describing general population and clinical studies on PBHEs. Given the relatively low number of articles, all peer-reviewed, published studies in English were included. No study characteristics or publication date restrictions were imposed. Results: Overall, evidence suggests a strikingly high prevalence of PBHEs – ranging from 30% to 60% – among widowed subjects, giving consistence and legitimacy to these phenomena. Limitations: Whereas general population studies had adequate sample size numbers, all studies in the bereaved population had a very small number of subjects. No consensus for method of evaluation exists in the literature, with some studies using a free interview method and others using semi-structured interviews. Conclusions: The available literature appears to support an elevated frequency of PBHEs in bereaved individuals, but further research is needed to increase the reliability of these findings and refine the boundaries between physiological and pathological experiences.

The authors wrote:

“Two different models have been postulated to account for the high prevalence of hallucinatory experiences in the general population . . . These two models – called the “splitting” and the “lumping” model – seem to hold true also for the sub-group of hallucinatory experiences addressed in this review – i.e. PBHE. From the “splitting” standpoint, the fact that PBHE are found among “normal” people suggest that either hallucinations are not as pathologic as they are typically taken to be, that less-than-hallucinatory experiences (i.e. pseudo-hallucination, illusion, inner speech, felt presence, memories), as previously discussed, are routinely mischaracterized as hallucinations, or that mechanisms which maintain hallucinatory experiences in non-clinical populations are different. According to the alternative and increasingly popular “lumping” model, the higher-than-expected rates of abnormal experiences among non-patients is justified by the existence of a distributed spectrum or continuum of severity between pathological and non-pathological experiences . . . In this view, pathology is determined by variables such as frequency, content control, subjective distress, objective impairment and co-occurrence with other symptoms. In clinical practice, it is generally defined by the level of distress and functional impairment beyond which therapeutic interventions are advisable or necessary . . . Whereas awareness of the internal origin of the phenomenon is also of importance, this cannot always be considered significant per se. Indeed, subjects who experience hallucinations present varying degrees of insight ranging from the firm belief of their existence in the external environment to a full acceptance of their internal origin. However, all intermediate interpretations are commonly observed and are known to depend on the subject’s cognitive level, culture and personality . . . While a continuum model based on distress and impairment is broadly supported by the literature and the clinical practice, it raised both theoretical and practical problems. The difficulty arises in the subjective reflection upon one’s experience: one may wrongly ascribe internal experience to outside reality because the phenomenon is obtrusive, undesired and vivid. When one is relying on memory to describe the experience, what was actually imagined may be judged as having being perceived.”

The authors concluded:

“Over the past decade or so, PBHE have been often reported, yet poorly investigated. A 30%-60% prevalence emerged from the reviewed literature, giving consistence and legitimacy to the phenomena described. However, current data should be cautiously interpreted, given the limited number of studies and the many   theoretical / methodological biases. It seems likely from the present review that several heterogeneous entities hidden under one general term confound epidemiological data. Nevertheless, compelling evidence encourages further well-designed studies, comprising a deeper phenomenological investigation and sub-categorization. As such, structured questionnaires in support of free clinical interviews need to be developed and refined, as well as new neuroimaging paradigms designed to shed initial light on the neurobiological substrates of these phenomena.”

Considering the “many theoretical/methodological biases” one wishes there was more attention paid in these studies to veridical experiences of the sort studied by psychical researchers.