How many bereaved people hallucinate about their loved one? A systematic review and meta-analysis of bereavement hallucinations.

Background: Bereavement hallucinations (BHs) entail a perception of a deceased in any sense modality or as a quasi-sensory sense of presence. BHs are an associated feature of the proposed Persistent Complex Bereavement Disorder (PCBD) in DSM-5. The goals of this review are to estimate the prevalence of BHs, identify possible moderators, and review the methodological status of this research field.

Methods: A systematic literature search was conducted through the databases PubMed, PsycINFO, and CINAHL. Studies systematically assessing the prevalence of BHs of a relative or friend were included.

Results: Twenty-one eligible studies were identified and 8 meta-analyses of BHs in different sense modalities were conducted. The prevalence of having one or more BHs was estimated to be 56.6% (95% CI 49.9-63.2), and the estimated prevalence of BHs in specific sense modalities ranged within 7.0-39.7%. Meta-regression analyses revealed associations to age and conjugal bereavement, but results are tentative and dependent on the type of BH in question.

Limitations: The included studies were methodologically heterogeneous. Limitations included the lack of a valid measure of BHs and low sample generalizability.

Conclusion: This first systematic review and meta-analysis of BHs suggests that more than half of the bereaved people experience some kind of BH. However, there are considerable methodological limitations in the research of BHs, which is of pertinent interest as BHs have been linked to the development of a future diagnosis of clinically impairing grief. A valid measure of BHs needs to be developed and used in high-quality epidemiological research using population-based designs.