The association between visual hallucinations and secondary psychosis: a systematic review and meta-analysis

ABSTRACT

Introduction:

Visual hallucinations are often considered to be suggestive of a secondary cause of psychosis, however, this association has never been assessed meta-analytically. We aimed to compare the presence of visual hallucinations in patients with psychosis due to a primary or secondary cause.

Method:

We conducted a meta-analysis of case-control studies directly comparing primary and secondary psychosis. A random-effects model, following the DerSimonian and Laird method, was used to pool studies and generate overall odds ratios (OR), 95% confidence intervals (CI) and prediction intervals (PI).

Results:

Fourteen studies (904 primary and 804 secondary psychosis patients) were included. Visual hallucinations were significantly associated with secondary psychosis (OR = 3.0, 95% CI = 1.7-5.1, p < 0.001) with moderate between-study heterogeneity (I²= 70%). Subgroup analysis by type of secondary psychosis (organic, drug-induced, mixed) was non-significant. Analysis of the content of visual hallucinations (51 primary and 142 secondary psychosis patients) found hallucinations of inanimate objects were significantly more likely to be associated with secondary psychosis (OR = 0.1, 95% CI = 0.01-0.8, p = 0.03).

Conclusions:

Visual hallucinations were strongly associated with a secondary cause of psychosis. The presence of visual hallucinations in a patient presenting with psychosis may serve as a potential “red flag” for a secondary cause and warrant further investigation.

KEYWORDS:

• Psychosis
• organic psychosis
• secondary psychosis
• hallucination
• visual hallucination
• psychopathology

Acknowledgements

D.FF. and G.B. are supported by the NIHR South London and Maudsley NHS Foundation Trust Mental Health Biomedical Research Centre (BRC). D.FF. was supported by NIHR Programme Grants for Applied Research (RP-PG-0610-10100 - SHAPED). The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Statements and declarations

Preliminary findings were presented at the Faculty of Neuropsychiatry Annual Conference 2020 and at the British Neuropsychiatry Association Annual Meeting 2021.

Author contributions

A.K.D and G.B designed the study. A.K.D, M.T.D and G.B conducted the search and data extraction. A.K.D and G.B analysed the data and wrote the first draft of the manuscript. A.K.D, G.B, M.T.D and D.FF contributed and edited the manuscript.

Data availability

The study was pre-registered through the Open Science Framework (OSF) website.

(https://osf.io/j9twg/?view_only = 5c0f63cccd574239aca07bccdae35f3c).

Relevance statement

Visual hallucinations are associated with secondary causes of psychosis. Visual hallucinations of inanimate (i.e. non-living) objects, in particular, were associated with secondary causes. Findings suggest that the presence of visual hallucinations should be routinely assessed as part of a standard psychiatric assessment. A positive finding may be considered a “red flag” for a secondary cause and warrant further investigation.