A comparison of visual hallucinations across disorders

Area of Science:

• Neuroscience
• Psychiatry
• Clinical Psychology

Background:

• Hallucinations are often studied as single sensory experiences, neglecting co-occurring multi-sensory hallucinations (MSH).
• Visual hallucinations (VH) in people with psychosis are frequently accompanied by hallucinations in other senses.
• Limited research exists on MSH prevalence across different groups experiencing VH.

Purpose of the Study:

• To investigate the prevalence of multi-sensory hallucinations (MSH) in four distinct patient groups with current visual hallucinations (VH).
• To compare MSH rates between people with psychosis, eye disease (ED), Lewy body dementia (LBD), and Parkinson's disease (PD).

Main Methods:

• Archival data from standardized assessments of VH were analyzed.
• The presence of MSH (auditory, olfactory, gustatory, tactile) was determined in 22 people with psychosis, 82 with ED, 41 with LBD, and 41 with PD.
• Statistical comparisons were made between the groups regarding MSH prevalence.

Main Results:

• People with psychosis reported significantly higher rates of MSH (auditory 73%, tactile 82%, olfactory/gustatory 27%) compared to LBD (auditory 21%, tactile 28%, olfactory/gustatory 6%), ED (auditory 1%, tactile 11%, olfactory/gustatory 0%), and PD (auditory 3%, tactile 8%, olfactory/gustatory 3%) groups.
• Participants experiencing MSH, regardless of diagnosis, showed greater conviction in the reality of their VH and reported increased distress.
• High rates of MSH were observed in people with psychosis and VH, unlike in older adult groups with VH.

Conclusions:

• People with psychosis and VH exhibit a notably higher prevalence of MSH compared to patients with ED, LBD, or PD.
• The findings suggest significant differences in MSH prevalence across diagnostic groups experiencing VH.
• These disparities have important implications for both clinical practice and theoretical understanding of hallucinations.