Visual, auditory hallucinations often co-occur in psychosis patients

By Mark Cowen

Visual hallucinations (VHs) are common in patients with psychosis spectrum disorders and often co-occur with auditory hallucinations (AH), researchers report.

The team also found that increased delusional ideation often precedes hallucinatory episodes in such patients, indicating that it does not only result from the hallucinatory experience.

The findings "support the idea of top-down processes being involved in the onset of real life hallucinatory experiences, suggesting that delusional beliefs may affect the salience of inner experiences and/or the source-monitoring mechanisms involved in the development of a hallucination," say Inez Myin-Germeys (Maastricht University, the Netherlands) and team.

The researchers investigated the phenomenology of VHs and AHs in daily life, and their associations with emotions and delusions, among 184 patients (71% men) with psychosis spectrum disorders.

Hallucinatory episodes were assessed over a 6-day period using the Experience Sampling Method (ESM) - a structured daily diary technique. Delusional and emotional experiences were assessed by self-report on a 7-point scale of increasing intensity.

In total, 73 (40%) participants reported hallucinations, of whom 10 reported VHs only, 25 AHs only, and 38 both VHs and AHs. Overall, 196 VH and 399 AH episodes were experienced by the participants over the 6-day study period.

The researchers found that patients with both VHs and AHs scored significantly higher than non-hallucinating patients on all subscales of the Positive and Negative Syndrome Scale, indicating greater illness severity, and had significantly greater delusional intensity and negative affect.

Patients with both VHs and AHs also had significantly lower levels of positive affect and greater delusional intensity compared with to AH-only patients, and significantly higher levels of negative affect and greater delusional intensity compared with VH-only patients.

The researchers also found that increased delusional intensity preceded the onset of hallucinatory episodes, whereas there was no increase in positive or negative affect before such episodes.

Myin-Germeys et al conclude in Schizophrenia Research that "the co-occurrence of AHs and VHs is a clear indicator of more severe illness and it is therefore advisable for clinicians to assess VHs routinely in clinical practice."

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