Effects of an unguided self-help intervention for distressing auditory verbal hallucinations in a heterogenous sample of voice hearers: A randomized controlled trial and explorative cluster analysis.

OBJECTIVE

Clinical care and research need to improve treatment availability for auditory verbal hallucinations (AVH). To provide further evidence, we examined the efficacy of an unguided six-weeks self-help intervention for AVH (MCTVoice) based on metacognitive training.

METHODS

N = 78 participants with distressing AVH were recruited from clinical and non-clinical settings. We conducted a randomized controlled trial (RCT) that compared the MCTVoice with a waitlist control group (WLcontrol), both receiving additional treatment-as-usual. Outcomes were the frequency and distress of AVH, general hallucinatory and psychiatric symptoms, quality of life, and satisfaction with the intervention, following an intention-to-treat (ITT) and per-protocol (PP) principle. Besides, we conducted an explorative cluster analysis to examine subgroups of voice hearers.

RESULTS

We found no significant differences between the groups on the frequency and distress of AVH. However, general hallucinatory experiences were significantly reduced in the MCTVoice compared to the WLcontrol group in PP-data (F(3,48) = 39.51, p = .038, η2p = 0.09). No other between group comparisons were significant. The cluster analysis revealed a two-cluster solution with a higher (type 1) and a lower (type 2) symptom burden group, with higher values of clinical and AVH characteristics in cluster 1. Besides, participants in cluster 1 showed significantly greater improvements in AVH compared to cluster 2 (F(1,44) = 7.97; p = .007, η2p = 0.15).

CONCLUSION

Even though we found no effect of the MCTVoice on the main outcome, results showed promising outcomes on general hallucinatory experiences in PP data. The identification of AVH clusters could contribute to implement individualized interventions that target specific characteristics and needs of voice hearers.