Acute cannabis administration can produce transient psychotic-like effects in healthy individuals. However, the mechanisms through which this occurs and which factors predict vulnerability remain unclear. We investigate whether cannabis inhalation leads to psychotic-like symptoms and speech illusion; and whether cannabidiol (CBD) blunts such effects (study 1) and adolescence heightens such effects (study 2).

Two double-blind placebo-controlled studies, assessing speech illusion in a white noise task, and psychotic-like symptoms on the Psychotomimetic States Inventory (PSI). Study 1 compared effects of Cann-CBD (cannabis containing Δ-9-tetrahydrocannabinol (THC) and negligible levels of CBD) with Cann+CBD (cannabis containing THC and CBD) in 17 adults. Study 2 compared effects of Cann-CBD in 20 adolescents and 20 adults. All participants were healthy individuals who currently used cannabis.

In study 1, relative to placebo, both Cann-CBD and Cann+CBD increased PSI scores but not speech illusion. No differences between Cann-CBD and Cann+CBD emerged. In study 2, relative to placebo, Cann-CBD increased PSI scores and incidence of speech illusion, with the odds of experiencing speech illusion 3.1 (95% CIs 1.3–7.2) times higher after Cann-CBD. No age group differences were found for speech illusion, but adults showed heightened effects on the PSI.

Inhalation of cannabis reliably increases psychotic-like symptoms in healthy cannabis users and may increase the incidence of speech illusion. CBD did not influence psychotic-like effects of cannabis. Adolescents may be less vulnerable to acute psychotic-like effects of cannabis than adults.

Open dialogue is an integrative approach to the organisation of specialist mental health services and therapeutic meetings.

This qualitative study sought to explore service users' and clinicians’ experiences of network meetings during the implementation of open dialogue in a modified version, for a UK-based mental health service.

In total 19 participants were interviewed (8 service users and 11 clinicians) and an inductive thematic analysis of the data was conducted.

Four dominant themes were identified: (1) open dialogue delivery, (2) the impact of open dialogue principles; (3) intense interactions and enhanced communication, and (4) organisational challenges. Clinicians considered open dialogue as a preferred, but challenging way of working, while being therapeutic. The data indicated that service users' experiences of network meetings were mixed. There was a wide variety of service user views as to what the purpose of a network meeting was and for some witnessing reflective conversations felt strange. However, the majority described feeling listened to and understood, excluding one service user who described their experience as distressing. Clinicians expressed an authentic self in their interactions with service users and both service users and clinicians described network meetings as emotionally expressive, although this was described as overwhelming at times.

The results of this thematic analysis indicate that service users' and clinicians’ experiences of open dialogue warrant further investigation. The intensity of interactions in network meetings should be carefully considered with service users before gaining consent to commence treatment. Implementation of open dialogue should be monitored to assess clinician- and service-level adherence to the principles of the approach.

None.