Development and validation of the cannabis experiences questionnaire - Intoxication effects checklist (CEQ-I) short form.

OBJECTIVE: To develop and validate a short form of the Cannabis Experiences Questionnaire - Intoxication Effects (CEQ-I), a 42-item scale which measures the euphoric and paranoid-dysphoric effects of cannabis intoxication. METHOD: Exploratory and confirmatory factor analyses were conducted among 604 past-month cannabis users to develop the short form. The factor structure was replicated in a second sample of 146 past-month cannabis users. The concurrent validity of the scale was also examined. RESULTS: Consistent with previous research, two factors were identified (paranoid-dysphoric; euphoric), and were replicated with confirmatory factor analyses. The most parsimonious scale consisted of 13 items. Correlations of short-form subscales with corresponding original subscales were high. The paranoid-dysphoric subscale was also moderately positively correlated with measures of psychotic-like experiences (PLEs) and psychological distress. CONCLUSIONS: The revised and validated CEQ-I short form can be used to explore the euphoric and paranoid-dysphoric effects of cannabis intoxication in young cannabis users, and whether these experiences increase their risk of developing cannabis use and psychotic disorders. The CEQ-I short form has the potential to aid in the identification of young cannabis users at risk of the paranoid-dysphoric effects of cannabis intoxication and may assist in the development of early intervention strategies targeting cannabis users with PLEs.

Are deficits in cognition associated with psychotic-like experiences after cannabis?

Not all individuals who smoke cannabis report psychotic-like experiences. Given that risk factors for psychotic disorders are multifaceted, precipitating factors to psychotic-like experiences after cannabis are likely to be equally complex. Reduced neurocognitive performance is associated with both psychosis risk and cannabis use. Therefore, it is possible cognitive performance may differentiate those who report psychotic-like experiences after cannabis from those who do not. We determined whether those reporting psychotic/dysphoric experiences after cannabis had reduced neurocognitive performance compared to those reporting primarily euphoric experiences. METHODS: Participants were recruited on the basis of responses to the cannabis high captured by the Psychosis-Dysphoric and Euphoric experiences subscales from the Cannabis Experiences Questionnaire (CEQ). RESULTS: Compared to participants reporting primarily euphoric cannabis experiences (n = 36; 44% male; mean age (SD) = 28 (9) years), those who reported psychotic/dysphoric experiences (n = 40; 45% male; mean age (SD) = 26 (5) years) demonstrated significantly faster responses to a trial and error learning task. In the presence of distracters, those with psychotic/dysphoric experiences after cannabis made more errors on a Continuous Performance Task. CONCLUSIONS: Those who report psychotic/dysphoric experiences after cannabis have subtle inefficiencies in their cognitive processes. The multiple factors which predict vulnerability to psychotic-like experiences after cannabis require further investigation.

Cognitive and neural processes in non-clinical auditory hallucinations.

BACKGROUND: The nosological status of auditory hallucinations in non-clinical samples is unclear. AIMS: To investigate the functional neural basis of non-clinical hallucinations. METHOD: After selection from 1206 people, 68 participants of high, medium and low hallucination proneness completed a task designed to elicit verbal hallucinatory phenomena under conditions of stimulus degradation. Eight subjects who reported hearing a voice when none was present repeated the task during functional imaging. RESULTS: During the signal detection task, the high hallucination-prone participants reported a voice to be present when it was not (false alarms) significantly more often than the average or low participants (P<0.03, d.f.=2). On functional magnetic resonance imaging, patterns of activation during these false alarms showed activation in the superior and middle temporal cortex (P<0.001). CONCLUSIONS: Auditory hallucinatory experiences reported in non-clinical samples appear to be mediated by similar patterns of cerebral activation as found during hallucinations in schizophrenia.