Cigarette smoking and cannabis use are equally strongly associated with psychotic-like experiences: a cross-sectional study in 1929 young adults

Abstract

Smoking is an equally strong independent predictor of frequency of PLEs as monthly cannabis use. Our results suggest that the association between moderate cannabis use and PLEs is confounded by cigarette smoking.

Cannabis use as a risk factor for psychotic‐like experiences: A systematic review of non‐clinical populations evaluated with the Community Assessment of Psychic Experiences

“…The majority of the studies ( n = 18) evaluated the positive CAPE dimension, as expected, because the positive symptoms would clearly be representative of PLEs (eg, hallucinations and delusions). In 13 studies, it was suggested that any use of cannabis was associated with the occurrence of PLEs, even when discontinued use was compared to no use at all (van Gastel et al, , ). In addition, the association increased as the frequency of use increased (Spriggens & Hides, ; Verdoux et al, ), even when the measure was less specific, for example, any lifetime use (Balzan, Delfabbro, Galletly, & Woodward, ; Galletly et al, ; Skinner et al, ; Stefanis et al, ).…”

“…Although the use of the CAPE via the Internet proved to be efficient for some research purposes (Vleeschouwer et al, ), it is not possible to eliminate the possibility of selection bias. Nevertheless, we understand that different criteria were used for the composition and analysis of each subsample, decreasing the possibility of overlapping (eg, van Gastel et al () included lifetime cannabis users whereas van Gastel et al () analysed current cannabis users).…”

Trajectory of adolescent cannabis use on addiction vulnerability

“…Self-medication due to a preexisting vulnerable state is also evident in regard to psychosis risk. Cannabis use is high among people with psychosis (Koskinen et al, 2010; van Gastel et al, 2013) and it has been documented that psychotic symptoms are evident in subjects who have never used cannabis before the onset of psychotic symptoms, which also predicts future cannabis use (Ferdinand et al, 2005). This suggests that current cannabis-dependent subjects may have underlying psychiatric disorders that contributed to self-medication and that through repeated use, led to dependence.…”

The current situation with cannabinoids

“…The adverse effect most often referred to is that cannabis can cause mental health problems, cannabis use being associated with psychotic symptoms (disordered thinking, hallucinations and delusions). In their study of cigarette smokers and cannabis users, van Gastel et al [19] concluded that smoking is an equally strong independent predictor of the frequency of psychotic-like experiences (PLEs) as monthly cannabis use, and that the association between moderate cannabis use and such experiences is confounded by cigarette smoking. There is accumulating evidence that cannabis use plays a significant role in aggravating a psychosis; those most at risk being heavy cannabis users who have a history of psychotic symptoms or a family history of these disorders.…”

“…In Europe, most cannabis is smoked in a mixture with tobacco. In their study of cigarette smokers and cannabis users, van Gastel et al [19] concluded that smoking is an equally strong independent predictor of the frequency of psychotic-like experiences (PLEs) as monthly cannabis use, and that the association between moderate cannabis use and such experiences is confounded by cigarette smoking. The authors conclude that 'our findings fit the hypothesis that individuals, who are prone to PLEs, particularly if associated with high distress, are more inclined to use cannabis.…”