Impact of previous tobacco use with or without cannabis on first psychotic experiences in patients with first-episode psychosis

González‐Blanco, Leticia; García-Portilla, María Paz; Gutiérrez, Miguel; Mezquida, Gisela; Cuesta, Manuel J.; Urbiola, Elena; Amoretti, Sílvia; Barcones, Fe; González‐Pinto, Ana; Pina‐Camacho, Laura; Corripio, Iluminada; Vieta, Eduard; Baeza, Immaculada; Toll, Alba; Sáiz, Pilar A.; Bobes, Julio; Bernardo, Miguel

doi:10.1016/j.schres.2021.07.017

Cited by 8 publications

(12 citation statements)

References 44 publications

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“…In the various studies, FTD was referred to as "cognitive disorganization" 30,[37][38][39] , "disorganization" 23,[40][41][42][43][44][45] , "thought disturbance" 29 , "FTD" 46,47 or "positive FTD" 13,[48][49][50][51] . This is linked to the scale used (see supplementary material "Scales" for details).…”

Section: Effect Measuresmentioning

confidence: 99%

“…Eight studies 23,30,[37][38][39]42,44,45 assessed FTD globally using two questionnaires, the Oxford-Liverpool Inventory of Feelings and Experiences 52 and the Schizotypal Personality Questionnaire 53 , as well as three scales: the Positive and Negative Syndrome Scale 54 , the Psychotomimetic States Inventory 52 , and the Structured Interview for Prodromal Symptoms 45 . Nine studies 13,29,40,41,46,[48][49][50][51] evaluated subcomponents of FTD using the Scale for the Assessment of Positive Symptoms 55 , the Brief Psychiatric Rating Scale 56 , the Young Mania Rating Scale 57 , the Operational Criteria for Psychotic Illness 58 and the Symptom Onset in Schizophrenia 59 . The main subcomponent assessed via these scales was positive FTD, characterized by disorganized speech.…”

Section: Effect Measuresmentioning

confidence: 99%

“…Since the other studies focused on either the global concept of FTD 13,29,30,37,47 , which includes positive FTD, or only positive FTD 23,46,50,51 , this dimension was the only one considered in order to maintain homogeneity between compared outcomes. Some studies also reported results as a proportion of participants in whom FTD was either present or absent 40,47,48,51 .…”

Section: Effect Measuresmentioning

confidence: 99%

“…The eligible studies included different types of population: (1) individuals with no history of diagnosed mental illness 23,30,38,39,[42][43][44][45] ; (2) individuals with a history of first-episode psychosis 13,37,40,46 1).…”

Section: Study Characteristicsmentioning

confidence: 99%

“…The overall risk of bias was considered as low: the quality of four studies was rated as "good" 29,37,44,51 , that of fourteen studies as "fair" 13,23,30,38,[40][41][42][43]45,46,[48][49][50]52 and that of one as "poor" 47 . Poor quality was firstly determined by the imprecise criteria for pertaining to the cannabis using group, i.e.…”

Section: Risk Of Biasmentioning

confidence: 99%

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Association between formal thought disorder and cannabis use: a systematic review and meta-analysis

et al. 2022

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Formal thought disorder (FTD) is a multidimensional syndrome mainly occurring along the psychosis continuum. Cannabis use is known to increase symptoms of psychosis, particularly positive symptoms. However, the impact of cannabis use on FTD in individuals presenting symptoms along the psychosis continuum remains unclear. To address this knowledge gap, we conducted a meta-analysis examining the association between cannabis use and FTD in those individuals. We hypothesized that cannabis would worsen FTD. We conducted a systematic search of the PubMed, ScienceDirect, PsycINFO, Web of Science, Embase and Google Scholar databases up to July 2022. The results were collated through a random-effects model using the statistical software R. Reference lists of included studies were searched for additional relevant publications. Nineteen studies were included, totalling 1840 cannabis users and 3351 non-cannabis users. The severity of FTD was found to be higher in cannabis users (SMD = 0.21, 95%CI [0.12–0.29], p = 0.00009). Subgroup analyses revealed that FTD severity was increased among cannabis users, regardless of the disorder severity: healthy individuals (SMD = 0.19, 95%CI [0.05–0.33], p = 0.02); patients with first-episode psychosis (SMD = 0.21, 95%CI [0.01–0.41], p = 0.04); patients with schizophrenia (SMD = 0.25, 95%CI [0.11–0.38], p = 0.005). Between-group differences were not significant. In line with its already known effect on positive symptoms in psychosis, cannabis use appears to be associated with increased FTD severity all along the psychosis continuum. Future research should consider potential confounding variables such as other substance use disorders and explore how FTD dimensions are impacted by cannabis use.

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