Cannabis use before age 15 and subsequent executive
                        functioning

Fontes, Maria Alice; Bolla, Karen I.; Cunha, Paulo Jannuzzi; Almeida, Priscila Previato; Jungerman, Flávia Serebrenic; Laranjeira, Ronaldo; Bressan, Rodrigo A.; Lacerda, Acioly L.T.

doi:10.1192/bjp.bp.110.077479

Cited by 247 publications

(175 citation statements)

References 36 publications

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“…Differences between marijuana user groups have appeared in these other cognitive domains (18,23,57,58). Nevertheless, there is no reason to expect such a difference would emerge in the present study.…”

Section: Are the Deficits In Crystallized Intelligence Specific To Macontrasting

confidence: 51%

“…There is evidence to suggest that the adolescent brain may be particularly vulnerable, especially with regard to neurocognitive functioning (10,11). Marijuana use in adolescence, when the brain is still undergoing major developmental changes, has been associated with decreased intelligence (12,13), reduced memory (13)(14)(15), poorer attention (16)(17)(18), and lower verbal ability (19)(20)(21). However, these findings come from cross-sectional studies, where the temporal ordering of cause and effect is uncertain.…”

mentioning

confidence: 62%

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Impact of adolescent marijuana use on intelligence: Results from two longitudinal twin studies

Jackson

Isen

Khoddam

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

156

129

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Marijuana is one of the most commonly used drugs in the United States, and use during adolescence-when the brain is still developing-has been proposed as a cause of poorer neurocognitive outcome. Nonetheless, research on this topic is scarce and often shows conflicting results, with some studies showing detrimental effects of marijuana use on cognitive functioning and others showing no significant long-term effects. The purpose of the present study was to examine the associations of marijuana use with changes in intellectual performance in two longitudinal studies of adolescent twins (n = 789 and n = 2,277). We used a quasiexperimental approach to adjust for participants' family background characteristics and genetic propensities, helping us to assess the causal nature of any potential associations. Standardized measures of intelligence were administered at ages 9-12 y, before marijuana involvement, and again at ages 17-20 y. Marijuana use was self-reported at the time of each cognitive assessment as well as during the intervening period. Marijuana users had lower test scores relative to nonusers and showed a significant decline in crystallized intelligence between preadolescence and late adolescence. However, there was no evidence of a dose-response relationship between frequency of use and intelligence quotient (IQ) change. Furthermore, marijuana-using twins failed to show significantly greater IQ decline relative to their abstinent siblings. Evidence from these two samples suggests that observed declines in measured IQ may not be a direct result of marijuana exposure but rather attributable to familial factors that underlie both marijuana initiation and low intellectual attainment.M arijuana is one of the most commonly used drugs in the United States, with a lifetime use prevalence of 50% (1, 2). Despite this, research on the long-term effects of marijuana use is scarce compared with that of other illicit substances. Changing cultural attitudes toward marijuana have recently led to social and legal acceptance of recreational use (3, 4), making research on the potential consequences particularly salient.Previous research has shown that marijuana use can have a high societal cost through increased unemployment, absenteeism, decreased productivity, and increased rates of crime and incarceration (5-8). Given that about 19% of youth and young adults (ages 18-25 y) in the United States have used marijuana in the past month (9), the potential impact is nontrivial. There is evidence to suggest that the adolescent brain may be particularly vulnerable, especially with regard to neurocognitive functioning (10, 11). Marijuana use in adolescence, when the brain is still undergoing major developmental changes, has been associated with decreased intelligence (12, 13), reduced memory (13-15), poorer attention (16-18), and lower verbal ability (19-21). However, these findings come from cross-sectional studies, where the temporal ordering of cause and effect is uncertain. For longitudinal studies examining marijuana use and ch...

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Section: Are the Deficits In Crystallized Intelligence Specific To Macontrasting

confidence: 51%

mentioning

confidence: 62%

Impact of adolescent marijuana use on intelligence: Results from two longitudinal twin studies

Jackson

Isen

Khoddam

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

156

129

View full text Add to dashboard Cite

show abstract

“…A nivel europeo, el último informe del European School Survey Project on Alcohol and Other Drugs [ESPAD] (ESPAD Group, 2016) señala que un 47% de los estudiantes entre 16-18 años comenzó a consumir alcohol antes de los 14 años, el 23% tabaco y un 3% cannabis. La evidencia empírica disponible pone de manifiesto que la edad a la que los adolescentes se inician en el consumo de las diferentes sustancias no es algo banal (Cadaveira, 2009;Fontes et al, 2011). Por otra parte, desde hace unos años se viene observando un cambio en el patrón de consumo de alcohol entre los más jóvenes (Calafat y Juan, 2003;Sánchez, Moreno, Rivera y Ramos, 2015).…”

Section: E L Crafft Substance Abuse Screening Testunclassified

Validación empírica del CRAFFT Abuse Screening Test en una muestra de adolescentes españoles

et al. 2018

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“…The measures of exposure to cannabis use included in the analyses were (a) current cannabis use (is the subject currently using cannabis: no = 0; yes = 1); (b) lifetime frequency of cannabis use [the frequency that characterized the subject's most consistent pattern of use: at weekends or less frequently (occasional) = 0; every day (daily) = 1]; and (c) age at first use (the age when the subject started to use cannabis regularly: prior to age 15 years = 0; above age 15 years = 1). This cut-off was based on previous studies showing an increased risk of mental health disorders in users of cannabis before the age of 15 (Arseneault et al 2002;Fontes et al 2011). On the basis of this data, EP patients were dichotomised between (a) regular cannabis users and (b) occasional users.…”

Section: Assessment Of Cannabis Usementioning

confidence: 99%

Cannabis use in early psychosis is associated with reduced glutamate levels in the prefrontal cortex

et al. 2017

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Rationale Recent studies have shown that cannabis may disrupt glutamate (Glu) signaling depressing Glu tone in frequent users. Current evidence have also consistently reported lower Glu-levels in various brain regions, particularly in the medial prefrontal cortex (mPFC) of chronic schizophrenia patients, while findings in early psychosis (EP) are not conclusive. Since cannabis may alter Glu synaptic plasticity and its use is a known risk factor for psychosis, studies focusing on Glu signaling in EP with or without a concomitant cannabis-usage seem crucial.Objective We investigate the effect of cannabis use on prefrontal Glu-levels in EP users vs. both EP non-users and healthy controls (HC). Methods Magnetic resonance spectroscopy was used to measure [Glu mPFC ] of 35 EP subjects (18 of whom were cannabis users) and 33 HC. For correlative analysis, neuropsychological performances were scored by the MATRICS-consensus cognitive battery. Results [Glu mPFC ] was lower in EP users comparing to both HC and EP non-users (p < 0.001 and p = 0.01, respectively), while no differences were observed between EP non-users and HC. A greater [Glu mPFC ]-decline with age was observed in EP users (r = −.46; p = 0.04), but not in EP non-users or HC. Among neuropsychological outcomes, working memory was the only domain that differentiates patients depending on their cannabis use, with users having poorer performances. Conclusions Cannabis use is associated with reduced prefrontal [Glu mPFC ] and with a stronger Glu-levels decline with age. Glutamatergic abnormalities might influence the cognitive impairment observed in users and have some relevance for the progression of the disease.

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Cannabis use before age 15 and subsequent executive functioning

Abstract: Early-onset chronic cannabis users exhibited poorer cognitive performance than controls and late-onset users in executive functioning. Chronic cannabis use, when started before age 15, may have more deleterious effects on neurocognitive functioning.

Cited by 247 publications

References 36 publications

Impact of adolescent marijuana use on intelligence: Results from two longitudinal twin studies

Impact of adolescent marijuana use on intelligence: Results from two longitudinal twin studies

Validación empírica del CRAFFT Abuse Screening Test en una muestra de adolescentes españoles

Cannabis use in early psychosis is associated with reduced glutamate levels in the prefrontal cortex

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