The Influence of Marijuana Use on Neurocognitive Functioning in Adolescents

Abstract

Marijuana use is common in adolescence, yet neural consequences have not been well delineated. This review seeks to ascertain whether heavy marijuana use in adolescence is associated with persistent neurocognitive abnormalities, and whether adolescents are more vulnerable to the impact of chronic marijuana use than adults.Among heavy marijuana using adults, neurocognitive deficits are apparent for several days following use, but may disappear after one month of abstinence. Studies of adolescent heavy users have identified impairments in learning and working memory up to six weeks after cessation, suggesting persisting effects, yet raise the possibility that abnormalities may remit with a longer duration of abstinence.Given ongoing neuromaturation during youth, adolescents may be more vulnerable to potential consequences of marijuana use than adults. This is supported by rodent models, which show greater memory impairments in animals exposed to cannabinoids as adolescents relative to those exposed as adults. Further, adult humans who initiated use in early adolescence show greater dysfunction than those who began use later. Together, these results suggest that adolescents are more vulnerable than adults to neurocognitive abnormalities associated with chronic heavy marijuana use; however, the impact of preexisting risk factors is unknown.Adolescents demonstrate persisting deficits related to heavy marijuana use for at least six weeks following discontinuation, particularly in the domains of learning, memory, and working memory. Further, adolescents appear more adversely affected by heavy use than adults. Longitudinal studies will help ascertain whether preexisting differences contribute to these abnormalities. KeywordsAdolescence; marijuana; cannabis; cognition; brain; development Marijuana is the most commonly used preparation of the psychoactive drug, Δ-9-tetrahydrocannabinol (THC), and is consistently the most widely used illicit drug among teenagers, and most users first experiment in adolescence [1]. While 17% of 8th graders have tried marijuana, by 12th grade almost half of teens have used [1,2]. After initial experimentation, many youths develop a regular pattern of use, with 20% of 12th graders reporting use in the past month, and 5% of 12th graders reporting daily use [2]. Adolescence *Address correspondence to this author at the Department of Psychiatry, University of California, 3350 La Jolla Village Drive, 151B San Diego, CA 92161, USA; Tel: (858)552-8585 x5592; stapert@ucsd.edu. NIH Public Access Author ManuscriptCurr Drug Abuse Rev. Author manuscript; available in PMC 2010 February 19. Published in final edited form as:Curr Drug Abuse Rev. 2008 January ; 1(1): 99-111. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscriptis also a period of continued neuromaturation, yet the potential neural consequences of marijuana use during these developments have not been well established, and may have implications for academic, occupational, and social achievements. This review will a...

Psychosocial Determinants of Marijuana Utilization among Selected Junior High School Students in the Central Region of Ghana

“…Even when used separately, these substances appear to create numerous public health problems. For example, marijuana use had the potential of causing structural brain abnormalities and altered neural activity among adolescents, subsequently leading to higher impulsivity and other neurocognitive effects [58,95]. in deviant behaviours [14,27].…”

Effects of marijuana use on prefrontal and parietal volumes and cognition in emerging adults

“…A review by Schweinsburg, Brown, and Tapert (2008a) suggests that while neuropsychological functioning may return after approximately one month of abstinence, adolescent users show deficits up to six weeks after last use. Our lab recently reported a dose-dependent association between past year MJ exposure and poorer sustained attention, psychomotor speed, and cognitive inhibition in emerging adult users ages 18–25 who had been abstinent for an average of 50 days (Lisdahl & Price, 2012).…”

Long-term consequences of adolescent cannabinoid exposure in adult psychopathology

“…Indeed, converging lines of evidence suggest that chronic use before the age of 17 is associated with deficits in working memory (Schweinsburg et al, 2008, 2010; Becker et al, 2010b), attention (Ehrenreich et al, 1999; Meier et al, 2012; Dougherty et al, 2013), decision-making (Dougherty et al, 2013), visual search (Huestegge et al, 2002), overall and verbal IQ (Pope et al, 1997; Meier et al, 2012), executive functioning (Medina et al, 2009; Becker et al, 2010a; Fontes et al, 2011; Solowij et al, 2012), visuospatial memory (Pope et al, 1997), cognitive inhibition (Fontes et al, 2011), and impulsivity (Dougherty et al, 2013). The magnitude of these deficits is proportional to the frequency, dose, and age at onset of use (Medina et al, 2007a; Schweinsburg et al, 2008, 2010; Becker et al, 2010a; Fontes et al, 2011; Meier et al, 2012). …”

“…In addition, adolescent users of cannabis have reduced cerebral blood flow in the temporal, insular, and PFC regions, and these reductions in blood flow are associated with cognitive deficits (Jacobus et al, 2012). Moreover, converging evidence suggests the presence of abnormal activation patterns in the PFC, limbic region, parietal region, and cerebellum (Schweinsburg et al, 2008; Becker et al, 2010a; Lopez-Larson et al, 2012; Vaidya et al, 2012) in adolescent users of cannabis compared to subjects who do not use cannabis. Interestingly, using diffusion-weighted MRI and connectivity mapping, Zalesky et al (2012) showed that axonal connectivity was impaired in the right fimbria and the corpus callosum, two structures that contain abundant levels of cannabinoid receptors in the developing brain (Romero et al, 1997; Molina-Holgado et al, 2002).…”