Increased Marijuana Use and Gender Predict Poorer Cognitive Functioning in Adolescents and Emerging Adults

Abstract

This study sought to characterize neuropsychological functioning in MJ-using adolescents and emerging adults (ages 18–26) and to investigate whether gender moderated these effects. Data were collected from 59 teens and emerging adults including MJ users (n = 23, 56% female) and controls (n = 35, 50% female) aged 18–26 (M = 21 years). Exclusionary criteria included independent Axis I disorders (besides SUD), and medical and neurologic disorders. After controlling for reading ability, gender, subclinical depressive symptoms, body mass index, and alcohol and other drug use, increased MJ use was associated with slower psychomotor speed/sequencing ability (p< .01), less efficient sustained attention (p< .05), and increased cognitive inhibition errors (p< .03). Gender significantly moderated the effects of MJ on psychomotor speed/sequencing ability (p< .003) in that males had a more robust negative relationship. The current study demonstrated that MJ exposure was associated with poorer psychomotor speed, sustained attention and cognitive inhibition in a dose-dependent manner in young adults, findings that are consistent with other samples of adolescent MJ users. Male MJ users demonstrated greater cognitive slowing than females. Future studies need to examine the neural substrates underlying with these cognitive deficits and whether cognitive rehabilitation or exercise interventions may serve as a viable treatments of cognitive deficits in emerging adult MJ users.

Marijuana Use Predicts Cognitive Performance on Tasks of Executive Function

“…Our results complement previous research using both correlation and regression analyses to address the role of marijuana use variables. Earlier age at marijuana onset has previously been shown to correlate with impaired performance on the Stroop and WCST tasks (Battisti et al, 2010;Gruber et al, 2012b), whereas increased frequency and magnitude of marijuana use have been shown to be related to impairment in psychomotor speed, sustained attention, and cognitive inhibition (Lisdahl & Price, 2012), as well as verbal memory (Solowij et al, 2011) and executive function (Gruber et al, 2012b;Harvey et al, 2007). In addition, this study incorporated logistic regression techniques and demonstrated that increased total perseverative errors on the WCST is a moderately accurate predictor of marijuana smokers, suggesting that this may be a clinical characteristic of chronic, heavy marijuana use.…”

“…Further, a longer period of marijuana abstinence was not utilized because studies using longer periods of abstinence (e.g. 7 days of abstinence [Lisdahl & Price, 2012] and 28 days of abstinence [Pope et al, 2003]) are more likely assessing cognitive function related to cessation of marijuana use. Instead, the 12-hour abstinence period was implemented to accurately reflect the impact of regular use on cognitive function in a naturalistic sample of current marijuana smokers.…”

“…Earlier age at onset of regular marijuana use as well as increased quantity of marijuana use (cones/bowls smoked per week) have also been shown to significantly predict verbal memory (Solowij et al, 2011). Lisdahl and Price (2012) reported that in a young adult sample, more frequent marijuana use (joints smoked per year) predicted poorer psychomotor speed, sustained attention, and cognitive inhibition. Harvey et al (2007) noted that more total days of marijuana use predicted poorer executive function and spatial working memory.…”

Long-term effects of adolescent-onset and persistent use of cannabis

“…The interconnectedness of mental health problems, persistent cannabis use, and neuropsychological functioning demands more careful attention, and the literature (12,13) suggests the value of controlling for more than just schizophrenia (as did Meier et al). Similarly, potential sex differences require closer scrutiny, given accumulating evidence that nonacute or persistent cannabis use may have differing effects on neurocognitive functioning of males and females (14)(15)(16)(17). Sex differences in brain cannabinoid receptor density, endocrine modulation of endocannabinoid activity, tolerance, and tetrahydrocannabinol metabolism may all contribute to these differences (18,19).…”

Prediction of vocational participation and global role functioning in help-seeking young adults, from neurocognitive, demographic and clinical variables

“…Alcohol consumption was not reported and biochemical assays were not undertaken to confirm self-reports. Future studies may consider more detailed assessment of recent consumption to rule out potential influence of acute usage and withdrawal on cognitive performance (Lisdahl and Price, 2012). The neurocognitive tests were presented in a fixed order between subjects.…”