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Objective: Verbal memory difficulties are the most widely reported and persistent cognitive deficit associated with early onset marijuana use. Yet, it is not known what memory stages are most impaired in those with early marijuana use., Method: Forty-eight young adults, aged 18-25, who used marijuana at least once per week and 48 matched nonusing controls (CON) completed the California Verbal Learning Test, Second Edition (CVLT-II). Marijuana users were stratified by age of initial use: early onset users (EMJ), who started using marijuana at or before age 16 (n = 27), and late onset marijuana user group (LMJ), who started using marijuana after age 16 (n = 21). Outcome variables included trial immediate recall, total learning, clustering strategies (semantic clustering, serial clustering, ratio of semantic to serial clustering, and total number of strategies used), delayed recall, and percent retention., Results: Learning improved with repetition, with no group effect on the learning slope. EMJ learned fewer words overall than LMJ or CON. There was no difference between LMJ and CON in total number of words learned. Reduced overall learning mediated the effect on reduced delayed recall among EMJ, but not CON or LMJ. Learning improved with greater use of semantic versus serial encoding, but this did not vary between groups. EMJ was not related to delayed recall after adjusting for encoding., Conclusions: Young adults reporting early onset marijuana use had learning weaknesses, which accounted for the association between early onset marijuana use and delayed recall. No amnestic effect of marijuana use was observed. (PsycINFO Database Record, ((c) 2016 APA, all rights reserved).)

Neuropsychological performance has historically been measured in laboratory settings using standardized assessments. However, these methods may be inherently limited in generalizability. This concern may be mitigated with paradigms such as ecological momentary assessment (EMA). We evaluated the initial feasibility and acceptability of administering a visual working memory (VWM) task on handheld computers across 1 EMA study week among adolescents/young adults (N = 39). Participants also completed standardized laboratory neurocognitive measures to determine the extent to which EMA VWM performance mapped onto scores obtained in traditional testing environments. Compliance with the EMA protocol was high as participants responded to 87% of random prompts across the study week. As expected, EMA VWM performance was positively associated with laboratory measures of auditory and VWM, and these relationships persisted after adjusting for predicted intelligence. Further, discriminant validity tests showed that EMA VWM was not linked with laboratory scores of verbal abilities and processing speed. These data provide initial evidence on the convergent and discriminant validity of interpretations from this novel, ecologically valid neurocognitive approach. Future studies will aim to further establish the psychometric properties of this (and similar) tasks and investigate how momentary fluctuations in VWM correspond with contextual influences (e.g., substance use, mood) and clinical outcomes., ((c) 2015 APA, all rights reserved).)

Objective: Co-occurring cannabis and tobacco use has become increasingly prevalent among young adults, but it is not clear how tobacco use may alter the neurocognitive profile typically observed among cannabis users. Although there is substantial evidence citing cannabis and tobacco's individual effect on episodic memory and related brain structures, few studies have examined the effect of combined cannabis and tobacco use on memory., Method: This investigation examined relationships between amount of past year cannabis and tobacco use on 4 different indices of episodic memory among a sample of young adults who identified cannabis as their drug of choice., Results: Results indicated that more cannabis use was linked with poorer initial acquisition, total learning, and delayed recall on the Hopkins Verbal Learning Test-Revised, but only among cannabis users who sporadically smoked cigarettes in the past year. Conversely, the amount of past year cannabis use was not associated with episodic memory performance among individuals who more consistently smoked cigarettes in the past year. These differences could not be explained by several relevant potential confounds., Conclusions: These findings provide important insight into a potential mechanism (i.e., attenuation of cognitive decrements) that might reinforce use of both substances and hamper cessation attempts among cannabis users who also smoke cigarettes. Ongoing and future research will help to better understand how co-use of cannabis and tobacco affects memory during acute intoxication and abstinence and the stability of these associations over time., ((c) 2015 APA, all rights reserved).)