Back from the sideline, but back to baseline? A pediatric case study examining neuropsychological functioning after sustaining multiple sport-related concussions.

Most individuals recover quickly from a concussion; however, youth who sustain multiple concussions may be at risk for long-term cognitive impairments. This case study examines the neuropsychological performance of a 13-year-old malewith five head injuries. After his first concussion during study participation (fourth injury overall), several improvements were observed, likely due to practice effects, yet after sustaining another concussion <2 years later,declines were observed in visuoconstruction, verbal memory, and intellectual functioning. Across serial re-evaluation, his vocabulary knowledge declined, and fewer improvements were observed than anticipated when accounting for serial practice effects, highlighting the possible cumulative impact of multiple concussions.

Female Sex as a Protective Factor in the Effects of Chronic Cannabis Use on Verbal Learning and Memory.

OBJECTIVE: The variability of findings in studies examining the effects of chronic cannabis use on neuropsychological functioning highlights the importance of examining contributing factors. Few studies examine the role of sex in the relationship between cannabis and neuropsychological functioning, despite known neurobiological structural differences between males and females. This study examined whether males and females experience differential cognitive effects of chronic cannabis use. METHOD: Chronic cannabis users (3+ days per week for >12 months, n = 110, 72% male) and non-users (n = 71, 39% male) completed a neuropsychological test battery. Two multivariate analyses of covariance (MANCOVAs) examined for sex differences in performance within users and non-users on neuropsychological tests, controlling for potential confounding variables. Bonferroni corrections were applied to adjust for multiple comparisons. RESULTS: Male and female cannabis users did not differ in cannabis use variables. Female cannabis users performed better than males on multiple subtests of the California Verbal Learning Test-II (CVLT-II), a verbal learning and memory test. Male cannabis users performed better than female users on Trial 1 of the CVLT-II (p = .002), and Trail Making Test B (p = .001), which measure attention and cognitive flexibility, respectively. Non-user males and females performed comparably, with the exception of Trail Making Test B (p = .001). CONCLUSIONS: Results suggest that chronic cannabis use differentially impacts males and females, with females exhibiting better verbal learning and memory despite males demonstrating better attention and cognitive flexibility. Further research is needed to understand the potential protective mechanism of female sex on learning and memory effects of cannabis use.

The "Jay-Dar" Phenomenon: Individuals Discriminate Cannabis Users from Nonusers Based Upon a Photograph.

OBJECTIVE: With increasing legalization of medicinal and recreational cannabis, use is on the rise. Research suggests individuals may be able to guess cannabis user status based upon appearance; however, these findings utilized a small sample of photographs that was not balanced on user status or gender. Further, no studies examined whether raters with cannabis experience are better at judging others' cannabis use, or what physical features they use to make these judgments. This study explored these factors using a larger, balanced photograph database. METHOD: An American sample (n = 249, 48.6% female, mean age = 35.19 years) rated 36 photographs (18 cannabis users, 18 nonusers) balanced on gender and age on the likelihood that the photographed individuals use cannabis, producing 8964 ratings. Respondents also reported physical features considered in their ratings, as well as their own cannabis use history. RESULTS: As hypothesized, photographs of users received higher ratings on the Marijuana Use Likelihood Index relative to nonusers. Further, results revealed a gender by rater user status interaction, indicating that raters with no previous cannabis experience rated males higher than females, while raters with cannabis experience did not demonstrate this rating discrepancy. Cannabis use explained over 9% of the variance in ratings across all photographs. CONCLUSIONS: Results suggest individuals do rate cannabis users as more likely to be users, relative to nonusers, based upon appearance alone. These findings have important implications, not only for research on chronic cannabis use effects, but also for social and achievement factors such as potential stigma.

Cream of the Crop: Clinical Representativeness of Eligible and Ineligible Cannabis Users in Research.

BACKGROUND: Experts have recommended criteria (Gonzalez et al., 2002) for recruiting pure chronic cannabis users (i.e., those without polysubstance use or psychiatric illness) when evaluating cannabis' non-acute effects on cognition. OBJECTIVES: We sought to demonstrate the implications of using such criteria by examining characteristics of respondents who completed an eligibility screening for a parent study evaluating the cognitive effects of chronic cannabis use. METHODS: Over a 3-year, 8-month period, 612 respondents from the community completed an eligibility screening based on recommendations in the cannabis literature. Using independent samples t-tests and chi-square tests, we examined whether qualified/eligible respondents (n = 219) differed from non-qualified/ineligible respondents (n = 393). RESULTS: Compared to ineligible cannabis users, eligible cannabis-using respondents were significantly younger, used cannabis more frequently, used alcohol less frequently, and were less likely to have a history of other drug use, a psychiatric diagnosis, or to have used psychiatric medication. Conclusions/Importance: Our findings indicate that eligible/pure cannabis users are not representative of typical cannabis users in the general community (i.e., ineligible users with polysubstance use and/or psychiatric diagnoses) who ultimately comprised the majority of our cannabis-using sample (65.2%). Thus, typical cannabis users may be more accurately characterized as polysubstance users, posing a number of challenges related to the generalizability of findings from studies utilizing pure samples of cannabis users. Recruiting samples of typical cannabis users will improve external validity in research. Furthermore, reporting comprehensive characteristics of such samples will enable consumers to gauge the applicability of study findings to populations of interest.

Don't Judge a Book by its Cover: Examiner Expectancy Effects Predict Neuropsychological Performance for Individuals Judged as Chronic Cannabis Users.

OBJECTIVE: The experimenter expectancy effect confound remains largely unexplored in neuropsychological research and has never been investigated among cannabis users. This study investigated whether examiner expectancies of cannabis user status affected examinees' neuropsychological performance. METHOD: Participants included 41 cannabis users and 20 non-users. Before testing, examiners who were blind to participant user status privately rated whether they believed the examinee was a cannabis user or non-user. Examiners then administered a battery of neuropsychological and performance validity measures. Multiple regression analyses compared performance between examinees judged as cannabis users (n = 37) and those judged as non-users (n = 24). RESULTS: Examiners' judgments of cannabis users were 75% accurate; judgments of non-users were at chance. After controlling for age, gender, and actual user status, examiner judgments of cannabis user status predicted performance on two measures (California Verbal Learning Test-II, and Trail Making Test B; p < .05), as individuals judged as cannabis users obtained lower scores than those judged as non-users. CONCLUSIONS: Examiners' judgments of cannabis user status predicted performance even after controlling for actual user status, indicating vulnerability to examiner expectancy effects. These findings have important implications for both research and clinical settings, as scores may partially reflect examiners' expectations regarding cannabis effects rather than participants' cognitive abilities. These results demonstrate the need for expectancy effect research in the neuropsychological assessment of all populations, not just cannabis users.