Many American and Dutch adolescents use marijuana regularly. There is concern that such use may impair cognitive function more in adolescents than adults. We examined effects of regular marijuana use on long-term memory and perseveration among American and Dutch adolescents. We administered Buschke's Selective Reminding Test (BSRT) to assess long-term memory and the Wisconsin Card Sorting Test (WCST) to assess perseveration in male teenagers. Usable test data were obtained for 12 American marijuana users, 13 American controls, 9 Dutch marijuana users, and 12 Dutch controls. In BSRT, users showed lower overall long-term storage than controls (adjusted means ± SE's for numbers of words per trial of 9.4 ± 0.2, 13.4 ± 0.3, 11.7 ± 0.2, and 12.4 ± 0.2 for American users, Dutch users, American controls, and Dutch controls, respectively). Marijuana was associated with memory effects only in American, not Dutch, users. Bivariate Pearson correlations for American and Dutch users combined showed associations of lower total recall with more uses in the previous year and lifetime (r = –0.61 and r = –0.53, respectively); and more perseverative errors with more uses in the previous year (r = 0.55). Some findings were consistent with the possibility that regular adolescent marijuana use causes deficits in cognition, especially memory. However, a causal interpretation cannot be inferred from our findings and is challenging to reconcile with the observation of memory deficits only in American users. Our study was novel in examining the influence of nationality on marijuana's cognitive effects. More studies of this topic should compare effects across nationalities or cultures.

许多美国和荷兰青少年经常使用大麻。有人担心这种使用可能会比成人更严重地损害青少年的认知功能。我们研究了定期吸食大麻对美国和荷兰青少年长期记忆和持久性的影响。我们使用 Buschke 的选择性提醒测试 (BSRT) 来评估长期记忆，并使用威斯康星卡片分类测试 (WCST) 来评估男性青少年的毅力。获得了 12 名美国大麻使用者、13 名美国对照、9 名荷兰大麻使用者和 12 名荷兰对照的可用测试数据。在 BSRT 中，用户的整体长期存储量低于对照组（对于美国用户、荷兰用户、美国对照组，每次试验的单词数的调整平均值 ± SE 分别为 9.4 ± 0.2、13.4 ± 0.3、11.7 ± 0.2 和 12.4 ± 0.2和荷兰控制）。大麻仅在美国人而非荷兰人中与记忆效应有关。美国和荷兰用户的双变量 Pearson 相关性显示较低的总召回率与前一年和生命周期中的更多使用相关（分别为 r = –0.61 和 r = –0.53）；以及在前一年使用更多的持续性错误（r = 0.55）。一些发现与经常使用青少年大麻导致认知缺陷，尤其是记忆缺陷的可能性一致。然而，无法从我们的研究结果中推断出因果解释，并且很难与仅在美国用户中观察到的记忆缺陷相一致。我们的研究在检查国籍对大麻认知效果的影响方面是新颖的。对该主题的更多研究应该比较不同民族或文化的影响。