Department of Psychiatry, University of California San Diego, San Diego, CA 92103, USA.
Aust N Z J Psychiatry. 2012 Feb;46(2):141-52. doi: 10.1177/0004867411433212.
Chronic use of methamphetamine (MA) has moderate effects on neurocognitive functions associated with frontal systems, including the executive aspects of verbal episodic memory. Extending this literature, the current study examined the effects of MA on visual episodic memory with the hypothesis that a profile of deficient strategic encoding and retrieval processes would be revealed for visuospatial information (i.e., simple geometric designs), including possible differential effects on source versus item recall.
The sample comprised 114 MA-dependent (MA+) and 110 demographically-matched MA-nondependent comparison participants (MA-) who completed the Brief Visuospatial Memory Test-Revised (BVMT-R), which was scored for standard learning and memory indices, as well as novel item (i.e., figure) and source (i.e., location) memory indices.
Results revealed a profile of impaired immediate and delayed free recall (p<0.05) in the context of preserved learning slope, retention, and recognition discriminability in the MA+ group. The MA+ group also performed more poorly than MA- participants on Item visual memory (p<0.05) but not Source visual memory (p>0.05), and no group by task-type interaction was observed (p>0.05). Item visual memory demonstrated significant associations with executive dysfunction, deficits in working memory, and shorter length of abstinence from MA use (p<0.05).
These visual memory findings are commensurate with studies reporting deficient strategic verbal encoding and retrieval in MA users that are posited to reflect the vulnerability of frontostriatal circuits to the neurotoxic effects of MA. Potential clinical implications of these visual memory deficits are discussed.
慢性使用甲基苯丙胺（MA）对与额系统相关的神经认知功能有中等程度的影响，包括言语情景记忆的执行方面。在这一文献的基础上，目前的研究通过假设会揭示出针对视觉情景记忆的策略性编码和检索过程缺陷的特征来检验 MA 的影响，包括对来源和项目回忆的可能的差异效应。
该样本包括 114 名 MA 依赖者（MA+）和 110 名在人口统计学上与之匹配的 MA 非依赖者（MA-）对照参与者，他们完成了简易视觉空间记忆测试修订版（BVMT-R），该测试对标准学习和记忆指数进行了评分，以及新颖的项目（即图形）和来源（即位置）记忆指数。
结果显示，在 MA+组中，立即和延迟自由回忆的表现较差（p<0.05），同时保留了学习斜率、保留和识别辨别力。MA+组在项目视觉记忆方面的表现也比 MA-组差（p<0.05），但在来源视觉记忆方面的表现没有差异（p>0.05），并且没有观察到组间任务类型的交互作用（p>0.05）。项目视觉记忆与执行功能障碍、工作记忆缺陷和从 MA 使用中禁欲的时间较短显著相关（p<0.05）。
这些视觉记忆发现与报告 MA 用户在策略性言语编码和检索方面存在缺陷的研究结果一致，这些缺陷被认为反映了额纹状体回路对 MA 的神经毒性作用的脆弱性。讨论了这些视觉记忆缺陷的潜在临床意义。
