Feinstein Institute for Medical Research/Psychiatry Research, Hofstra North Shore Long Island Jewish School of Medicine, Manhasset, NY 11030, USA.
Biol Psychiatry. 2012 Mar 15;71(6):545-51. doi: 10.1016/j.biopsych.2011.11.021. Epub 2012 Jan 23.
Research has implicated IQ and executive function (EF) as contributors to episodic memory impairments in schizophrenia. However, it has been difficult to quantitatively apportion the respective contributions of these factors. We conducted a series of analyses to objectively parse the associated variance and to determine to what extent episodic memory impairment in schizophrenia is independent of IQ and EF.
Participants included 323 schizophrenia patients and 327 healthy controls from the National Insitute of Mental Health Sibling Study. Neurocognitive tests assessing IQ, EF, and episodic memory were administered. We examined group differences while controlling for IQ or EF in analyses of covariance, we used linear regression to quantify the amount of variance not explained by IQ or EF, and we matched control and patient subgroups on IQ or EF to determine if memory measures remained different.
Analyses of covariance revealed significant group differences between schizophrenia individuals and healthy control subjects across multiple episodic memory measures after controlling for IQ or EF. Furthermore, regressions with IQ and/or EF factors entered left more than 50% of variance in memory unaccounted. Follow-up true score variance analyses indicated that the majority of this variance was directly related to memory function. Matched subgroups also yielded subgroup differences on all memory measures.
Findings across the multiple statistical strategies suggested that the mechanisms underlying the memory impairment in schizophrenia are fully attributable neither to IQ nor EF. Rather, they most likely reflect compromises in episodic memory processing itself and, by inference, the medial temporal system.
研究表明智商和执行功能（EF）是精神分裂症患者情节记忆损伤的原因。然而，很难定量分配这些因素的各自贡献。我们进行了一系列分析，以客观地解析相关方差，并确定精神分裂症患者的情节记忆损伤在多大程度上独立于智商和 EF。
参与者包括来自国家心理健康研究所兄弟姐妹研究的 323 名精神分裂症患者和 327 名健康对照者。进行了评估智商、EF 和情节记忆的神经认知测试。我们在协方差分析中控制了 IQ 或 EF 后，检查了组间差异，我们使用线性回归来量化 IQ 或 EF 无法解释的方差量，我们还根据 IQ 或 EF 对对照和患者亚组进行匹配，以确定记忆测量是否仍然不同。
协方差分析显示，在控制 IQ 或 EF 后，精神分裂症个体与健康对照组之间在多个情节记忆测量上存在显著差异。此外，带有 IQ 和/或 EF 因素的回归留下了超过 50%的记忆方差未被解释。后续的真分数方差分析表明，大部分方差直接与记忆功能有关。匹配的亚组在所有记忆测量上也存在亚组差异。
多种统计策略的发现表明，精神分裂症患者记忆损伤的机制既不能完全归因于智商，也不能完全归因于 EF。相反，它们最有可能反映了情节记忆处理本身的妥协，并且推断，是内侧颞叶系统。
