Ohi Kazutaka, Takai Kentaro, Sugiyama Shunsuke, Kitagawa Hiromi, Kataoka Yuzuru, Soda Midori, Kitaichi Kiyoyuki, Kawasaki Yasuhiro, Ito Munechika, Shioiri Toshiki
Department of Psychiatry and Psychotherapy, Gifu University Graduate School of Medicine, Gifu, Japan.
Department of General Internal Medicine, Kanazawa Medical University, Kahoku, Japan.
CNS Spectr. 2021 Mar 18:1-7. doi: 10.1017/S1092852921000298.
Major depressive disorder (MDD), bipolar disorder (BD), and schizophrenia (SCZ) are associated with impaired intelligence that predicts poor functional outcomes. However, little is known regarding the extent and severity of intelligence decline, that is, decreased present intelligence quotient (IQ) relative to premorbid levels, across psychiatric disorders and which clinical characteristics affect the decline.
Premorbid IQ, present IQ, and intelligence decline were compared across patients with MDD (n = 45), BD (n = 30), and SCZ (n = 139), and healthy controls (HCs; n = 135). Furthermore, we investigated which factors contribute to the intelligence decline in each diagnostic group.
Significant differences were observed in premorbid IQ, present IQ, and intelligence decline across the diagnostic groups. Patients with each psychiatric disorder displayed lower premorbid and present IQ and more intelligence decline than HCs. Patients with SCZ displayed lower premorbid and present IQ and more intelligence decline than patients with MDD and BD, while there were no significant differences between patients with MDD and BD. When patients with BD were divided based on bipolar I disorder (BD-I) and bipolar II disorder (BD-II), degrees of intelligence decline were similar between MDD and BD-II and between BD-I and SCZ. Lower educational attainment was correlated with a greater degree of intelligence decline in patients with SCZ and BD but not MDD.
These findings confirm that although all psychiatric disorders display intelligence decline, the severity of intelligence decline differs across psychiatric disorders (SCZ, BD-I > BD-II, MDD > HCs). Higher educational attainment as cognitive reserve contributes to protection against intelligence decline in BD and SCZ.
重度抑郁症（MDD）、双相情感障碍（BD）和精神分裂症（SCZ）都与智力受损有关，而智力受损预示着功能预后不良。然而，关于智力衰退的程度和严重性，即相对于病前水平目前智商（IQ）的下降，在各种精神疾病中的情况以及哪些临床特征会影响这种衰退，我们知之甚少。
比较了MDD患者（n = 45）、BD患者（n = 30）、SCZ患者（n = 139）和健康对照者（HCs；n = 135）的病前IQ、目前IQ和智力衰退情况。此外，我们还研究了每个诊断组中导致智力衰退的因素。
在各诊断组之间，病前IQ、目前IQ和智力衰退方面观察到显著差异。每种精神疾病患者的病前和目前IQ均低于HCs，且智力衰退程度更大。SCZ患者的病前和目前IQ低于MDD和BD患者，且智力衰退程度更大，而MDD和BD患者之间无显著差异。当根据双相I型障碍（BD-I）和双相II型障碍（BD-II）对BD患者进行分组时，MDD和BD-II之间以及BD-I和SCZ之间的智力衰退程度相似。受教育程度较低与SCZ和BD患者而非MDD患者的智力衰退程度较大相关。
这些发现证实，尽管所有精神疾病都存在智力衰退，但不同精神疾病（SCZ、BD-I > BD-II、MDD > HCs）的智力衰退严重程度有所不同。较高的受教育程度作为认知储备有助于预防BD和SCZ患者的智力衰退。
