Study Contradicts Diathesis-Stress Model of Psychosis
一項新的研究發現，隨著人們經歷更多的創傷事件，遺傳風險在解釋精神病方面變得不那麼重要。
A new study found that as people experience more traumatic events, genetic risk becomes less important in explaining psychosis.
by 彼得·西蒙斯-2022 年 8 月 8 日

為什麼有些人在創傷後會出現精神病而有些人卻沒有？解釋這一點的一個常見理論被稱為“素質 – 應力模型”。根據該理論，遺傳風險（“素質”）會引發一個人經歷精神病，但需要創傷事件（“壓力”）來觸發這種經歷。
Why do some people experience psychosis after trauma while others do not? A common theory to explain this is known as the “diathesis-stress model.” According to the theory, genetic risk (“diathesis”) primes a person to experience psychosis but requires traumatic events (the “stress”) to trigger the experience.

但現在，頂級精神病學雜誌JAMA Psychiatry上的一項新研究揭穿了素質壓力模型。研究人員發現，隨著人們經歷更多的創傷事件，遺傳風險變得不那麼重要。
But now, a new study in the top-tier psychiatric journal JAMA Psychiatry has debunked the diathesis-stress model. The researchers found that genetic risk becomes less important as people experience more traumatic events.

這與模型的假設相矛盾。在素質-壓力模型中，當人們經歷創傷時，遺傳風險應該更為重要。遺傳學應該解釋為什麼對於兩個經歷過創傷的人來說，只有一個人會發展成精神病的經歷。研究人員寫道：
This contradicts the assumptions of the model. In the diathesis-stress model, genetic risk should be more important when people experience trauma. Genetics is supposed to explain why, for two people who experience trauma, only one of them develops psychotic experiences. The researchers write:

“這是一個重要的信息，即青春期精神病經歷的早期表現並沒有那麼強的遺傳性，尤其是在環境暴露較高的情況下。”
“It is an important message that early manifestations of psychotic experiences during adolescence are not so strongly heritable, especially in the context of higher environmental exposure.”

相比之下，研究人員提出了生物生態模型，該模型“假設遺傳因素在更有利的環境中變得更加相關，導致在環境暴露背景下雙胞胎研究的遺傳力降低。”
In contrast, the researchers suggest the bioecological model, which “posits that genetic factors become more pertinent in more favorable environments, leading to lower heritability in twin studies in the context of environmental exposure.”

從本質上講，研究人員假設遺傳學可能有助於解釋為什麼一些經歷很少創傷的人會患上精神病。
Essentially, the researchers posit that genetics might help explain why some people who experience very little trauma develop psychosis.

研究人員寫道：“這些結果與生物生態學框架一致，該框架可以預測更有利的環境將導致更高的遺傳力。” “我們的結果與通向精神病經歷的素質壓力途徑相反，這將預測環境風險會引發對特定疾病的遺傳易感性，從而在存在環境風險的情況下導致表型的更高遺傳性。”
“It is an important message that early manifestations of psychotic experiences during adolescence are not so strongly heritable, especially in the context of higher environmental exposure.”

這項研究是瑞典研究人員的共同努力，包括卡羅林斯卡學院的 Mark Taylor、哥德堡大學的 Sebastian Lundström 和厄勒布魯大學的 Henrik Larsson，以及英國的研究人員，包括牛津大學的 Daniel Freeman 和 Angelica Ronald倫敦伯貝克大學。
The study was a combined effort, with Swedish researchers, including Mark Taylor at the Karolinska Institutet, Sebastian Lundström at the University of Gothenburg, and Henrik Larsson at Örebro University, and UK researchers, including Daniel Freeman at the University of Oxford and Angelica Ronald at Birkbeck University of London.

研究人員觀察了英國和瑞典的雙胞胎，以估計精神病的遺傳性。然後，他們將他們的發現與五個環境因素相關聯：欺凌、“依賴生活事件”的數量（一個包羅萬象的術語，表示嚴重的關係喪失或目睹犯罪等經歷）、大麻使用、煙草使用和低出生體重。
The researchers looked at twins in both the UK and Sweden to estimate the heritability of psychosis. Then, they correlated their findings with five environmental factors: bullying, number of “dependent life events” (a catchall term for experiences like a serious relationship loss or witnessing a crime), cannabis use, tobacco use, and low birth weight.

研究人員首先分析了英國雙胞胎早期發育研究 (TEDS) 的數據，其中 4855 對雙胞胎的平均年齡為 16.5 歲。然後，他們還分析了瑞典兒童和青少年雙胞胎研究 (CATSS) 的數據，其中 6435 對雙胞胎的平均年齡為 18.6 歲。
The researchers began by analyzing the data from the UK’s Twins Early Development Study (TEDS), in which the 4855 pairs of twins were, on average, 16.5 years old. They then also analyzed the data from the Child and Adolescent Twin Study in Sweden (CATSS), in which the 6435 pairs of twins were, on average, 18.6 years old.

他們的第一個發現是創傷對精神病具有極強的預測作用。他們寫：
Their first finding was that trauma was extremely predictive of psychosis. They write:

“更多地接觸環境風險因素與更多的精神病經歷有關。”
“More exposure to environmental risk factors was associated with having more psychotic experiences.”

這與先前的研究發現，經歷童年創傷，而不是遺傳，與精神病有關。
This is consistent with previous studies that found that experiencing childhood trauma, not heritability, was associated with psychosis.

在這項研究中，隨著偏執狂、認知混亂、誇大和快感缺乏等特定經歷的環境風險增加，遺傳性變得不那麼重要。然而，對於幻覺和“陰性症狀”，遺傳力並未因環境暴露而改變。
In this study, heritability became less important as environmental risk increased for the specific experiences of paranoia, cognitive disorganization, grandiosity, and anhedonia. However, for hallucinations and “negative symptoms,” heritability did not change based on environmental exposure.

研究人員指出，他們樣本中的參與者是年輕的青少年，可能有他們的第一次精神病經歷。然而，年輕人的早期精神病經歷並不罕見，並且在大多數情況下是短暫的（它們不會導致後來診斷為精神分裂症或其他精神病）。因此，這項捕捉到這些早期經驗的研究可能不是對成熟“疾病”遺傳力的最佳估計。
The researchers note that the participants in their sample were young—teenagers—potentially having their first psychotic experiences. However, early psychotic experiences in young people are not rare and are transient in most cases (they do not lead to later diagnoses of schizophrenia or other psychotic disorders). Thus, this study, which captured these early experiences, may not be the best estimate of the heritability of full-fledged “disorders.”

事實上，對於像精神分裂症這樣的精神病診斷，遺傳率可能低於這些研究人員發現的。遺傳學研究表明，遺傳風險在解釋精神分裂症方面的作用微乎其微，其預測能力低至 0.5% ——這表明 99.5% 的精神病“原因”與環境因素有關，尤其是童年創傷。
In fact, for psychotic diagnoses like schizophrenia, it’s likely that the heritability is lower than that found by these researchers. Genetics studies have identified that genetic risk plays a minimal role in explaining schizophrenia, with a predictive power as low as 0.5%—indicating that 99.5% of the “cause” of psychosis is related to environmental factors, especially childhood trauma.

在當前的文章中，研究人員補充說，與普通人群相比，精神分裂症的可能性略有增加對於預測並不是很有用。
In the current article, the researchers add that a slight increase in the likelihood of schizophrenia compared to the general population is not very useful for prediction.

“大多數精神分裂症患者的親屬並沒有患上精神分裂症，”他們寫道。
“Most relatives of individuals with schizophrenia do not develop schizophrenia,” they write.

他們認為，雖然家庭成員患有精神分裂症確實會增加其他家庭成員患精神病的風險；這也可以用共同的環境來解釋，而不是遺傳。
They suggest that while having a family member with schizophrenia does increase the risk of psychosis for other family members; this could also be explained by a shared environment, not genetics.

2021 年的一項薈萃分析揭穿了被宣傳為精神病潛在原因的主要生物學假設——多巴胺和谷氨酸的作用——因此，即使以某種方式涉及遺傳性，也不清楚它會採取何種生物學途徑。
A meta-analysis in 2021 debunked the main biological hypotheses promoted as potential causes of psychosis—the role of dopamine and glutamate—so even if heritability is involved in some way, it is unclear what biological pathway it would take.

總之，研究人員寫道，在解釋精神病方面，環境因素，如創傷經歷，遠比遺傳學重要。
In conclusion, the researchers write that environmental factors, like traumatic experiences, are far more important than genetics in explaining psychosis.

“據我們所知，這項雙胞胎研究是第一個結果表明環境因素在精神病經歷的病因學中比遺傳因素發揮更大的作用。”
“To our knowledge, this twin study was the first with results that suggest that environmental factors play a greater role in the etiology of psychotic experiences than genetic factors.”

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Taylor, MJ, Freeman, D., Lundström, S., Larsson, H. 和 Ronald, A. (2022)。青少年精神病經歷的遺傳性和與環境風險的相互作用。JAMA精神病學。2022 年 8 月 3 日在線發布。doi:10.1001/jamapsychiatry.2022.1947 （鏈接）
Taylor, M. J., Freeman, D., Lundström, S., Larsson, H., & Ronald, A. (2022). Heritability of psychotic experiences in adolescents and interaction with environmental risk. JAMA Psychiatry. Published online August 3, 2022. doi:10.1001/jamapsychiatry.2022.1947 (Link)

文章來源:
https://www.madinamerica.com/2022/08/study-contradicts-diathesis-stress-model-psychosis/

Peter SimonsPeter Simons was an academic researcher in psychology. Now, as a science writer, he tries to provide the layperson with a view into the sometimes inscrutable world of psychiatric research. As an editor for blogs and personal stories at Mad in America, he prizes the accounts of those with lived experience of the psychiatric system and shares alternatives to the biomedical model.