Levy F, Mouchabac S, Peretti C S
Département de psychiatrie et psychologie médicale, CHU Saint-Antoine, 184, rue du Faubourg-Saint-Antoine, 75012 Paris, France.
Département de psychiatrie et psychologie médicale, CHU Saint-Antoine, 184, rue du Faubourg-Saint-Antoine, 75012 Paris, France.
Encephale. 2014 Apr;40(2):154-9. doi: 10.1016/j.encep.2013.04.008. Epub 2013 Jul 4.
Delusions of pregnancy are not well known. The delusion of pregnancy is defined as the belief of being pregnant despite factual evidence to the contrary. The clinical picture is heterogeneous (duration, mechanisms, topics and pre-existing psychiatric disorders). Several causes have been proposed to explain the occurrence of the delusions of pregnancy: cenesthetic theory, hyperprolactinemia, polydipsia and psychodynamic conflicts. Hyperprolactinemia is an interesting hypothesis (physiologic increase during pregnancy and similar manifestations in the course of gestation). The abductive inference theory is a probabilistic model that can clarify the role of hyperprolactinemia in the delusions of pregnancy. The purpose of this paper is to study the role of hyperprolactinemia in the delusions of pregnancy using a literature review. The abductive inference model is used to specify the etiopathogeny of this pathology.
A research in Medline, Sudoc, BIUM and PSYLINK using the following key words "delusional pregnancy" or "delusion of pregnancy" and "hyperprolactinemia" was conducted.
Three articles (case reports) about delusions of pregnancy associated with hyperprolactinemia were found. The cases have some similitudes. First of all, they have similar chronology: delusion appears at the same time as hyperprolactinemia and resolves with biological normalization. Secondly, hyperprolactinemia is always caused by a neuroleptic (haloperidol, olanzapine, risperidone). Concerning pre-existing disorders, a psychiatric pathology for each case was found (schizophrenia, schizo-affective disorder and bipolar disorder). Chronology, reproductivity and reversibility are strong arguments to involve hyperprolactinemia in the delusions of pregnancy (Bradford Hill criteria). Furthermore, this association is biologically plausible: physiologic increase during pregnancy (gestational signal), similar symptoms to those during pregnancy and the role in parental behavior (parental signal). Nevertheless, not everyone with hyperprolactinemia will develop a delusion of pregnancy; the interaction is more complex (non linear); the theory of abductive inference clarifies this relationship.
Abductive inference is a probabilistic model whose goal is to explain the occurrence of delusional beliefs. The first factor is the abnormal data. The second factor is the cognitive process (abductive inference), which uses Bayes' theorem to select the most likely hypothesis to explain the abnormal data. In the delusion of pregnancy, abnormal data is the hyperprolactinemia, signal of gestation without pregnancy. Hypotheses in order to explain this signal are then produced (pregnancy or no pregnancy). In the second part, probabilities associated with each hypothesis, given the hyperprolactinemia, are compared. Since hyperprolactinemia is a gestational signal, the pregnancy hypothesis is most likely. Probabilities associated with each hypothesis without taking hyperprolactinemia into account are compared (prior probability). Since any element of reality indicates a pregnancy, the absence of pregnancy is most likely. In the last step, the posterior probability is calculated using the first two comparisons. The probability associated with the pregnancy hypothesis (taking into account hyperprolactinemia) is relatively higher than the probability associated with the no-pregnancy hypothesis (without taking into account hyperprolactinemia). So, the posterior probability associated with the pregnancy hypothesis is more likely than the posterior probability associated with the no-pregnancy hypothesis. Thus, the subject believes in a pregnancy.
The research and the treatment of hyperprolactinemia must be conducted when faced with a delusion of pregnancy.
妊娠妄想并不为人所熟知。妊娠妄想被定义为尽管有相反的事实证据，但仍坚信自己怀孕。临床表现具有异质性（持续时间、机制、主题及既往精神障碍）。已提出多种原因来解释妊娠妄想的发生：本体感觉理论、高催乳素血症、烦渴及心理动力学冲突。高催乳素血症是一个有趣的假设（孕期生理性升高及孕期过程中类似表现）。溯因推理理论是一种概率模型，可阐明高催乳素血症在妊娠妄想中的作用。本文旨在通过文献综述研究高催乳素血症在妊娠妄想中的作用。采用溯因推理模型来明确该病症的病因。
在医学文献数据库（Medline）、法国国家图书馆数据库（Sudoc）、巴黎医学图书馆数据库（BIUM）和精神医学文献数据库（PSYLINK）中进行检索，使用关键词“妄想性妊娠”或“妊娠妄想”以及“高催乳素血症”。
发现三篇关于与高催乳素血症相关的妊娠妄想的文章（病例报告）。这些病例有一些相似之处。首先，它们有相似的时间顺序：妄想与高催乳素血症同时出现，并随着生物学指标恢复正常而消失。其次，高催乳素血症总是由抗精神病药物（氟哌啶醇、奥氮平、利培酮）引起。关于既往疾病，每个病例都发现有一种精神病理学（精神分裂症、分裂情感性障碍和双相情感障碍）。时间顺序、可重复性和可逆性是使高催乳素血症与妊娠妄想相关的有力论据（布拉德福德·希尔标准）。此外，这种关联在生物学上是合理的：孕期生理性升高（妊娠信号）、与孕期相似的症状以及在亲代行为中的作用（亲代信号）。然而，并非每个高催乳素血症患者都会出现妊娠妄想；这种相互作用更为复杂（非线性）；溯因推理理论阐明了这种关系。
溯因推理是一种概率模型，其目的是解释妄想信念的发生。第一个因素是异常数据。第二个因素是认知过程（溯因推理），它使用贝叶斯定理来选择最有可能解释异常数据的假设。在妊娠妄想中，异常数据是高催乳素血症，即无妊娠时的妊娠信号。然后产生用于解释此信号的假设（怀孕或未怀孕）。在第二部分，比较在高催乳素血症情况下与每个假设相关的概率。由于高催乳素血症是一种妊娠信号，怀孕假设最有可能。比较不考虑高催乳素血症时与每个假设相关的概率（先验概率）。由于任何现实因素都表明未怀孕，未怀孕最有可能。在最后一步，使用前两个比较来计算后验概率。与怀孕假设相关的概率（考虑高催乳素血症）相对高于与未怀孕假设相关的概率（不考虑高催乳素血症）。所以，与怀孕假设相关的后验概率比与未怀孕假设相关的后验概率更有可能。因此，个体相信自己怀孕。
面对妊娠妄想时，必须对高催乳素血症进行研究和治疗。
