Extreme Overvalued Beliefs
==========================

* Tahir Rahman
* Sarah M. Hartz
* Willa Xiong
* J. Reid Meloy
* Jeffrey Janofsky
* Bruce Harry
* Phillip J. Resnick

## Abstract

An extreme overvalued belief is shared by others in a person's cultural, religious, or subcultural group. The belief is often relished, amplified, and defended by the possessor of the belief and should be differentiated from a delusion or obsession. Over time, the belief grows more dominant, more refined, and more resistant to challenge. The individual has an intense emotional commitment to the belief and may carry out violent behavior in its service. Study participants (*n* = 109 forensic psychiatrists) were asked to select among three definitions (i.e., obsession, delusion, and extreme overvalued belief) as the motive for the criminal behavior seen in 12 randomized fictional vignettes. Strong interrater agreement (kappa = 0.91 [95% CI 0.83–0.98]) was seen for vignettes representing extreme overvalued belief. Vignettes representing delusion and obsession also had strong reliability (kappa = 0.99 for delusion and 0.98 for obsession). This preliminary report suggests that forensic psychiatrists, given proper definitions, possess a substantial ability to identify delusion, obsession, and extreme overvalued belief. The rich historical foundation of extreme overvalued belief and this small survey study highlight the benefit of inclusion of “extreme overvalued belief” in future glossaries of the Diagnostic and Statistical Manual.

Forensic psychiatrists face the challenging problem of evaluating odd or unusual beliefs while conducting threat assessments and forensic evaluations. Psychotic beliefs can be confused with shared ideologies as motives for terrorism and mass shootings. In an effort to provide forensic psychiatry with a concise definition for such shared beliefs, the term “extreme overvalued belief” was derived from earlier, less concise definitions. It was adapted from the term “overvalued idea” (Ueberwertige Idee), first coined by Carl Wernicke, the German neuropsychiatrist who is well known for his work with aphasias and Wernicke-Korsakoff syndrome.1,–,3 The main problem we uncovered is that the definition in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), is strikingly different from Wernicke's original conceptualization from 1892 and many subsequent textbook definitions.1,4 The DSM-5 describes overvalued idea as a belief held with “less than delusional intensity” and “not shared by others” in their cultural or subcultural group (Ref. 4, p 826). The proper definition of delusion affects several important diagnostic terms often seen in forensic criminal cases, including schizophrenia, delusional disorder, *folie à deux*, and erotomania. To provide a framework based on historically validated phenomenology in describing disorders, we reviewed an extensive body of psychiatric literature to describe extreme overvalued belief, which we defined in a previous article as follows: An extreme overvalued belief is one that is shared by others in a person's cultural, religious, or subcultural group. The belief is often relished, amplified, and defended by the possessor of the belief and should be differentiated from an obsession or a delusion. The belief grows more dominant over time, more refined, and more resistant to challenge. The individual has an intense emotional commitment to the belief and may carry out violent behavior in its service (Ref. 3, p 2).

The definition of extreme overvalued belief was first described in a prior article in the *Journal* in response to an analysis of the insanity trial of Anders Breivik, a Norwegian terrorist responsible for the massacre of 77 people, mostly youth, in Oslo and toya, Norway, in July 2011.2 Mental health professionals disagreed as to whether he held delusions due to schizophrenia or shared beliefs with other right-wing extremists. Prior to his attacks, Breivik released a bizarre manifesto and proclaimed that he was a “Knight Templar” on a mission to cleanse Norway of immigrants. He believed that he would become the New Regent in Norway following a *coup d'état* and that he would acquire the name “Sigurd the Crusader” as a pioneer in an impending European civil war. Both forensic teams agreed that he did not have hallucinations, nor did he exhibit grossly disorganized speech or behavior. This left his unusual beliefs as the main source of disagreement during his forensic evaluations. The Norwegian court declared that he held extremist beliefs shared by other right-wing groups in Norway and not idiosyncratic, fixed, and false beliefs from delusions, thus rejecting the insanity defense.2,5

Similar controversies regarding the source of fixated beliefs erupted in the cases of John Hinckley, Jr. (i.e., fixation on Jodi Foster), and other cases of lone-actor terrorism (such as Theodore Kaczynski's fixation on protecting the environment of the Earth).6 Moreover, in the past two decades, online interaction has been of increasing concern to counterterrorism experts. Reports of violent attacks by lone-actor offenders has increased dramatically.3,7 For example, in a recent case, an individual sent package bombs to political leaders and former U.S. President Barack Obama after viewing online extremist conspiracy theories. In a sentencing memorandum, his attorneys argued that he developed “delusions” and “obsessions” from online interaction.8 In a separate incident, called “Pizzagate,” a man fired shots into a pizza restaurant after he was “self-investigating” an online conspiracy theory that the restaurant was harboring “child sex slaves” linked to the Democratic Party.9–10 Mass shootings and acts of terrorism are well known to be inspired by online interaction and social media.2

In our review of the literature, we discovered that the term “overvalued idea” varies in its exact wording.11,–,17 It is usually described as being different from a delusion or obsession and as having shared ideologies (in keeping with Wernicke's seminal definition).11,–,16 These definitions are summarized in Table 1. Karl Jaspers was also a key figure in bringing rigorous definitions to abnormal psychic phenomena. He defined delusion as qualitatively different from normal belief, with a radical transformation from the meaning attached to events and incorrigible to an extent unlike normal belief. Jaspers also contrasted delusion from overvalued idea; he described the latter as an isolated notion associated with strong affect and an abnormal personality, similar in quality to passionate political, religious, or ethics convictions that are strongly toned by affect and best understood in terms of an individual's personality and unique biography. Thus, Jaspers emphasized that overvalued ideas are isolated notions that develop comprehensibly out of a given personality and situation.15 Frank Fish also brought the German tradition (including Wernicke) of descriptive psychopathology to English-speaking psychiatrists. His classic British clinical guide continues to influence students of the Royal College of Physicians.17 He observed that there was frequently a discrepancy between the degree of conviction in overvalued ideas and the extent to which the beliefs directed abnormal behavior. He also argued that patients with overvalued ideas acted on them, determinedly and repeatedly, and compared them to the drive of an instinct, like nest building.15,17

View this table:
[Table 1](http://jaapl.org/content/48/3/319/T1)

Table 1 
Definitions of Overvalued Idea from Psychiatric Texts

### Fixated Beliefs and Psychopathology

The classic descriptions of overvalued idea (Table 1) from various international texts are similar; however, they all are clearly different from the definitions in the DSM-5 and the DSM-IV, Text Revision.11,–,16 To further confuse matters, several British texts categorize the following conditions as disorders with overvalued ideas: anorexia nervosa; paranoid state, querulous or litigious type; morbid jealousy; hypochondriasis; dysmorphophobia; and parasitophobia (Ekbom's syndrome).12,15,17 Some of these disorders are seen as the product of delusions in U.S. texts.6,17

Wernicke's 1892 description of overvalued idea,1 which was recently published in English translation,6 does not mention these disorders. Instead, he described overvalued ideas in the context of criminality and insanity.1,6 Although Wernicke did not explicitly define delusion, obsession, and overvalued idea, he gave case examples and stated that these three cognitive drivers of fixations can be easily distinguished on clinical grounds. He went on to describe overvalued ideas as experienced by the patient as normal and justified, fully explained by the events that led to their formation.6,18

The historical aspects of Wernicke's seminal work on overvalued idea is elaborated upon in several other articles.1,–,3,6 The definition of extreme overvalued belief utilizes the terms “culture” and “subculture.” Section III of the DSM-5 is called “Emerging Measures and Models.” It states that “culture refers to systems of knowledge, concepts, rules, and practices that are learned and transmitted across generations. Culture includes language, religion, and spirituality, family structures, life-cycle stages, ceremonial rituals, and customs, as well as moral and legal systems” (Ref. 4, p 749). We believe that online transmission of beliefs also belongs in this model of culture systems. The definition of subculture does not appear in this section but can be thought of as a cultural group within a larger culture, often having beliefs and behavior at variance with those of the larger culture.

Some of these beliefs can be of such peculiar content to people outside of their group that they appear psychotic. For instance, many people believe that being thin is healthy and desirable, but some individuals overvalue these ideals and develop anorexia nervosa. Another individual might become infatuated with a celebrity and may begin stalking the celebrity. For example, John Hinckley, Jr., despite being infatuated with Jodi Foster, admitted that he had no chance of being with her. Similar behavior arises with religious beliefs, where a subculture (e.g., Al-Qaeda) embraces terrorism. In an online world, the rapid and repeated transmission of false information makes individuals increasingly susceptible to such extreme overvalued beliefs.3,6

### Form and Content of Beliefs

The terms obsession, delusion, and overvalued idea are often used interchangeably by forensic examiners as well as the media.3 Statements such as, “he was obsessed with anti-government videos” or “he had a delusional belief that he was saving babies by destroying an abortion clinic” provide examples of the confusion arising with various fixated beliefs. The beliefs are of critical importance in determining the motive during insanity evaluations. They are also critical in threat assessment and management because they may require different monitoring and treatment strategies. For instance, antipsychotic drugs may help decrease the intensity of delusions in schizophrenia, but they have limited use in treating disorders due to overvalued ideas. For example, eating disorders and Ekbom's syndrome (delusional parasitosis) have both been described as founded on overvalued ideas. The infestation in Ekbom syndrome and learning new ways to diet can be transmitted online. Antipsychotic drugs are not effective for many of these patients; although psychotherapy and separation from others with similar shared beliefs can reduce the contagion effect.19,20 Therefore, it is critical for examiners to identify the appropriate nature of the beliefs in the context of other signs and symptoms such as mania, disorganized speech, or personality traits.

The concept of extreme overvalued belief as a choice for examiners in forensic cases has been of interest to our group of academic researchers. Addressing pathological fixation by studying these three phenomena (obsession, delusion, and extreme overvalued belief) in psychiatry provides a step toward more precise definitions for the field. Therefore, we decided to conduct a workshop21 with a live audience survey to test the ability of forensic psychiatrists to apply the above definition of extreme overvalued belief, along with established DSM-5 definitions of obsession and delusion to fictional case vignettes.

## Methods

We created 12 fictional case vignettes (four each of extreme overvalued belief, obsession, and delusion cases) of criminal behavior (Table 2). We deliberately chose simple vignettes to demonstrate shared ideologies to differentiate them from fixed false beliefs and obsessions. We first gave them to 10 psychiatry residents at the Washington University in St. Louis, Missouri, to ensure clarity. The discussion and study were conducted during a workshop at the 49th Annual Meeting of the American Academy of Psychiatry and the Law (AAPL) in Austin, Texas in 2018. The simple vignettes were written to simulate cases that the authors hypothesized would have high interrater agreement among attendees of the workshop. They were based on a synthesis of our experience and cases in the psychiatric literature. We recognized that beliefs could not easily be identified without further data such as a person's culture and background, as many textbooks have stated. Therefore, the vignettes detailed beliefs which, along with other clear signs or symptoms (e.g., disorganized speech and auditory hallucinations for delusional beliefs or repeated intrusive images for obsessional beliefs), could be easily classified. These rigid contours were included to emphasize the need to examine other signs and symptoms in the case narrative to provide a controlled context to identify the type of belief. Because overvalued idea is clearly described in the literature, we chose to assign definitions in that tradition as opposed to the DSM-5 definition (see Table 3) and to assess whether extreme overvalued belief had good interrater reliability among U.S. forensic psychiatrists. The main purpose of our workshop was to gather some preliminary data on the reliability of extreme overvalued belief and to begin a discourse with AAPL members regarding definitions and scenarios described in the survey.

View this table:
[Table 2](http://jaapl.org/content/48/3/319/T2)

Table 2 
Vignettes

View this table:
[Table 3](http://jaapl.org/content/48/3/319/T3)

Table 3 
Definitions for Workshop Survey

The protocol was approved on an exempt status by the institutional review board at Washington University in St. Louis. The participants were 109 AAPL forensic psychiatry workshop attendees.21 Data were collected anonymously using the Turning Point22 live-audience response system in which participants responded using a handheld clicker. The fictional vignettes for each category were presented in random order.

Based on the responses from the participants, Cohen's kappa coefficients and corresponding variances were computed for each vignette.23 To quantify the overall reliability of the definition of extreme overvalued belief, a random effects meta-analysis of the kappa coefficients was conducted corresponding to each extreme overvalued belief vignette, weighted by the inverse variance. All statistical analyses were conducted in R software.24

## Results

Out of 109 forensic psychiatrists surveyed, a high degree of interrater agreement was found in selecting one of the three definitions for beliefs commonly encountered during threat assessments and forensic evaluations. The kappa scores for the vignettes corresponding to extreme overvalued belief (vignettes 1, 5, 6, and 10) are presented in Table 4. A meta-analysis of the four vignettes found the summary kappa = 0.91 (95% CI 0.83–0.98), representing “a nearly perfect” degree of interrater reliability as defined by kappa > 0.8. One vignette involving shared religious ideology and the planet Jupiter had a lower agreement score (vignette 6). Vignettes representing delusion and obsession also had very high reliability: summary kappa = 0.99 for delusion and 0.98 for obsession.

View this table:
[Table 4](http://jaapl.org/content/48/3/319/T4)

Table 4 
Interrater Reliability of Definitions

## Discussion

Clear definitions of the beliefs we describe here are of importance to clinicians, forensic examiners, the criminal justice system, media, and researchers. An increasingly online world has changed the way group dynamics influence beliefs. Forensic examiners often struggle to categorize odd and unusual beliefs in the individuals they examine.25 A failure to recognize shared versus idiosyncratic beliefs, as highlighted by the Breivik, Hinckley, Kaczynski, and recent online inspired terrorism cases, may lead to inaccurate diagnostic classification.2,3,6,13,21,26 Our results provide some preliminary data that an extreme overvalued belief can be reliably separated from delusion or obsession (within the constraints of the survey's limitations). Extreme overvalued belief needs further empirical assessment with larger numbers and in the context of real-world cases.

We acknowledge that there is inherent bias in creating controlled fictionalized vignettes with obvious signs of disorders such as auditory hallucinations along with delusions (schizophrenia) or intrusive thoughts since childhood (obsessive-compulsive disorder). This was done with the hope that future study designs could be extrapolated from our initial investigation. Although there was almost perfect agreement among forensic psychiatrists in selecting the motives in the fictional case vignettes here, we are cautious in interpreting these results. A genuine evaluation should be conducted only after a thorough review and examination in accordance with established forensic guidelines.

In vignette 6, there was less agreement among examiners, as noted in Table 4. We speculate that this was because of changes to the DSM-5 that participants may not have appreciated, specifically that the bizarre content of beliefs (e.g., “souls going to the planet Jupiter”) was given less importance as a Schneiderian first-rank symptom of a bizarre delusion or special hallucination in the DSM-5 compared with the DSM-IV.15,16

We also acknowledge that the survey is limited by forcing the psychiatrists to choose one of three categories of pathological beliefs (i.e., without allowing for the possibility of no diagnosis, normal belief, or culturally sanctioned belief). Extremist ideology itself is not a diagnosis, and the pathological nature of a belief does not always depend on a criminal act (behavior). In fact, it is the criminal act that is extreme in the vignettes, without the cases making an argument that the beliefs themselves are. Therefore, the results provided here are not intended to explain why some people with shared beliefs engage in socially deviant behavior while others do not. It is often difficult in psychiatry to distinguish psychotic from nonpsychotic symptoms when there are no easily identified symptoms as provided in the fictional vignettes. For example, an individual with schizophrenia could have both delusions and extreme overvalued beliefs. Another individual might present with manic symptoms, cognitive deficits, and have extreme overvalued beliefs. Such cases could prove difficult and create equally strong yet opposing forensic opinions regarding insanity. Our survey, with its easily identifiable diagnostic clues, may be vastly different from such actual cases.

Finally, although forensic psychiatrists are trained to identify delusions in insanity cases, our survey might be prejudicial in associating extreme overvalued beliefs with violence, but not delusions. Among the three definitions surveyed, only extreme overvalued belief contains a propensity toward violence in the definition: “the individual has an intense emotional commitment to the belief and may carry out violent behavior in its service” (Ref. 3, p 2). Individuals operating under the influence of delusions may also be predisposed toward violence (driven by fear of persecution, revenge, etc.). Psychosis involving persecutory or Capgras delusions represent salient risk factors for violence among individuals with a major mental illness26,–,28 and were not equally stressed in the survey. Delusions and extreme overvalued beliefs may contribute to violent behavior. It is also important to note that many persons with such beliefs may never engage in such acts.

## Conclusion

Current definitions of delusion and overvalued idea in the DSM-5 pose a challenging problem for differentiating delusion from rigidly held, nondelusional, culturally shared beliefs. We believe that classifying beliefs by putative causation would promote progress in forensic psychiatry.27 The concept of an overvalued idea has been ignored by psychiatry in the United States,16 and it is now seen as an important cognitive driver in many cases of terrorism, assassinations, and targeted violence.2,3,29,30 Regardless of the diagnosis, we stress that it is important for forensic psychiatrists to properly identify a defendant's belief as either a fixed false conviction (i.e., a delusion) or as an intense emotional commitment to a commonly held belief shared by other members of his or her cultural group (i.e., an extreme overvalued belief).6

Fixation on a person or cause with an accompanied deterioration in social or occupational function has recently been identified as an important correlate and warning behavior for targeted violence. This includes a noticeable increase in perseveration, strident opinion, negative statements about the target(s), increasing anxiety or fear about the target, and an angry emotional undertone.29,30 Our preliminary findings provide evidence of high interrater reliability of extreme overvalued belief among forensic psychiatrists when forced to choose among three definitions with fictionalized vignettes. Further studies should be conducted to determine reliability in real-world cases without the controlled clues given in fictional vignettes.

We believe the definition can aid research to discover mechanisms by which a pathological transition occurs from “normal-valuedness” to “over-valuedness.” Cognitive dissonance has been found to be an effective tool in the prevention of anorexia nervosa, a common disorder caused by overvalued ideas.31 Further study of such disorders, utilizing data derived from a more precise definition, may uncover new ways to prevent targeted violence.3 The overlooked historical definition of overvalued idea merits consideration for use in forensic psychiatry. This study, with its rudimentary controlled design, showed high agreement among the forensic psychiatrist participants. We believe the historical foundation along with the preliminary data from this study highlight the benefit of inclusion of extreme overvalued beliefs in future versions of the DSM's glossary. This addition to the DSM's differential diagnosis sections of schizophrenia, delusional disorder, *folie à deux*,32 and erotomania is recommended to bolster this important distinction.26 We further emphasize that extreme overvalued beliefs may not be a diagnosis of a mental disorder, just as personality dimensions, intellectual ability, deviant sexual behavior, and grief may not be diagnoses; however, as the Anders Breivik and cases of online inspired lone-actor violence have highlighted, forensic experts can now explain abnormal and sometimes criminal behavior in concise terms when there is no clear mental disorder to describe.

## Footnotes

*   Disclosures of financial or other potential conflicts of interest: None.

*   © 2020 American Academy of Psychiatry and the Law

## References

1.  1.Wernicke C: Ueber fixe Ideen. Deutsche Medicinische Wochenschrift 25, 1892
    
    

2.  2.Rahman T, Resnick PJ, Harry B: Anders Breivik: extreme beliefs mistaken for psychosis. J Am Acad Psychiatry Law 44:28–35, 2016
    
    [Abstract/FREE Full Text](http://jaapl.org/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NToiamFhcGwiO3M6NToicmVzaWQiO3M6NzoiNDQvMS8yOCI7czo0OiJhdG9tIjtzOjIwOiIvamFhcGwvNDgvMy8zMTkuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9) 

3.  3.Rahman T: Extreme overvalued beliefs: how violent extremist beliefs become “normalized”. Behav Sci (Basel) 8:E10, 2018
    
    

4.  4.American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. Washington, DC: American Psychiatric Press, 2013
    
    

5.  5.Melle I: The Breivik case and what psychiatrists can learn from it. World Psychiatry 12:16–21, 2013
    
    [CrossRef](http://jaapl.org/lookup/external-ref?access_num=10.1002/wps.20002&link_type=DOI) 
    
    [PubMed](http://jaapl.org/lookup/external-ref?access_num=23471788&link_type=MED&atom=%2Fjaapl%2F48%2F3%2F319.atom) 
    
    [Web of Science](http://jaapl.org/lookup/external-ref?access_num=000319870500003&link_type=ISI) 

6.  6.Rahman T, Meloy JR, Bauer R: Extreme overvalued belief and the legacy of Carl Wernicke. J Am Acad Psychiatry Law 47:180–7, 2019
    
    [Abstract/FREE Full Text](http://jaapl.org/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NToiamFhcGwiO3M6NToicmVzaWQiO3M6ODoiNDcvMi8xODAiO3M6NDoiYXRvbSI7czoyMDoiL2phYXBsLzQ4LzMvMzE5LmF0b20iO31zOjg6ImZyYWdtZW50IjtzOjA6IiI7fQ==) 

7.  7.1.  Ghose A, 
    2.  Seamans R
    
    Chan J, University of Minnesota, Ghose A, Seamans R: The internet and racial hate crime: offline spillovers from online access. MISQ 40:381–403, 2016
    
    

8.  8.United States v. Cesar Altieri Sayoc, 88 F. Supp. 3d 300 (S.D.N.Y. 2019).
    
    

9.  9.Berghel H: Lies, damn lies, and fake news. Computer 50:80–5, 2017
    
    

10. 10.Gillin J: How Pizzagate went from fake news to a real problem for a DC business. Politifact, December 8, 2016. Available at: [https://www.politifact.com/article/2016/dec/05/how-pizzagate-went-fake-news-real-problem-dc-busin/](https://www.politifact.com/article/2016/dec/05/how-pizzagate-went-fake-news-real-problem-dc-busin/). Accessed March 27, 2020
    
    

11. 11.Freudenreich O: Psychotic Disorders: A Practical Guide. Philadelphia: Lippincott Williams and Wilkins, 2007
    
    

12. 12.1.  Gelder M, 
    2.  Gath D, 
    3.  Mayou R, 
    4.  Cowan P
    
    Oxford Textbook of Psychiatry, Third Edition. Edited by Gelder M, Gath D, Mayou R, Cowan P. New York: Oxford University Press, 1996
    
    

13. 13.McHugh PR: The Mind Has Mountains: Reflections on Society and Psychiatry. Baltimore: Johns Hopkins University Press, 2006
    
    

14. 14.Winokur G, Clayton P: The Medical Basis of Psychiatry. Philadelphia: Saunders, 1986
    
    

15. 15.Oyebode F: Sims' Symptoms in the Mind: An Introduction to Descriptive Psychopathology, Fourth Edition. Philadelphia: Elsevier Health Sciences, 2008
    
    

16. 16.Fish FJ: An Outline of Psychiatry for Students and Practitioners, Second Edition. Bristol, UK: John Wright and Sons Ltd, 1968
    
    

17. 17.Veale D: Over-valued ideas: a conceptual analysis. Behav Res Ther 40:383–400, 2002
    
    [CrossRef](http://jaapl.org/lookup/external-ref?access_num=10.1016/S0005-7967(01)00016-X&link_type=DOI) 
    
    [PubMed](http://jaapl.org/lookup/external-ref?access_num=12002896&link_type=MED&atom=%2Fjaapl%2F48%2F3%2F319.atom) 

18. 18.Wernicke C: Grundriss der Psychiatriein Klinischen Vorlesungen [Foundation of Psychiatry in Clinical Lectures]. Leipzig: Fischer & Wittig, 1900
    
    

19. 19.Attia E, Steinglass J E, Walsh B. T, et al: Olanzapine versus placebo in adult outpatients with anorexia nervosa: a randomized clinical trial. Am J Psychiatry 176:449–56, 2019
    
    

20. 20.Lepping P, Russell I, Freudenmann RW: Antipsychotic treatment of primary delusional parasitosis: systematic review. Br J Psychiatry 191:198–205, 2007
    
    [Abstract/FREE Full Text](http://jaapl.org/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6MTA6ImJqcHJjcHN5Y2giO3M6NToicmVzaWQiO3M6OToiMTkxLzMvMTk4IjtzOjQ6ImF0b20iO3M6MjA6Ii9qYWFwbC80OC8zLzMxOS5hdG9tIjt9czo4OiJmcmFnbWVudCI7czowOiIiO30=) 

21. 21.Rahman T, Xiong W, Resnick PJ, et al: Extreme overvalued beliefs or delusions? Presented at the 49th Annual Meeting of the American Academy of Psychiatry and Law, Austin, TX, October 2018
    
    

22. 22.Quinn A: Audience response system (clickers) by TurningPoint. J Technology Human Services 25:107–14, 2007
    
    

23. 23.Sun S: Meta-analysis of Cohen's kappa. Health Serv Outcomes Res Method 11:145–63, 2011
    
    

24. 24.Team RC: R: a language and environment for statistical computing. Vienna: R Core Team, 2015
    
    

25. 25.Pierre JM: Integrating non-psychiatric models of delusion-like beliefs into forensic psychiatric assessment. J Am Acad Psychiatry Law 47:171–9, 2019
    
    [Abstract/FREE Full Text](http://jaapl.org/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NToiamFhcGwiO3M6NToicmVzaWQiO3M6ODoiNDcvMi8xNzEiO3M6NDoiYXRvbSI7czoyMDoiL2phYXBsLzQ4LzMvMzE5LmF0b20iO31zOjg6ImZyYWdtZW50IjtzOjA6IiI7fQ==) 

26. 26.Weiss KJ: At a loss for words: nosological impotence in the search for justice. J Am Acad Psychiatry Law 44:36–40, 2016
    
    [Abstract/FREE Full Text](http://jaapl.org/lookup/ijlink/YTozOntzOjQ6InBhdGgiO3M6MTQ6Ii9sb29rdXAvaWpsaW5rIjtzOjU6InF1ZXJ5IjthOjQ6e3M6ODoibGlua1R5cGUiO3M6NDoiQUJTVCI7czoxMToiam91cm5hbENvZGUiO3M6NToiamFhcGwiO3M6NToicmVzaWQiO3M6NzoiNDQvMS8zNiI7czo0OiJhdG9tIjtzOjIwOiIvamFhcGwvNDgvMy8zMTkuYXRvbSI7fXM6ODoiZnJhZ21lbnQiO3M6MDoiIjt9) 

27. 27.McHugh PR, Slavney PR: Mental illness—comprehensive evaluation or checklist? N Engl J Med 366:1853–5, 2012
    
    [CrossRef](http://jaapl.org/lookup/external-ref?access_num=10.1056/NEJMp1202555&link_type=DOI) 
    
    [PubMed](http://jaapl.org/lookup/external-ref?access_num=22591291&link_type=MED&atom=%2Fjaapl%2F48%2F3%2F319.atom) 
    
    [Web of Science](http://jaapl.org/lookup/external-ref?access_num=000304083000003&link_type=ISI) 

28. 28.Sarteschi CM: Mass and serial murder in America. Springer International Publishing, 2016
    
    

29. 29.Meloy JR, Hoffmann J, Guldimann A, James D: The role of warning behaviors in threat assessment: an exploration and suggested typology. Behav Sci & L 30:256–79, 2012
    
    

30. 30.Meloy JR, Gill P: The lone-actor terrorist and the TRAP-18. J Threat Assess Manag 3:37–52, 2016
    
    

31. 31.Stice E, Becker CB, Yokum S: Eating disorder prevention: current evidence‐base and future directions. Int J Eat Disord 46:478–85, 2013
    
    [CrossRef](http://jaapl.org/lookup/external-ref?access_num=10.1002/eat.22105&link_type=DOI) 
    
    [PubMed](http://jaapl.org/lookup/external-ref?access_num=23658095&link_type=MED&atom=%2Fjaapl%2F48%2F3%2F319.atom) 

32. 32.Rahman T, Grellner KA, Harry B, et al: Infanticide in a case of folie à deux. Am J Psychiatry 170:1110–1112, 2013