13Psychiatry needs operational definitions to appreciate differences seen in idiosyncratic, psychotic 14 thinking, and shared subcultural beliefs or ideologies. Carl Wernicke first described overvalued idea in 151906. The concept has been applied to describe it as a motive in mass shootings and terrorism. We review 16 the concept of overvalued idea and extreme overvalued belief as a basis for making the distinction 17 between delusions and non-delusions. 18Keywords: psychosis; delusion; over valued idea; terrorism; mass shootings; violence; forensic psychiatry 19 20 Psychiatry lacks operational definitions to differentiate idiosyncratic, psychotic thinking from 21 shared subcultural beliefs or ideologies. Rigidly-held non-delusional beliefs are an important 22 aspect behind the motive for many global and homegrown violent and terrorist attacks (1). The 23 fact that no particular sociodemographic information has been found to be associated with this 24 often aberrant behavior requires new strategies to be developed. Terrorism is a behavior that 25 Peer-reviewed version available at Behav. Sci. 2018, 8, 10; doi:10.3390/bs8010010 comes with enormous direct and indirect costs-lost lives, expensive counter-terrorism 26 programs, political division, loss of civil liberties, and psychological disorders (2). A literature 27 search on the topic of primary prevention of terrorism and mass shootings reveals strikingly little 28 scholarly academic work by psychiatrists. Media often erroneously report a terrorist attack as 29 based on delusional thinking, obsessional thinking or psychosis. This article reviews the concept 30 of over-valued idea, first defined by Carl Wernicke and later applied to terrorism as an important 31 area of psychopathology with important implications for both forensic evaluations and primary 32 prevention of terrorism and mass shootings. 33
Extreme Overvalued Beliefs 34There has previously been a lack of agreement as to what precisely constitutes an over-35 valued idea (3). Consensus regarding definitions is helpful to facilitate research and the 36 development of innovative strategies. In 2016, our group of forensic psychiatrists (Rahman, 37 Peer-reviewed version available at Behav. Sci. 2018, 8, 10; doi:10.3390/bs8010010 This definition expands on what was first described as Ueberwerthige Idee (overvalued 50 idea) by Carl Wernicke in Gundriss der Psychiatrie (1906) and later invoked by then 51 psychiatrist-in-chief Paul McHugh at Johns Hopkins in response to the 9/11 terrorist attacks (4). 52 FBI trained forensic behavioral specialist Matt Logan also discusses this concept in Lone Wolf 53
Killers: A Perspective on Overvalued Ideas (5). 54Wernicke is honored by having his name describe a type of aphasia, but his psychiatric 55 contributions have largely been neglected. Gundriss der Psychiatrie was recently translated 56 from German into English. In his classical description of overvalued idea, Wernicke stated that 57 "special conditions must prevail before such overemphasis takes o...