Evolution of the human fear-circuitry and acute sociogenic pseudoneurological symptoms: the Neolithic balanced-polymorphism hypothesis

An ethologically based view into human fear

The quality of the defensive response to a threat depends on the elements that trigger the fear response. The current classification system of phobias does not account for this. Here, we analyze the fear-eliciting elements and discern the different types of fears that originate from them. We propose Pain, Disgust, Vasovagal response, Visual-vestibular and postural interactions, Movement and Speed, Distance and Size, Low and mid-level visual features, Smell, and Territory and social status. We subdivide phobias according to the fear-eliciting elements most frequently triggered by them and their impact on behavior. We discuss the implications of a clinical conceptualization of phobias in humans by reconsidering the current nosology. This conceptualization will facilitate finding etiological factors in defensive behavior expression, fine-tuning exposure techniques, and challenging preconceived notions of preparedness. This approach to phobias leads to surprising discoveries and shows how specific responses bear little relation to the interpretation we might later give to them. Dividing fears into their potentially fear-eliciting elements can also help in applying the research principles formulated by the Research Domain Criteria initiative.

Confederates in the Attic: Posttraumatic Stress Disorder, Cardiovascular Disease, and the Return of Soldier's Heart

Da Costa originally described Soldier's Heart in the 19th Century as a syndrome that occurred on the battlefield in soldiers of the American Civil War. Soldier's Heart involved symptoms similar to modern day posttraumatic stress disorder (PTSD) as well as exaggerated cardiovascular reactivity felt to be related to an abnormality of the heart. Interventions were appropriately focused on the cardiovascular system. With the advent of modern psychoanalysis, psychiatric symptoms became divorced from the body and were relegated to the unconscious. Later, the physiology of PTSD and other psychiatric disorders was conceived as solely residing in the brain. More recently, advances in psychosomatic medicine led to the recognition of mind-body relationships and the involvement of multiple physiological systems in the etiology of disorders, including stress, depression PTSD, and cardiovascular disease, has moved to the fore, and has renewed interest in the validity of the original model of the Soldier's Heart syndrome.

Political attitudes vary with physiological traits

Although political views have been thought to arise largely from individuals' experiences, recent research suggests that they may have a biological basis. We present evidence that variations in political attitudes correlate with physiological traits. In a group of 46 adult participants with strong political beliefs, individuals with measurably lower physical sensitivities to sudden noises and threatening visual images were more likely to support foreign aid, liberal immigration policies, pacifism, and gun control, whereas individuals displaying measurably higher physiological reactions to those same stimuli were more likely to favor defense spending, capital punishment, patriotism, and the Iraq War. Thus, the degree to which individuals are physiologically responsive to threat appears to indicate the degree to which they advocate policies that protect the existing social structure from both external (outgroup) and internal (norm-violator) threats.

Expanding the theory of symptom modeling in patents with psychogenic nonepileptic seizures

Symptom modeling has been used to explain the development of psychogenic nonepileptic seizures (PNES) in predisposed patients, but has been understood only in the context of individuals who have both PNES and epileptic seizures. Our aim in the study described here was to learn whether this concept applies to patients with PNES who do not have epileptic seizures, that is, to determine whether the prevalence of having personally witnessed a seizure prior to the occurrence of their event differs in patients with PNES and those with epileptic seizures. We interviewed 27 patients with PNES and 35 patients with epileptic seizures. A significantly larger number of patients with PNES (66%) admitted to having witnessed a seizure prior to their event compared with patients with epileptic seizures (11%) (P<0.001). This suggests that symptom modeling plays a key role in the development of PNES, even among individuals without a coexisting history of epilepsy.

Traumatic entrapment, appeasement and complex post-traumatic stress disorder: evolutionary perspectives of hostage reactions, domestic abuse and the Stockholm syndrome

Evolutionary theory and cross-species comparisons are explored to shed new insights into behavioural responses to traumatic entrapment, examining their relationships to the Stockholm syndrome (a specific response to traumatic entrapment) and complex post-traumatic stress disorder (PTSD). A selective literature review is undertaken examining responses to traumatic entrapment (including hostage, domestic abuse and similar situations) and the Stockholm syndrome, before examining mammalian, reptilian and other defensive responses to relevant threats. Chimpanzees, the closest relatives of humans, are closely examined from this perspective and commonalities in behavioural responses are highlighted. The neurobiological basis of defensive behaviours underlying PTSD is explored with reference to the triune brain model. Victims of protracted traumatic entrapment under certain circumstances may display the Stockholm syndrome, which involves paradoxically positive relationships with their oppressors that may persist beyond release. Similar responses are observed in many mammalian species, especially primates. Ethological concepts including dominance hierarchies, reverted escape, de-escalation and conditional reconciliation appear relevant and are illustrated. These phenomena are commonly encountered in victims of severe abuse and understanding these concepts may assist clinical management. Appeasement is the mammalian defence most relevant to the survival challenge presented by traumatic entrapment and appears to be the foundation of complex PTSD. Evolutionary perspectives have considerable potential to bridge and integrate neurobiology and the social sciences with respect to traumatic stress responses.

Utility of fear severity and individual resilience scoring as a surge capacity, triage management tool during large-scale, bio-event disasters

Threats of bioterrorism and emerging infectious disease pandemics may result in fear-related consequences. If left undetected and untreated, fear-based signs and symptoms may be extremely debilitating and lead to chronic problems with a risk of permanent damage to the brain's locus coeruleus and stress response circuits. The triage management of susceptible, exposed, and infectious victims seeking care must be sensitive and specific enough to identify individuals with excessive levels of fear in order to address the nuances of fear-based symptoms at the initial point of contact. These acute conditions, which include hyper-vigilant fear, are managed best by timely and effective information, rapid evaluation, and possibly medications that uniquely address the locus-coeruleus-driven noradrenalin over-activation. It is recommended that a Fear and Resilience (FR) Checklist be included as an essential triage tool to identify those most at risk. The use of this checklist facilitates an enhanced capacity to respond to limitations brought about by surge capacity requirements. Whereas the utility of such a checklist is evident, predictive validity studies will be required. In addition to identifying individuals who are emotionally, medically, and socially hypo-resilient, the FR Checklist simultaneously identifies individuals who are hyper-resilient and can be asked to volunteer, and thus, rapidly expand the surge capacity.

Testing the Paleolithic-human-warfare hypothesis of blood-injection phobia in the Baltimore ECA Follow-up Study--towards a more etiologically-based conceptualization for DSM-V

OBJECTIVE

The research agenda for the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-V) has emphasized the need for a more etiologically-based classification system, especially for stress-induced and fear-circuitry disorders. Testable hypotheses based on threats to survival during particular segments of the human era of evolutionary adaptedness (EEA) may be useful in developing a brain-evolution-based classification for the wide spectrum of disorders ranging from disorders which are mostly overconsolidationally such as PTSD, to fear-circuitry disorders which are mostly innate such as specific phobias. The recently presented Paleolithic-human-warfare hypothesis posits that blood-injection phobia can be traced to a "survival (fitness) enhancing" trait, which evolved in some females of reproductive-age during the millennia of intergroup warfare in the Paleolithic EEA. The study presented here tests the key a priori prediction of this hypothesis-that current blood-injection phobia will have higher prevalence in reproductive-age women than in post-menopausal women.

METHOD

The Diagnostic Interview Schedule (version III-R), which included a section on blood and injection phobia, was administered to 1920 subjects in the Baltimore ECA Follow-up Study.

RESULTS

Data on BII phobia was available on 1724 subjects (1078 women and 646 males). The prevalence of current blood-injection phobia was 3.3% in women aged 27-49 and 1.1% in women over age 50 (OR 3.05, 95% CI 1.20-7.73). [The corresponding figures for males were 0.8% and 0.7% (OR 1.19, 95% CI 0.20-7.14)].

CONCLUSIONS

This epidemiological study provides one source of support for the Paleolithic-human-warfare (Paleolithic-threat) hypothesis regarding the evolutionary (distal) etiology of bloodletting-related phobia, and may contribute to a more brain-evolution-based re-conceptualization and classification of this fear circuitry-related trait for the DSM-V. In addition, the finding reported here may also stimulate new research directions on more proximal mechanisms which can lead to the development of evidence-based psychopharmacological preventive interventions for this common and sometimes disabling fear-circuitry disorder.

Human brain evolution and the "Neuroevolutionary Time-depth Principle:" Implications for the Reclassification of fear-circuitry-related traits in DSM-V and for studying resilience to warzone-related posttraumatic stress disorder

The DSM-III, DSM-IV, DSM-IV-TR and ICD-10 have judiciously minimized discussion of etiologies to distance clinical psychiatry from Freudian psychoanalysis. With this goal mostly achieved, discussion of etiological factors should be reintroduced into the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V). A research agenda for the DSM-V advocated the "development of a pathophysiologically based classification system". The author critically reviews the neuroevolutionary literature on stress-induced and fear circuitry disorders and related amygdala-driven, species-atypical fear behaviors of clinical severity in adult humans. Over 30 empirically testable/falsifiable predictions are presented. It is noted that in DSM-IV-TR and ICD-10, the classification of stress and fear circuitry disorders is neither mode-of-acquisition-based nor brain-evolution-based. For example, snake phobia (innate) and dog phobia (overconsolidational) are clustered together. Similarly, research on blood-injection-injury-type-specific phobia clusters two fears different in their innateness: 1) an arguably ontogenetic memory-trace-overconsolidation-based fear (hospital phobia) and 2) a hardwired (innate) fear of the sight of one's blood or a sharp object penetrating one's skin. Genetic architecture-charting of fear-circuitry-related traits has been challenging. Various, non-phenotype-based architectures can serve as targets for research. In this article, the author will propose one such alternative genetic architecture. This article was inspired by the following: A) Nesse's "Smoke-Detector Principle", B) the increasing suspicion that the "smooth" rather than "lumpy" distribution of complex psychiatric phenotypes (including fear-circuitry disorders) may in some cases be accounted for by oligogenic (and not necessarily polygenic) transmission, and C) insights from the initial sequence of the chimpanzee genome and comparison with the human genome by the Chimpanzee Sequencing and Analysis Consortium published in late 2005. Neuroevolutionary insights relevant to fear circuitry symptoms that primarily emerge overconsolidationally (especially Combat related Posttraumatic Stress Disorder) are presented. Also introduced is a human-evolution-based principle for clustering innate fear traits. The "Neuroevolutionary Time-depth Principle" of innate fears proposed in this article may be useful in the development of a neuroevolution-based taxonomic re-clustering of stress-triggered and fear-circuitry disorders in DSM-V. Four broad clusters of evolved fear circuits are proposed based on their time-depths: 1) Mesozoic (mammalian-wide) circuits hardwired by wild-type alleles driven to fixation by Mesozoic selective sweeps; 2) Cenozoic (simian-wide) circuits relevant to many specific phobias; 3) mid Paleolithic and upper Paleolithic (Homo sapiens-specific) circuits (arguably resulting mostly from mate-choice-driven stabilizing selection); 4) Neolithic circuits (arguably mostly related to stabilizing selection driven by gene-culture co-evolution). More importantly, the author presents evolutionary perspectives on warzone-related PTSD, Combat-Stress Reaction, Combat-related Stress, Operational-Stress, and other deployment-stress-induced symptoms. The Neuroevolutionary Time-depth Principle presented in this article may help explain the dissimilar stress-resilience levels following different types of acute threat to survival of oneself or one's progency (aka DSM-III and DSM-V PTSD Criterion-A events). PTSD rates following exposure to lethal inter-group violence (combat, warzone exposure or intentionally caused disasters such as terrorism) are usually 5-10 times higher than rates following large-scale natural disasters such as forest fires, floods, hurricanes, volcanic eruptions, and earthquakes. The author predicts that both intentionally-caused large-scale bioevent-disasters, as well as natural bioevents such as SARS and avian flu pandemics will be an exception and are likely to be followed by PTSD rates approaching those that follow warzone exposure. During bioevents, Amygdala-driven and locus-coeruleus-driven epidemic pseudosomatic symptoms may be an order of magnitude more common than infection-caused cytokine-driven symptoms. Implications for the red cross and FEMA are discussed. It is also argued that hospital phobia as well as dog phobia, bird phobia and bat phobia require re-taxonomization in DSM-V in a new "overconsolidational disorders" category anchored around PTSD. The overconsolidational spectrum category may be conceptualized as straddling the fear circuitry spectrum disorders and the affective spectrum disorders categories, and may be a category for which Pitman's secondary prevention propranolol regimen may be specifically indicated as a "morning after pill" intervention. Predictions are presented regarding obsessive-compulsive disorder (OCD) (e.g., female-pattern hoarding vs. male-pattern hoarding) and "culture-bound" acute anxiety symptoms (taijin-kyofusho, koro, shuk yang, shook yong, suo yang, rok-joo, jinjinia-bemar, karoshi, gwarosa, Voodoo death). Also discussed are insights relevant to pseudoneurological symptoms and to the forthcoming Dissociative-Conversive disorders category in DSM-V, including what the author terms fright-triggered acute pseudo-localized symptoms (i.e., pseudoparalysis, pseudocerebellar imbalance, psychogenic blindness, pseudoseizures, and epidemic sociogenic illness). Speculations based on studies of the human abnormal-spindle-like, microcephaly-associated (ASPM) gene, the microcephaly primary autosomal recessive (MCPH) gene, and the forkhead box p2 (FOXP2) gene are made and incorporated into what is termed "The pre-FOXP2 Hypothesis of Blood-Injection-Injury Phobia." Finally, the author argues for a non-reductionistic fusion of "distal (evolutionary) neurobiology" with clinical "proximal neurobiology," utilizing neurological heuristics. It is noted that the value of re-clustering fear traits based on behavioral ethology, human-phylogenomics-derived endophenotypes and on ontogenomics (gene-environment interactions) can be confirmed or disconfirmed using epidemiological or twin studies and psychiatric genomics.

Somatoform disorders in neurological practice

PURPOSE OF REVIEW

Patients with medically unexplained symptoms continue to intrigue, fascinate and frustrate clinicians. They are common in general medicine and often present with apparent neurological disorder. This review aims to provide insight into the recent literature that has sought to clarify epidemiology, diagnostic issues, aetiologic understanding and treatment of patients with psychogenic disorders who usually first present to neurologists.

RECENT FINDINGS

Somatoform disorders are common in neurological practice. A number of papers have addressed issues of epidemiology and identified that medically unexplained symptoms in neurological populations are higher than originally thought. A number of recent review papers have served to summarize areas of considerable information (e.g. treatments) and areas of rapid growth in knowledge (e.g. neuroimaging). Studies investigating the role of psychological factors are well represented and clarify our psychopathological understanding of somatoform disorders in patients presenting to neurologists. Treatment studies are few and continue to be limited by population sizes and study designs.

SUMMARY

Somatoform disorders are common in neurological populations. Comorbidity related to somatoform disorders with known organic neurological conditions requires further study. On account of the limitations of treatment studies, evidence-based clinical management of these patients is awaited.