What is post-traumatic stress disorder?

Nancy C. Andreasen, MD, PhD

AbstractAlthough post-traumatic stress disorder (PTSD) andtraumatic brain injury (TBI) are categorized as sep-arate and discrete disorders, the boundary betweenthem is sometimes indistinct. Their separation isbased on the assumption that PTSD results primar-ily from psychological stress, while TBI is the conse-quence of an identifiable injury to the brain. This dis-tinction is based on an antiquated polarity betweenmind and brain, and the separation of the two disor-ders often becomes arbitrary in day-to-day psychi-atric practice and research.

This issue of Dialogues in Clinical Neuroscience istitled “Trauma, Brain Injury, and Post-traumaticStress Disorder.” The articles between its coversaddress both post-traumatic stress disorder (PTSD)and traumatic brain injury (TBI). As the combina-tion of these articles indicates, the various recentwars in the Middle East have awakened an old con-troversy about the relative impact of physical andpsychological stress in causing neuropsychiatric dis-orders. Although the term TBI suggests the occur-rence of some type of physical lesion, while PTSDsuggests a disorder occurring as a consequence ofpsychological stress, the boundary between the twois often unclear and sometimes permeable or over-lapping.The first systematic discussion of the relationshipbetween physical and psychological stress datesback to World War I. The history of that discussionprovides an informative context for current contro-versies concerning PTSD and TBI.1 Combat tech-niques in World War I introduced new types of com-bat stress that had not existed during previous wars.Soldiers engaged in trench warfare were relativelyimmobile and therefore more vulnerable. They were

also chronically exposed to new and perverselylethal threats, such as poison gas, machine gun fire,mortar attacks, land mines, and tanks. Casualtieswere devastating, and fatality rates were frighten-ing. Men watched their friends die beside them, andthey confronted the possibility of their own demiseon a daily basis. Alternatively they might be maimedand consigned to a life of chronic disability. As thewar progressed, the high casualty rate made it clearthat Britain and continental European countrieswere losing many of an entire generation of youngmen—a social loss from which they would be slowto recover. This sense of futility and despair was elo-quently expressed by British war poets such asWilfred Owen and Siegfried Sassoon:

Earth's wheels run oiled with blood. Forget we that.Let us lie down and dig ourselves in thought.Beauty is yours and you have mastery,Wisdom is mine, and I have mystery.We two will stay behind and keep our troth.Let us forego men's minds that are brute's natures,Let us not sup the blood which some say nurtures,Be we not swift with swiftness of the tigress.Let us break ranks from those who trek from progress.Miss we the march of this retreating worldInto old citadels that are not walled.Let us lie out and hold the open truth.Then when their blood hath clogged the chariot wheelsWe will go up and wash them from deep wells.What though we sink from men as pitchers fallingMany shall raise us up to be their fillingEven from wells we sunk too deep for warEven as one who bled where no wounds were.Wilfred OwenStrange MeetingProject Gutenberg Etext of Poems by Wilfred Owen

In this context of brutal bloodshed and omnipresentfear, a new and somewhat unfamiliar type of dis-ability emerged that had not been described in pre-vious wars: a syndrome characterized by confusion,memory impairment, headache, difficulty concen-

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trating, tremor, and sensitivity to loud noises. Thiswas initially assumed to be due to exposure to explo-sions, leading to concussions of the brain (“commo-tion cerebri”) in the absence of visible signs of exter-nal head trauma, and the disorder began to bereferred to as “shell shock.” Postmortem examina-tion of two cases revealed a variety of abnormalities,particularly vascular damage and congestion.2 As thewar progressed, the number of shell shock casualtiesgrew alarmingly. By mid-war, however, it was observed that some sol-diers presenting with the symptoms of shell shockdid not have any evidence of exposure to explo-sions. This puzzling paradox—a concussion-like syn-drome in the absence of documentable headtrauma—challenged the explanatory powers of con-temporary medicine, particularly in an era when notools were available to explore the living brain non-invasively. Ultimately this paradox led to the intro-duction of a distinction between a neuras-thenic/emotional/”nervous” condition and a morephysically based one caused by a specific explosionexposure. During subsequent years multiple schol-arly attempts were made to determine whetherthese two conditions represented discrete disordersor syndromes and whether clear boundaries couldbe set to distinguish between them.3-6

This debate was paralleled by the rise of two com-peting traditions within neuropsychiatry: biologicalvs psychodynamic explanations for the develop-ment of disorders. Within the biological traditionone important perspective (particularly relevant tothe etiological debate and remarkably prescient offuture developments) was presented by Selye, whocoined the term “stress” and hypothesized that itwas mediated by the hypothalamic-pituitary-adrenal (HPA) axis.7 He described the GeneralAdaptation Syndrome as a response to stress andconsidered the traumatic neuroses to be a conse-quence of chronic or severe stress. Walter Cannonalso proposed a related physiological basis for fearresponses in his description of the “fight or flight”syndrome.8 A second important perspective wasprovided by the psychodynamic tradition, which

developed an extensive explanatory system thatcould account for the role of psychological factorsin producing symptoms and in developing bothhealthy and unhealthy coping mechanisms.9

This debate, and the perspectives provided by thecompeting traditions, had a significant impact onpolicy decisions. This distinction was invoked inmaking decisions about the grounds for determin-ing disability both during and after combat, and itwas also significant for determining criteria forawarding pensions.6,10,11 Veterans from World War Iwere eligible for pensions as a consequence of suf-fering from shell shock, but concerns were raisedabout the large number of recipients and the possi-bility of malingering. As World War II loomed in thefuture and then occurred, British policy createdstrict criteria for recognizing and awarding disabil-ities secondary to shell shock/stress/neurasthenia—all in the direction of minimizing or eliminating anyrewards for disabilities considered to be psy-chogenic.10

After the end of World War II, American psychia-try decided to create a standard nomenclature thatwould be used by all psychiatrists; the impetus cameinitially from the Veterans’ Administration and wasinfluenced by the World War II experience, whichrequired that psychiatrists from across the UnitedStates and from diverse training backgroundsdevelop a common language for discussing psy-chopathology, making diagnoses, and determiningdisability. This led to the formulation of a diagnos-tic category called Gross Stress Reaction, whichappeared in the first Diagnostic and StatisticalManual (DSM-I), published in 1952. Its descriptionemphasized that the disorder was a reaction to agreat or unusual stressor that invoked overwhelm-ing fear in a normal personality. It emphasized thatthe disorder was transient and reversible; if thesymptoms persisted, another diagnosis was to begiven. Thus the definition was more influenced bythe psychodynamic traditions that prevailed at thetime than by biological models, and it did not lenditself to making frequent diagnoses of service-con-nected disabilities in the post-World War II era.

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G u e s t e d i t o r i a lThereafter the diagnosis went into oblivion. Since itwas closely linked to the history of warfare, it wascompletely omitted from DSM-II, published in1968—23 years after the last Great War and duringa period of relative peace.When the DSM-III Task Force was assembled in theearly 1970s, one of the tasks that it confronted wasto decide whether the diagnosis of Gross StressReaction should be reinstated in the DSM noso-logical system. The Vietnam War was winding downand had been very unpopular. Unfortunately, thegeneral public was not able to distinguish betweenthe war and the people that our country had draftedto fight in it, and so Vietnam veterans quite under-standably felt defensive, undervalued, and angry. Asmall but militant subgroup of Vietnam veteransclamored for the introduction of a diagnosis thatwould recognize the potential consequences ofexperiencing the stress of combat, and that mightperhaps provide disability and treatment benefitsfor the psychiatric disorder that combat stressinduced. Bob Spitzer, the Task Force chair, askedme to deal with the problem; he knew that I washard-working and intellectually agile; but he did notknow that I was actually already an expert on thetopic of stress-induced neuropsychiatric disorders. Ibegan my psychiatry career by studying the physi-cal and mental consequences of one of the mosthorrible stresses that human beings can experience:suffering severe burn injuries. Within this model ofstress, I had already examined brain abnormalitiesusing electroencephalography, the pattern of acuteand chronic symptoms, the long-term outcome andits predictors, and the role of coping mechanisms.12-16

I was also well aware of the extensive research thathad been done to identify symptom patterns thatarise as a consequence of exposure to a wide vari-ety of stressors, ranging from natural disasters todeath camps to military combat. The answer to the veterans’ request was obvious tome: there is a well-established syndrome, defined bya characteristic set of physiological (autonomic) andcognitive and emotional symptoms, that occurs afterexposure to severe physical and emotional stress. In

fact, its scientific basis was as strong as that availablefor disorders such as depression or even schizo-phrenia. To call it “post-Vietnam-syndrome” (thename chosen by the veteran advocacy groups)would demean its well-established validity and nar-row its range excessively. It would be best to call it“Post-traumatic stress disorder.” I wrote the defini-tion of PTSD for DSM-III based on my recognitionthat a variety of stressors can induce a final com-mon pathway that is expressed by a variety of auto-nomic/physiologic, cognitive, and emotional symp-toms that occur in response to a severe stressor.Because I knew from my research with burnpatients that individuals with prior disabilities (eg,epilepsy, abuse of alcohol or illegal drugs, depres-sion) were more vulnerable to developing PTSD, Ithrew out the requirement that the symptoms hadto arise in a previously normal individual. Thisopened the gate a bit, as compared with the defini-tion for Gross Stress Reaction. But I also narrowedthe gate by requiring that the stressor—the actualetiological factor—had to be “outside the range ofnormal human experience” in order to avoid therisk of overdiagnosis.Once the diagnosis of PTSD became available afterthe publication of DSM-III in 1980, it quicklyenjoyed widespread use, often in ways that were notanticipated. The genie was out of the bottle andbegan to actively intervene in psychiatric practiceand research. Although the precipitating stressor wassupposed to be “outside the range of normal humanexperience,” and was conceptualized with deathcamps and life-threatening combat experiences as amodel, this concept was steadily broadened. Therecognition that the response to the stressor mightbe delayed (largely because it is maladaptive withinthe context of combat) was also broadened in unan-ticipated ways: for example, the diagnosis becamewidely used for adults who described themselves asbeing abused by their parents when young children.Subsequent revisions of DSM adapted to theseapplications by steadily broadening the definition ofthe stressor and modifying its relationship to theonset of the disorder in a variety of ways.

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Since the introduction of the concept of PTSD intopsychiatric nomenclature in 1980, the controversybetween the role of biological and psychological fac-tors has re-emerged. The maturation of the disciplineof neuroscience, which is now widely perceived as the“basic science of psychiatry,” has had a significantinfluence. The development of the tools of neu-roimaging has provided an opportunity to conduct invivo exploration of the brain in individuals who arediagnosed as suffering from PTSD. And the neu-ropsychiatric casualties of the wars in Iraq andAfghanistan, who have been exposed to new combattechniques and new types of combat stress much asoccurred during World War I, have reawakened thecontroversy about the relationship between physicaland psychological injuries. Terrorism, guerilla warfare,and patrols confronting IEDs (improvised explosivedevices) and land mines have replaced the mortarsand trench warfare of World War I. TBI has beencalled the “signature injury” for these wars, much asshell shock was during World War I. And the samepolicy issues concerning provision of pensions andhealth care for veterans are the subject of concernand debate, and they are informed by the same con-

troversy about “physical” vs “emotional” injuries;these have been the subject of three Institute ofMedicine reports written to clarify diagnostic, treat-ment, and compensation issues.17-19

What is PTSD? And how is it related to TBI? Thereare still no easy answers to these questions. Thisissue of Dialogues in Clinical Neuroscience makes asignificant and useful contribution to addressingthem. It makes it clear that the disorders have manyoverlapping features, both symptomatically and bio-logically. It highlights the progress that has beenmade in understanding the underlying biology ofboth disorders by using the tools of neuroscienceand neuroimaging. And this progress makes it clearthat the old polarity between physical vs emotionalunderpinnings for PTSD is an antiquated way ofthinking that is no longer useful in the 21st century.Whatever PTSD is, it is a disorder that cannot bedismissed as purely psychological or a refuge formalingerers. As this issue illustrates, psychologicaltrauma has neurobiological effects, and these effectscan now be visualized and measured in the livingbrain. To some extent, the legacy of the World War Icontroversy has finally been resolved.

REFERENCES

1. Jones J, Fear NT, Wessely S. Shell shock and mild traumatic braininjury: a historical review. Am J Psychiatry. 2007;164:1641-1645.2. Mott FW. The microscopic examination of the brains of two mendead of commotion cerebri (shell shock) without visible external injury.BMJ. 1917;2:612–615.3. Schaller WF. After-effects of head injury, the post-traumatic concus-sion state, and the post-traumatic psychoneurotic state. JAMA.1939;113:1779–1785.4. Lishman WA. Brain damage in relation to psychiatric disability afterhead injury. Br J Psychiatry. 1968;114:373–410.5. Lishman WA. Physiogenesis and psychogenesis in the "post-concus-sional syndrome." Br J Psychiatry. 1988;153:460–469.6. Denny-Brown D. Post-concussion syndrome: a critique. Ann Intern Med.1943;19:427–432.7. Selye H. Stress and psychiatry. Am J Psychiatry. 1956;113:423-427.8. Cannon WB. New evidence for sympathetic control of some internalsecretions. Am J Psychiatry. 1922;79:15-30.9. Fenichel O. The Psychoanalytic Theory of Neurosis. 2nd ed Routledge;1996.

10. Shephard B. "Pitiless psychology": the role of prevention in British mil-itary psychiatry in the Second World War. Hist Psychiatry. 1999;10:491–542.11. Shephard B. A War of Nerves, Soldiers, and Psychiatrists,. 1914–1994.London, Jonathan Cape,. 2000.12. Andreasen NC. Posttraumatic stress disorder: a history and a critique.Ann NY Acad Sci. 2010; 1208:67-71.13. Andreasen NJC, Hartford CE, Knott JR, Canter A. Cerebral deficitsafter burn encephalopathy. N Engl J Med. 1974;29:1487-1488.14. Andreasen NJC, Noyes R, Hartford CE. Management of emotionalreactions in severely burned adults. N Engl J Med. 1972; 28:65-69.15. Andreasen NJC, Norris AS, Hartford CE. Incidence of long-term psy-chiatric complications in severely burned adults. Ann Surg. 1971; 174:785-793.16. Andreasen NJC, Norris AS. Long-term adjustment and adaptationmechanisms in severely burned adults. J Nerv Ment Dis. 1972; 154:352-362.17. Institute of Medicine. Posttraumatic Stress Disorder: Diagnosis andAssessment. Washington DC; 2006.18. Institute of Medicine. Treatment of PTSD: An Assessment of the Evidence.Washington DC; 2007.19. Institute of Medicine. PTSD Compensation and Military Service.Washington DC; 2007.

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