Brain Basis of Demonic Possession (Patrick McNamara, 2011)

NOTE: The following article is taken from Spirit Possession and Exorcism, History Psychology and Neurobiology, Volume 2, pp. 15-32.


To develop a naturalistic theory of the nature and functions of demonic possession it would help to understand its neuropsychologic correlates. Understanding the brain basis of possession might also lead to new somatic treatments for people who become possessed. The best way to study brain correlates of a demonic possession experience is to find someone who is currently possessed and then put that person through a neuroimaging protocol. To my knowledge this sort of study has not yet been done. There are no publications that I know of that describe functional magnetic resonance imaging scans or PET scans or computerized tomographic scans of brains of people who are demonically possessed. One can imagine how difficult it would be to do such a study. In lieu of direct brain scans of demonically possessed people we can begin to get a picture of the brain activity in a possessed person via systematic neuropsychologic investigation of the possessed and of people with disorders that are similar to possession states such as dissociative identity disorder and epilepsy. In addition, we can garner clues as to brain regions and functions implicated in possession by using the information we have addressed in other chapters on issues such as who gets possessed? What kind of behavioral and cognitive changes do the possessed undergo? And so on.

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Who gets possessed? As we have seen, most scholars who have studied possession phenomena seem to believe that young women are more likely to undergo negative, demonic forms of possession than men or older women. I could, however, find no hard epidemiologic data on this issue.

I therefore conducted an informal analysis of all of the “complete” case studies available to me when writing this book. 1 Complete studies were defined as published cases that contained basic information on the possessed, the demon, behavioral changes in the possessed, and subsequent outcomes of the possession. There were 51 studies where enough information was presented on the case that that information could be scored unambiguously. We scored the sex and age of the possessed, the behaviors of the possessed, and the characteristics of the demon or demons who did the possessing. Here is what we found: females were far more likely to present with demonic possession than men (73% vs. 27% respectively). A little over half (55%) of the cases involved adults; 20% involved young adults or teenagers. We were surprised to find that 12% of cases involved children. About half of the cases involved Christians. In the other half of the cases religion was unspecified. Virtually all of the cases (94%) contained descriptions of behavioral changes with 71% describing mental changes of one kind or another and a surprising 65% describing physical changes in the possessed. Here are some of the mental changes that were noted with demonic possession:

  1. Personality/demeanor changed (e.g., affable person becomes quiet and isolative, a person begins to engage in hostile and/or paranoid thoughts);
  2. Experienced apparent “onset” of multiple personalities and/or severe and abrupt mood changes;
  3. Engaged in violent and/or abusive behavior (sometimes toward other humans/animals);
  4. Appeared catatonic;
  5. Insulted, cursed, and/or swore excessively (when that was uncharacteristic of that person’s usual behavior);
  6. Acted out sexually preoccupied thoughts (e.g., crudely sexual conversation, masturbating in front of others, etc.);
  7. Participated in acts of humiliation (e.g., urinating on oneself);
  8. Practiced self-mutilation;
  9. Averse to religious objects (i.e., a person who normally went to church suddenly despised the thought, destroyed religious materials);
  10. Experienced severe nightmares or night terrors;
  11. Showed evidence of blackouts in memories;
  12. Exhibited obvious changes in sleep patterns;
  13. Lost or gain weight suddenly;
  14. Changed dress;
  15. Changed the way the person took care of himself (e.g., changes in personal hygiene);
  16. Changed diet (foods that were once favorites were now repulsive and/or foods that were once detested were now favorites);
  17. Exhibited “precognition” or the ability to predict the future;
  18. Displayed “retro cognition” or the ability to know about past events that person should not know about;
  19. Exhibited telepathic powers (knowing what someone else was thinking) or knew something about someone that person had not met; and
  20. Exhibited clairvoyance or the ability to gain information about a person, location, or object through means other than the known human senses (e.g., feel what another person is feeling).

Often the physical changes involved changes in posture or strength or changes in the voice of the possessed—female voices became male voices, and so on. Here are some of the physical changes that could occur:

  1. Spoke in tongues or a language they could not possibly know (or spoke with unusual accent);
  2. Changed voice (e.g., high to low to guttural);
  3. Became completely rigid so that he or she could be moved only with difficulty, even by multiple people;
  4. Seemed to speak in multiple voices at the same time;
  5. Did not blink eyes;
  6. Changed eye or eye color (e.g., eyes turn black, almost like shark eyes);
  7. Changed or distorted features in some way;
  8. Possessed inhuman strength (e.g., multiple people had a difficult time restraining the possessed);
  9. Moved in a way that seemed unusual and nonhuman-like (e.g., a person who seemed to glide instead of walk);
  10. May have had writing or symbols on the body in the form of welts and scratches (especially in areas that the person could not physically reach);
  11. May have had a decrease in body temperature although the surrounding room temperature stayed constant; and
  12. Energy was drained; person had seemingly unexplainable fatigue.

Unusual occurrences were also very often noted—things like poundings on the floor or flying objects and the like. Here are some of these unusual occurrences:

  1. Objects moved around seemingly by themselves (or objects flew around as if they were thrown from unseen hands);
  2. Objects disappeared and could not be found again;
  3. Objects disappeared (sometimes to be found in another location or later in same location, known as teleporting);
  4. Knocking, banging or pounding could be heard in the surrounding environment (often heard in threes, as if mocking the Holy Trinity);
  5. Religious articles disappeared or were destroyed;
  6. Sounds (e.g., growling, howling, scratching, voices) could be heard and foul smells experienced, but the source could not be located;
  7. Odd lights were seen or shot around a room;
  8. People or dark shadows were seen that might or might not have form;
  9. Sudden temperature fluctuations occurred (or temperature decreased);
  10. There was a sensation of wind blowing even with the windows closed;
  11. Doors and drawers opened and closed on their own;
  12. Electrical appliances turned on or off seemingly by themselves;
  13. Spontaneous fires started up;
  14. Glass broke for no reason (or sounds of glass breaking were heard but there was no evidence of it happening);
  15. Animals seemed to be frightened or bothered by something beyond human detection;
  16. People had a feeling of being watched or that they were not alone;
  17. Any talk of God or religion (or the recitation of prayers) caused an outbreak of activity;
  18. Apparent retaliation took place after some attempt to stop the activity (i.e., consulting a clergyman, exorcism);
  19. The possessed or others were attacked by a seemingly outside force (e.g., punching, scratching, biting, hair pulling, shoving to the ground);
  20. The possessed was sexually assaulted by a seemingly outside force (e.g., fondling, penetration, rape);
  21. Objects or people were levitated;
  22. Involuntary babbling/cries/roars were heard that were obviously caused by an outside force; and
  23. The possessed has involuntary movements/gestures that suggest possession by a spirit/demon; inhibition of normal functioning (e.g., seemingly unable to speak).

The Healing of the Demon-Possessed Gadarene Man

Demonic possession was far more common (73%) in this nonrepresentative sample of well-described cases than mere spirit possession (27%). Three-quarters of the cases (75%) involved possession by a single entity, but 24% involved possession by more than one entity. Most often the sex of the possessing spirit was unspecified but seemed to be male. In 39% of cases the possessing spirit was clearly male. In only 4% of cases was the possessing spirit clearly female. When cases were scored for the amount of aggression exhibited by the possessed the mean score was 5 out of a possible 8. Behavioral indices of “primitivity” included display of disinhibited or unsocialized impulses such as aggression and sexual impulses. Cases were scored a 3 out of a possible 5, indicating that many cases displayed extremely primitive impulsive behaviors. Two-thirds of our sample of possessed “patients” sought help, with one-half undergoing formal exorcism rituals; 82% of these exorcisms were successful but in one-third of the cases possession re-occurred after some interval of time.

What does this cursory analysis of 51 well-described cases tell us about demonic possession? Results of the analysis are consistent with our discussion of case studies and with the views of authorities who have written on the topic. If we perhaps unwisely treat this small set of cases as representative of the general population of people who become possessed, then we would have to conclude that females are more likely to become demonically possessed than males, and that the possessing demonic agent is almost always male or unspecified but very rarely female, and that behavior of the possessed is very disinhibited, involving display of unsocialized sexual and aggressive impulses. Exorcism rituals furthermore are extremely effective in curing patients of this affliction. One-third of patients, however, experience a relapse or recurrence of the “illness.” In most cases there are also all kinds of “paranormal” manifestations as well—at least this is what observers report. These paranormal phenomena are fascinating as many involve unusual feats or capacities of mental life or cognitive processing. Of course, extreme caution is in order when interpreting this set of data. These 51 cases are not a random sampling of all of the cases of demonic possession that have ever occurred. Generalizations based on this sample therefore must be cautious. It would be more accurate to characterize this sample along the following lines:

These are a small sampling of cases that made it into the published record and that McNamara was able to find and deem “well-described” after relatively intensive searches in books and journals available to a large urban university in 2008–2009.


On the other hand this sample’s characteristics are congruent with estimations and statements of most other scholars who have studied possession phenomena over the last couple of centuries. Negative forms of possession tend to involve women being possessed by male demons and engaging in profoundly disinhibited aggressive and sexual displays. It is these kinds of facts that have led many scholars to claim that negative possessions, and “ecstatic states” more generally, are used by women the world over as a political tool to turn the tables on oppressive patriarchal groups and institutional structures. Whatever the functional uses of negative possession for women, it seems to me that we must conclude that these facts are relatively accurate . . . demonic forms of possession occur mostly in women and involve possession by a male demon that displays antisocial and antireligious behaviors. Even if this later turns out to be false as a characterization of the entire population of cases involving demonic possession, it must be the case that a significant portion of cases of demonic possession involves females and male demons. So even if we cannot claim that we are piecing together the phenomenology of all cases of demonic possession, we can safely claim that we are building on a significant portion of the possession dataset, namely that portion of the dataset involving females who become possessed. So what might be the brain correlates of demonic possession involving females who are possessed by male demonic agents?



Not surprisingly, the brains of females differ in significant ways from the brains of males. Sex differences in the brain are largely determined by steroid hormone exposure during a perinatal sensitive period that alters subsequent behaviors throughout the lifespan. There have now been hundreds of studies on sex differences in the human brain but there is as of yet no strong consensus on what those studies demonstrate. I think it is fair to say that when one controls for overall brain volume, women have a higher percentage of gray matter and men a higher percentage of white matter with structures in the left hemisphere being slightly larger in woman than in men (Cosgrove, Mazure, and Staley 2007). Women may also represent language functions in both hemispheres while men’s representation of language functions is primarily left-sided. Women are more vulnerable to aphasic and other language disorders no matter what hemisphere sustains a stroke while men tend to get aphasia with left hemisphere strokes only.

Brun et al. (2009) applied a new method to compare the three-dimensional profile of sex differences in brain structure based on MRI scans of 50 men with 50 women, matched for age and other relevant demographics. They found that left-hemisphere auditory and language-related regions were proportionally larger in women versus men. In men, primary visual and visuospatial association areas of the parietal lobes were proportionally expanded. These results are consistent with the better performance by women versus men on verbal tasks and the better performance of men versus women on spatial tasks.

All of these aforementioned findings suggests that functional cognitive differences in men and women become manifest primarily at the hemispheric level. Interestingly, functional cerebral asymmetries are, in fact, sex specific: While they are relatively stable in men, they are reduced during the menstrual cycle in women, indicating that sex hormones might play an important role in modulating interhemispheric communication and functioning brain (Weis and Hausmann 2010).

In an important respect, then, women appear to be less functionally lateralized than men. Women’s bilateral representation of language-related functions and more fluid interhemispheric communication gives them an advantage over men in language-dependent forms of information processing. On the other hand, women pay a price for this reduced (relative to men) asymmetry in that they are deficient relevant to men in spatially based forms of information processing. This latter functional difference is seen clearly in the case of Turner’s syndrome.

Turner’s syndrome (TS) individuals lack the male Y chromosome and are phenotypically female. TS behavioral features can be associated not only with complete monosomy X but also with partial deletions of either the short (Xp) or long (Xq) arm of the X chromosome (partial monosomy X). TS individuals are typically impaired on visual-spatial/perceptual tasks but are intact on language-processing tasks. The lack of the male chromosome leads to androgen deficiency during development of the neuraxis and thus the brain does not masculinize during development (Ross, Roeltgen, and Zinn 2006).

Thus, both XX females and TS individuals outperform males on verbal tasks, and both demonstrate behavioral signs of reduced asymmetry in terms of brain organization. Interestingly, homosexual men also tend to outperform heterosexual men on verbal tasks. Indeed their performance profiles on cognitive tasks tend to be more like females than males (see Collaer, Reimers, and Manning 2007). Homosexuals are known to have a higher frequency of atypical lateralization for some functional traits, such as handedness (Lalumière, Blanchard, and Zucker 2000).

St. Marina

Taken together these data from adult females, TS females, and male homosexuals suggests that the feminized brain is characterized by a reduction in the asymmetrical organization that characterizes the brain of heterosexual adult males. What is the relevance of all this to demonic possession phenomena? As we have seen above females are more likely to become possessed than males. I now want to suggest that those males that are more vulnerable to possession are males with reductions in cerebral asymmetry that are like the reductions seen in the female and homosexual brains. In short, a reduction in asymmetry may be a risk factor for demonic possession.

A reduction in asymmetry, however, is not all that is required for possession. Older people evidence reductions in cerebral asymmetry and they are not as likely to become demonically possessed as younger females. On the other hand, older people in traditional societies are much more likely to become spirit possessed (positive spirit possession) and experience religious visions (see the narratives in Walker 1991). Perhaps it is a matter of degree. The young female brain may be more “symmetric” or less lateralized than the older individual’s brain, which is more symmetric relative to the young adult heterosexual male. At present we cannot decide this issue. It may be as well that a particular form of reduction in asymmetry is necessary to enhance the odds of possession. After all, many brain disorders involve reductions in the typical asymmetric organization of brain functions among other brain changes. While most of these disorders do involve changes in religiosity, they do not always or even frequently lead to possession. Nevertheless they can be associated with possession. Consider the case of epilepsy. Epilepsy involves brain tissue, usually deep in the temporal lobes, that is somehow damaged and around which develop groups of neurons that discharge in synchronous fashion. The synchronous fi ring of groups of neurons is associated with seizures. It has long been noted that one form of epilepsy, temporal-lobe epilepsy (TLE), can occasionally be associated with heightened religiosity. Patients describe intense religious experiences or undergo repeated conversions to different religious sects or ideologies and so on. Trimble and Freeman (2006) looked at the clinical correlates of TLE patients with and without self-reported high interest in religion and compared these two groups of patients to a healthy control group of regular churchgoers. They found that the hyperreligious TLE patients more frequently had bilateral seizure foci than unilateral (right or left) foci and more frequently reported episodes of post-ictal psychoses. Compared to the healthy churchgoer group, hyperreligious TLE patients more often reported actual experiences of some great spiritual figure or supernatural being—either an evil presence or a benign spiritual presence.

If we can associate bilateral seizure foci with reduced asymmetry, then the epilepsy data can be read as partially consistent with the idea that reduced asymmetry increases risk for spirit-possession phenomena. Just how does reduced asymmetry, especially in the case of epilepsy, give rise to heightened religiosity and possession phenomena? With respect to the issue of heightened religiosity, Geschwind (1979) argued that that symptom was often associated with hypergraphia (a tendency to highly detailed writing often of a religious or philosophical nature), hyposexuality (diminished sex drive), and irritability of varying degree. In TLE overexcitation or hyperconnectivity between limbic and temporal sites leads to the TLE behaviors where everything but sex is significant and requires attention. That sense of heightened significance gives rise to religiosity. What causes the hyperconnectivity? If interhemispheric callosal fibers can no longer inhibit their targets in the opposite hemisphere, then the reduction in transcallosal inhibition will lead to enhanced bilateral subcortical to cortical functional connectivity.

Bear and Fedio (1977), in fact, argued that heightened religiosity was due to a greater number or density of connections between cortical sites handling the senses and the limbic system, including the amygdala, so that patients with TLE experienced a greater number of sensory events as “significant” relative to a healthy person with fewer such connections. In their recent review of religious and spiritual experiences in epilepsy Devinsky and Lai (2008) largely endorse the hyperconnection model for interictal hyper-religiosity and they agree with Trimble and Freeman that interictal religiosity may be linked with bilateral temporal-lobe seizure foci. But can possession phenomena emerge from the reduction in asymmetry associated with epilepsy?

Now consider the following cases reported by Carrazana et al. (1999).


Case 1 This 24-year-old Haitian man had his first generalized tonic-clonic seizure at the age of 17 years during the wake of an uncle. The patient had been sleep deprived during the vigil of the corpse. The seizure was attributed to possession by Ogu (the warrior god), the dead uncle’s protecting loa. Subsequent seizures and morning myoclonus were explained as harassment by the wandering soul of the uncle. The possession was interpreted as a punishment, for the patient had been disrespectful toward the deceased in the past. He was treated by the local mambo (priest) for 6 years and did not see a physician until coming to the United States. His EEG showed 3- to 4-Hz bursts of generalized spike-wave complex discharges occurring spontaneously and during photic stimulation. In retrospect, the patient had a history of waking myoclonus, which had been ignored. He remained seizure free after treatment with valproic acid (VPA). The likely diagnosis is juvenile myoclonic epilepsy. (Carrazana et al. 1999,239)

Comment: This case does not tell us anything specific about reduced asymmetry as a contributing cause to the possession. But the sleep disorder is interesting as it may have involved a form of reduced asymmetry manifesting as a parasomnia. Both seizure and sleep disorders promote parasomnias or difficulty transitioning from one sleep state into another or from sleep to waking. Dissociative identity disorder (DID) can also be understood as involving difficulty in keeping brain states appropriately separated from one another and DID can involve possession phenomena. But let us continue with the issue of epilepsy and possession.


Case 2 This 27-year-old Haitian woman, with a history of complex partial and secondarily generalized seizures since adolescence, was the product of a long and difficult delivery, which was attributed to a “grip” in the mother’s belly by a loa. At the age of 14 years, she fell in an open fire during a seizure and suffered extensive burns to her arm, leg, and parts of the face and trunk. Burns were treated at a local hospital, but the family brought the patient back to the mambo to treat the “possession.” This incident was interpreted by the mambo as possession by “Marinnette.” Marinnette-bwa-chech is one of the most dreaded loas, an agent for underhand dealings and an expert sorceress. Those possessed by this loa are said to throw themselves in the fi re and stamp about until they put the flames out. The patient had bitemporal independent spikes on EEG. Treatment with antiepileptic drugs (AEDs) has decreased the frequency of seizures. (Carrazana et al. 1999,239–240)

Comment: The possession experience in this case was associated with bitemporal spikes, thus implying reduced asymmetry.


Case 3 This 36-year-old woman had several years of recurrent complex partial seizures that manifested as a strong sense of fear and epigastric coldness, followed by loss of awareness, utterances of nonsensical phrases, and complex motor automatisms. The local mambo attributed the events to her being taken by “Melle Charlotte,” a french loa, with the nonsensical speech being interpreted as a foreign language. It is said that during the possession by this spirit, a person will speak perfect French or other languages, even though in life, the person has no knowledge of that language. She continued to have seizures despite the Mambo’s attempts to conjure the spirit. He explained his failure to the fact that Melle Charlotte is a very particular loa who makes only sporadic appearances. She was not treated with AEDs until she left Haiti at the age of 34. An EEG revealed a right anterior temporal focus, and magnetic resonance imaging (MRI) showed right hippocampal atrophy. Seizures improved with carbamazepine (CBZ), although compliance with medication was a problem, largely because of family interference. (Carrazana et al. 1999,240)

Comment: This case is particularly interesting as glossolalia was part of the clinical picture. Also we have localizing information: the EEG revealed a right anterior temporal focus. This is a site implicated in hyperreligosity (see McNamara 2009).


Case 4 This 44-year-old Dominican woman (of Haitian parents) for years has been experiencing partial seizures which she refers to as “la cosa” (the thing). Her seizures, with a sudden overwhelming sensation of emptiness, were attributed to her “good angel” leaving her as the spirit of the dead tried to take hold of her (“me mandaron un muerto”). The sending of the dead, l’envs morts, is a feared Voodoo curse, which is said to affect health and prosperity. The mambo explained the failure of the attacks to respond to his exorcisms to the strong hold of the spirit. EEG showed a right temporal focus, and the MRI was normal. Seizures were controlled with phenytoin (PHT) monotherapy. (Carrazana et al. 1999, 240)

Comment: Once again we have localizing information that refers to right temporal lobes as the site of the focus. In addition, in this case the patient was able to report an experience associated with the switch in identities. She felt an emptying out before the onset of the negative possession experience.


Case 5 This 47-year-old Jamaican woman of Haitian descent, with a history of Chiari I malformation, syringomyelia, and arrested hydrocephalus, has a long-standing history of complex partial seizures with and without secondary generalization. The patient and her family attributed the seizures to Voodoo spirit possessions, being influenced by the olfactory hallucination of a burning smell, and a rising epigastric aura “taking over the body.” A prolonged postictal psychosis would follow, in which the patient would alternate chanting and wooing with periods of total unresponsiveness. EEG demonstrated independent bitemporal interictal epileptiform discharges. She denied her diagnosis of epilepsy, resisted diagnostic and therapeutic interventions, and insisted that she was possessed by spirits of the dead. On immigrating to the United States, she ultimately became seizure free with PHT monotherapy. (Carrazana et al. 1999, 240)

Comment: Bitemporal foci and reduced asymmetry appear to be associated with more severe phenomenology than cases with right-sided foci. It is striking how convinced the patient apparently was that she was possessed by spirits of the dead. We are not told by Carrazana et al. if treatment with antiseizure medicine also treated the delusional beliefs (assuming that the beliefs were delusional).

These cases of negative possession states from Carrazana et al. (1999) are interesting for development of a neurology of possession because where localizing information was available it implicated either reduced asymmetry in the form of bitemporal foci or the anterior temporal lobe on the right side.



Dissociative identity disorder (DID; previously known as multiple personality disorder) is the most severe and chronic manifestation of the more fundamental cognitive capacity to dissociate one’s identity from trauma or memory of trauma. There is a continuum of capacity to enter into and “use” dissociative states for various culturally sanctioned uses (Seligman and Kirmayer 2008). I will review the ability to enter dissociative states for positive cultural functions below. Although everyone appears to have the capacity to enter dissociative mind states, occasionally the process goes awry, resulting in mental disorder.

Dysfunctional dissociation can manifest as the presence of two or more distinct identities or personality states that recurrently take control of the individual’s behavior. There may be transient amnesia or fugue states and in extreme cases changes in neuropsychologic performance that, in turn, point to dynamic changes in brain organization associated with the dissociative process. Is there evidence for reduced asymmetry in DID? Most authorities suggest that while dissociation is common in both men and women, DID is more common among women. In addition, non-righthandedness appears to be more common in DID than in the general population. Indeed there are cases where handedness switched with a switch in identities states (Savitz et al. 2004). As we have seen above, reduced asymmetry is associated with non-right-handedness. Non-right-handedness, in turn, can be associated with unusual cognitive and behavioral phenomena such as mirror writing in which the individual writes in a script that is a mirror reflection of typical right-handed scripts. Mirror writing must require bilateral communication between the motor engrams for script in each hemisphere (i.e., a reduction in asymmetry). Thus, if DID is associated with reduced asymmetry we should see cases of mirror writing in DID patients. Le, Smith, and Cohen (2009) in fact report just such a case.

There are very few studies of neuroimaging of patients with DID. One such study reported significantly smaller volumes of the hippocampus and amygdala among those with DID as compared to healthy controls (Vermetten et al. 2006; though see Smeets, Jelicic, and Merckelbach, 2006). An fMRI study of a woman diagnosed with co-morbid DID and PTSD (Tsai et al. 1999) reported that the switch from native to alter personality involved bilateral hippocampal inhibition, thus indicating reduced asymmetry. The right parahippocampal and medial temporal regions were also inhibited. Finally there was inhibition of small regions of the globus pallidus and substantia nigra. Interestingly, switching back to the native personality was associated with activation of the right-sided hippocampus . This latter result implies that re-establishment of normal asymmetric brain organization is associated with normalization of ego-identity states.

In summary, DID patients fit the profile of reduced asymmetry—they tend to be female and non-right-handed. In behavioral experiments using dichotic listening paradigms individuals high on dissociative experiences scales, evidence reduced asymmetry (Marinos 1997). With respect to the mechanics of the switch to an alter personality, there is a reduction in asymmetry via inhibition of structures in both hemispheres. For DID that inhibition involves hippocampal functions. Given that the hippocampus is involved in memory consolidation it seems reasonable to suppose that hippocampal inhibition in DID mediates DID associated amnesia.

Taken together with the evidence from TLE and the DID, data suggest that possession may involve an inability to activate right-sided hippocampal and amygdalar structures in order to support ongoing ego-identity functions. Instead, asymmetry of organization and function is blocked and the individual operates out of an altered identity.



Dissociative ability has been proposed as a universal trait or capacity that lies along a continuum that measures the ability to enter altered states of consciousness. All people possess the trait to some degree and people with DID lie at one extreme of the continuum. As we have seen dissociative ability may act as a diathesis that when trauma is present may push the individual toward full-blown DID. DID patients are thought to be highly hypnotizable and to exhibit other phenomena such as absorption, high imagery or fantasy preference, frequent mystical or spiritual experiences, time distortions, and so on, collectively called “altered states of consciousness” or ASC. Given the wide diversity and phenomenology of ASC it seems unlikely that there will be any single neurologic account of the experiences. Yet I would like to suggest that reduced asymmetry plays a critical role in all ASC. Reduced asymmetry cannot account for all manifestations or symptoms of ASC but I suggest that reduced asymmetry is one crucial anatomical common denominator for increasing the frequency and intensity of ASC.

Smith (2008) showed that absorption, as measured by the Tellegen Absorption Scale (TAS) was a significant predictor of intensity and frequency of mystical experiences. Laidlaw et al. (2005) showed that individuals with low “self-directedness” (SD) scores on the temperament and character inventory (perhaps indicating relatively weak central ego-identity functions) proved to have significantly raised scores on hypnotizability, absorption, self-transcendence, and significantly lower scores on co-operativeness. Prohaska (2002) compared the trait absorption scores as measured by the Tellegen Absorption Scale (TAS), and religious orientation as measured by the Religious Orientation Scale (ROS) among 261 adults between ages 25 and 78 (M = 46.7) who verbally reported no serious mental disorder or physical disease. She found elevated absorption capacities among the intrinsically oriented versus the extrinsically oriented religious responders. The intrinsically religious participants had 21% higher absorption scores than the extrinsically religious participants or nonreligious participants. Interestingly Spanos et al. (1980) found that absorption predicted dream recall rates in females but not males. Finkel and McGue (1997) applied a behavior genetic model including sex limitation of heritability to personality data from 1,257 twin families. Data indicated lower female heritability for alienation and control and higher female heritability for absorption. The gene that codes for the enzyme catechol-O-methyltransferase (COMT, which is involved in cortical dopamine catabolism), and a serotoninergic receptor gene have been linked to trait absorption. Ott et al. (2005) reported a significant interaction effect between the 5-HT2a and the COMT genes such that hypnotic absorption scores were highest in subjects homozygous for the TT-genotype of 5-HT2a as well as for the VAL/VAL genotype of COMT. Given that the trait absorption/ hypnotic susceptibility is correlated with measures of religiousness (Batson, Shoenrade, and Ventis 1993, 112–113) and dissociative abilities, it seems likely that these genes have infl uenced variation in levels of dissociative abilities and religiosity across individuals.

Vaitl et al. (2005) conducted an exhaustive review of the literature on the psychobiology of ASC and reported that ASC can be characterized in terms of alteration in each of four psychobiologic dimensions: activation, awareness span, self-awareness, and sensory dynamics. Crossing these four dimensions with the source of induction into the ASC, results in a relatively complete phenomenology of existing ASC. Contrary, however, to Vaitl et al.’s classification of hypnotic phenomena, I would classify hypnosis (the ASC closest to the trait dissociation and absorption that we have been considering here) as high on activation and arousal, but low on self-awareness and a constricted awareness span, depending partially on induction method (self versus environmentally induced by a hypnotist). Absorption clearly involves a restriction of awareness span to one or a small set of objects or events along with a transient reduction in sense of self. All of these cognitive alterations allow for extraordinary forms of information processing and unusual experiential phenomena, including the capacity to experience possession.

How, then, might absorption work physiologically? Consistent with the flow of the argument in this chapter I suggest that reduced asymmetry is the key to absorption and related phenomena. Many investigators (see Dietrich 2004 for a recent review) have suggested that prefrontal inhibition and limbic disinhibition are the key neurodynamic correlates of “flow” or of absorption and related states. Nakamura and Csikszentmihalyi (2005) suggest that flow is a state of complete absorption attained during activities whose perceived challenges precisely match the subject ’ s skill level so that attention is effortlessly engaged, directed, and maintained. The experience is usually quite enjoyable. Flow likely involves a transient inhibition of midline callosal structures supporting self/agency and then a heightened integration across hemispheres of subcortical basal ganglia and limbic systems with prefrontal attentional and self-regulatory systems. In short, flow and absorption likely involve a transient reduction in asymmetrical brain organization in order to facilitate integrative capacities of both hemispheres. This is the crux of the matter with respect to possession states. Both negative and positive possession states can involve enhanced cognitive capacities. These are transient in the case of negative possession and enduring in the case of positive possession. Reduced asymmetry likely always involves both costs and benefits when it comes to information processing. Everything depends on whether the initial reduction in transcallosal inhibition is followed by a process or phase of limbic-cortical integration. In positive possession this is the case, but in negative possession the integrative process occurs for some while but eventually breaks down entirely and then the negative possession is merely destructive. During that transient period when some integrative processing is still occurring we see those striking manifestations of demonic possession when the “devil” demonstrates paranormal knowledge of foreign or ancient languages or precognitive or clairvoyant sight and so on.

Only future research will clarify the issues of brain correlates of demonic possession experiences. But if we keep in mind the available neuropsychologic data and how it points to a consistent reduction in asymmetry as a predictor for dissociative states and possession, then it becomes less surprising that pharmacologic agents have long been used to induce possession. Virtually all known hallucinogenic agents alter the interhemispheric interaction patterns. For example, Serafetinides (1965) in the 1960s showed that LSD had no effects in patients whose right temporal lobes had been removed. All hallucinogenic agents appear to induce their effects by altering serotoninergic and dopaminergic activity levels in right-sided temporal and prefrontal sites. By doing so these pharmacologic agents reduce the normal asymmetry that these neurotransmitter systems normally support. Since the era of the Upper Paleolithic some 50,000 years ago and very likely even before that, human beings have been taking psychoactive substances to induce altered states of consciousness and more specifically spirit-possession experiences. People did not ingest these substances merely to become deranged. They took these “entheogens” to experience the supernatural. The drugs had specific effects on the brain, not global effects. Those specific effects must have involved some reduction in the normal pattern of asymmetry by heightening the activity of one hemisphere over the other.



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