Monday, November 26, 2012

Eating Disorders and the Not So Female Brain

Attempts to link eating disorders to a hypothetical "extreme female brain" involve some convoluted logic 
A well-known theory of psychological sex differences proposed that autism represents a manifestation of an ‘extreme male brain’ type. A recent paper has claimed that the opposite type, or ‘extreme female brain’ is manifested in eating disorder symptoms, such as anorexia and bulimia. The evidence provided in the paper for this notion seems rather mixed, especially considering that some of the results applied more clearly to males than females. Additionally, there is evidence that eating disorders and autism have certain features in common even though they are supposed to represent opposite brain types. Characterising certain conditions as extremely ‘male’ or ‘female’ based on gender stereotypes may actually create more confusion than real understanding.
Is there a distinct "female brain" type? (Image courtesy of Victor Habbick at

Autism and the ‘extreme male brain’
Simon Baron-Cohen[1] proposed that men and women have evolved different brain-types[2] specialising in either of two distinct information processing modes. The two modes are empathizing, considered to be the drive to understand other people’s thoughts and feelings in order to predict how they will behave, and systematizing, considered as the drive to understand the rules that govern a system in order to predict how the system works. Individuals have their own balance of how much they have developed either of these capacities and most people have reasonable ability in both. According to Baron-Cohen’s research, men tend to be more specialised in systematizing, whereas women tend to be more specialised in empathizing. Baron-Cohen applied this theory to understanding the nature of autism spectrum conditions including Asperger’s syndrome. People with autism tend to have social and communication difficulties due to impairments in their ability put themselves ‘in another person’s shoes’, that is, to imagine another person’s thoughts and feelings. On the other hand, autistic people often have particular strengths in understanding physical systems. For example, studies on autistic children have found that they tend to have an unusually good grasp of intuitive physics. Baron-Cohen therefore argued that autistic people have a profile of well develop systematizing and poorly developed empathizing. He referred to this profile as representing the ‘extreme male brain’ on the grounds that autism occurs many times more frequently in males than females.

Mr Spock: someone with an extreme male brain?
Baron-Cohen proposed that therefore an ‘extreme female brain’ type might exist. This profile would be associated with particular strength in the area of empathizing and difficulty in the area of systematizing. He argued that this profile should be more common in women than men but did not attempt to describe what such a condition might be like, although he suggested that people like this might get along well in modern society due to their well-developed people skills, as long as they could avoid dealing with modern technology. 
Evidence for an ‘extreme female brain’?
Bremser and Gallup (2012) proposed that eating disorders are a manifestation of an ‘extreme female brain’ (EFB) that is a ‘mirror image of autism’. They justify this on the grounds that eating disorders are much more prevalent in females than males and cite evidence linking eating disorders to sex hormones. Additionally, they claim that fear of negative evaluation and social anxiety play an important role in the development of eating disorders. They argue that fear of negative evaluation and social anxiety can be linked to high levels of empathizing. Therefore, high empathizing (a feature of the proposed EFB) could predispose a person to eating disorders by making them vulnerable to fear of negative evaluation and social anxiety.
Their argument for the connection between empathizing and social anxiety is that sociability can be represented on a continuum with social apathy (characteristic of autism) at one end and social anxiety at the high end. However, anxiety about social interaction indicates that one is lacking confidence in one’s social skills. According to Baron-Cohen though empathizing is supposed to be a particular strength of the EFB. I therefore find it puzzling that high levels of empathizing would be assumed to go hand in hand with inadequate social skills. Current theories suggest that social anxiety is associated with self-focused rumination (thinking about oneself too much during social interactions) which does not sound much like empathic concern for other people. Furthermore, their own results contradict their argument. They did find that fear of negative evaluation and social anxiety were positively related to disordered eating. However, self-reported empathizing was found to have no relation at all to fear of negative evaluation and to be negatively correlated with a measure of social anxiety. That is, people who were high in empathizing were actually low in social anxiety and vice versa.[3]
Restrictive eating is more common in women than men. (Image courtesy of sattva at

A reasonably detailed description of the Bremser and Gallup study appears at Christian Jarrett’s blog. (A briefer description can be found here, while a more critical view can be found here.) Briefly, the authors performed a series of four studies to test their hypothesis that eating disorder symptoms are associated with a pattern of high empathizing and low systematizing. They did find modest positive correlations between self-reported empathizing and disordered eating when gender was not considered, apparently supporting their hypothesis. However, when they looked at differences between males and females there were some puzzling findings. In study 2 females who were either high or low in disordered eating did not differ in their level of self-reported empathizing (see Figure 2, p. 471). However, males who were high in disordered eating were higher in self-reported empathizing than males low in disordered eating. An even more puzzling finding was evident when they examined the relationship between emotion recognition (a test of empathic ability) and disordered eating (see Figure 1). Females high on disordered eating scored somewhat higher than other participants on this task, although it was not really clear from the authors’ report if this difference was statistically significant. What was more striking was that males high in disordered eating actually scored noticeably lower than all other participants on the emotion recognition task. Now remember that the authors’ hypothesis was that high empathizing would be associated with disordered eating, yet males with disordered eating actually scored worse than everyone else on a test of empathic ability, even though their self-reported empathy was higher. This suggests to me that these males had a lack of insight into their actual ability to register another person’s emotions. Yet quite oddly the authors claim that this anomalous finding actually supports rather than refutes their hypothesis:

“The data from males are consistent with the idea that disordered eating is associated with the hyper-empathizing that characterizes the EFB type.”
They attribute the failure of these males to correctly identify emotions as due to “hyper-mentalizing associated with the EFB” manifesting as “faulty inferences about mental states”. So they found a pattern associated with a particular group of males and then decide that this is evidence of an extreme female brain, even though none of the females manifested this pattern. Furthermore, failure in a test of empathic ability is interpreted as due to ‘hyper-empathizing’. In other words, when people are too high in empathizing they over-analyse other people and therefore make mistaken attributions about what they are thinking and feeling. The authors go on to explain: “This may be because they are using their own experience to model the experience of others, and their bias to classify emotions with a negative bias may influence their attributions.” In other words, they project their own concerns onto other people rather than trying to understand others on their own terms. This does not sound much like empathy to me. It actually sounds more like autism. People with autism also have trouble imagining that other people feel differently from themselves.
The authors actually cite research findings that people with eating disorders often show impaired emotion recognition. This would imply a failure of empathizing, yet Bremser and Gallup argue that this is actually due to “hyper-mentalizing”. They also appear to ignore previous research findings indicating commonalities between eating disorders and autism. For example, research had found that autism spectrum disorders sometimes precede the development of eating disorders and that 16% of teenage sufferers of anorexia have been estimated to have autism (Oldershaw, Treasure, Hambrook, Tchanturia, & Schmidt, 2011). Additionally, autism and anorexia may coexist within the same family suggesting they could have a shared genetic basis.
The authors argue that errors in emotion recognition tasks may be due to either a deficit in understanding (as in Asperger’s syndrome) or to abnormal or excessive attribution of mental states associated with psychotic type mental processes (referred to in the paper as schizotypal traits). I think they actually made a valid point about this. There is evidence that schizotypal traits play a role in eating disorders, particularly anorexia. This might seem to justify their claim that failures of emotion recognition are related to “hyper-mentalizing”. However, their own results show that although schizotypal traits were related to disordered eating they were largely unrelated to empathizing (see Table 7). Therefore their claim that “hyper-mentalizing” (associated with schizotypal traits) is related to “hyper-empathizing” seems unwarranted.
There was a significant correlation between the schizotypal scale ‘constricted affect’ and empathizing but this was in the negative direction. That is, people who were high in empathizing tended to be less constricted in their emotional expression. The authors noted that males who were low in constricted affect (and therefore emotionally expressive) also scored higher on disordered eating. In females there was no such relationship. The authors once again try to claim that this supports their theory by arguing that emotional expressiveness is a ‘feminine’ trait that is also related to empathizing. So therefore the finding that emotionally expressive men were more eating disordered is evidence of a relationship between the EFB and disordered eating. So yet again, a relationship found in men, but not women, is taken as evidence of a female brain type.
As previously noted the EFB is supposed to be high in empathizing and also poor in systematizing. Therefore, the authors predicted that disordered eating would be associated with poor systematizing. The actual results they found were mixed. Self-reported systematizing and a test of intuitive physics were unrelated to disordered eating. However, a test of mental rotation was found to have a significant negative correlation with disordered eating, indicating that those who performed more poorly on the mental rotation task had more disordered eating. Research has found that men tend to perform much better on tests of mental rotation than women, although some scholars have claimed that this is due to the psychological effects of gender stereotypes rather than innate differences between men and women (Ortner & Sieverding, 2008).  Bremser and Gallup did not report results for each gender so we do not know if men and women had different patterns of results. The authors acknowledge that self-starvation associated with disordered eating can produce deficits in task performance. This might explain why mental rotation was poorer in people with disordered eating. On the other hand, there were no impairments in performance on the intuitive physics task, so the results are difficult to interpret. 
What Conclusions can be drawn
Bremser and Gallup proposed that disordered eating would be associated with a pattern of high empathizing and poor systematizing they refer to as the EFB. They did find that there were modest positive associations between self-reported empathizing and disordered eating. Also, one of their studies found a moderate negative association between a systematizing task (mental rotation) and disordered eating, although two other studies using different systematizing measures found no such relationship. However, closer inspection of their results found that, when gender differences were reported, the relationship between empathizing and disordered eating occurred in men but not women. Their findings would seem to indicate that a pattern of high self-reported empathizing, poor emotion recognition, and emotional reactivity is associated with disordered eating in males but not females. Yet they claim this as evidence for an extreme female brain. Perhaps they should call this the ‘stereotypically feminine brain that leads to eating disorders in men’. Not nearly as catchy I know. Furthermore, they use some rather convoluted reasoning to explain why deficits in emotion recognition (that is, failures in empathizing) found in eating disorders should be associated with high empathizing by invoking “hyper-mentalizing”. The latter could plausibly be a feature of fear of negative evaluation and schizotypal tendencies, yet their own results indicated that these were unrelated to empathizing. There is in fact evidence for at least some overlap between eating disorders and autism, even though the EFB is supposed to represent the opposite of an autistic condition. I get the impression that the authors of this study decided that because eating disorders are so strongly associated with females that they would make a good candidate for an EFB, so they decided to try to force the result to fit their theory.

Image courtesy of Ventrilock at

Williams Syndrome: a better EFB?
So if eating disorders are not a very good candidate for a manifestation of an EFB is there something that is? The most logical candidate I am aware of is a rare condition known as Williams Syndrome. This condition is associated with extreme friendliness and sociability, and high levels of empathy (Klein-Tasman & Mervis, 2003), as well as subnormal IQ scores and difficulty understanding how a whole is made up of its parts, although language skills are generally highly developed (Farran & Jarrold, 2003). Williams Syndrome has even been referred to at times as the ‘anti-autism’ syndrome. For example, while people with autism show a disinterest in looking at faces, people with Williams Syndrome are fascinated by them (Riby & Hancock, 2008). Williams Syndrome neatly fits the profile of Baron-Cohen’s proposed EFB in that it combines strength in empathizing and difficulty in systematizing and seems more like a true ‘mirror image’ of autism. However, Williams Syndrome apparently occurs equally in males and females. Therefore, even though it meets most criteria for an EFB it does not seem to be particularly female. Anorexia is a predominantly female disorder yet it has actually been linked with autism, a supposedly extreme male disorder. Perhaps this shows that stereotyping certain conditions as extremely ‘male’ or extremely ‘female’ is actually misleading and hinders understanding them. Just because men tend to have more interest in systematizing than women does not necessarily make it a male province. Nor should empathizing be seen as a particularly female one. Furthermore, describing systematizing as a male domain and empathizing as a female one might have the effect of alienating member of the opposite sex from activities associated with each one and of needlessly reinforcing limiting gender stereotypes.

[1] Yes, he actually is related to Sacha Baron-Cohen of ‘Borat’ fame.
[2] The term ‘brain type’ seems a misnomer as the theory is based on observations about personality and behaviour rather than direct studies of the brain. However, to maintain consistency with the existing literature the term ‘brain’ will continue to be used in this article.
[3] See results for Study 3, Table 7. 
This post has previously appeared on my blog at Psychology Today Unique - Like Everybody Else.

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© Scott McGreal. Please do not reproduce without permission. Brief excerpts may be quoted as long as a link to the original article is provided.


Bremser JA, & Gallup GG Jr (2012). From one extreme to the other: negative evaluation anxiety and disordered eating as candidates for the extreme female brain. Evolutionary psychology : an international journal of evolutionary approaches to psychology and behavior, 10 (3), 457-86 PMID: 22947672
Farran, E. K., & Jarrold, C. (2003). Visuospatial Cognition in Williams Syndrome: Reviewing and Accounting for the Strengths and Weaknesses in Performance. Developmental Neuropsychology, 23(1-2), 173-200. doi: 10.1080/87565641.2003.9651891
Klein-Tasman, B. P., & Mervis, C. B. (2003). Distinctive Personality Characteristics of 8-, 9-, and 10-Year-Olds With Williams Syndrome. Developmental Neuropsychology, 23(1-2), 269-290. doi: 10.1080/87565641.2003.9651895
Oldershaw, A., Treasure, J., Hambrook, D., Tchanturia, K., & Schmidt, U. (2011). Is anorexia nervosa a version of autism spectrum disorders? European Eating Disorders Review, 19(6), 462-474. doi: 10.1002/erv.1069
Ortner, T. M., & Sieverding, M. (2008). Where are the Gender Differences? Male Priming Boosts Spatial Skills in Women. Sex Roles, 59(3-4), 274-281. doi: 10.1007/s11199-008-9448-9
Riby, D. M., & Hancock, P. J. B. (2008). Viewing it differently: Social scene perception in Williams syndrome and Autism. Neuropsychologia, 46(11), 2855-2860. doi: 10.1016/j.neuropsychologia.2008.05.003

Monday, November 12, 2012

Psilocybin could improve quality of life in the terminally ill

A recent study of people with advanced-stage cancer found that a single dose of psilocybin led to improvements in anxiety and depression. Psilocybin might enhance mood by shifting attention away from negative and towards positive emotional information. Mystical experiences occurring under the influence of psilocybin could help ease existential anxiety by changing a person’s attitudes towards death and dying. Research studies in this area have not used adequate experimental controls and therefore these results should be considered tentative until more rigorous research has been conducted. 

A pioneering studies in the 1970s found that psychotherapy combined with the use of psychedelic drugs such as LSD appeared to help to reduce depression, physical pain and anxiety about death in people with terminal cancer (Grof, Goodman, Richards, & Kurland, 1973). The authors’ impression was that the patients who made the most dramatic changes were those who had a “peak mystical experience” of oneness with the universe usually preceded by an experience of spiritual “death and rebirth”. Profound experiences of this nature were seen in 25% of sessions. The authors argued that profound religious and spiritual experiences, such as a “peak mystical experience” were particularly effective in helping patients accept death. However, they also noted that other kinds of emotional improvements frequently occurred even without the presence of a mystical experience.

This study was of an exploratory nature and due to the absence of any control group it is not possible to know whether the effects observed were specifically due to drug effects, the psychotherapy, or even placebo effects. In spite of these promising results, psychedelic drug research was effectively banned when these substances were made illegal. In recent years there has been something of a revival of interest in this area. A 2011 study again examined the use of psychedelic drugs in people with advanced-stage cancer (Grob et al., 2011). This study used psilocybin rather than LSD because research suggests that the effects of psilocybin are more euphoric and less likely to produce panic or paranoid reactions than LSD. The drug produced no adverse medical effects and was well-tolerated.

The treatment appeared to have beneficial effects on depression and anxiety. Six months after taking psilocybin, the patients had a significant reduction in depression. What I found particularly interesting was that they also showed a reduction in trait anxiety that was significant at 1 and 3 months after treatment. Trait anxiety refers to how much anxiety a person generally feels and is usually considered a stable feature of one’s personality, closely related to a broader trait called neuroticism. The results of this study might seem to suggest that psilocybin could produce a lasting change in this feature of personality. As noted in a previous article, another study using healthy volunteers found that psilocybin produced lasting changes in the personality trait of openness to experience (MacLean, Johnson, & Griffiths, 2011). However, this study found no change in other personality traits, including neuroticism. It seems plausible that when people have advanced-stage cancer their ratings of their general levels of anxiety would be elevated compared to healthy people due to their illness. If this is the case, perhaps psilocybin helped reduce their heightened anxiety to more normal levels. However, without knowing the patients’ levels of trait anxiety before their illness it is not possible to draw any definite conclusions.

Another limitation of this study, like the 1970s study cited earlier, is that there was no comparison group of patients who did not receive psilocybin to serve as an experimental control. For this reason, it is not possible to rule out the possibility that the beneficial effects observed were due to placebo effects. For example, the patients might have benefited simply from the care and attention they received from the researchers during the study. The authors of the study acknowledged this limitation and explained that they believed that it would have been unethical to withhold a potentially beneficial treatment from the terminally ill. One possible response to this is that the psilocybin treatment could have been compared to a more conventional treatment such as psychotherapy. If a single-dose of psilocybin could be shown to be as or even more beneficial than more costly and intensive treatment strategies such as psychotherapy then care of the terminally ill could be enriched.

In spite, of these limitations, the study results remain suggestive. Studies with healthy volunteers have found that after a single dose of psilocybin, volunteers reported improvements in mood, attitudes to life and the self, positive behaviour changes including improved relationships, and increased spirituality, as well as increased satisfaction with life that persisted for months afterwards (Griffiths et al., 2011; Griffiths, Richards, McCann, & Jesse, 2006). Interestingly, Griffiths et al. (2011) found that volunteers reported increases in “death transcendence”. That is, participants expressed an increased belief that there is continuity after death, e.g. belief that death is not an ending but a transition to something even greater than this life. It seems worth noting that all the participants in this study were involved in religious or spiritual activities prior to the study. Thus, they might have been especially receptive to the idea that “spiritual” experiences induced by the drug could represent real insights into reality.

A forthcoming paper on the effects of psilocybin on attention provides insights into why psilocybin might have beneficial effects on mood and relieving depression (Kometer et al., 2012). People who are depressed show a bias towards paying more attention to negative than to positive stimuli. Depressed people find it harder to recognise happy facial expressions and respond more slowly to positive compared to negative words in emotional tasks. This emotional bias has been linked to problematic functioning in the serotonin system in the brain. Psilocybin and LSD produce their hallucinogenic effects by acting on the serotonin system, and Kometer et al.’s study found evidence that psilocybin can influence attentional biases in a positive way. In this study, volunteers under the influence of psilocybin experienced increased positive mood and took longer to react to negative or neutral words compared to positive ones. Interestingly, these effects did not occur when participants had been administered a drug called ketanserin, which blocks serotonin receptors[1], before being given psilocybin. This suggests that psilocybin can induce biases of attention towards positive and away from negative emotional stimuli. Additionally, these effects appear to be due to the action of psilocybin on the serotonin system. If it is true that psilocybin treatment can be effective in reducing depression, these findings seem to suggest a plausible mechanism. This might explain why volunteers in the studies by Griffiths et al. reported persistent positive changes in their attitudes to many aspects of their lives.
The findings from these studies seem very promising. The research cited does seem to suggest that mystical experiences induced by psilocybin can help a person overcome the fear of death. Additionally, psilocybin seems to have a generally positive effect on mood and attitude that could alleviate depression. A limitation of the studies cited is that they did not use no-drug control groups for comparison to show that the effects were actually due to the drug rather than other factors such as placebo effects. Thus, it would be premature to definitely conclude that psilocybin is an effective treatment for depression and existential anxiety in people with cancer, even though the results seem very suggestive. More rigorous research designs are needed to provide more conclusive evidence. Additionally, it would be interesting to examine whether psilocybin might help a person with cancer accept death if they do not have any religious or spiritual beliefs. 

[1] For those who are interested, ketanserin specifically blocks 5-HT2A receptors. The 5-HT2A receptor system has been implicated in depressive pessimism and is known to be affected by antidepressant drugs.  

This post has previously appeared on Psychology Today in my blog Unique - Like Everybody Else

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© Scott McGreal. Please do not reproduce without permission. Brief excerpts may be quoted as long as a link to the original article is provided.  

Other posts about psychedelic drugs and/or spirituality
            Griffiths RR, Johnson MW, Richards WA, Richards BD, McCann U, & Jesse R (2011). Psilocybin occasioned mystical-type experiences: immediate and persisting dose-related effects. Psychopharmacology, 218 (4), 649-65 PMID: 21674151
           Griffiths RR, Richards WA, McCann U, & Jesse R (2006). Psilocybin can occasion mystical-type experiences having substantial and sustained personal meaning and spiritual significance. Psychopharmacology, 187 (3) PMID: 16826400
            Grob CS, Danforth AL, Chopra GS, Hagerty M, McKay CR, Halberstadt AL, & Greer GR (2011). Pilot study of psilocybin treatment for anxiety in patients with advanced-stage cancer. Archives of general psychiatry, 68 (1), 71-8 PMID: 20819978
Grof, S., Goodman, L. E., Richards, W. A., & Kurland, A. A. (1973). LSD-Assisted Psychotherapy in Patients with Terminal Cancer. Int. Pharmacopsychiat., 8, 129-144.
            Kometer M, Schmidt A, Bachmann R, Studerus E, Seifritz E, & Vollenweider FX (2012). Psilocybin biases facial recognition, goal-directed behavior, and mood state toward positive relative to negative emotions through different serotonergic subreceptors. Biological psychiatry, 72 (11), 898-906 PMID: 22578254
MacLean, K. A., Johnson, M. W., & Griffiths, R. R. (2011). Mystical Experiences Occasioned by the Hallucinogen Psilocybin Lead to Increases in the Personality Domain of Openness. Journal of Psychopharmacology. doi: 10.1177/0269881111420188

Thursday, November 1, 2012

Your brain on psilocybin

As reported in a previous article, a number of fascinating studies recently have focused on the effects of the drug psilocybin, a classic psychedelic drug. Scientists still do not have a good understanding of the brain mechanisms by which psilocybin produces its effects. A recent study used brain scanning (specifically, functional magnetic resonance imaging) to obtain a window into the brain of 30 volunteers injected with this drug in order to understand what happens during the transition between normal waking consciousness and the onset of drug effects (Carhart-Harris et al., 2012). The researchers were surprised to discover that drug effects were associated with decreases in activity in a number of key brain areas, rather than the expected increase. This finding has led to speculations about the relationship between brain activity and mystical states experienced under psychedelic drugs. However, the actual implications of the study’s findings are far from clear.

In this study, participants received two brain scans each, once after receiving a saline injection, and once after receiving a psilocybin injection. The effects on brain activity were then compared. After receiving psilocybin brain blood flow decreased, indicating reduced activity. In particular, activity in areas regarded as important network hubs that maintain the connectivity of the various areas of the brain showed the most consistent deactivation. These areas are known as the medial prefrontal cortex (mPFC) and the posterior cingulate cortex (PCC). (If you’re put off by neuroscience please don’t quit reading just yet! I’ll try to keep the brain science as simple as possible.) These two areas appear to play important roles in the regulation of self-awareness as they are particularly activated when people are asked to think about themselves for example (Wicker, Ruby, Royet, & Fonlupt, 2003). The authors thought it was quite interesting that these areas actually show much higher activity than other parts of the brain under normal conditions, yet showed the greatest deactivation under the drug. Additionally, the intensity of the alterations of conscious experience reported by the volunteers was proportional to the decrease in brain activity. That is, the more brain activity decreased, the more vivid the “trip” experienced.  

Why psilocybin might induce reductions in brain activity is not known, but it is natural to speculate. The authors argued that the findings are consistent with Aldous Huxley’s idea that normal consciousness acts like a “reducing valve” that actually constrains how much information a person normally takes in, so that one is not overwhelmed by chaotic stimuli. Therefore, the apparent “mind-expanding” effect of psychedelic drugs is due to a relaxation of this constraining effect. The reduced activity of the brains connector hubs might permit an “unconstrained style of cognition” producing psychedelic effects (Carhart-Harris, et al., 2012).

In an article for Time magazine, Carhart-Harris takes these speculations even further. Under high doses of psilocybin many people experience a sense of ego-transcendence in which the boundaries of the self appear to dissolve resulting in a blissful state of oneness with the universe. As noted earlier, areas of the brain associated with self-awareness, the mPFC and the PCC, showed a marked reduction in activity under psilocybin. This could imply that ego-transcendence might be facilitated by reduced activity in these brain areas. This idea seems appealing when considering that contemplative traditions aim to produce ego-transcendence by quietening the mind.

 However, let’s not jump to conclusions just yet. There is a potential problem with Carhart-Harris et al.’s interpretation of their results that they appear to have overlooked. Previous research has found that a number of areas of the brain, including the mPFC and the PCC actually show heightened levels of activity when a person is simply at rest and show decreased activity when concentrating attention on various tasks unrelated to thinking about oneself (D'Argembeau et al., 2005; Wicker, et al., 2003). So while it is true that these brain areas are important for self-awareness, simple tasks such as looking out a window or thinking about another person can reduce activity in these areas under normal circumstances. In the Carhart-Harris et al. study brain activity under psilocybin was compared to brain activity when simply resting. This is potentially a problem because activity in the mPFC and PCC tends to be highest when at rest. Therefore, reduced activity in these regions under psilocybin might simply be because volunteers were paying attention to the unfolding hallucinatory experience as opposed to thinking of nothing in particular. Future studies could test this by using a comparison condition where participants were engaged in an attentional task as opposed to simply resting. If there were noticeable differences in the degree of deactivation in the key brain areas this might provide evidence that these particular brain areas do play a special role in the psilocybin experience.

In spite of these concerns, I do think the idea that psilocybin permits an “unconstrained style of cognition” is an intriguing one. As discussed in my previous article there is a strong association between the personality trait absorption and the degree to which a person experiences alterations in consciousness under psilocybin (Studerus, Gamma, Kometer, & Vollenweider, 2012). Absorption is associated with a tendency to have unusual ideas and loose associations, suggesting that high absorption is associated with a style of cognition that is much less constrained than that of the average person. Additionally, one study of volunteers who had never taken psychedelic drugs before found that volunteers who experienced a profound mystical experience under psilocybin underwent a long-term increase in openness to experience (MacLean, Johnson, & Griffiths, 2011), a personality trait closely related to absorption. This suggests that for some people, taking psilocybin could lead to a lasting change in their cognitive style, perhaps related to the intensely “unconstrained” style experienced under psilocybin.

The study of the effects of psilocybin on brain function is in its infancy. More research into this area could lead to some intriguing findings about the relationship between the brain and consciousness.

Further reading
Another critique of the Carhart-Harris et al. study can be found here.

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© Scott McGreal. Please do not reproduce without permission. Brief excerpts may be quoted as long as a link to the original article is provided. 

This article also appears on Psychology Today on my blog Unique - Like Everybody Else.

            Carhart-Harris RL, Erritzoe D, Williams T, Stone JM, Reed LJ, Colasanti A, Tyacke RJ, Leech R, Malizia AL, Murphy K, Hobden P, Evans J, Feilding A, Wise RG, & Nutt DJ (2012). Neural correlates of the psychedelic state as determined by fMRI studies with psilocybin. Proceedings of the National Academy of Sciences of the United States of America, 109 (6), 2138-43 PMID: 22308440
            MacLean, K., Johnson, M., & Griffiths, R. (2011). Mystical experiences occasioned by the hallucinogen psilocybin lead to increases in the personality domain of openness Journal of Psychopharmacology, 25 (11), 1453-1461 DOI: 10.1177/0269881111420188
           Wicker, B., Ruby, P., Royet, J., & Fonlupt, P. (2003). A relation between rest and the self in the brain? Brain Research Reviews, 43 (2), 224-230 DOI: 10.1016/j.brainresrev.2003.08.003