Monday, May 26, 2014

Let's Face It: Publishing Weak Data on Face Processing in Pedophiles Is Pointless

Modified from Fig. 2 (Ponseti et al., 2014). Brain areas that selectively respond to faces of the sexually preferred age.

Just when we thought it was safe to bury the dead salmon of uncorrected statistical thresholds in neuroimaging studies, a new and incendiary study on face processing in pedophiles emerges (Ponseti et al., 2014). Even if it were surprising and informative that “Human face processing is tuned to sexual age preferences” (Ponseti et al., 2014), the fMRI data analyses failed to correct for multiple statistical comparisons, which is standard in the field. Therefore, by using a very liberal statistical threshold of p < 0.01 uncorrected for the large number of tests, the results could be a series of untrustworthy false positives.1

Importantly, the basic pattern of findings, that visual parts of the brain are more responsive to pictures of faces that fall within the broad category of “sexual attractiveness”, does not tell us why someone has a particular sexual orientation, nor does it tell us if this preference is “hard wired” (i.e., innate).

The participants in the study were 56 men, 11 of whom were heterosexual pedophiles (prefer young girls), 13 homosexual pedophiles (prefer young boys), 18 heterosexual teleiophiles (prefer adult women) and 14 homosexual teleiophiles (prefer adult men). These are small groups, but to complicate matters, half of the pedophiles had committed sexual offenses and the other half had not. This is a critical difference, as one might expect differences between men who could refrain from acting on their impulses and those who could not. Yet, activation in the dorsal striatum was interpreted as a potential indicator of “efforts in withholding actions”.

Furthermore, the results presented here were part of a larger study that aimed to classify pedophiles solely on the basis of their brain responses to nude photos showing whole-body frontal views or genitals only (Ponseti et al., 2012). The authors claimed an astounding 95% accuracy in distinguishing between pedophiles and non-pedophiles.2

Overall, the participants viewed 14 different categories of visual stimuli in these two papers, so you can see that the number of potential statistical comparisons is astronomical.

The take-home message is that the participants' subjective attractiveness ratings of each face (completed after the fMRI study) were much more reliable at identifying their sexual preferences (p < 0.001) than the brain imaging data. Neuroscientists working with such controversial populations need to be especially careful in analyzing their data, and aware of how their work may be used in a broader social context.


1 Thanks to commenter Com__Truise on reddit who alerted me to this paper and who noted:
Published cognitive Neuroscientist here. This should not have gotten through peer review. The fMRI analysis is invalid. The study uses an uncorrected threshold (not corrected for multiple comparisons) of p< 0.01 (considered very liberal!) and all the results are probably false positives. This is not to say that the theory is not correct - however, the statistics are invalid and meaningless. You can read more here:

Here is another cautionary note from Professor James Ogloff, Director of the Centre for Forensic Behavioural Science and Legal Studies at Swinburne University of Technology, Victoria.

2 Critical and ethical evaluation of this study is beyond the scope of the present post.


Ponseti J, Granert O, Jansen O, Wolff S, Beier K, Neutze J, Deuschl G, Mehdorn H, Siebner H, Bosinski H. (2012). Assessment of pedophilia using hemodynamic brainresponse to sexual stimuli. Arch Gen Psychiatry 69(2):187-94.

Ponseti, J., Granert, O., van Eimeren, T., Jansen, O., Wolff, S., Beier, K., Deuschl, G., Bosinski, H., & Siebner, H. (2014). Human face processing is tuned to sexual age preferences Biology Letters, 10 (5), 20140200-20140200 DOI: 10.1098/rsbl.2014.0200

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Sunday, May 18, 2014

Does Gamma tACS Really Induce Lucid Dreaming?

Dream scene from Inception

DIY brain stimulation geeks were supercharged last week by the finding that dream awareness could be enhanced by transcranial alternating current stimulation (tACS)1 at frequencies of 25 and 40 Hz (Voss et al., 2014). Headlines were abuzz with zingers like Brain Zaps Can Trigger Lucid Dreams and A Jolt to the Brain Triggers Lucid Dreams and Brain Zap Could Help You Control Your Dreams. Visualize all the incipient Kickstarter campaigns ready to capitalize on the lucid dreaming market...

Except did the stimulation really induce lucid dreaming? The only critical evaluation of this claim (that I'm aware of) came from Christian Jarrett in his post, Psychologists Give People Control of Their Dreams Using Brain Stimulation. Really? He closely examined the Lucidity and Consciousness in Dreams scale (LuCiD) used by the experimenters (Voss et al., 2013) and saw that the participants' self-ratings weren't actually indicative of lucid dreaming.

Although the scores on some LuCiD factors were indeed significantly higher after frontal stimulation at 25 Hz (beta, actually) and/or 40 Hz (gamma) frequencies (relative to sham or other frequencies), this did not mean the dreams were technically “lucid”.

Fig. 3 (Voss et al., 2014). Mean scores for three LuCiD factors [NOTE: each self-rating scale goes from 0: strongly disagree to 5: strongly agree].

The LuCiD scale consists of 28 statements, each followed by a 6-point rating scale (0: strongly disagree, 5: strongly agree). Insight is the awareness that one is currently dreaming, Dissociation is taking a third-person perspective, and Control is control over the dream plot.

Of the eight LuCiD factors, Insight is the single most important criterion for lucid dreaming (Voss et al., 2013).  However, the mean Insight score in the current study is well below that reported for lucid dreams in the earlier study used to construct the scale.

modified from Fig. 5 (Voss et al., 2013). Mean scores for LuCiD scales for non-lucid vs. lucid dream reports [NOTE: each scale goes from 0: strongly disagree to 5: strongly agree. The yellow bars indicate means after 25 or 40 Hz tACS in Voss et al. 2014].

In other words, the 25 Hz and 40 Hz brain stimulation significantly increased Insight and Control, but not to the levels reported in lucid dreams (according the authors' previous definition). The definition in the present study was less stringent: “Lucidity was assumed when subjects reported elevated ratings (>mean + 2 s.e.) on either or both of the LuCiD scale factors insight and dissociation.”

Nonetheless, induced gamma band oscillations did result in a heightened perception of self-awareness during REM sleep, in particular the ability to view the ongoing dream activities as a detached observer. But don't waste your money investing in the latest neurocrap that claims to induce lucid dreaming... As Seen On Nature Neuroscience.

Further Reading

Psychologists Give People Control of Their Dreams Using Brain Stimulation. Really?

Neurocrap Funded by the Masses: NeuroOn and No More Woof


1 Note that tACS is different from the usual DIY tDCS (transcranial direct current stimulation). tACS is thought to modulate and entrain brain oscillations in a frequency-specific manner, although others are much more cautious in their interpretation.


Voss, U., Holzmann, R., Hobson, A., Paulus, W., Koppehele-Gossel, J., Klimke, A., & Nitsche, M. (2014). Induction of self awareness in dreams through frontal low current stimulation of gamma activity. Nature Neuroscience DOI: 10.1038/nn.3719

Voss, U., Schermelleh-Engel, K., Windt, J., Frenzel, C., & Hobson, A. (2013). Measuring consciousness in dreams: The lucidity and consciousness in dreams scale. Consciousness and Cognition, 22 (1), 8-21 DOI: 10.1016/j.concog.2012.11.001

“Shared Dreaming” scene from Inception

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Saturday, May 17, 2014

The Smouldering Glances of Neuroscience Information

Neuroscience Information May Provide an Illusion of Explanatory Depth

In our continuing twilight saga on the seductive allure of all things neuroscientific comes this new entry by Rhodes et al. (2014). The paper isn't available yet so the abstract will have to do for now:

Rhodes RE, Rodriguez F, Shah P. Explaining the alluring influence of neuroscience information on scientific reasoning. J Exp Psychol Learn Mem Cogn. 2014 May 12. [Epub ahead of print]. PMID: 24820673


Previous studies have investigated the influence of neuroscience information or images on ratings of scientific evidence quality but have yielded mixed results. We examined the influence of neuroscience information on evaluations of flawed scientific studies after taking into account individual differences in scientific reasoning skills, thinking dispositions, and prior beliefs about a claim. We found that neuroscience information, even though irrelevant, made people believe they had a better understanding of the mechanism underlying a behavioral phenomenon. Neuroscience information had a smaller effect on ratings of article quality and scientist quality. Our study suggests that neuroscience information may provide an illusion of explanatory depth. (PsycINFO Database Record (c) 2014 APA, all rights reserved).

Do colorful brain images and neuroscientific information hold powerful sway over the unsuspecting reader's logic, leading them to overlook shoddy science coverage? From what I can gather, the seductive allure of neuroimages has not replicated (Farah & Hook, 2013; Michael et al., 2013; Schweitzer et al., 2013), but the appeal of neuroscience information (à la Weisberg et al., 2008) has yet to lose all its luster.1

Credit for the "smouldering glance" terminology goes to Vaughan Bell.


1 This is debatable, however:
Farah and Hook also debunked the study of Weisberg et al., (2008), which didn't use images at all but added neuroscience-y explanations to 18 actual psychological phenomenon. The problem was that the neuroscience-y paragraphs were longer than the no-neuroscience paragraphs. The author of the excellent but now-defunct Brain In A Vat blog had a similar objection, as explained in I Was a Subject in Deena Weisberg's Study...

Neuroskeptic also raised this point in his otherwise [mostly] positive evaluation of the study, Critiquing a Classic: "The Seductive Allure of Neuroscience Explanations"...

Photo Credits:
Kristen Stewart by Inez & Vinoodh for V Magazine (Spring Preview 2013)
Ian Somerhalder by Angelo Kritikos

ADDENDUM May 20 2014: Bianca del Rio is 
America's Next Drag Superstar!

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Sunday, May 11, 2014

The Seductive Allure of Spintronics™ Neuroimaging mock mind reading scanner

Spintronics™ Neuroimaging mock scanner used in experiment by Ali, Lifshitz & Raz (2014)

A new study has tricked undergraduates into believing that “Spintronics,” a whimsical new “mind reading” technology constructed using an old hair dryer, was able to accurately read their thoughts  (Ali et al., 2014). This held even for students enrolled in a class on the pros and cons of neuroimaging methods taught by the senior author (McGill Professor Amir Raz). The paper coined the phrase “empirical neuroenchantment” to explain why a highly dubious experimental setup would lead to such a deficit in critical thinking.

The participants were 58 McGill students, 26 of whom were upper-level psychology, neuroscience or cognitive science majors enrolled in a skeptical neuroimaging course that warned them about overblown claims. Furthermore, the professor had lectured about his experience as a “mind reading” magician who fools audiences into believing he has paranormal abilities:
The professor in the course (AR) repeatedly harped on the present impossibility of mind-reading and tested this information on the final examination verifying that students internalized these points. He also spoke about his background as a mentalist – a magician who performs psychological tricks, such as mind-reading – and led class demonstrations to exemplify why the public often misinterprets these effects and takes them for genuine paranormal powers.

And in fact, sleight of hand was used to further the ruse that the hair dryer contraption was able to read their minds. Subjects were told they were participating in a study on “The Neural Correlates of Thought” (amusingly described in the Methods) where they...
...encountered a rickety mock brain scanner built from discarded medical scraps from the 1960s and adorned with an old-fashioned hair-dryer dome [shown in the figure above]. We told participants that scientists at the Montreal Neurological Institute had developed new experimental technology to decode resting state brain activity and read the human mind. We labeled the technology Spintronics and displayed warning signs around the scanning equipment similar to those found in MRI environments.

The participants were told to think of a two-digit number, a three-digit number, a color, and a country and to write down their answers on a piece of paper. The first author cleverly pocketed their answers,1 then participants were told to think about their choices while their brains were faux scanned. During this time, “a pre-recorded video displayed rotating three-dimensional brain slices with accompanying scanner-like audio, lending the appearance of collecting and analyzing patterns of brain activity.”

Afterwards, the subjects were shown the results of the scan. Lo and behold, the machine could read their minds! A brief questionnaire rated their level of belief on a 0 to 6 point scale (from “not at all” to “extremely”).

How did the informed students fare against the non-Neuro controls? The Neuro students found the results significantly less believable (3.96 vs. 4.96), and they rated themselves as more skeptical (3.42 vs, 1.94) than the controls. However, they were not immune to ascribing even greater mind-reading capabilities to Spintronics© after being shown that the contraption successfully “read” their thoughts.

Can we conclude from the present study that neuroimaging is special in the annals of scientific technology in its ability to dupe even those who should know better? No, and the authors acknowledge as much. We don't know whether the dual phenomena of deferring to experts in a professional laboratory, and overriding scientific knowledge on the basis of one compelling experience, would occur in other fields of study. We could potentially see meteoroenchantment or roboenchantment in the realms of weather prediction and artificial intelligence, respectively.

Nonetheless, the Spintronics study ups the ante in the Brainwashed sweepstakes on The Seductive Appeal of Mindless Neuroscience, which maintains that the media can easily dupe an unsuspecting public into believing nearly anything couched in the guise of neuroscience.

The Seductive Allure of Neuroscience Explanations

Remember the “seductive allure” of colorful brain images? This was the idea that college undergraduates could be swayed to believe implausible explanations for psychological phenomena if accompanied by brain images (McCabe & Castell, 2008). For example, a fictitious news article explaining that ‘Watching TV is Related to Math Ability’ since watching television and completing math problems both lead to activation in the temporal lobe, watching TV will of course improve math skills was more believable when accompanied by a brain scan than by a bar graph.

The Not So Seductive Allure of Colorful Brain Images

However, this finding was not replicated in more recent studies (Farah & Hook, 2013; Michael et al., 2013; Schweitzer et al., 2013). Is this because participants in psychology experiments have gotten more sophisticated in the past five years? 2  Or is it because the results weren't that strong to begin with?

It'll be much more difficult for other labs to replicate the present results of Ali and colleagues (2014), namely because (1) most Principal Investigators aren't magicians, and (2) recruiting 1,068 participants via the online marketplace Mechanical Turk just won't work here...

Further Reading

Are Brain Scans Really So Persuasive?

The Not So Seductive Allure of Colorful Brain Images


1 I should add here that the first author, Sabrina Ali, was an undergraduate researcher at the time, and thus the participants may have had fewer suspicions that she would try to dupe them (as opposed to the magician, Dr. Raz). The present experiment was a portion of Ali's Master's Thesis at McGill.

2 More sophisticated, say, from reading critical neuroscience blogs?  Or much more likely, reading critical coverage in places like the New York Times?  Or am I living in a bubble which assumes way too much public interest in these topics?


Sabrina Ali, Michael Lifshitz, and Amir Raz (2014). Empirical Neuroenchantment: From Reading Minds to Thinking Critically. Frontiers in Human Neuroscience doi: 10.3389/fnhum.2014.00357

Farah MJ, Hook CJ (2013). The seductive allure of "seductive allure". Perspectives in Psychological Science 8:88-90.

McCabe DP, Castel AD. (2008). Seeing is believing: the effect of brain images on judgments of scientific reasoning. Cognition 107:343-52.

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Sunday, May 04, 2014

Not tonight dear, I had zymosan A injected into my hind paw

We now have definitive proof that the propensity of womankind to postpone sex due to a headache is of evolutionary origin! This annoying habit has been traced back directly to a strain of ovariectomized CD-1® IGS mice supplied by Charles River.

In a naturalistic design that precisely mimics the mating habits of humans, sexual receptivity was induced in the female mice with subcutaneous injections of estradiol. Then the female mice and their preferred male partners were injected in various body parts with two different compounds to induce inflammatory pain. Lo and behold, the mounting behaviors of male mice were hardly deterred by these painful treatments, but the females declined sexual congress and hid from the males.

“These findings suggest that the well known context sensitivity of the human female libido can be explained by evolutionary rather than sociocultural factors, as female mice can be similarly affected,” concluded the authors (Farmer et al., 2014).

Of Mice and Women

This study was published in the Journal of Neuroscience, and the strongly worded quote above is how the authors chose to conclude their abstract. They go to great lengths to “prove” that the loss of libido was due to lack of sexual motivation in the female mice, rather than a direct consequence of pain. The authors also stretch the clinical applicability (and evolutionary validity) of their work a bit beyond belief, in my view. Why? Perhaps because promoting a viable animal model of low sexual motivation in women will ultimately serve drug development purposes (Farmer et al., 2014):
The link between pain and sexual motivation is evident in human sexual relations. The widespread aphorism, “Not tonight, dear, I have a headache” refers to a lack of sexual motivation due to pain. No clinical data exist on the direct impact of pain on sexual motivation, yet high prevalence of reduced sexual desire in chronic pain populations (Basson et al., 2010; Fine, 2011) suggest that pain may adversely influence sexual motivation.

It's not exactly true that “No clinical data exist on the direct impact of pain on sexual motivation...” (as we'll see later), but first let's take a look at the actual study.1

Pairs of vigorously mating mice were assigned to either male “open field” or female “paced mating” situations, which mimics their respective natural preferences. One member of each pair was injected with a pain-inducing inflammatory compound (zymosan A or λ-carrageenan) into their genital or nongenital (hind paw, tail, cheek) regions. Sexual behavior was measured by mounting in open field (for males) or in paced mating (for females) conditions. In the latter situation, the smaller females could run into their safe room to avoid the males. 

The results generally indicated that the females hid from the males when injected with painful substances (Fig. 1A), but the males were not bothered (based on the total number of mounts) with the exception of a non-significant decline when the penis was injected with zymosan (Fig. 1C).

Fig. 1 (modified from Farmer et al., 2014). Reduction of sexual behavior in female but not male mice by inflammatory pain. A. Decreased mounting behavior in a paced mating paradigm when female mice receive zymosan (ZYM) or carrageenan (CARR) injections to the vulva, hind paw, tail, or cheek, compared with uninjected female mice (No Inj.). Bars represent mean ± SEM mounts with (shaded) or without (open) intromissions. C. No decreases in mounting behavior in an open field when male mice are treated in a similar fashion. *p < 0.05, **p < 0.01 compared with vehicle [NOTE: using uncorrected t-tests].

[As an aside, one could imagine that the mating behavior of human males might be more greatly affected by penile injections of any sort, and by inflammogen injections into the hand or cheek than what we're seeing here in the male mice.]

In addition to mounts, Table 1 in Farmer et al. lists 8 other behaviors × 2 treatments. Of these 16 comparisons to the vehicle control, five indicated reductions and one indicated an increase in activity of some sort, meaning that certain behaviors (number of ejaculations, latency to first mount, number of crossings to the male side, latency to return to the male side) were unaffected by one or both treatments [NOTE: using Dunnett's post-hoc comparisons that do correct for multiple comparisons]. Make of that what you will.

However, the pained females did indeed spend significantly less time in their male partner's side of the apparatus.

Next, some of the pained female mice were given pregabalin (Lyrica), an anticonvulsant drug used to treat neuropathic pain (kindly provided by one of the study sponsors, Pfizer). You'll be comforted to hear that analgesic administration and concomitant pain relief will lead to increased sexual activity in injured female mice (and probably in injured creatures of any sort).

On the other hand, administration of the non-selective dopamine agonist apomorphine, which is “pro-sexual” in mice but strongly emetic in humans, is unlikely to be welcomed by women as an antidote to a pain-quashed libido. Apomorphine (not related to morphine) is sometimes given to Parkinson's patients, but always in conjunction with other drugs to prevent vomiting. In fact, apomorphine is so unpleasant to humans that it has been used for aversion therapy in gay people (an “anti-sexual” agent if there ever was one).

Anyway, it was interesting to learn that rodents do not vomit, and that apomorphine reverses the pain-induced reduction in sexual behavior exhibited by female mice. This was interpreted to mean that sexual motivation was enhanced. But since apomorphine also increases locomotion in rodents, I wonder if other appetitive behaviors were enhanced as well.

The other pro-sexual drug used in the current study was melanotan-II, which is converted to the melanocortin-3/melanocortin-4 receptor agonist, bremelanotide (formerly known as PT-141, developed by Palatin Technologies). Intranasal bremelanotide underwent clinical testing to treat sexual dysfunction in humans (male and female), but trials were halted in 2008 because of untoward elevations of blood pressure in some individuals.

When given to injured female mice, melanotan-II reversed the reduction in sexual behavior. Unlike apomorphine, however, melanotan-II: (1) does not increase locomotion, and (2) is undergoing further testing in humans via a subcutaneous route of administration that doesn't increase blood pressure. Moreover, the authors are highly aware of their potential animal model:
Thus, the reversal of pain-induced reductions in female-paced sexual behavior likely reflects an enhanced incentive value of the paced mating context, indicating that motivational mechanisms can overcome the effects of pain. We suggest that restoration of pain-induced loss of libido may provide a more sensitive test of prosexual drugs than current paradigms. 2

According to the highly reputable Men's Journal, a co-author on the current paper, Dr. Jim Pfaus, is “arguably the world's preeminent expert on bremelanotide.” The 2009 magazine article states:
...Originally developed as a self-tanning agent, the drug had been repurposed when male study subjects reported a surprising side effect: erections.   ...

Pfaus showed me stunning testimonials from human test subjects. "On the five-point scale, I would rate the erection I had as a six," said one of the 1,300 anonymous testers. "You get this humming feeling," said another. "You're ready to take your pants off and go."

The drug worked equally well on women, who chronicled "an intense arousal" that lasted from six to 72 hours. "I was focused on sex," said one of the women.

However, the pesky side effects of increased blood pressure (in some men) and nausea (in one third of the women) were still an issue. That didn't stop the black market bremelanotide distributors.
But was it safe? "Well," says Pfaus, "we never resolved that blood pressure thing. There's no guarantee of purity. The FDA won't regulate it."

Five years later, Palatin has its subcutaneous version of bremelanotide in Phase 2B clinical trials for Hypoactive Sexual Desire Disorder (poster PDF) and other Female Sexual Dysfunctions (poster PDF). HSDD is a controversial diagnosis, discussion of which is beyond the scope of this post. 3

The media furor over the “not tonight, dear, I have a headache” evolutionary interpretation of sexual behavior in mice has completely overshadowed the potential drug marketing angle.

The Media Frenzy

Pain can kill ‘women’s sex drive’ but not men’s screams one headline. Not tonight dear, I have a headache: science behind the excuse: “Chronic pain diminishes a woman's sexual desire but has no impact on a man's, according to a study published in the journal of Neuroscience,” claims The Telegraph. 4

Quite obviously, no humans were tested by Farmer et al., 2014 and yet even the McGill press release plays up that angle, assisted by helpful quotes from the senior author:
“Not tonight, dear, I have a headache.” Generally speaking, that line is attributed to the wife in a couple, implying that women’s sexual desire is more affected by pain than men’s.

Now, researchers from McGill University and Concordia University in Montreal have investigated, possibly for the first time in any species, the direct impact of pain on sexual behaviour in mice.  ...

“We know from other studies that women’s sexual desire is far more dependent on context than men’s – but whether this is due to biological or social/cultural factors, such as upbringing and media influence, isn’t known,” says Jeffrey Mogil, a psychology professor at McGill and corresponding author of the new study. “Our finding that female mice, too, show pain-inhibited sexual desire suggests there may be an evolutionary biology explanation for these effects in humans – and not simply a sociocultural one.”

I've written at length about whether animal models of sexual problems are appropriate stand-ins for the human condition:
Which brings us to animal models for what we typically regard as profoundly human states: longing, angst, futility.  Or Desire, Dread, and Despair. The words don't easily lend themselves to rodent analogues, because they remind us of an unrequited crush or an existential crisis...

The animal models of these states are more mundane and less abstract, yet important for potentially explaining the neural mechanisms underlying human suffering: addiction, anxiety, and depression. But are they really adequate stand-ins for the human condition? Of course not. My purpose here isn't to critique animal research, but rather to consider actual behaviors and how they map onto the terminology used to describe them.

Does the model of pain-induced reduction of sexual behavior in female mice hold up in humans? The claim is that a lack of sexual motivation (or libido, if you will) is the inhibiting factor, rather than the pain itself.

Real Pain in Real Humans

How does chronic pain affect human sexual behavior? Is there a pronounced difference between men and women in terms of responsiveness? Is it true that this topic has never been studied?

One survey of 327 chronic pain patients (Ambler et al., 2001) found few differences between men and women:
Seventy-three percent of respondents had pain-related difficulty with sexual activity; most had several, in various combinations of problems with arousal, position, exacerbating pain, low confidence, performance worries, and relationship problems. ... There were few differences between men and women, and only weak relations emerged between specific problems and mood and disability.

Furthermore, it wasn't easy to attribute the problems to reduced libido or to physical limitations, as there wasn't a simple relationship between primarily physical and primarily psychological issues and overall physical, psychological, and emotional health.

Several other studies have examined sexual function specifically in patients with arthritis, a chronic pain condition. van Berlo et al. (2006) analyzed surveys from 271 patients with rheumatoid arthritis and found that men felt less sexual desire, while women masturbated and fantasized less often than controls. However, the patients did not report a difference in sexual satisfaction (although we don't know about the 77% who did not return the questionnaire).

An earlier study examined the effects of osteoarthritis of the hip joint on sexual activity (Currey, 1970). The author mailed a questionnaire to 235 potential patients and received replies from 121. He found that sexual problems were more commonly reported in women, but this was literally caused by stiffness and pain. A decline in sexual motivation was not the primary factor. In fact, the causes of sexual difficulty (i.e., interfering with heterosexual intercourse) did not differ between men and women. For women, it was pain in 49%, stiffness in 76% and loss of libido in only 20%. For men, those numbers were 50%, 75% and 27%.

So much for bremelanotide in female patients with chronic pain...

You may complain about demand characteristics and biased samples among those who complete and return surveys about sexual behavior, even when anonymous. Mice are so much simpler, they're not embarrassed to talk about it, they're not influenced by how their partner or doctor may react. Male mice are not less inclined to report sexual problems because they might be perceived as less macho. And female mice don't become sexually disinterested if their husbands are inconsiderate at any number of levels.

Oh wait, those are all sociocultural factors, which simply cannot explain the flighty female libido.

Further Reading

Of Mice and Women: Animal Models of Desire, Dread, and Despair

Lybrido for Low Libido?

How to Measure Female Desire

Underwear Models and Low Libido

Media HSDD: "Hyperactive Sexual Disorder Detection"

The Joy of Melanocortin Receptors


1 DISCLAIMER: Note that I am not an expert in mouse sexual behavior, so I am not qualified to critique the study on those grounds. I recognize that the present experiments represent a huge amount of work that builds upon a body of research by established investigators.

2 “The authors declare no competing financial interests.”

3 As I've written previously:
Hypoactive Sexual Desire Disorder (HSDD) is a controversial diagnosis given to women who have a low (or nonexistent) libido and are distressed about it. Dr. Petra Boynton has written extensively about the problematic aspects of the HSDD diagnosis and the screening tools used to assess it, as well as the medicalization of sexuality for pharmaceutical marketing purposes.
4 But Were the Experimenters Male or Female? Another study by the same research team received even more press coverage: the finding that male experimenters stress out laboratory rodents to a much greater extent than female experimenters. However, we don't know whether the animal handlers in the present study were male, female, or both.

ADDENDUM May 5 2014: Bethany Brookshire has a fantastic summary of that study, You smell, and mice can tell. A closer examination of the author contributions on the Farmer et al. paper suggests that the majority of investigators handling the mice (perhaps 10 out of 11) were female.


Ambler N, Williams AC, Hill P, Gunary R, & Cratchley G (2001). Sexual difficulties of chronic pain patients. Clinical Journal of Pain, 17 (2), 138-45 PMID: 11444715

Currey HL. (1970). Osteoarthrosis of the hip joint and sexual activity. Ann Rheum Dis. 29:488-93

Farmer, M., Leja, A., Foxen-Craft, E., Chan, L., MacIntyre, L., Niaki, T., Chen, M., Mapplebeck, J., Tabry, V., Topham, L., Sukosd, M., Binik, Y., Pfaus, J., & Mogil, J. (2014). Pain Reduces Sexual Motivation in Female But Not Male Mice Journal of Neuroscience, 34 (17), 5747-5753 DOI: 10.1523/JNEUROSCI.5337-13.2014

van Berlo WT, van de Wiel HB, Taal E, Rasker JJ, Weijmar Schultz WC, van Rijswijk MH. (2007). Sexual functioning of people with rheumatoid arthritis: a multicenter study. Clin Rheumatol. 26:30-8.

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