1 Shitty and 4 Kinda Interesting Articles about Orgasm and Prolactin
Happy Holidays, and you're welcome. I finally got my shit together enough to do another installment of A Journal Article I Read! Today I'll be talking about not 1, not 2, not 3,or 4, but FIVE journal articles. I started out intending to summarize the Brody one below, but then I kept reading back into the supporting articles, and realized this should all be a package deal. It won't be quite like most of the latest ones I have summarized. I won't be slipping so deeply into the details of these. It would be way too long and way too boring, and it's already probably at least a little of those things. What I'm doing is closer to over-viewing. Three of the articles have almost the exact same experimental conditions, so I'll go a little bit deep into the first one and then skip over a lot in the later ones. Have fun.
Superduper Quick Overview of All 5 Studies
Together, 4 articles by mostly the same group of researchers investigate levels of the hormone prolactin (other things too, but prolactin ends up being the focus) in the blood of men and women before/during/after sexual arousal and orgasm. The studies seem to indicate that prolactin is released upon orgasm, helping with sexual satiation, and could possibly be a marker for orgasm.
Orgasms were not physically verified in any of the articles, which particularly creates weakness in the article about intercourse-induced orgasms. Spoiler alert: I have a lot to say about the researchers assuming 100% of females will orgasm from nothing more than a penis moving in a vagina. I also have an issue with the researchers choosing to ignore the possibility that prolactin might get released from sexual nipple stimulation and that it could skew their data. I appreciate, though, that the research team continued on this topic and worked to answer more questions with each new study.
The 5th article is authored by 1 of the authors of all the articles above and Stuart Brody, a notorious vag-gasm obsesser. By swooping in to compare the prolactin release in the masturbation vs. intercourse articles, he took his chance to remind us ladies that orgasms without a dick up the junk basically suck. He claims that more prolactin is released in an intercourse induced orgasm than in a masturbation induced one and concludes that means intercourse orgasms leave a person more satiated than jerking off. As with all Brody articles, it's got problems, dude. I mean, among other things, the whole deal is based on an unsubstantiated assumption that the more prolactin there is, the more satiated one is.
Overall, though, there's some cool aspects to these articles (minus Brody's), and the idea of prolactin as an orgasm marker remains interesting and possible in my book even if the intercourse-orgasm related articles are super messy and weak.
The Male Masturbation Study
Neuroendocrine and cardiovascular response to sexual arousal and orgasm in men. Krüger T1, Exton MS, Pawlak C, von zur Mühlen A, Hartmann U, Schedlowski M. Psychoneuroendocrinology. 1998 May;23(4):401-11.
The Method Details
Basically some researchers tested 10 men's Heart Rate (HR), Blood Pressure (BP), and a bunch of chemicals in their blood (adrenaline, noradrenaline, cortisol, luteinizing hormone (LH), follicle stimulating hormone (FSH), prolactin, growth hormone (GH), beta-endorphin and testosterone) while the men masturbated to orgasm as they watched porn movies. Then they compared it to HR, BP and those blood chemicals while the same men watched a non-erotic doc and did not masturbate on a different day. Here is a quote from the article that will help describe how the experiment was run.
Initially, subjects were informed about the aim and the procedure of the study. Volunteers were then asked to refrain from any kind of sexual activity and to avoid alcoholic beverages or other drugs 24 h prior to the lab investigation. A cross-over design was used, involving two sessions on consecutive days. Each session started at 1500h. Subjects were seated in a comfortable armchair in front of a video screen. Subjects completed the experimental procedure in a separate room in which they stayed alone during the whole experiment. In the control session subjects viewed a neutral documentary tape about culture in Nepal for 60 min. The experimental session was composed of sequences, each lasting 20 minutes. The first and last sections of this tape were composed of sections of the documentary film used in the control session. However, the middle section consisted of a 20 minute pornographic film which showed different couples having sexual intercourse. The order of the presentation was balanced, with five subjects watching the pornographic film on the first day and 5 on the second. At the beginning of the film the blood sampling was initiated. Blood was drawn continuously with the samples divided into six 10 minute intervals (Schedlowski et al. 1996). Following 10 minute viewing of the pornographic video (anticipatory phase) subjects in the experimental session were required to masturbate until orgasm. -p.403
So, the participants had a needle in their vein slowly extracting blood the whole 60 minutes, but every 10 minutes it would move the blood into a new capture tube. So, the blood from the 1st sample was kind of like an averaging of the blood content going through the dude's veins throughout the 1st 10 minutes of the experiment. So in the experimental session, the 1st and 2nd blood samples represented what was happening during the doc. The 3rd sample represented what was happening during the anticipatory period where the subject was watching the porn but not masturbating. The 4th sample represented what happened while he was masturbating, when he orgasmed, and possibly some of the post-orgasm time while the porn was still on - depending on how quickly he orgasmed during that 10 minute masturbation period. It seems to me that there may be differences in the blood content depending on whether the subject orgasmed towards the beginning or end of that 10 minute section, but there is no information in the study about how the timing differs among the participants and doesn't really discuss that the timing may be different among them. The 5th sample represents what was happening the first 10 minutes of watching the doc after orgasm, and the 6th sample represents the last 10 minutes of watching the doc post orgasm.
Results and Stuff
The researchers found the same thing that's already known about HR and BP; it increases during arousal and orgasm. The blood chemicals didn't show much that was interesting except for Prolactin, which is best known for it's part in lactation. Prolactin seemed to spike in the participants' blood specifically in the sample that represented the orgasm. From background info known about prolactin (for instance that it's related to lack of interest in sex), the researchers thought this might indicate that prolactin signals sexual satiation in the body. So, in simple terms the idea is something like this:
Based on the belief that after a person orgasms, they tend to lose the strong sexual desire and physical sexual arousal they had just seconds before, the assumption is that maybe what does that, what gives a person that satiation is the release of prolactin.
I have no major qualms with this article. It's simple, exploratory, and as well thought out as any other orgasm-related article. This was released in 1998.
The Female Masturbation Study
Cardiovascular and endocrine alterations after masturbation-induced orgasm in women. Exton MS1, Bindert A, Krüger T, Scheller F, Hartmann U, Schedlowski M. Psychosom Med. 1999 May-Jun;61(3):280-9.
The Method etc.
In 1999, a group of mostly the same researchers decided to do the exact same test on 10 females that they had done for the males. The only real difference being that all the women were tested on the midfollicular phase of their menstrual cycle. Otherwise, the experimental design was exactly the same.
Results and Things
They also found in this study that there was a spike in prolactin in the blood sample representing what happened the the last 10 minutes of the porn movie where the women were required to masturbate to orgasm. All the women indicated they did indeed orgasm. The women were in complete privacy during this, so there was no information or discussion at all in the study regarding what the women were doing to themselves in order to elicit orgasm - except to say they masturbated. I would imagine it involved clitoral glans stimulation for most if not all the women given that in surveys that is how almost all women say they masturbate (Lloyd 24-25).
This study indicated that in both males AND females one might expect to see a spike in prolactin at orgasm. It further seemed to support the researcher's thoughts that a prolactin spike may be a marker of orgasm and also that it may be related to sexual satiation.
I wish they would have physically verified the orgasms, but at least they were masturbating which means odds are at least most of them did orgasm
This was also a simple and generally well thought out experiment, at least as well thought out as most orgasm related experiments. However, as always, I have to mention that any study involving female orgasm should always have a physical check to see if the involuntary muscle contractions that are known to release muscle tension and blood congestion at orgasm actually happened when a woman said she orgasmed. To be fair, I think it's sensible to assume at least most of the women in this study did in fact orgasm when they said they did because masturbation is a realistic way that women can physically elicit orgasm. Most women in surveys say they stimulate their clitoral glans/vulva area and that they do almost always or always orgasm. This is not the case, by far, for women and orgasms during partnered sex - particularly intercourse. (Lloyd 24-39). So, although I think this study would be better if they had verified the orgasms physically, I think the whole masturbation situation puts the odds in the women-probably-did-orgasm-when-they-said-they-did corner.
but, like, researchers still really do need to start verifying women's orgasm claims in their studies
However, in general, I'm unconvinced that a woman saying she orgasmed is a good way to mark orgasm in a scientific experiment. I think it is possible that any person could say they orgasmed when they in fact physically did not have the specific involuntary pelvic muscle contractions of orgasm, but I believe it is particularly likely for a woman due to a wide variety of factors including a lifetime of misinformation about her orgasm, incredible cultural pressure to fake orgasms, and a sexual culture that glorifies non-female-orgasmic acts and largely ignores the female organ of sexual pleasure (the clitoral glans). It creates a world where males tend to expect orgasm, physically understand how their orgasm happens, and orgasm quite frequently by themselves and with others....and for women it is just the opposite. Yet we act and speak as it is just the same as it is for males.
So, what I'm saying is women are confused about our orgasms and frankly if you are a researching our orgasms, you really should be checking to see if the involuntary muscle contractions that are pretty universally understood to mark orgasm are actually happening when we say that we orgasmsed. This did not happen in this study, but again, at least the conditions were good for women to orgasm.
The Male/Female Arousal Study
Neuroendocrine response to film-induced sexual arousal in men and women. Exton NG1, Truong TC, Exton MS, Wingenfeld SA, Leygraf N, Saller B, Hartmann U, Schedlowski M. Psychoneuroendocrinology. 2000 Feb;25(2):187-99. (you might be able to find the full text article available HERE)
So then in 2000, a research team that included 3 of the researchers from the previous 2 articles dug a little deeper. A scientific study is only a tiny slice of a truth, and to get really into a subject, lots of follow-up investigations are needed, so I very much appreciate this bit of extra investigation from this research team. Basically, they were testing whether it was just sexual arousal and not necessarily orgasm that caused that prolactin spike.
Method etc.
So, you know how in the above 2 studies they had people masturbating to a porn movie and just sitting and watching a non-erotic movie as the control? Well the control here was still sitting chill and watching a non-erotic documentary movie for 60 minutes, but the experiment was just sitting and watching the experimental movie which consisted of 20 min of the non-erotic doc, then 20 minutes of porn, and then another 20 minutes of the non-erotic doc. They did not masturbate though, so there was no physical sexual stimulation or the physical movement involved in masturbation, and there was, of course, no orgasm there to possibly affect the prolactin levels. It was just a comparison between arousal vs. non-arousal. Also to document if and how much the participants aroused during the sessions, they were each asked to rate their arousal at the beginning and end of both the control and experimental sessions and also after 40 minutes into the movie. For the experimental session, this would be right after the porn section, and they were asked to rate how aroused they felt during the middle of the porn section. 9 males and 9 females participated in this study and all of them felt sexual arousal during that time - with no significant difference between the males as a group and the females as a group. The experimental design was pretty much exactly the same as the previous 2 studies other than that.
Results and such
Turns out there was not a spike in Prolactin for either men or women just from being aroused. The researchers felt this study indicated it was the orgasm specifically and not just being aroused that caused the spike in prolactin, which seemed to further supported their hypothesis that a prolactin spike could be a marker for orgasm and that it indicates sexual satiation.
It still leaves questions about other variables though - more studies please!
I love that they did this study, and I think it is, like the others, as well done as any orgasm-related study I see. However, it would have been even better to have another variable in there. It would have been cool for the subjects to watch the porn movie and masturbate, but not to orgasm. If there was still no prolactin spike, it would indicate that physical sexual stimulation and the physical exertion of moving one's hands over their genitals and moving their body and hips was not related to the prolactin spike either (*they may have a later study like this for men. i'll update when I find it). Eliminating those physicality variables as well as the variable of simple arousal being cause for the prolactin spike would have given much stronger support for theorizing that orgasm specifically is the initiator of the prolactin spike.
It would have been even more cool if for each of the participants, the prolactin levels for almost-orgasming-but-not were compared to the the prolactin levels with a physically verified orgasm. This would help eliminate the possibility that a certain level of high arousal or something related to the immediate lead-up to orgasm causes the prolactin spike instead. It might also help understand if prolactin levels alone could be used to correctly identify whether or not the involuntary muscle contractions of orgasm had occurred (the orgasm claims gots to be physically verified, ya'll). This would help answer whether prolactin really could be used as a physical marker of orgasm. But...that's more studies, more time and more money, so I can understand why it hasn't yet happened, but I hope some nice researcher sees this and picks up the torch.
The Male/Female Intercourse Study
Coitus-induced orgasm stimulates prolactin secretion in healthy subjects. Exton MS1, Krüger TH, Koch M, Paulson E, Knapp W, Hartmann U, Schedlowski M. Psychoneuroendocrinology. 2001 Apr;26(3):287-94.
Then in 2001 a research group where 4 of the 6 had been involved in at least 1 of the articles above decided to check if prolactin levels also spiked in coitus (intercourse) induced orgasm. This is not a terrible study in that it has basic adherence to scientific method and could help expand understanding of the previous studies. However, it is also pretty shitty in that it ignores very practical problems.
Practical, should-be-obvious shit this study ignores (i.e why the hell would they expect 100% of the women in their study to come from intercourse when nothing would indicate that's a sensible expectation)
I am not exaggerating when I say it is common scientific knowledge that a 'coitus induced orgasm' is something that in studies only about 30% of women say they have ever had. That's not many women, and if you ask me, in a very practical sense, that 30% in reality is probably something closer to 0%. Why? Because 'coitus-induced' specifically means that the act of coitus, the act of moving the penis in and out of the vagina, is causing the orgasm, and frankly an orgasm caused through stimulation inside the vagina has literally never been physically verified (through checking for the involuntary muscle contractions of orgasm) in all of scientific literature - #truestory.
Yes, some women, and I think this is where the 30%ish numbers make more sense, do have orgasms during intercourse due to clitoral glans/vulva stimulation that happens simultaneously through grinding against the partners body, or manual/vibrator stimulation, or something, but that's not technically 'coitus-induced' even though I think women on studies might designate it that way.
Put that all together with the fact that women do often admit in surveys to faking orgasms and that media, sex ed and pop sex knowledge confuse the fuck out of everyone by regularly giving the incorrect impression that women are supposed to orgasm from intercourse - nay are more sexual/mature/healthy if they orgasm through intercourse. And, it's not crazy to imagine women may sometimes say they orgasm when they actually do not, whether it be because they are confused about what an orgasm is, feel pressure to be orgasmically 'normal', or a number of other sensible reasons.
ON THE OTHER HAND, when women masturbate, the percent of them that orgasm from it is closer to the 96% range - basically the same as men. There's lots of studies that corroborate those numbers I discuss above, but if you ask me, chapter 1 of Elisabeth Lloyd's 2006 book The Case of the Female Orgasm: Bias in the Science of Evolution has the most comprehensive look at the studies and numbers related to female orgasms during both masturbation and intercourse.
Point is, there's a drastic difference between rates of female orgasm during masturbation vs. during intercourse that would tell any researcher caring to pay attention that women can orgasm as easily as men, but when it comes to intercourse, they almost always don't...and they don't for a very simple and obvious reason - intercourse alone is a shit way to stimulate the the clitoral glans (i.e. female organ of sexual pleasure)
Dear lady-gasm researchers, do your background research, check your bias, and design better experiments
Which brings me to my major problem with this study; these researchers don't address this at all. They don't mention that coitus induced orgasms are statistically rare for women. They ignore all that very available info I just discussed and blindly assume that they can expect every one of the 10 women in their study to orgasm from intercourse, even though pretty much every available survey on the subject would indicate at least some of those 10 would not. That is either incredibly naive or intentionally negligent. Either way it ain't great experimental design.
I personally think the researchers got lucky and at least some of these women probably did orgasm during intercourse - probably through some clitoral stimulation happening during the ol' in and out, Honestly, though, neither I nor the researchers know for sure because the sexual acts in this study were completely private. The researchers don't know what exactly was physically happening during orgasm and they did not verify the claimed orgasms actually, physically occurred because the researchers did not take the additional step to measure the involuntary muscle contractions of orgasm.
So, right off the bat this study is weak in 2 important ways:
1. If the researchers really were trying to study 'coitus-induced' orgasms as they say they were, they failed to design the experiment appropriately to do that. They have no idea if there was additional clitoral stimulation that would negate a 'coitus-induced' designation.
2. They got unlikely results and didn't even question it. They should have statistically expected about three of these women to actually orgasm during intercourse, yet all 10 said they did. That's a red flag in the data that's left unanswered because they didn't physically verify those statistically unlikely orgasms actually happened. Any thoughtful reader should be extremely skeptical - especially given the researchers didn't seem to even be aware the results they got were so unlikely.
Method Details
Okay, so those are my issues. On to the details! This experiment had a similar layout to the previous ones, but obviously had some difference. Here is the researchers describing the experiment:
Each couple participated in four sessions (two experimental and two control sessions), and were informed of the sequence of sessions prior to participation. Each experimental session per couple focused on one partner (one 'male' and one 'female'), with care taken to ensure privacy for the participants during the experimental procedures. Each session commenced at 1500h . During the 'male' experimental session, the male partner (passive) laid on a comfortable bed in front of a video screen. The female (active) partner sat alongside. The reverse was the case for the 'female' experimental session. The experimental session comprised the viewing of three video sequences, each lasting 20 min. The first and last sections of the video were composed of emotionally neutral documentary film. The middle 20 min of experimental video was a pornographic film which displayed different heterosexual couples having sexual intercourse (Kruger et al, 1998, Exton et al., 1999, 2000). During the first 10 min viewing of the pornographic video (anticipatory phase), the active partner stimulated the passive partner sexually. Subsequently, the couple had intercourse until orgasm of the passive partner. All physical movement during coitus was conducted by the active partner to ensure that the endocrine changes were due specifically to sexual intercourse and orgasm, and not the general physical activity. Each couple also participated in two control sessions, which were conducted in the same environment and same time of day as the experimental sessions. However, during this phase the participants sat quietly whilst they watched a neutral documentary film for the entire 60 min. No physical contact occurred during this phase. (p 288-289)
They also add a blood test 40 minutes after the movie in this study to see if the prolactin is still high.
Results and discussion and stuff:
Did all these women really orgasm? My mind is blown.
So what the researchers found was that just like the male and female masturbation study, there was a prolactin spike in the blood taken during the 10 minute period that represented the last 10 minutes of the porn film/the intercourse/the orgasm for both males and females.
To tell the truth, I was kinda flabbergasted by this. I mean, in the previous masturbation studies, I thought the researchers had begun to make a good case for a prolactin spike maybe being a physical marker for orgasm specifically - not just arousal, and here I am with my skepticism (a healthy and completely valid skepticism though it may be) that many of these women would even orgasm in this situation anyway. Yet, I'm looking at what seems to be maybe some valid physical data that these 10 women did come during intercourse just like the men did. Granted, it doesn't in any way mean that these women orgasmed from penile stimulation inside the vagina (coitus-induced). These couples were in complete privacy and nothing in the study said they were forbade from stimulating the clitoris during intercourse, so it's not like this is proof of vaginal orgasm (i.e coitus or intercourse induced orgasm)...but still. It was rather surprising that all 10 of these random women actually physically orgasmed given that about 70% of women don't come during intercourse (ya know, because of a shit sexual culture where it's doesn't seem obvious or important to stimulate the clit during partner sex, much less intercourse).
Results and discussion and stuff:
Mmm...the data for the coitus-induced lady-gasms are maybe kinda sketchy
Anyway, my interest was piqued. So I started looking through it again, and I thought, well, the article never says that ALL the women had a spike, just that on average the women as a group had a spike that was significant over the women's prolactin levels during the control experiment. So, then I started looking a little closer at the graphs of the male and the female experimental vs. control prolactin levels...and then compared those to the same graphs but for the masturbation studies.
Now, I'm no statistician (like really I'm not, so correct me if I say something crazy), but the difference between the average prolactin levels between the experimental and control for women masturbators, male masturbators and male intercoursers had higher p values (was more statistically significant) than for the women intercoursers. Like, the graphs for the female masturbaters and both the male groups looked to me like the group prolactin increase was so much more clear between the data points before and after the orgasm than in the female intercoursers. The female intercoursers were the only group where the Standard Error (SE) in the data point (mean) for post orgasm prolactin level dipped down into the SE of the pre-orgasm data point. In fact the SE dipped so far down it went below the data point (mean) of the pre-orgasm prolactin levels.
And, I don't know what it exactly means, but I also think it's noteworthy and probably worthy of further investigation that women, in both the masturbation and intercourse studies have a little higher control baseline and seem to have an average prolactin increase in the experimental section even before the porn movie begins. Also, the intercourse study seems to have a higher prolactin control baseline than the masturbation studies for both sexes.
I (well my husband did actually) created a grouping of the prolactin level graphs from the male and female masturbation articles, the intercourse articles, and also arousal article for you to compare.^^
So, * means the p value is less than .05; ** means p value is less than .01; *** means p value is less than .001. In general a p value is statistically significant only if it is less than .05, and anything above .05 is not significant and would indicates weak evidence against the control. So it would seem, it seem in these graphs * is barely statistically significant, ** is more significant and *** is even more significant.
Also, I just want to mention this because I'm not sure what to make of it. The time frame where the participants are watching the last 10 minutes of the porn and were required to masturbate to orgasm, it's labeled in the men's masturbation study as 'orgasm' and in the women's as 'arousal'. It's just weird because the study is clear that the women orgasmed during that time and also the first 10 minutes of the porn where they just watched and didn't masturbate seems like a more appropriate place to label arousal. Anyway, it's strange. If you ever want more info about these graphs or this these articles, just hit me up btw.
Masturbating Male Study
Masturbating Female Study
Intercourse Males Study
Intercourse Female Study
Arousal Study
^^Just to be clear, I normally use a direct excerpt of graphs I'm discussing from articles, but I recreated them here. It was not because I wanted to trick you or change them in any way. They are basically exactly the same with different color elements and line types. It's just that I'm getting some help from an amazing and incredibly fab person in acquiring full articles to review, and given that they are behind a paywall and copyrighted, I promised I wouldn't copy excerpts from the articles. I've always felt fine about it before because I think it lays squarely in Fair Use laws, but I ain't no lawyer, and I will happily adhere if it means I can get better access to journal articles.
Results and discussion and stuff:
Why are we not talking about nipple stimulation? another complaint from me. I'd also like to point out something I imagine for people working with prolactin should be obvious; sucking on nipples can stimulate prolactin. Granted, most of the research on this is in relation to pregnant and nursing mothers, but it's what prolactin is maybe best known for, and it's truly not crazy to think maybe it could be important to this study and its experimental design. Yet the researchers don't even mention it, like not at all - not even to say they don't think it would matter.
But, what if in this intercourse experiment, when the woman is passively lying down with the man beside her 'sexually stimulating' her, he sucks on or manually manipulates her nipples? Or if her breast and/or nipples are stimulated while they are having intercourse? Neither I nor the researchers know if any of that happened because, as they stated, they were careful to allow complete privacy to the couple and nowhere in the study did anyone mention telling the subjects to avoid nipple stimulation. I mean why wouldn't they put some thought into the possibility that there would be some nipple play in these sessions and that it is a variable that could (maybe strongly) affect prolactin levels? I mean boob and nipple play is pretty basic sex stuff. To me, ignoring even the discussion of this possible connection seems scientifically negligent to me.
Results and discussion and stuff:
Cool study, but I think there's a hidden world inside that lady-gasm data
All in all, I think this is an interesting study that is severely weakened by an apparent lack of understanding of background data on female orgasm and bad experimental design.
First, the researchers put no thought into controlling for nipple stimulation in this study even though it certainly could occur in the experiment's private sexual activity and if it did, it could be an important variable affecting prolactin levels.
Second, the researchers ignored the possibility that a female might say they orgasmed when they physically did not and also ignored how statistically unlikely it would be that 100% of 10 random women all would orgasm during intercourse, so the result that all 10 women claim orgasm goes unquestioned in the study. That opens up space for valid skepticism that cannot be answered since the researchers didn't put in place a physical verification of the orgasm claims (check for involuntary pelvic muscle contractions, people!).
Thirdly, the prolactin increase for the women in this study was less statistically significant than the men's increase in this study as well as for both the men and women when masturbating.
Put those 3 things together and it paints a possible picture in my mind where only some of the women in this study actually physically orgasmed. I mean it's sensible to imagine, statistically speaking, at least 1/3 of these women orgasmed during intercourse through things like diddling the clit or grinding the clit against the male's pelvis during intercourse. So if prolactin spiking is a marker of orgasm as the studies seem to indicate, it's sensible to me that the women's group average would include some actual spikes because some women probably actually orgasmed - making the group average look like more of a spike than if none had, but depending on how many and how high their spikes were, it may or may not look statistically significant. And here's another thing. Maybe women, whether they orgasmed or not, who had nipple stimulation during the experiment had some extra level of increase in their prolactin during those 20 minutes of sexual activity. Maybe one wouldn't call it a spike, but it helped increase the group average to a level that showed a statistically significant increase over the control levels? Put that all together and it seems to me you'd get the kind of data we're seeing; a less significant increase for the group of women in the intercourse study and more SE overlap than was seen in the males of this study or the males and females of the masturbation study.
I could be way off base, I'm only speculating (although there's some statistical backing of that speculation) about whether women came or didn't or had their nipples sucked or didn't, but that's the point. The researchers didn't take the time to account for questions about these, if I do say so, quite valid variables and so it makes their data weak. Yeah, I might be wrong, but my thoughts also make some kind of sense, and with the information available I'm no more likely to be wrong than the researchers are.
The Brody Coitus-Induced vs. Masturbation Prolactin Level Comparison
The post-orgasmic prolactin increase following intercourse is greater than following masturbation and suggests greater satiety. Brody S1, Krüger TH. HBiol Psychol. 2006 Mar;71(3):312-5.
That brings us to the original paper I wanted to write this post about. I found it hard to describe my problems with it without discussing the papers it's based off of first, so that's why you have all of the above. Now let's talk about this dude and this paper.
Brody.
One of the authors is a dude named Stuart Brody. He wasn't an author in any of the previous 4 studies. No, as is his way, he just swooped into this because, I assume, he got a whiff of the possibility to assert vaginal orgasm superiority. Brody is an absolutely prolific scientific-paper-writer of all things supporting the idea that vaginal orgasms and unprotected p-in-v intercourse make for mentally/physically/psychologically healthier women.
Here's a list of his publications . Really start reading down that list for some fun.
This article.
Anyway, this is a tiny 4-page article that takes the 2 masturbation papers and the intercourse paper I just discussed and compares their data against each other. Brody co-authors this with Kruger, who is an author on all 3 of the papers being compared here. I don't know what Kruger's deal is, but co-authoring with Brody doesn't do much for my belief in a person's actual understanding of the existing scientific knowledge on female orgasm (sadly many of the big names in female orgasm research have hooked up with Brody, so that's what it is).
Anyway, Brody, always one to find a way to show that p-in-v intercourse is better for us than masturbation, had done studies in the past that he believes show 'vaginal orgasm' (i.e. coitus-induced orgasm) to be healthier for the ladies than the ol' clit stimulation that goes along with masturbation.
So, combining his own vag-gasms-are-better-for-health studies with the results of the prolactin studies above, the hypothesis in this study is that if you compare the data from the masturbation studies to the coitus studies, you'll find that even though there was a prolactin increase after orgasm during masturbation and during intercourse, the increase after intercourse should be much higher - indicating more satiation (you know, since intercourse induced orgasms are clearly the better orgasm even though most women mostly don't have orgasms during intercourse at all and stimulating the inside of the vagina like penises do during sex with no additional clit action has never been shown to induce physical orgasm in all of scientific literature, but whatever Brody - I guess vaginal orgasms will save us all or something).
So, low and behold, the authors concluded that they found that to be the case! Here's what they say in the discussion section.
For both sexes, penile-vaginal intercourse (adjusted for response to control conditions, the increase was about five times as great) post-orgasmic prolactin increase than did masturbation . The characteristic post-orgasmic prolactin increase reflects sexual satiety produced by a negative feedback loop (Kruger et al. 2002, 2003). The results imply that for both men and women, there is a neuroendorine indication of greater satiation following an intercourse orgasm than following a masturbation orgasm.
My criticism.
First off, I'll say it again, I'm no statistician, but what I do know is that statistics are only as good as the assumptions behind them. This article is quite short and nothing more than a bunch of numbers comparing the data in the 3 papers i discussed. I don't know enough to get deep into how the numbers were calculated and if those are appropriate ways to calculate those numbers for this situation, but I do know there's some fundamental concerns any thoughtful researcher should have with the data and conclusions in this article that simply are not addressed.
All research has some unanswered questions and weaknesses, and that's fine as long as it's acknowledged and addressed as much possible. However, the fact that they are not addressed makes me feel like the authors want to just skim over this stuff and create a nice pretty package, and that makes me think they are somewhere between problematically naive and intentionally negligent with their scientific inquiry.
Let me list my grievances:
1. All the problems with the data, assumptions about ladygasms, etc. I discussed regarding the intercourse study above applies here too. I mean if that study is weak, then a study based of that study is weak in all the same ways.
2. How do the authors know that a higher amount of prolactin actually correlates to a higher feeling of or physical level of satiation? I mean hormones and their interactions are hella complicated. Maybe there is a level to which satiation happens and anything over that doesn't have extra effect. Ya gotta prove that a 7 ng/ml increase is more satiating than a 5ng/ml increase - because it's not just obvious. And, what exactly does more satiated mean anyway? What's the difference between satiated and more satiated?
3. This is a vague concern of mine because, again, I'm no statistician, nor am I deeply knowledgeable about human hormone activity, but women in all these studies seem to have a higher level of Prolactin to begin with. I mean the authors kind of touch on this, but really just to mention it and then say it doesn't matter. But, does it not matter? Does the way they are testing the prolactin accurately reflect the active amount in the person's body? Do females and males tend to have different levels of prolactin inhibitors and activators in their blood that might affect the prolactin levels in these blood test and the level at which prolactin is fully active for sexual satiation? Also is it possible women's bodies have a different relationship to prolactin and just produce more and maybe producing more affects women physically or mentally differently, and then again, maybe it doesn't? Anyway, these are questions I would have for almost any study about hormones in blood samples, because it is a complicated business these hormones - particularly how to accurately test for and understand the impact of different amounts on our bodies.
Seriously, though, if you are a statistician, please post your thoughts on this. In fact if you are a statistician, I'd like to talk with you in detail. I feel like I need to take a stats class, or partner with a bad ass statistician on these.
My final words on the non-Brody studies
So, in conclusion...I think the 4 studies (not Brody's) I talk about above are interesting, mostly careful studies that begin to give real evidence that a prolactin spike could be a marker for orgasm. In fact, this research team continues on this path of investigation, and although I don't see any more that specifically work with ladygasms, there's definitely more articles worth checking out if you're interested in this idea of prolactin as a possible marker for orgasm. I linked 4 at the bottom of this article where you can read the full text for free. Anyway, respect to these researchers even if they fall into the same problems most lady-gasms researchers fall into and even if one of them did partner with Brody. I do appreciate their work. However, particularly the intercourse study, has some problems, and I do have questions and hopes for further studies.
For instance:
Why didn't the researcher think to physically verify orgasms or at least mention that they couldn't or chose not to for some reason? As always I would like to strongly advocate for physical verification of the involuntary muscle contractions of orgasm for any claimed orgasms in a study. I know it's more work, but not doing it is a surefire way to skew the data and weaken conclusions.
Does every person that has a physically verified orgasm also have that prolactin spike? Is that prolactin spike clear enough on its own to identify physically verified orgasms?
Did every person that said they orgasmed in these studies actually show that steep increase or did some not show that steep of an increase yet showed enough to not mess up the trend of increase in the full group? Like I discussed earlier, I think it is sensible to wonder if some of the women in the intercourse study did not physically orgasm even though they said they did, and maybe did not show that steep prolactin increase - which is maybe what caused the average group increase to be somewhat less significant than the men or the masturbating women.
Is the prolactin increase after/during orgasm enough different than the increase caused by the arousal and physical movement of getting right to the point of orgasm but not orgasming? That data doesn't exist yet, but would be insightful.
What affect on prolactin release does sexual nipple stimulation have? Babies sucking on nipples absolutely releases prolactin in women. Does nipple stimulation affect the data on prolactin release and orgasm in any important ways in women - or in men? We don't have that data either.
My final words on the Brody article
This article blindly ignores all the, I must say fairly obvious, issues I discussed about the intercourse article. Plus it sets its hypothesis upon an unsubstantiated theory that more prolactin in the body creates more satiation. It might (whatever more satiation exactly is) but there also might be a point were more prolactin is just more prolactin. I get that it's worth considering if more prolactin means more satiation, but I find it incredibly negligent that the authors don't even acknowledge that a weakness of their conclusion is that they simply don't know for sure whether you can keep upping sexual satiation by simply upping prolactin.
Also...to be honest, I wonder how appropriate the statistical analysis they did in this study is for the situation. And that's just, like, my no-statistics-knowing opinion man - and opinions, as we all know, are like assholes, but the whole blindly-follow-all-routes-to-proving-vag-gasm-superiority-and-ignoring-anything-that-might-weaken-my-conclusions vibe of Brody and this article makes me feel slightly okay with questioning some statistical shit I have no idea about. If I may be so bold to say so, I believe it was initiated not out of genuine scientific interest, but out of a bit of an obsession with hyping up 'vaginal orgasms', intercourse, and oddly enough barebacking (he writes about it a fair amount).
Don't get me wrong. I'm not actually against bias in scientific inquiry. I'm not. I'm actually for it and believe it is inevitable and can be a powerful tool for scientific growth, but an area of study needs a lot of different people and studies with a lot of different perspectives working against and with each other. Otherwise you don't get healthy criticism and debate, but a skewed, weak, and maybe deeply flawed field of knowledge. I think overall the field of female orgasm research is closer to the latter and Brody articles are some of the worst of it.
Links to some other Full Text Articles about Prolactin and orgasm by this team
Absence of orgasm-induced prolactin secretion in a healthy multi-orgasmic male subject. Haake P1, Exton MS, Haverkamp J, Krämer M, Leygraf N, Hartmann U, Schedlowski M, Krueger TH. Int J Impot Res. 2002 Apr;14(2):133-5.
Orgasm-induced prolactin secretion: feedback control of sexual drive? Krüger TH1, Haake P, Hartmann U, Schedlowski M, Exton MS. Neurosci Biobehav Rev. 2002 Jan;26(1):31-44.
Specificity of the neuroendocrine response to orgasm during sexual arousal in men. Krüger TH1, Haake P, Chereath D, Knapp W, Janssen OE, Exton MS, Schedlowski M, Hartmann U. J Endocrinol. 2003 Apr;177(1):57-64.
Effects of acute prolactin manipulation on sexual drive and function in males. Krüger TH1, Haake P, Haverkamp J, Krämer M, Exton MS, Saller B, Leygraf N, Hartmann U, Schedlowski M. J Endocrinol. 2003 Dec;179(3):357-65.
Also this was referenced above:
Llyod, Elisabeth A. The Case of the Female Orgasm: Bias in the Science of Evolution. Harvard University Press. 2005.