It's All in Your Mind. Maybe
Dr. Diamond and his colleagues ran MRI scans of 19 pre-menopausal women who had been diagnosed with HSSD and 7 women who had comparatively high sex drives (a very small sample, but not unusual for MRI studies). The women's brains were scanned while they watched a television screen which alternated between showing neutral programming and erotica. The researchers found that the insular cortex in women who did not have HSSD lit up during erotic scenes while those of women with HSDD did not. The conclusion that's being touted by the researchers is that HSDD is a real disease with real physiological causes, not something that's "only in the mind," which seems like kind of a weird thing to conclude from a study that only looked at responses in the brain.
Technically speaking they're right of course, anything that affects the brain is physiological, despite our tendency to think of it as something separate from our physical bodies. But there's nothing in the news reports that indicates that the differences in how women with HSDD's brains react to erotic stimuli give any clue as to the source of the problem. It could in fact originate in the mind, just as depression does, for example, or it could be caused by something more global, like a hormonal imbalance. In fact, it seems most likely that there is actually more than one cause for HSDD, since many things, such as depression, hormonal birth control, and polycystic ovary syndrome are known to affect women's libidos. Any of those things could be expected to produce the brain patterns seen in the study, since by definition having a low libido means subjects will not respond strongly to sexual stimuli. The researchers themselves don't appear to be claiming that the brain effects they see are the cause of the disorder, but many outlets are reporting it that way, which is frustrating because it's misleading. Even as the media is telling women their problem is real, they're also sort of backhandedly saying it is, actually, all in their minds.
Another thing that bothers me about the news reports on this issue is the slightly sexist slant they take. Men can and do suffer from low sex drives as well, but no such studies seem to have been done to determine if the cause lies in their brain. Rather, Doctors are more likely to look for things like low testosterone levels, prostate issues, or pituitary tumors. It's telling that researchers look at women's brains and men's bodies for what is essentially the same problem. I suspect that men with low sex drives would also not respond as strongly to erotica as men with high sex drives, but nobody is testing that. Scientists are human, and they bring their own biases into their research, especially when the subject involves human behavior in any way. Take for example, the way the brain activity is interpreted. The news reports state that the area of the brain that lights up in sexually responsive women is involved in processing and interpreting emotion, but it is also involved in perception of the body's state and motor control, as well as a host of other things. The results are framed as an emotional effect (typical women, it's all about emotions!), when they could just as easily have to do with miscommunication between the body and the brain. (The insular cortex, by the way, is also involved in the sensation of pain, and it lights up when subjects look at images of painful events. It would make sense if the sexual arousal response behaved similarly). Maybe the actual study has more detail on this, as well as information on other parts of the brain that may react differently in women with HSDD and those without it, but without seeing the study itself, it seems like the associations being drawn are inherently sexist.
It's probably going too far to say that these results detect anything more than a symptom of low sex drive - the lack of response to visual sexual stimuli - at least based on the information present in the news. The difference in brain response does indicate that this disorder is a general problem with arousal and not indifference to a particular partner. That may not help much in treating the issue, but it might be comforting for both women who suffer from the disorder and their partners, since a person's low sex drive can lead to their partner feeling rejected and cause a significant strain on relationships (and it's just as bad when the person with the low sex drive is male, which is one of the reasons I wish the medical community didn't think of this as a problem that affects only one sex). On the other hand, if these results hold up in further studies they may provide a way to detect if treatment for the disorder is working. It's likely that drugs to treat HSSD will continue to take the route that flibanserin attempted, by tackling the brain (flibanserin was originally intended as an anti-depressant), so knowing which part of the brain is primarily affected by low sex drive might be useful, though that's a very big might, since knowing which part of the brain is affected and knowing how to target that part of the brain are two different things. In the meantime, at least women (and men) suffering from HSSD have evidence that the problem is a physiological issue and not imaginary, even if it does turn out to be all in their heads.
Dr. Pisaster has a doctorate in biophysics, not actually anything sexy. She does however enjoy having sex, reading about sex, and talking about sex. Especially when she's had a little whiskey.