Did this study replicate Voon et al.?
When exposed to cues, hypersexuals had greater brain activity, compared to controls in all brain regions of interest. So yes it did, but the only region both studies had in common was the dorsal anterior cingulate cortex.
- Voon studies addressed these brain regions: ventral striatum, dorsal anterior cingulate cortex, and amygdala.
- Seok & Sohnaddressed these brain regions: thalamus, right dorsolateral prefrontal cortex (DLPFC), left caudate nucleus, right supramarginal gyrus, and right dorsal anterior cingulate gyrus
In addition, and important, is the cue exposure:
- Voon used 9-second videos as the cue,
- Seok & Sohn used 5-second exposure to still images.
- Kuhn used .530 seconds to photos
- Prause et al used 1.0 second exposure to photos
Key Points
1) I find it odd that Seok and Sohn omitted the ventral striatum (nucleus accumbens), as that is one place every study assesses for cue reactivity. That said, their research adds evidence from other brain regions.
2) Seok and Sohn had really telling results for the DLPFC in hypersexuals: a) It lit up for porn, b) but the response dropped below baseline for neutral pictures. This response perfectly matches drug addiction: the DLPFC lights up for drug cues, yet has lower activity for normal rewards. The discussion calls it “altered activation in the PFC“. This excerpt expands on it:
“In particular, these studies have identified the disrupted function of DLPFC as an impairment in salience attribution, which results in symptoms, such as the abnormally increased sensitivity to an addictive cue as in substance and addicted behaviors and decreased interest to normal-rewarding stimuli”
3) In this excerpt Seok and Sohn suggest their findings don’t align with Kuhn (but I disagree):
In a study of the neural responses associated with pornography consumption, frequent activation as a result of pornography exposure might result in the wearing down and downregulation of the striatum, including the caudate nucleus, in healthy controls (Kühn and Gallinat, 2014). However, in the current study, greater activation was observed in the caudate nucleus in the PHB group, even though the PHB group watched pornography more often
Apples and oranges: Kuhn described less gray matter volume in the caudate, not less activation. Kuhn reported more porn use correlating with less activation of the putamen.
4) Seok and Sohn then suggest that the above difference might be due to differing subjects:
These differences between the results of the present study and those of Kühn and Gallinat (2014) might be explained by the difference in the participants. That is, in contrast to the use of healthy male adults in the previous study, our study was conducted on individuals with PHB.
This brings up a larger issue: Why do Prause et al and Kuhn & Gallinat both report LESS brain activation to so-called cues, while Voon and this study report GREATER activation to so-called cues. The reasons given so far: a) difference in stimuli, b) differences in subjects.
- Stimuli for LESS brain activation: Kuhn – .530 seconds photos; Prause – 1.0 second photos.
- Stimuli for MORE brain activation: Voon – 9 seconds of film; Seok – 5 seconds of photo.
Unsolvable conundrum: We cannot compare the current studies with cue-reactivity drug studies. Viewing porn is the addictive behavior for a porn addict. On the other hand, one could make an argument that viewing porn is also a cue…for viewing more porn. But is it?
The ‘difference in stimuli’ argument would say that more time (especially film) leads to cue reactivity. But does that hold water when even subliminal sex images alter brain activity? Just wondering.
The ‘difference in subjects’ argument would suggest that heavy porn users are desensitized/habituated (less response), while addicts are not desensitized/habituated (greater brain response). Since that is not the case, the argument would be that cue reactivity (incentive salience) momentarily overcomes habitation to produce greater reward system activity. A very plausible scenario, considering that Voon also found faster habituation in her latest study (Banca et al.)
The ‘difference in subjects’ could also work if Voon and Seok subjects were true hypersexuals and not pure “porn addicts” (not engaging much with partners). That was definitely the case for Seok, as their subjects were taken from treatment facilities and had many more sexual partners, and far greater sexual activity than controls. Voon’s subjects were technically hypersexuals: scored high hypersexuality questionnaires, some were referred from therapists, and all experienced severe negative effects. That said, I think Voon’s group was more mixed, with a few that were largely hooked on porn – and not engaging with partners.
It could be that photos could be a strong cue for a hypersexual whose most arousing activity involves acting out (prostitutes, sex clubs, etc). The photo could trigger thoughts/urges about a real-life scenario. On the other hand, a photo for a heavy porn user who is not yet fully addicted, and/or who never acts out (maybe never has sex), would seem dull and a bit of a disappointment. His dopamine would drop because he’s used to video sessions and his expectations were not met (a negative reward prediction).
Finally, maybe we cannot compare the Voon findings (film) to any other study as all the other studies used still images.
I think the big problem facing these types of studies is to make sure the subjects are as homogenous as possible. Either have 1) hypersexuals whose problems revolve around acting out or 2) porn addict who never act out and only use porn. And do not mix the two.
Did This Study Replicate Kuhn/Gallinat?
Sort of – in that both studies implicate alterations in the dorsolateral prefrontal cortex (DLPFC), a very significant region related to addiction.
Kuhn reported less “functional connectivity” correlating with more porn use (excerpts):
Functional connectivity of the right caudate to the left dorsolateral prefrontal cortex was negatively associated with hours of pornography consumption.
We found that a region within the left dorsolateral prefrontal cortex (DLPFC) (Figure 1C) was negatively associated with PHs, implicating that participants who consumed more pornographic material had less connectivity between the right caudate and left DLPFC
Seok & Sohn reported greater activation to sexual images, but far less activation to “normal stimuli” (excerpts):
In the current study, the observation of greater DLPFC activation in the PHB group compared to the control group might reflect excessive salience attribution to sexual cues.
Similar to the findings of studies on neural activity in individuals with addiction during cue-induced desire, we found altered PFC function in the PHB group.
They don’t clearly describe “less activation to normal stimuli”, yet the figure 2, picture B shows this. And they say the following:
In particular, these studies have identified the disrupted function of DLPFC as an impairment in salience attribution, which results in symptoms, such as the abnormally increased sensitivity to an addictive cue as in substance and addicted behaviors and decreased interest to normal-rewarding stimuli
I think Seok & Sohn provide very strong evidence for “sex addiction”. The subjects were all “sex addicts”, and these men had
- far greater cue reactivity in all regions of interest, and
- their prefrontal cortex reaction (greater cue reactivity to sex, but inhibited for natural rewards) mirrors drug addiction.
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