EP 80. Sexual processing of pedophilic patients and healthy controls and the role of its metabolic markers - A fMRI and MRS study

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• 作者：I. Ristow^a ; ; S. Li^b ; R. Demenescu^a ; L. Colic^a ; M. Li^a ; H. Walter^c ; K. Beier^d ; T. Krü ; ger^e ; B. Schiffer^f ; J. Ponseti^g ; M. Walter^a
• 刊名：Clinical Neurophysiology
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：127
• 期：9
• 页码：e273
• 全文大小：102 K

文摘

We aimed to investigate differential activation patterns in brain areas subserving attentional control of behavior and perception of salient stimuli in pedophilia using ultra-high magnetic resonance imaging (fMRI). Moreover, we wanted to measure whether behavioral inhibition deficits can be observed in those brain regions on the level of inhibitory neurotransmitter using magnetic resonance spectroscopy (MRS). Previous neuroimaging studies underlined the crucial role of the dorsalanterior cingulate cortex (dACC) in sexual anticipation processes, impulse control, reward based decision making as well as in attention modulation

We designed a paradigm to expose whether pedophilic patients show any different effects when expecting pictures of naked children in comparison to healthy controls. We hypothesized stronger dACC responses in pedophilic patients during expectancy of naked children pictures, compared to healthy controls. During expectancy of naked adult pictures we hypothesized inverse activation patterns in both groups. Furthermore, we assumed that child sexual offending may be linked to decreased GABA levels in dACC.

Methods

13 pedophilic patients and 13 age-, gender- and handedness matched healthy controls underwent a 7 Tesla MRI. Seven patients were under antiandrogen therapy causing a lower testosteron level. All

patients had committed sexual offenses against children. The number of victims sexually assaulted by the offenders ranged from 1 to 13 (mean: 5, 62 ± 3,61). Subjects percieved pictures of naked adults and naked children in a randomized order. Half of the pictures were preceded by an expectancy cue. Participants were instructed to actively expect a picture depending on the cue (↑ = adult, ↓ = child). MRS data was acquired during rest before the expectancy task. MRS data was obtained using STEAM sequence and analyzed using LCModel. fMRI data was preprocessed and analyzed (two-sample t-test) in SPM8 and SPSS20.0.

Results

1) Patients showed stronger dACC activation than healthy controls when expecting child pictures as compared to expecting adult pictures (two sample t-Test, covariate of no interest: age, p < 0.05 (FWEc)).

2) Pedophiles show reduced GABA in dACC compared to healthy control subjects: One-way ANOVA controlling for age and gray matter content revealed significant effect for group on dACC GABA levels (p < 0.05). Posthoc t-test revealed that patients had significantly lower GABA/Cr in dACC (p < 0.05).

Conclusion

Pedophiles with a history of child sexual offending show abnormal BOLD signal changes during anticipation processes in brain areas associated with cognitive control and attention in. In our study the activity in dACC is a predictor for the sexual salience of the following pictures. Functional abnormalities in dACC overlap with abnormal GABAergic metabolism in pedophilic patients. MRS results reveal significantly lower GABA levels in dACC which may be seen as a neuronal correlate of disinhibition. We assume lower GABA levels being associated with a decreased ability to control motor responses and sexual drives.