Association between brain structure and phenotypic characteristics in pedophilia

Abstract

Studies applying structural neuroimaging to pedophiles are scarce and have shown conflicting results. Although first findings suggested reduced volume of the amygdala, pronounced gray matter decreases in frontal regions were observed in another group of pedophilic offenders. When compared to non-sexual offenders instead of community controls, pedophiles revealed deficiencies in white matter only. The present study sought to test the hypotheses of structurally compromised prefrontal and limbic networks and whether structural brain abnormalities are related to phenotypic characteristics in pedophiles. We compared gray matter volume of male pedophilic offenders and non-sexual offenders from high-security forensic hospitals using voxel-based morphometry in cross-sectional and correlational whole-brain analyses. The significance threshold was set to p < .05, corrected for multiple comparisons. Compared to controls, pedophiles exhibited a volume reduction of the right amygdala (small volume corrected). Within the pedophilic group, pedosexual interest and sexual recidivism were correlated with gray matter decrease in the left dorsolateral prefrontal cortex (r = -.64) and insular cortex (r = -.45). Lower age of victims was strongly associated with gray matter reductions in the orbitofrontal cortex (r = .98) and angular gyri bilaterally (r = .70 and r = .93). Our findings of specifically impaired neural networks being related to certain phenotypic characteristics might account for the heterogeneous results in previous neuroimaging studies of pedophilia. The neuroanatomical abnormalities in pedophilia seem to be of a dimensional rather than a categorical nature, supporting the notion of a multifaceted disorder.

Connectivity and functional profiling of abnormal brain structures in pedophilia

“…However, OFC dysfunction has been assumed to account for impaired executive functions, particularly response inhibition, in pedophilia [Schiffer and Vonlaufen, ]. This assumption is in line with the correlation of our seed's anatomical features with executive functions in healthy subjects [Takeuchi et al, ] and its structural alteration in pedophilia [Poeppl et al, ]. Moreover, these morphology‐based inhibitory deficits in pedophiles should also impact the sexual domain, given the mOFC's contribution to tonic inhibition of sexual arousal [Stoléru, ].…”

“…(3) Left insular cortex , whose GM volume was found to be reduced in pedophiles [Schiffer et al, ], to be inversely correlated with pedosexual interest and sexual recidivism [Poeppl et al, ] and to abnormally respond to visual sexual stimulation [Poeppl et al, ; Walter et al, ]. (4 and 5) Left and right temporoparietal junction that featured the less GM in pedophilic perpetrators, the younger their victims [Poeppl et al, ], as well as pedophilia‐related dysfunction in a sexual context [Poeppl et al, ; Walter et al, ]. (6) Medial orbitofrontal cortex (mOFC) , whose GM volume showed the same relationship to victim age as the TPJ [Poeppl et al, ], and which was differentially activated in pedophiles during visual sexual stimulation [Schiffer et al, ,b].…”

“…(4 and 5) Left and right temporoparietal junction that featured the less GM in pedophilic perpetrators, the younger their victims [Poeppl et al, ], as well as pedophilia‐related dysfunction in a sexual context [Poeppl et al, ; Walter et al, ]. (6) Medial orbitofrontal cortex (mOFC) , whose GM volume showed the same relationship to victim age as the TPJ [Poeppl et al, ], and which was differentially activated in pedophiles during visual sexual stimulation [Schiffer et al, ,b].…”

“…These qualitative neurological case reports have been complemented by quantitative voxel-based morphometric studies that demonstrated volume reductions of the right amygdala, hypothalamus, and septal regions [Poeppl et al, 2013;Schiltz et al, 2007], structural deficits of temporal cortices and fiber bundles [Cantor et al, 2008;Schiffer et al, 2007], and morphologic abnormalities of OFC and basal ganglia [Schiffer et al, 2007]. Further alterations appeared in areas in the parietal lobe [Cantor et al, 2008;Schiffer et al, 2007] as well as the cingulate cortex, insula, and cerebellum [Schiffer et al, 2007], when comparing pedophilic with nonpedophilic men.…”

Evidence for superior neurobiological and behavioral inhibitory control abilities in non-offending as compared to offending pedophiles

“…However, up to now, studies addressing the neurobiological correlates in this regard are scarce and most of them showed inconsistent results [Mohnke et al, ; Tenbergen et al, ]. The only replicated finding is limited to an amygdala volume reduction in offending pedophiles [Poeppl et al, ; Schiffer et al, ; Schiltz et al, ], although other authors using more stringent type‐1 error correction did not corroborate this result [Cantor et al, ; Cantor et al, ; Gerwinn et al, ], suggesting insufficient effect sizes of the aberrant amygdala volume. In addition, there are studies reporting evidence for frontocortical neural dysfunction in pedophiles with a history of CSO (P + CSO) as indicated by regionally decreased brain volume [Mendez and Shapira, ; Schiffer et al, ], impaired neuro‐cognitive functions [Kruger and Schiffer, ; Schiffer and Vonlaufen, ], as well as altered activity in prefrontal areas comprising the orbitofrontal cortex (OFC) [Habermeyer et al, ], dorsolateral prefrontal cortex (DLPFC) [Schiffer et al, ], and the anterior cingulate cortex (ACC) [Schiffer et al, ] during the processing of sexual stimuli.…”