Idiopathic and acquired pedophilia as two distinct disorders: an insight from neuroimaging

Sexual offenses and the brain

Sexual offenses are a great concern worldwide due to the devastating physical and psychological consequences the victims of such crimes often experience. It is an important task to investigate potential mechanisms that may underlie sexual offending and predispose an individual for such antisocial behavior. Advanced techniques in neuroscience are increasingly used to uncover biomarkers in psychiatric disorders and organic brain disease. As this type of research is flourishing, preliminary studies with the aim to explore the neural basis of sex offenders have started to appear. To this purpose, researchers began to study the brain's structural and functional changes and the neurocognitive profiles of sex offenders, in comparison to nonoffenders and nonsex offenders, or among different subtypes of sex offenders. Most of the research to date has focused on pedophilia, with some inconsistent findings, which hampers the translation of the results into the forensic and clinical context. Any attempt to increase convergent evidence may profit from the harmonization of data analysis and avoidance of methodological inconsistencies, which can account for the different results across studies. Today, uncovering the neural basis of sex offences has to become a priority, not only for clinical interventions, but might also be important knowledge for crime prevention.

Patterns of risk-Using machine learning and structural neuroimaging to identify pedophilic offenders

Background

Child sexual abuse (CSA) has become a focal point for lawmakers, law enforcement, and mental health professionals. With high prevalence rates around the world and far-reaching, often chronic, individual, and societal implications, CSA and its leading risk factor, pedophilia, have been well investigated. This has led to a wide range of clinical tools and actuarial instruments for diagnosis and risk assessment regarding CSA. However, the neurobiological underpinnings of pedosexual behavior, specifically regarding hands-on pedophilic offenders (PO), remain elusive. Such biomarkers for PO individuals could potentially improve the early detection of high-risk PO individuals and enhance efforts to prevent future CSA.

Aim

To use machine learning and MRI data to identify PO individuals.

Methods

From a single-center male cohort of 14 PO individuals and 15 matched healthy control (HC) individuals, we acquired diffusion tensor imaging data (anisotropy, diffusivity, and fiber tracking) in literature-based regions of interest (prefrontal cortex, anterior cingulate cortex, amygdala, and corpus callosum). We trained a linear support vector machine to discriminate between PO and HC individuals using these WM microstructure data. Post hoc, we investigated the PO model decision scores with respect to sociodemographic (age, education, and IQ) and forensic characteristics (psychopathy, sexual deviance, and future risk of sexual violence) in the PO subpopulation. We assessed model specificity in an external cohort of 53 HC individuals.

Results

The classifier discriminated PO from HC individuals with a balanced accuracy of 75.5% (sensitivity = 64.3%, specificity = 86.7%, P ₅₀₀₀ = 0.018) and an out-of-sample specificity to correctly identify HC individuals of 94.3%. The predictive brain pattern contained bilateral fractional anisotropy in the anterior cingulate cortex, diffusivity in the left amygdala, and structural prefrontal cortex-amygdala connectivity in both hemispheres. This brain pattern was associated with the number of previous child victims, the current stance on sexuality, and the professionally assessed risk of future sexual violent reoffending.

Conclusion

Aberrant white matter microstructure in the prefronto-temporo-limbic circuit could be a potential neurobiological correlate for PO individuals at high-risk of reoffending with CSA. Although preliminary and exploratory at this point, our findings highlight the general potential of MRI-based biomarkers and particularly WM microstructure patterns for future CSA risk assessment and preventive efforts.

Abnormal behavioral and neural responses in the right dorsolateral prefrontal cortex during emotional interference for cognitive control in pedophilic sex offenders

Studies within the last decade have reported neural and behavioral differences in cognitive control between men with the pedophilic disorder who commit (CSO+) and do not commit (CSO-) child sexual abuse. Prior studies reported a higher number of errors in Go/Nogo task and lower activity of the prefrontal cortex in NoGo trials, in CSO+ compared with CSO-. Moreover, negative mood was reported as a risk factor for child sexual abuse in pedophilic men. We aimed to examine differences in brain function and behavior between CSO+ and CSO- patients regarding emotional interference on cognitive processes and inhibition. We recruited CSO+ (n = 11) and CSO- (n = 14) patients as well as matched healthy controls (HC) (n = 17). Participants performed the affective Go/NoGo task in a block-design functional magnetic resonance imaging experiment. The task comprised the following four conditions: Negative Go, including only Go stimuli and negatively valenced pictures; Negative NoGo, including 50% of Go and 50% of NoGo trials as well as negatively valenced pictures; and two corresponding conditions with neutral pictures. Brain analysis was restricted to the dorsolateral prefrontal (DLPFC), orbitofrontal, and anterior cingulate cortices. The HC and CSO- groups, but not the CSO+ group, showed significantly slower reactions in negative blocks compared with neutral blocks. Brain analysis revealed increased activation in the right DLPFC during emotional interference contrast (Negative > Neutral) in the HC and CSO- groups; however, there was decreased activation in the CSO+ group. In the CSO+ group, negative distractors did not increase cognitive control processes, which was observed in the CSO- and HC groups at the behavioral and neural levels. These results support previous reports indicating offender status is associated with cognitive and emotional impairments.

Interference inhibition in offending and non-offending pedophiles: A preliminary event-related fMRI study

The ability to inhibit behavior is thought to be an import skill for avoiding criminal conduct, especially when combined with personal predispositions or criminogenic needs such as a pedophilic preference disorder. While previous research emphasized the relationship between impulsivity and child sexual offending, not pedophilia per se, studies on the underlying neurobiological mechanisms in subdomains of impulsivity remained scarce. Here, we focused on interference inhibition and examined event-related functional magnetic resonance imaging (fMRI) data of three groups of men performing a color-word Stroop task: (1) pedophiles with a history of CSO (P+CSO, n = 11), (2) pedophiles without a history of CSO (P-CSO, n = 8) and (3) non-pedophilic, non-offending healthy controls (HC, n = 10). On the behavioral level, P+CSO revealed increased Stroop interference as compared to P-CSO and HC. Moreover, increased Stroop interference in P+CSO was accompanied by enhanced conflict-related activity in left superior parietal cortex and precentral gyrus as compared to P-CSO. Albeit behavioral analyses of error and post-error processing revealed no significant between-group differences, P-CSO showed increased post-error-related activity in left posterior cingulate, precuneus and middle temporal gyrus as compared to P+CSO. Our preliminary data highlight inhibition deficits in offending as compared to non-offending pedophiles or healthy men and suggest that functional alterations in attention reallocation and impulse suppression/control may moderate the risk for committing CSO in men suffering from pedophilia.

A case of developmental pedophilia unmasked by frontotemporal dementia

A 65-year-old right-handed man gradually became socially indifferent and less active. Four years later, he was indicted for molesting children on multiple occasions. Psychomotor slowness and executive impairment contrasted with sparing of language, semantic memory, visuospatial perception, construction praxis, and right-left orientation. Neuroimaging showed asymmetric atrophy of dorsomedial frontal and anterior temporal lobes, and hypoperfusion of medial prefrontal cortex consistent with a diagnosis of behavioral variant of frontotemporal dementia. Further information revealed that the patient exhibited pedophilic behavior several years prior to symptom onset. We conclude that preexisting developmental pedophilia was "unmasked" by the underlying progressive frontotemporal degeneration.

Translational Application of a Neuro-Scientific Multi-Modal Approach Into Forensic Psychiatric Evaluation: Why and How?

A prominent body of literature indicates that insanity evaluations, which are intended to provide influential expert reports for judges to reach a decision "beyond any reasonable doubt," suffer from a low inter-rater reliability. This paper reviews the limitations of the classical approach to insanity evaluation and the criticisms to the introduction of neuro-scientific approach in court. Here, we explain why in our opinion these criticisms, that seriously hamper the translational implementation of neuroscience into the forensic setting, do not survive scientific scrutiny. Moreover, we discuss how the neuro-scientific multimodal approach may improve the inter-rater reliability in insanity evaluation. Critically, neuroscience does not aim to introduce a brain-based concept of insanity. Indeed, criteria for responsibility and insanity are and should remain clinical. Rather, following the falsificationist approach and the convergence of evidence principle, the neuro-scientific multimodal approach is being proposed as a way to improve reliability of insanity evaluation and to mitigate the influence of cognitive biases on the formulation of insanity opinions, with the final aim to reduce errors and controversies.