Studies of brain damage and dysfunction in sex offenders

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.

The neuropsychology of sex offenders: a meta-analysis

Typically, neuropsychological studies of sex offenders have grouped together different types of individuals and different types of measures. This is why results have tended to be nonspecific and divergent across studies. Against this background, the authors undertook a review of the literature regarding the neuropsychology of sex offenders, taking into account subgroups based on criminological theories. They also conducted a meta-analysis of the data to demonstrate the cognitive heterogeneity of sex offenders statistically. Their main objective was to test the hypothesis to the effect that the neuropsychological deficits of sex offenders are not broad and generalized compared with specific subgroups of participants based on specific measures. In all, 23 neuropsychological studies reporting data on 1,756 participants were taken into consideration. As expected, a highly significant, broad, and heterogeneous overall effect size was found. Taking subgroups of participants and specific cognitive measures into account significantly improved homogeneity. Sex offenders against children tended to obtain lower scores than did sex offenders against adults on higher order executive functions, whereas sex offenders against adults tended to obtain results similar to those of non-sex offenders, with lower scores in verbal fluency and inhibition. However, it is concluded that neuropsychological data on sex offenders are still too scarce to confirm these trends or to test more precise hypotheses. For greater clinical relevance, future neuropsychological studies should consider specific subgroups of participants and measures to verify the presence of different cognitive profiles.

Toward a neuropsychology of personality in sex offenders against children: an exploratory psychometric study

Little is known about the relationship between neuropsychological functioning and normal personality in sex offenders. The aim of this study was to examine the relations between personality traits and executive functioning in child molesters. The NEO-Five Factor Inventory was used to assess personality, and the Trail Making Test (parts A and B) was used to assess executive functioning in a sample of child molesters (n = 33). We found the time required to complete Trail Making Test part A significantly predicted Extraversion scores, whereas the time to complete Trail Making Test part B significantly predicted Openness scores. Brief measures of executive functioning can thus predict the score in Extraversion and Openness in child molesters. These personality traits may be related to the functioning of brain areas implicated in having to complete the Trail Making Test.

Executive function profiles of pedophilic and nonpedophilic child molesters

There is increasing evidence of neurocognitive dysfunction among child molesters, supporting the notion of brain anomalies among pedophiles. However, approximately half of child molesters are not pedophilic (i.e., are not primarily attracted to children), and neurocognitive differences between pedophilic (PED) and nonpedophilic (NPED) child molesters are not well understood. The purpose of this study was to assess neurocognition, specifically executive functioning (EF), among phallometrically defined PED and NPED child molesters, relative to nonsexual offenders (NSO). Participants (N = 89) were compared on seven EF domains. Results revealed that (a) child molesters exhibited an overall executive profile that was different from that of NSOs, with PEDs differing from NSOs but not from NPEDs; (b) child molesters on the whole performed better than NSOs on abstract reasoning and more poorly on inhibition; and (c) PEDs performed better than NPEDs on planning and exhibited better overall performance accuracy relative to NPEDs. These results suggest that PEDs exhibit a more deliberate, planful response style characterized by greater self-monitoring; whereas NPEDs appear to respond more impulsively. The current report further elucidates neurocognition among child molesters and highlights the need for future research examining subtypes of child molesters.

Investigating the relationship between sexual and chemical addictions by comparing executive function in subjects with pedophilia or opiate addiction and healthy controls

Disorders of driven sexual behavior have been conceptualized as sexual addictions. In the following study, we compared 51 subjects with pedophilia, 53 subjects with opiate addiction, and 84 healthy control subjects on neuropsychological tests that tap executive functions. The test battery included the Wisconsin Card Sorting Test (WCST), Stroop Color-Word Test, the Matching Familiar Figures Test (MFFT), Porteus Mazes, Controlled Word Association (COWA), and Trailmaking Test. The groups differed on tests of cognitive flexibility and set switching (WCST), sustained attention (Stroop), and impulsivity (MFFT and Porteus Mazes). There were no differences on verbal fluency (COWA). The subjects with pedophilia differed significantly from those with opiate addiction on several tests, with longer latency to response on MFFT and fewer completed mazes but also fewer errors on Porteus Mazes. Thus, while both subjects with pedophilia and those with opiate addiction show executive dysfunction, the nature of that dysfunction may differ between the two groups; specifically, opiate addicted subjects may be more prone to cognitive impulsivity.

Neurocognitive differences between pedophilic and nonpedophilic child molesters

Although some evidence exists that child molesters may be characterized by structural and functional brain abnormalities, findings across studies are inconsistent. Past cognitive research in this area has been extensively criticized for relying on conceptually weak batteries, measures of questionable reliability, and poorly defined samples (i.e., failing to distinguish between pedophilic and nonpedophilic child molesters). The present study aimed to address the weaknesses of past research by comparing 40 child molesters (20 pedophilic and 20 nonpedophilic) and 20 demographically matched nonoffender controls on six well-defined neurocognitive composite scores of comparable reliability (i.e., semantic knowledge, executive functioning, processing speed, motor speed, auditory memory, and visual memory). Results indicated that pedophilic child molesters exhibit slower processing speed, nonpedophilic child molesters exhibit poorer semantic knowledge, and both molester groups exhibit executive weaknesses as compared to nonoffender controls. This study is the first to compare the two molester types on neurocognitive functions. The observed differences between the molester groups help explain inconsistencies in past research and demonstrate the need to distinguish between the two types of child molesters when studying neurobiologic underpinnings of sexual offending.

Facial and prosodic affect recognition among pedophilic and nonpedophilic criminal child molesters

The present study compared facial and prosodic affect recognition abilities among pedophilic and nonpedophilic child molesters and community-dwelling controls. Pedophilic child molesters are characterized by primary sexual interest in prepubescent children, whereas nonpedophilic child molesters are characterized by offending against children despite being primarily sexually attracted to adults. The results showed that nonpedophilic child molesters made more errors in recognizing both facial and prosodic affect, performing more poorly than both controls and pedophilic child molesters. These findings are consistent with greater psychopathic tendencies among nonpedophilic molesters as well as with prior findings of smaller amygdala volume among child molesters.

Cerebral white matter deficiencies in pedophilic men

The present investigation sought to identify which brain regions distinguish pedophilic from nonpedophilic men, using unbiased, automated analyses of the whole brain. T1-weighted magnetic resonance images (MRIs) were acquired from men who demonstrated illegal or clinically significant sexual behaviors or interests (n = 65) and from men who had histories of nonsexual offenses but no sexual offenses (n = 62). Sexual interest in children was assessed by participants' admissions of pedophilic interest, histories of committing sexual offenses against children, and psychophysiological responses in the laboratory to erotic stimuli depicting children or adults. Automated parcellation of the MRIs revealed significant negative associations between pedophilia and white matter volumes of the temporal and parietal lobes bilaterally. Voxel-based morphometry corroborated the associations and indicated that the regions of lower white matter volumes followed, and were limited to, two major fiber bundles: the superior fronto-occipital fasciculus and the right arcuate fasciculus. No significant differences were found in grey matter or in cerebrospinal fluid (CSF). Because the superior fronto-occipital and arcuate fasciculi connect the cortical regions that respond to sexual cues, these results suggest (1) that those cortical regions operate as a network for recognizing sexually relevant stimuli and (2) that pedophilia results from a partial disconnection within that network.

The neuropsychology and neurology of sexual deviance: a review and pilot study

Current neurological hypotheses of paraphilia posit that sexual deviance is associated with frontal and/or temporal lobe damage. This broad conception is based on few investigations, however, and the first goal of this study was to review the existing data derived from neuropsychiatry, neuroimaging and neuropsychology. It is concluded that although fronto-temporal dysfunctions are sporadically reported among sexual offenders, the evidence is scarce and it might not be specific to this type of offending. The second objective of this investigation was to gather preliminary neuropsychological data with more homogeneous subgroups of sexual offenders. A profile of lower-order executive dysfunctions (e.g. sustained attention and inhibition) and verbal deficits with intact or good capacities for higher-order executive functioning (e.g. reasoning and cognitive flexibility) and visuo-spatial processing was preferentially found among sexual offenders, suggesting basal fronto-temporal anomalies. Importantly, pedophiles were more consistently and severely impaired than rapists of adults. However, this basal fronto-temporal profile is not characteristic of sexual deviance, as it is also found in association with delinquency and criminality in general. Future neuropsychological and brain imaging studies should consider subgroups of sexual offenders and recruit non-sexual violent persons and non-violent individuals in order to disentangle the complex relations between brain anomalies and sexual deviance.

Quantitative reanalysis of aggregate data on IQ in sexual offenders

General intelligence has been the most commonly studied neuropsychological characteristic of sexual offenders for over 70 years. Results, however, have been highly inconsistent. To assess whether sexual offenders score lower in IQ than nonsexual offenders and to explore which sexual offense characteristics relate to IQ, the authors reanalyzed all reports providing sufficient information. Data spanned 236 samples, comprising 25,146 sexual offenders and controls. The literature contained sufficient information to permit comparison of adult versus juvenile sexual offenders, offenders targeting children versus adults, offenders targeting their own versus unrelated children, and offenders targeting boys versus girls. Results confirm the association between IQ and sexual offending and suggest that previous discrepancies are attributable to how many pedophilic individuals were in each sample.

On intelligence and crime: a comparison of incarcerated sex offenders and serious non-sexual violent criminals

The impact of low IQ on crime has been a focus of debate for several decades now. Although sociologists have virtually removed it from the list of possible factors influencing crime, the impact of IQ on crime continues to generate a significant amount of scientific research and a substantial number of publications. The purpose of this study is to assess intellectual levels and to compare two groups of incarcerated criminals. Using MANCOVA and ANCOVA procedures, 261 sex offenders and 150 non-sexual violent criminals were compared on IQ subscales. The results show significant differences on vocabulary, comprehension, arithmetic, mental math computations, object assembly, letter-number sequencing, and perception subscales, as well as on performance IQ and total IQ. The impacts of penal filtering and sample composition are hypothesized to explain differences between the two subgroups. Theoretical and practical implications are discussed.

Intelligence, Memory, and Handedness in Pedophilia

A sample of 473 male patients with pedophilia (assessed by the patients' sexual history and penile response in the laboratory to standardized, erotic stimuli) or other problematic sexual interests or behaviors received brief neuropsychological assessments. Neuropsychological measures included a short form of the Wechsler Adult Intelligence Scale--Revised (D. Wechsler, 1981), the Hopkins Verbal Learning Test--Revised (R. H. B. Benedict, D. Schretlen. L. Groninger. & J. Brandt, 1998), the Brief Visuospatial Memory Test--Revised (R. H. B. Benedict, 1997), and the Edinburgh Handedness Inventory (S. M. Williams, 1986). Pedophilia showed significant negative correlations with IQ and immediate and delayed recall memory. Pedophilia was also related to non-right-handedness even after covarying age and IQ. These results suggest that pedophilia is linked to early neurodevelopmental perturbations.

Blows to the head during development can predispose to violent criminal behaviour: rehabilitation of consequences of head injury is a measure for crime prevention

Criminal behaviour and violence may be the consequence of head injuries acquired during childhood and youth (gang fights, domestic violence, small blows to the head while driving, falls and so forth). In this study, a comparison was made of the school and head injury histories of violent and non-violent prisoners. It was found that the delinquent subjects in both groups had a history of academic difficulties. However, what differentiated the violent from the non-violent group was a history of having suffered head injuries that were never treated. Problems at school are not enough themselves to predict violent behaviour. A history of discrete neurological damage as a consequence to blows received to the head must also be present. The results suggest to the authors that the treatment of the cognitive, behavioural and emotional consequences of brain injury could be a measure for crime prevention. Measures both for prevention and rehabilitation are discussed.

Some implications of prenatal alcohol exposure for the treatment of adolescents with sexual offending behaviors

Prenatal alcohol exposure can seriously harm the fetus, resulting in a wide range of physical and central nervous system abnormalities. A follow-up study of persons prenatally exposed to alcohol found that 49% of adolescents and adults had repeatedly displayed inappropriate sexual behavior. While these persons are likely to present to sexual offender treatment programs, they are unlikely to be recognized as neurologically impaired because the sequelae of prenatal alcohol exposure are seldom accurately identified by clinicians. Persistent impairments in response inhibition, memory, and executive functions are common, requiring adaptations to standard sexual offender assessment and treatment.

Hippocampal pathology in two mentally ill paraphiliacs

Paraphilias or disorders of sexual behavior have markedly increased in prevalence during the last decade. Until now no published neuropathological studies on paraphilia have appeared in the medical literature. A computerized search was done on all available medical and autopsy records of a large urban hospital (St. Elizabeths Hospital, Washington, DC) for any mention of deviant sexual behavior. Cases were then reviewed for presence of a history consistent with DSM-IV diagnoses of paraphilia. Two such cases were identified. Neuropathological examination in both cases revealed simple cell atrophy of pyramidal cells confined to different hippocampal subfields. Reactive astrocytosis was present in the outer strata of the affected regions. The pathological changes in the hippocampus resemble those reported after persistent stress or long-term chronic glucocorticoid administration. The accompanying astrocytosis indicates a reactive, ongoing process. The findings suggest new therapeutic interventions in the treatment of paraphilia.

The paraphilic and hypersexual disorders: an overview

In this article, the first of a two-part series, the authors present reasons for considering the paraphilic and hypersexual disorders together and provide an overview of these disorders. The DSM-IV diagnostic criteria for paraphilias are reviewed, and proposed criteria for hypersexual disorders are presented. The question of whether the paraphilic and hypersexual disorders should be considered within the spectrum of obsessive-compulsive disorders is considered. The authors then review the epidemiology of these disorders, and discuss some implications of recent sexual predator legislation. The authors discuss the etiology of the paraphilias and hypersexual disorders, and consider the role of endocrinological function, findings from brain imaging and neuropsychological testing, findings from primate research, the monoamine hypothesis, the imprinting hypothesis, social learning theory, the concept of courtship disorder, the role of obsessive-compulsive elements, psychodynamic theories, and genetic factors. The phenomenology of the paraphilias and hypersexual disorders is discussed, including the tendency for multiple paraphilias to co-occur, the lack of a specific offender profile, the predominance of males among those with paraphilias, the incidence of a history of victimization in individuals with paraphilias and compulsive sexual disorders, the onset and course of both types of disorders, and the lack of internal motivation for change in individuals with paraphilias and hypersexual disorders. The authors then discuss disorders that commonly co-occur with paraphilias and compulsive sexual disorders, including mood disorders, substance abuse and dependence disorders, attention-deficit/hyperactivity disorder, anxiety and impulse control disorders, and personality disorders. The second article in the series will discuss the clinical assessment and the behavioral and psychopharmacological treatment of these disorders. A guide for clinicians and patients on where and how to find specialized clinicians and treatment resources in the United States will also be provided.

Neuropsychiatry of hypersexuality

Relatively few studies of the psychobiology of hypersexuality have been undertaken. Nevertheless, the literature does suggest the possibility of a neurobiology of hypersexuality. Three cases of hypersexual behavior are presented in the context of neuropsychiatric disorders, and the literature on this phenomenon is briefly reviewed. These case studies and the literature provide evidence that different brain systems may play a role in this disorder. Frontal lesions may be accompanied by disinhibition, including impulsive hypersexual response to external cues, while striatal lesions may be accompanied by repetitive triggering of internally generated response patterns. Temporal-limbic lesions may be accompanied by disturbances in sexual appetite itself, including change in the direction of sexual drive. These case studies demonstrate that a neurobiology of hypersexuality may prove of some heuristic value in the clinic. However, further research is required to consolidate the literature in this area.