Pedophilia
Conditions
Brief summary
This project will investigate if transcranial direct current stimulation can be used as treatment for Pedophilia. Treatment efficacy will be evaluated with behavioral tasks and the recording of eye-movement.
Detailed description
Pedophilia is an important motivation for sexual offenses involving children, including child pornography and sexual contacts with children (henceforth, pedosexual behavior). Indeed, approximately half of individuals convicted for sexual offenses against children have a Pedophilic disorder and offenders with a Pedophilic disorder are much more likely to sexually reoffend. A promising line of research has examined the neurocognitive basis of pedophilia. Pedophilic individuals display altered activity in the dorsolateral prefrontal cortex (dlPFC) when attending to child-related stimuli. This brain area is involved in the cognitive control of sexual arousal. Transcranial Direct Current Stimulation (tDCS) has been examined as a non-invasive method to increase activity in the dlPCF, ultimately increasing inhibitory control over impulses. Accumulating evidence also shows that individuals have an attentional bias towards sexually preferred stimuli. These attentional processes can be investigated by recording eye movements. Early automatic eye movements are particularly relevant in discriminating individuals with pedophilia from those without pedophilia. The proposed study will examine the effects of tDCS over the dlPFC of pedophilic individuals and healthy controls, while they complete a task requiring controlled attention to virtual (computer-generated) images of children and adults. In two separate sessions, participants will be randomly assigned to an active and a placebo (sham) tDCS condition. Eye movements will be recorded during the task. The investigators expect to observe a conflict between automatic and controlled attention when participants are presented with their sexually preferred stimuli. Specifically, the investigators expect pedophiles to show an attentional bias towards virtual child stimuli. The investigators predict that the attentional conflict will be reduced when tDCS is applied, compared to the sham condition. If the attentional bias is a key cognitive feature of sexual interest, the investigators expect to measure changes in reported or indirectly assessed sexual preferences.
Interventions
DEVICETranscranial Direct Current Stimulation
Conductive saline-soaked rubber electrodes super-imposed on sponge plates will be placed on the scalp at F3 (active electrode, 4.4×4.4cm) and on the contralateral supraorbital area (reference electrode, 5.1×10.2cm). Stimulation will be applied using a battery-driven constant-current regulator (Oasis Pro, Edmonton, Alberta, Canada). For each stimulation, the direct current is initially increased in a ramp-like fashion over 10 s until reaching 2 milliampere (mA) and will be similarly decreased at the end of stimulation. In the active tDCS condition, stimulation will be maintained for 20 min; in the sham condition, it will be turned off after 15 s of stimulation, with a ramp-up/down of 10 s (i.e., 35 s total).
Sponsors
University of Zurich
Study design
Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
TREATMENT
Masking
DOUBLE (Subject, Investigator)
Eligibility
Sex/Gender
MALE
Age
18 Years to 65 Years
Healthy volunteers
Yes
Inclusion criteria
Patients * Diagnosed with pedophilia (further psychiatric illnesses possible) * Sufficient German language skills Controls: * Not diagnosed with Pedophilia (or other psychiatric illnesses) * Sufficient German language skills
Exclusion criteria
Patients * Prior head injury with loss of consciousness for at least 5 min * Neurological diagnosis (including epilepsy) or prior medical conditions with possible central nervous system sequelae * Metallic implants inside the brain or any electrical medical device (e.g. pacemaker) in the body * Visual or hearing impairment, to the extent that it interferes with task instructions Current medication in patients (antiandrogenic medication among the pedophilic subjects, in particular) will be recorded and acknowledged as a covariate. Controls * Prior head injury with loss of consciousness for at least 5 min * Neurological diagnosis (including epilepsy) or prior medical conditions with possible central nervous system sequelae * Metallic implants inside the brain or any electrical medical device (e.g. pacemaker) in the body * Visual or hearing impairment, to the extent that it interferes with task instructions * Current or previous pedophilic sexual interest For both groups further exclusion (prematurely) will occur if initial data shows that participants don't comply with instructions or if questionnaires hint toward a lack of sexual interest in general.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Entry Time | Through study completion, an average of 10 months. The outcome measure is not an event but a performance measure recorded for every participant in every session. | In the Antisaccade task entry time will be recorded with an eye-tracker in both active and sham tDCS conditions. Time to first fixation (entry time) is defined as the time from stimulus onset to the first fixation directed to the target stimulus. This index can be treated as reaction time (RT) and will provide a measure of controlled attention. The location of the first fixation indicates which stimulus captures subject's automatic attention. The proportion of correct/incorrect fixations (%) will inform us about automatic attentional processes. Thus entry time is a single performance index measured with a unit of time, in this case Milliseconds (ms). Every participant's performance in the Antisaccade task will be measured with entry time (ms) as well as the percentage (%) of correct responses. Since the task is not difficult, the percentage values only serve to check for compliance with task instructions. The real focus of the study lies in the RT as recorded with entry time in ms. |
| differential AAT index (∆RT) | Through study completion, an average of 10 months. The outcome measure is not an event but a performance measure recorded for every participant in every session. | In the Approach-Avoidance Task (AAT) the differential AAT index (∆RT) will be recorded in both active and sham tDCS condition using the response on the joystick. The proportion of correct/incorrect responses (%) will inform us about automatic attentional processes. Thus the ∆RT is a single performance index for speed tests measured with a unit of time, in this case Milliseconds (ms). It gives information on how fast participants responded using the joystick. In addition, the percentage (%) of correct responses with the joystick will be recorded. Since the task is not difficult, the percentage values only serve to check for compliance and if task instructions were understood. The real focus of the study lies in the RT as recorded with ∆RT in ms. |
Countries
Switzerland
Contacts
Primary ContactNathalie Brackmann, Dr.
Backup ContactAnastasios Ziogas, M.Sc.
Outcome results
None listed