Megan Brooks

June 27, 2012

June 27, 2012 (Dublin, Ireland) — When exposed to erotically stimulating visual images, patients with Parkinson's disease (PD) and hypersexuality disorder show increased cerebral blood flow on functional magnetic resonance imaging (fMRI) in multiple brain regions involved in emotional and motivational processing, a novel study has shown.

The findings of this study have "direct implications on how mass media could influence hypersexuality in PD," the study team reported here at The Movement Disorder Society's 16th International Congress of Parkinson's Disease and Movement Disorders.

Stimulation through exposure to common erotic cues in PD patients with hypersexuality may provide "a motivational force for seeking this reward behavior through activations and deactivations of cerebral cortex, consequently leading to devastating individual consequences," Marios Politis, MD, MSc, PhD, from Hammersmith Hospital, Imperial College London, United Kingdom, and colleagues write in their abstract.

Restrict Erotic Advertising?

This study, "while small, demonstrates clear neurophysiological evidence of brain activity associated with hypersexuality and possibly other addictive behaviors," Lawrence Elmer, MD, PhD, medical director of the Center for Neurological Disorders, University of Toledo, Ohio, told Medscape Medical News. He was not involved in the study.

Dr. Politis and colleagues say governmental restrictions on erotic images "could help to reduce the onset of pathological sexual behavior, particularly in vulnerable populations such as the people receiving dopamine drugs."

But Dr. Elmer indicated that the study is "too small to warrant an extreme response such as asking for government regulation of visual images in our society. In addition, that request is likely to fall upon deaf ears. Perhaps the best application of this data would be to encourage PD patients with a history of hypersexuality and/or other addictive behaviors to avoid viewing explicit material whenever possible," Dr. Elmer said.

Impulse control disorders (ICDs), such as compulsive gambling, shopping, eating, and hypersexuality, are common in patients with PD on dopaminergic therapy. As previously reported by Medscape Medical News, results of a large study suggest that they occur in about 14% of all patients with PD. That number climbs to about 17% of those patients taking a dopamine agonist — 2 to 3 times higher than in those not receiving a dopamine agonist.

Yet relatively little is known about the pathophysiology of hypersexuality in PD and how common erotic cues affect the brain and behavior in such susceptible individuals.

To investigate, Dr. Politis and colleagues studied 12 PD patients with hypersexuality and a control group of 12 PD patients without hypersexuality or other ICDs. During fMRI examinations, patients were exposed to common visual erotic cues and neutral visual cues.

The researchers found that exposure to common erotic cues significantly increased sexual desire and liking of sexual content among PD patients with hypersexuality compared with controls.

These behavioral changes corresponded to "significant blood-oxygen-level dependence (BOLD) signal increases and decreases in regions laying within limbic, paralimbic, temporal, occipital, somatosensory, and prefrontal cortices that correspond to emotional, cognitive, autonomic, visual, and motivational processes," the researchers say. "Enhanced activations in cingulate and orbitofrontal cortices strongly correlated with increased sexual desire," they add.

Study Adds "Valuable Insight"

In a conference statement, David Eidelberg, MD, of The Feinstein Institute for Medical Research, notes that the occurrence of ICDs such as hypersexuality in PD patients on chronic dopaminergic therapy, "and their sometimes devastating individual consequences, is increasingly recognized."

"Although recent functional imaging studies have improved the understanding of the pathophysiology underlying these troubling side-effects, their specific neuronal correlates remain to be elucidated," he noted.

"Politis and colleagues provide valuable insights into the neuronal basis of hypersexuality in PD. The identification of altered neuronal function related to ICD is potentially useful in the evaluation of novel dopaminergic agents in this regard," Dr. Eidelberg explained.

Dr. Politis has disclosed no relevant financial relationships. Dr. Elmer has received compensation for activities with Lundbeck Research USA Inc, Teva Neuroscience, UCB Pharma, GlaxoSmithKline Inc, and Novartis, and research support from GlaxoSmithKline Inc. He is a member of the Medscape Neurology Editorial Advisory Board.

Movement Disorder Society's 16th International Congress of Parkinson's Disease and Movement Disorders: Abstract 759. Presented June 19, 2012.

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