Scientists believe the hormone oxytocin may play a role in the development of hypersexual disorder.
People with the condition, also known as compulsive sexual behavior disorder, suffer from an inability to control their sexual impulses, to the extent that such activities become the focus of their daily life and they neglect their responsibilities, health and personal care. The condition was classified as a disorder by the World Health Organisation last year, but not a form of addiction. At the time WHO expert Geoffrey Reed stressed the AFP news agency that the condition does not excuse sexual abuse or rape.
Between 3 to 6 percent of people suffer from hypersexual disorder. But as lead author Adrian Boström from the Department of Neuroscience at Uppsala University, Sweden, told the condition is controversial and little is known about its neurobiology. Some argue it is a manifestation of other mental disorders, such as addiction.
The team set out to see whether they could find any clues in the genes of sufferers, and see if it had any hallmarks that set it apart from other health issues. This could help to develop treatments, said Boström.
The study involved 93 participants; 60 patients with hypersexual disorder, and 33 healthy individuals who acted as the control. As the condition has elements of addictive behavior, the team also looked at samples from 107 subjects with alcohol dependency. The findings were published in the journal Epigenetics.
The team looked at what is known as methylation on 8,852 DNA regions to see if it differed in the patients and the control group. DNA methylation is where a methyl group—or clusters of hydrocarbons—attach to DNA strands to signal whether to turn genetic activity on or off. The researchers also studied microRNAs, which regulate gene expression.
In patients with hypersexual disorder, the team found two regions of DNA were under-methylated, as were microRNA linked to whether certain genes are expressed. This could have an effect on levels of the hormone oxytocin, the scientists believe.
Past studies have linked oxytocin to bonding, reproduction and aggression in animals and humans.
The participants with alcohol problems had similar differences in methylation to those with the sexual disorder.
The differences in DNA methylation between the patients with the sexual disorders and the control group was 2.6 percent.
"Our results motivates further research in the efficacy of, for example, oxytocin regulating drug therapy in hypersexual disorder," Boström told .
Boström aruged the work adds to the debate around hypersexual disorder, and suggests it is provides evidence the condition is "not simply an extension of manifestation of an existing mental condition."
"Our findings indicate that there are distinct epigenetic hallmarks involving both DNA methylation and microRNA activity that separate hypersexual disorder [patients] from healthy volunteers," he said. "Further studies are needed to fully ascertain that the identified epigenetic changes are not presented in any co-morbid disorders."