According to some estimates, 3-6 percent of the population experience hypersexuality, defined by a compulsion to perform sexual acts, loss of control in relation to sex or risky sexual habits. However, even the existence of the condition is controversial. How different are those things, after all, from the teenage stereotype? Might hypersexuality really just be a handy excuse for those caught cheating on their partners or a manifestation of other mental conditions?
New evidence supports those who argue there is more to it than that, with people diagnosed with hypersexuality found to regulate DNA regions associated with oxytocin activity in the brain differently from the rest of the population.
"We set out to investigate the epigenetic regulatory mechanisms behind hypersexual disorder so we could determine whether it has any hallmarks that make it distinct from other health issues,” Uppsala University PhD student Adrian Boström said in a statement. Boström and colleagues measured the methylation of DNA from 60 people who had been diagnosed with hypersexual disorder and 33 controls. Methylation can stop or reduce the production of proteins coded for by genes, reducing the effect those genes have on the body.
In Epigenetics Boström describes finding certain genes that were regulated statistically differently in the two populations studied. The authors then looked at the gene expression of microRNA associated with those genes.
MicroRNA-4456 was found to be significantly under-expressed in the hypersexual patients compared to the control group. It is known that microRNA4456 targets genes that regulate oxytocin in the brain. The researchers expect, although they have yet to confirm, the reduced microRNA activity would lead to higher production of brain oxytocin.
A further comparison with people being treated for alcohol addiction found the same genes were also under-methylated, offering support to the notion of hypersexuality as an addiction.
Boström acknowledges the methylation of the relevant sections of DNA is only 2.6 percent lower in the hypersexual participants than the control group, but claims similar subtle differences are implicated in conditions such as schizophrenia.
Hypersexuality diagnosis is controversial because in a society that so strongly stigmatizes enthusiasm for sex, particularly among women, there is a risk of pathologizing people with healthy but above average libidos. On the other hand, it is generally accepted certain medications have side effects of impulsive and subsequently regretted sexual activity. Established mental health conditions, such as bipolar disorder and injuries to certain parts of the brain are similarly associated with behavior that may justify the diagnosis.
Blame for hypersexuality has a long and rather embarrassing history. John Harvey Kellogg, founder of the cereal chain, blamed it on sugar consumption, and that was a relatively scientific explanation compared to beliefs in demonic possession.