Undeniably distressing for those affected, a lack of sexual desire is also a highly contro-versial subject.
Opinion is divided about whether it should be treated as a medical problem, and we do not really know how many men and women suffer from it. Now, to add to the debate, scientists think they have discovered a treatment — a naturally occurring hormone called kisspeptin.
It could be the first drug to help both men and women with hypoactive sexual desire disorder (HSDD), the medical name for a low sex drive for more than six months that causes distress and has no medical cause.
Research suggests one in ten women and one in eight men suffer from it.
The problem can have a devastating effect, leading to depression, breakdown of relationships and poor quality of life.
Opinion is divided about whether low sex drive should be treated as a medical problem, and we do not really know how many men and women suffer from it
Currently, those affected may be referred for talking therapies, such as cognitive behavioural therapy, but it doesn’t work for everyone.
Now new research by Imperial College Healthcare NHS Trust in London suggests that kisspeptin, a hormone that stimulates the release of other reproductive hormones from the hypothalamus in the brain, could be the answer.
Two recent studies, both published in the journal JAMA Network Open, found that when men and women with HSDD were given an infusion of the hormone, it boosted their sexual responses.
In both studies — one involving 32 pre-menopausal women and the other 32 men with HSDD — participants were given a 75-minute infusion of the hormone, and on a separate occasion a placebo (the participants were not told when they were receiving kisspeptin so as not to influence the results).
They were then shown erotic videos and images of attractive faces and their brain activity monitored via an MRI scan, to assess their sexual responses; they also underwent blood and behavioural tests before and after treatment.
Results showed that, in women, kisspeptin improved sexual activity and arousal in areas of the brain disrupted in HSDD.
Furthermore, the more kisspeptin activated a key part of the brain (called the posterior cingulate cortex) in response to attractive male faces, the less women reported an aversion to sex.
Low sex drive can have a devastating effect, leading to depression, breakdown of relationships and poor quality of life. [File image]
Women also reported feeling ‘more sexy’ while having the kisspeptin infusions, compared with a dummy treatment, according to tests of mood and behaviour.
In men, the hormone significantly boosted brain activity in key areas linked to sexual desire — while also increasing penile rigidity by up to 56 per cent, compared with placebo while viewing an erotic video.
Dr Alexander Comninos, a consultant endocrinologist at Imperial College Healthcare NHS Trust who was involved in the research, said: ‘These two studies provide the first evidence that kisspeptin is a potentially safe and effective therapy for both women and men with distressing low sexual desire. Kisspeptin has the potential to be a real game-changer.’
Low libido or sex drive can be caused by a range of factors: low hormone levels (oestrogen in women and testosterone in men is usually age-related), depression and as a side-effect of certain medications such as beta blockers for blood pressure and opiate painkillers. Although people with hsdd also have little or no sex drive, one defining characteristic is that hsdd causes them great distress.
It was first identified in the psychiatrists’ bible, the Diagnostic and Statistical Manual of Mental Disorders, in 1987.
hsdd is linked to excessive self-monitoring and concerns about sexual performance which reduce sexual desire, says Dr Comninos.
‘The main people seeking help are men and women aged 30 to 50,’ he says. ‘Many men are wrongly categorised as having erectile dysfunction when they really have HSDD.’
Kisspeptin is thought to work by deactivating the areas of the brain related to excessive self-monitoring and introspection, while at the same time activating the sexual arousal centres.
There are no treatments available for HSDD in the UK (Viagra can help men to get an erection by increasing blood flow, but does not address the psychological aspect of sexual desire).
In the U.S. there are two drugs for low sexual desire in pre-menopausal women. The first is bremelanotide (brand name Vyleesi), an injection that is self-administered 45 minutes before sexual activity, which was originally designed for weight loss and activates receptors in the body linked to sexual behaviour.
The other drug, flibanserin (brand name Addyi), is a pill taken daily, originally developed as an antidepressant. It works by raising levels of the brain chemicals dopamine and norepinephrine, which are important for sexual excitement. It also lowers levels of serotonin which can inhibit sexual desire.
However, both drugs have side-effects such as dizziness and nausea; and neither is licensed in the UK. Moreover, HSDD remains a controversial diagnosis, with critics arguing that it medicalises normal variations in sexuality.
Dr Christopher Lane, a professor emeritus of medical humanities at Northwestern University in the U.S. and author of the book Shyness: How Normal Behaviour Became a Sickness, says: ‘There is a risk here of conflating low sexual desire, which is common and often stress-related, with a new and still-controversial psychiatric diagnosis.
New research by Imperial College Healthcare NHS Trust in London suggests that kisspeptin, a hormone that stimulates the release of other reproductive hormones from the hypothalamus in the brain, could be the answer. [File image]
‘HSDD is not fully understood and there is a risk of presuming that lack of lust is a psychiatric condition rather than a psychological one,’ he says.
‘There are many facets that contribute to low libido; anxiety, stress and disgust can all block desire. So can body dysmorphia, a condition where a person spends a lot of time worrying about perceived flaws in their appearance.
‘This suggests that the condition’s primary driver may not be neurobiological [i.e. linked to the nervous system] and that, rather than defaulting to drug therapies, the focus might turn more usefully to finding ways to reduce stress and anxiety tied to sex,’ adds Dr Lane.
Marianne Johnson, a psychosexual and relationship therapist at The Thought House Partnership in London, told Good Health: ‘Taking a drug to enhance desire would understandably be very tempting for someone experiencing significant distress around their low libido.
‘I would hope that before reaching for medication like this, a person would have an opportunity to examine all factors at play in their experience of low desire.
‘Without some exploration of the wider picture, there is potential to miss vital information about a person’s internal world and their understanding of the blocks — and the accelerators — to their own desire.’
Dr Comninos says that it’s important not to ‘over-medicalise low sexual desire — in many people it is not distressing and they don’t have HSDD’, yet for others, ‘it is very distressing’.
He has received hundreds of emails from people with HSDD around the world, desperate to take part in research. ‘It can affect their daily quality of life, their mood, their personal and intimate relationships and even their fertility if they have no desire for sex,’ he says.
Bigger studies of kisspeptin’s effects on sexual desire are now planned by the Imperial team — including on post-menopausal women.
Low libido is a common side-effect of menopause, when levels of the hormone oestrogen drop dramatically. This can persist even once low hormone levels have been treated with hormone replacement therapy (HRT).
The new study will examine whether post-menopausal women with low libido who have been treated with HRT experience an increase in sexual desire after taking kisspeptin.
Researchers are investigating whether the hormone could be given as a nasal spray, taken twice a week roughly half an hour before sexual activity. Future studies could also involve the hormone being taken at home, rather than in hospital, which researchers hope might elicit a ‘greater response’, as people may feel more at ease.
If future studies are successful, it could be available as a treatment ‘in the next five to ten years’, says Dr Comninos. ‘My vision is that down the line a couple could go on a date, the affected person takes a puff of the kisspeptin spray and they end the evening having sex that they both enjoy,’ he says.
‘And because it is effective on both men and women, I am hopeful it may work across the spectrum of genders and sexualities.’