It is common for people living with multiple sclerosis (MS) to experience sexual dysfunction: previous studies have found that approximately 40-80% of women and 50-90% of men with MS report some form of sexual dysfunction. However, there has been limited information on the effect of MS and sexual dysfunction and the relationship between sexual dysfunction and related factors of age, level of physical disability, fatigue, and depression. This was the focus of a recent study in the United Kingdom: the Trajectories of Outcomes in Neurological Conditions (TONiC) study.
TONiC included 722 people who live with MS from across the UK. Of those, 538 were sexually active and 431 (80%) answered questions on sexual functioning. (Respondents were given the choice not to respond, with options of “Not active, and thus not relevant,” “Active and no impact,” and “Active and impact but do not wish to complete the questionnaire.”)
The impact of MS on sexual function
Of those who were sexually active, only 12.5% reported no impact on any aspect of sexual function. (Another 6% declined to complete the sexual functioning portion of the questionnaire on the grounds that their MS had no effect on their sexual function.) The types of sexual dysfunction were classified into three areas:
- Primary – MS-related neurological changes that may directly affect sexual response, such as orgasm dysfunction, reduced sexual interest, perineal sensory loss, or problems with erections or vaginal lubrication.
- Secondary – MS-related physical changes that indirectly affect the sexual response, including bladder, bowel, pain, or spasticity problems.
- Tertiary – Psychological and social aspects of MS that affect sexuality, such as being afraid of being rejected because of MS, feeling less attractive and worried about sexually satisfying a partner. These aspects were collectively designated as “worries” by the researchers.
Only 16.5% reported no primary aspects, meaning the large majority of survey respondents (83.5%) experience some MS-related symptoms that directly affect their sexual functioning. In addition, only 22.5% reported no secondary aspects and another 22.5% reported no tertiary aspects. Almost two-thirds (63.8%) reported some impact across all three domains.
As expected, the level of disability from MS was correlated with sexual dysfunction across all three areas. This connection has been corroborated in other studies as well.
Other factors that influence sexual functioning
There were some differences in the impact of sexual functioning by type of MS, with secondary progressive (SP) MS having more primary sexual dysfunctions and relapsing remitting (RR) MS having the least dysfunctions across all three categories. However, researchers note that while the total sample size is adequate for statistical significance, the distribution of respondents across subtype is significantly uneven, as expected. (By subtype, 57.9% had RR, 22.3% had SP, 5.5% had rapidly evolving relapsing-remitting, 9.8% had primary progressive, and 4.4% had unknown disease type.)
The influence of age on sexual dysfunction differed by gender and was a significant factor only for the female respondents. Age also only played a role in sexual dysfunction in the RR group. Male respondents had significantly higher worries (tertiary aspects) than females, although the researchers note that the type of worries varied by gender, with females being more likely to worry about feeling less attractive due to their MS and males being more likely to worry about sexually satisfying their partner.
Depression, fatigue, and physical functioning were evaluated as independent predictors of sexual functioning, but none of these factors contributed significantly. Depression, rather than directly impacting sexual functioning, was found to be impacted by the tertiary aspects, with worries about sexual functioning worsening depressive symptoms.
Significance of the study
The TONiC study findings indicate that the effect of MS on sexual functioning is significant. The tertiary aspects (“worries”) were found to have a considerable impact, largely contributing to the other areas of sexual dysfunction. The psychological aspect of sexual dysfunction is an area that is important to address for the well being of people living with MS.