Intellectual disability (ID) is characterized by mild to severe impairments in general cognitive abilities and adaptive functioning, leading to a decrease in the capacity for personal independence [14]. Due to reliance on others for care and daily functioning, many life domains of people with IDs have historically been restricted, including the right to sexuality and parenting [15]. Despite advances in human rights for individuals with IDs, academic research focuses mostly on sexual abuse, sexual perpetration, and societal attitudes towards sexual activity in individuals with ID, giving much less attention to positive experiences of sexuality.

People with intellectual disabilities are more likely than their peers to be victims of sexual abuse [16], with the rate being significantly higher for women, who also tend to have more negative feelings about the abuse [17]. Murphy and O’Callaghan [18] point to the delicate balance between empowering individuals with IDs to express their sexual rights and protecting them from unwanted sexual contact, as adults with IDs had difficulty distinguishing between consensual and abusive sexual relationships. However, this capacity significantly increased with sexual education and higher IQ [18].

Notably, there is insufficient sexual and intimacy education and training for individuals with IDs and their parents/caregivers, respectively. Only about half of adolescents with disabilities ever talked about sex with their parents [19]. Staff carers, despite holding generally positive attitudes, could benefit from more targeted training on how to support sexuality in persons with ID [20, 21].

Qualitative research has provided a window into the subjective sexual experiences of people with IDs, indicating that the majority of women with IDs could not conceptualize themselves as sexual beings, had negative attitudes about sex, believed others did not permit them to engage in sex [22], and remained abstinent due to fears based on misconceptions about sex [23]. Additionally, young people with IDs of both genders face stigma related to their ID, which can overshadow their developing sexual identity [24, 25].

Despite many barriers to a sexual well-being, persons with IDs do desire intimate relationships and consider them important [26]. The increasing social awareness of sexual needs in this population and the accompanying emergence of sexual educational programs are promising for lowering sexual abuse rates and increasing sexual well-being among persons with IDs.

Autism spectrum disorder (ASD) is a complex condition, presenting as social interaction deficits in multiple domains as well as a restrictive, repetitive behavioral pattern [14]. The number of children diagnosed with the disorder is rising, with a 2016 report citing 23.6 boys and 5.3 girls per 1000 children aged 8 years meeting the diagnostic criteria [27]. Recent years have seen substantial attention given to autism both by academia and the general public; however, many aspects of pathophysiology and psychology of autism remain poorly understood. Studies on the well-being of autistic individuals show generally lowered quality of life [28, 29]. However, investigation of sexual functioning specifically is limited by small sample sizes, focuses on high functioning samples only, and groups lower functioning autistic individuals with other intellectually disabled populations. For these and other reasons, many reports on sexual satisfaction and sexual behaviors show contradictory conclusions.

Persons with ASD are shown to generally desire romantic relationships and sexual experiences [30–32], but may face difficulty engaging in romance and sexual activities due to deficits in social communication [33, 34]. Lower sexual satisfaction tends to be correlated with autistic symptom severity [35, 36]. Additionally, higher satisfaction with romantic relationship was shown among individuals whose partners were also diagnosed with ASD [30].

There are significant gender differences in sexual functioning of autistic men and women. Higher prevalence of ASD in males, as well as relatively strong social skills “masking” ASD diagnosis in females, leads to an underrepresentation of autistic girls and women in research. In Byers et al. [35] study of 68 women and 61 men with ASD, women reported significantly higher sexual anxiety, more frequent sexual problems, and lower sexual arousability. In a different study, Byers [37] found that autistic men reported better solitary sexual well-being, more sexual thoughts and desires, despite having lower sexual knowledge. Although most research points to normative sexual behaviors in individuals with ASD, some report increased presence of paraphilias [32, 38] and sensory fascination with a sexual connotation [31].

Attention-deficit/hyperactivity disorder (ADHD) is characterized by a persistent pattern of attention deficits and/or hyperactivity-impulsivity that causes impairments in functioning or development [14]. It is a neurodevelopmental disorder with childhood onset that persists into adulthood, with a prevalence of 2.5% in adults and 5% in children [14].

Symptoms related to hyperactivity and excitability have brought about investigations into the link between ADHD and increased sexual impulsivity. Both male and female adolescents typically report having more romantic partners in comparison with their peers [39, 40], with Rokeach et al. citing double the number of lifetime sexual partners. Individuals with ADHD are more likely to engage in risky sexual activities [41] and are being treated for STDs more often [42]. They also report having earlier dating experiences [43], more partner pregnancies [40] and become parents earlier than the general population [42]. However, high prevalence of comorbidities such as addiction and conduct disorders pose several methodological limitations, as risky sexual behaviors may be attributable to comorbid conduct disorder, substance or alcohol use [44], rather than ADHD.

Although some studies report good overall quality of romantic relationships in adolescents with ADHD [39], others report higher incidence of verbal aggression and violence towards partners [45] and lower relationship quality, possibly mediated by hostile relationship conflicts [46]. Adults with ADHD symptomatology may also experience more fear of intimacy, despite lack of sexual anxiety [47].

Neurodevelopmental disorders also include communication disorders, specific learning disorder, as well as motor disorders. Research on sexual functioning in individuals with Communication Disorders is severely lacking. Learning disorders are often included in studies sampling populations with intellectual disabilities and share some of the same limitations as research on IDs, such as inclusion of participants with vastly different symptomatology. Inappropriate sexual behaviors, exhibitionism, and copropraxia are common symptoms of Tourette’s syndrome [48, 49]. However, research on pharmacological treatment is based mostly on case studies [50, 51] and there is a lack of investigation into psychotherapy and psychological factors involved in sexual symptoms of this disorder.

The cardinal features of MDD include depressed, low mood and/or anhedonia (decreased pleasure in activities previously enjoyed), causing significant distress and impair functioning [14]. MDD is one of the most common psychiatric disorders, with a 7% 12-month prevalence rate in the USA [14], with the highest rates of sexual dysfunction among other common mental disorders [94].

The DSM-5 states that for some individuals the diminished interest or pleasure in activities may be experienced as a loss of sexual interest or desire [14]. Therefore, sexual dysfunction is built into the criteria of MDD and significant impairment in marital adjustment and sexual functioning frequently accompany the negative symptoms of this diagnosis [95, 96]. MDD is associated with loss of libido for both men and women [96], which may be among the most distressing symptoms of depression and contributed to deteriorated quality of life [97]. Besides lower sexual drive, MDD is also correlated with decreased interest in sexually explicit material, and reduced sexual fantasizing for males and females alike [96, 97]. Masturbation rates among depressed individuals have received inconsistent findings, with some studies showing reductions and others purporting increases in solitary sexual experiences [96]. Ramrahka et al. [98] established that diagnosis of depressive disorders among young people predicted risky sexual intercourse, contraction of sexually transmitted infections, and first sexual intercourse prior to age 16. Laurent and Simons [96] maintain that the relationship between depression and sexual functioning is complex, with sexual and depressive symptoms often co-occurring.

Sexual arousal concerns are also common in men with depression, with erectile dysfunction and nocturnal penile tumescence being the most frequently reported and studied [96]. Less research is available on female sexual arousal and depression; still, more sexual arousal issues and vaginal dryness is noted for depressed versus non-depressed females [99], and compared to women without any history of MDD [100]. Increased rates of sexual pain or intercourse difficulty (functional dyspareunia) and inhibited orgasm (anorgasmia) in women, and premature as well as delayed ejaculation in men have been linked to emotional problems and depression [96]. While sexual satisfaction among depressed individuals has insufficient research, it is lower for depressed individuals than controls [96]. Laumann et al. [101] found that sexual well-being was substantially lower in depressed women than depressed men, paralleling the gender discrepancy in prevalence of depression. Overall, Laurent and Simons [96] contend that sexual dysfunction should be considered as part of internalizing disorders, which include depression and anxiety, due to the degree of interconnectedness between their symptoms and impact on one another.

Some medications used to treat depression, particularly selective serotonin reuptake inhibitors (SSRIs) , have common adverse effects on sexual functioning, which are poorly tolerated and may exacerbate existing sexual dysfunction caused by depression [9, 102]. Please refer to the chapter on Evaluation and Treatment of Substance/Medication-Induced Sexual Dysfunction for a thorough discussion of these effects. Hence, sexual functioning needs to be assessed prior to the commencement of medication in order to fully understand the impact of both depressive disorders and medications on sexual functioning.

Obsessive-compulsive disorder (OCD) is characterized by the presence of persistent, distressing, and time-consuming intrusive thoughts, urges, or images (obsessions) and/or repetitive unrealistically related or excessive behaviors or mental acts that individuals feel impelled to perform (compulsions) in response to their obsessions or rigid rules to impart temporary relief [14]. Sexual dysfunction in OCD is a complex phenomenon that cannot be simply explained by the impact of the disorder itself, or the pharmacological treatment of it [115]. Despite methodological limitations of poor generalizability [116, 117], the available literature converges on the presence of high rates of sexual dysfunction among both men and women with OCD, with 54–73% reporting sexual dissatisfaction and sexual avoidance [115]. Individuals with OCD’s capacity for intimacy is impeded by their excessive need for control, need to control their thoughts, high disgust sensitivity, and concealing of obsessional beliefs due to shame or fears of increased probability of occurrence with disclosure [118], resulting in increased interpersonal impairment and distress [115]. Further, cognitive biases and inflexible rules present in OCD are implicated in reduced sexual satisfaction and functioning [115].

In exploring the role of disgust in sex, de Jong and colleagues [119] discuss that the mouth and vagina, while playing a central role in sexual activity, also display the highest disgust sensitivity. This, paired with the high correlation between bodily secretions and disgust may perpetuate contamination fears, chronic sexual disgust, and avoidance of sexual behavior [119]. Intuitively, individuals with OCD and sexual dysfunction experience significantly more distress than those without sexual concerns [117]. Sexual dysfunction occurs in 39% of females with OCD, including sexual disgust, lack of sexual desire, reduced sexual arousal, anorgasmia, and increased avoidance of sexual intercourse [107, 117]. Further, sexual infrequency was observed among 57.1% of men and 63.6% of women with OCD [107].

Sexual obsessions are under-reported, frequently misdiagnosed, and often involve the thought-action fusion cognitive bias, leading to increased distress [120, 121]. Common OCD clinical features of contamination fears and sexual taboo obsessions are related to impaired sexual performance and satisfaction [122]. A subset of sexual obsessions, sexual orientation preoccupation, is often easily misperceived as sexual identity confusion, resulting in inappropriate treatment planning [115].

Additionally, there is some clinical overlap between OCD features and compulsive-impulsive sexual behavior [115]. Inconsistencies over the association between OCD and paraphilias exist in the literature; yet, sexual obsessions within OCD tend to be ego-dystonic, unpleasurable, and unbearable, as differentiated from the ego-syntonic, exciting thoughts observed in paraphilic and compulsive sexual behaviors [115]. Further, when thoughts are perceived as unacceptable and unwanted (e.g., non-consensual, aggressive, or incestuous), as often noted by individuals with OCD, sexual activity tends to be avoided [115]. However, the research also cautions that relying on the distressing versus non-distressing differential alone leaves much room for misdiagnosis, potential exacerbation of symptoms [123], and iatrogenic treatment [124].

With the presence of additional psychiatric diagnoses, such as depression, the phenomenology of sexual dysfunction in OCD becomes more complex and multidirectional [117].

Body dysmorphic disorder (BDD) involves distressing preoccupation with one or more perceived or slight defect or flaw in physical appearance, and engaging in repetitive behaviors or mental acts in response to appearance concerns [14]. BDD also includes muscle dysmorphia, which is defined by the belief that one’s body build is too small or not muscular enough [14].

The emphasis on physical appearance dissatisfaction has received more attention than the diagnosis of BDD with regard to sexual functioning research. Overall self-image and body image are significant predictors of sexual activity, including orgasm, initiating sex, comfort undressing in front of partners, having sex with the lights on, trying new sexual behaviors, and pleasing their partners sexually [125]. Yet positive body esteem and self-perceived sexual attractiveness are not consistently correlated with sexual satisfaction for women across the literature [125–127]. Pujols et al. [126] suggest that distress and cognitive distractions over appearance and body image predict sexual satisfaction, even after accounting for sexual dysfunction. Women who experienced cognitive distractions during sexual activity report proportionately lower sexual esteem and sexual satisfaction, less consistent orgasms, and higher incidence of faking orgasm [128]. More recent research adds that cognitions, evaluations, and self-consciousness also interfere with sexual avoidance and risky sexual behavior among females [129].

Due to the high frequency of individuals with BDD pursuing various cosmetic procedures to improve their body esteem [126, 130, 131], the literature on BDD and cosmetic procedures offers possible avenues for further empirical investigation. A descriptive study by Veale et al. [132] indicates that the women presenting for labiaplasty endorsed reduced sexual satisfaction, interference with quality of life, greater avoidance of sexual intimacy and intercourse, as well as greater probability of BDD diagnosis related to their body image, compared to controls. Moreover, sexual dysfunction was identified as one of the motivators for seeking genital modification procedures [132]. In another small-sampled psychosexual outcome study following labiaplasty, Veale et al. [133] also report that of the nine women that met criteria for BDD pre-operation, eight showed full remission of BDD and enhanced sexual satisfaction at three months, with 26% reporting minor side effects. More research with larger studies is required to determine actual connections between sexual functioning and genital dissatisfaction.

Penile dysmorphic disorder (PDD) has been used to distinguish men who have BDD with predominant preoccupations about their penis size [134]. Veale and colleagues [134] reveal that men with BDD were more likely to experience erectile dysfunction, orgasmic dysfunction, and reduced sexual intercourse satisfaction, compared to controls and men with small penis anxiety; however, all three groups maintained their sexual desire/libido. Additionally, BDD has been closely linked to EDs due to the presence of similar clinical variables including body image disturbance [135, 136].

Posttraumatic stress disorder (PTSD) is characterized by direct exposure to a traumatic or stressful event to self or close other, recurrent and distressing intrusive symptoms, persistent avoidance of triggers associated to traumatic event, negative alterations in cognitions and mood, hyperarousal, and reactivity associated to traumatic event [14].

Significantly poorer sexual functioning was found across all domains (desire, arousal, orgasm, activity, and satisfaction) for patients with treated and untreated PTSD, in comparison to controls without PTSD [137]. Indeed, Yehuda and colleagues [138] propose that post-traumatic sexual dysfunction is possibly mediated by PTSD-related biological, cognitive, and affective processes. Letourneau et al. [139] assert that PTSD serves as a moderator for the development of sexual dysfunction for both sexually and non-sexually traumatized women.

The sexual functioning of individuals with histories of sexual trauma has received relatively greater empirical attention, compared to other types of trauma or abuse [140]. Noll and colleagues [141] studied the impact of childhood sexual trauma (CSA) on sexuality, finding that history of CSA was correlated with anxiety, sexual aversion, sexual ambivalence, and dissociation. The authors [141] also imply that sexual abuse by biological father may be related to higher sexual aversion and ambivalence. Shaaf and McCanne [142] note that women who experienced not only sexual but also physical abuse in childhood faced the greatest risk for sexual victimization in adulthood, which then exposed them to increased risk of developing PTSD . In addition, CSA increases risk of being sexually exploited [143] and PTSD-related symptoms can both precede and accompany sexual exploitation [144]. Sexually exploited populations also are at greater risk for sexually transmitted diseases and HIV/AIDS, posing a grave public health concern [145, 146]. The impact of sexual exploitation on sexual dysfunction may include hypersexuality, preoccupation with sex, younger age at initial intercourse, teen pregnancies, anorgasmia, vaginal pain, as well as other emotional vulnerabilities pertinent to sexual functioning [143, 147].

While the connection between PTSD and intimate relationship problems for combat veterans is well documented in the literature [148] the exploration of sexual functioning of this population has received less attention. Combat veterans with PTSD experience higher rates of sexual dysfunction compared to veterans without PTSD, and demonstrate impaired overall sexual satisfaction, orgasmic function, intercourse satisfaction, and erectile dysfunction or vaginal pain [149–151]. Greenberg [149] suggests that PTSD symptoms co-occur with intimacy and sexual dysfunction, such as impotency and/or hypersexuality. Joannides [152] further emphasizes that due to the powerful physical sensations and emotional vulnerability of sex, PTSD symptoms (i.e., flashbacks) can be triggered for veterans and hence, impair sexual relationships. The author [152] specifically highlights the combat imagery and language in sexual activity, paralleling explosion with the sensation of orgasm and the sounds made amid sexual pleasure and release that could sound like cries of pain. Also, the fluctuation between sexual urgency and sexual disinterest often experienced by combat veterans may be confusing for their spouses, leading their spouses to avoid intimate interactions and complicating sexual relationships further [149]. Additionally, extramarital affairs are reportedly high among combat veterans with PTSD due to potential sexual acting out, experience of sexual activities as mundane compared to the intensity of combat, discomfort sharing sexual fantasies or desires with spouses, or the spouses’ inability to sustain their sexual intensity [149].

From a neurobiological stance, sexual dysfunction among veterans with PTSD was not resultant from an organic disorder, and has been associated with plasma DHEA and cortisol, urinary catecholamines, and glucocorticoid sensitivity , even after accounting for concurrent depressive symptoms [153]. Additionally, PTSD predicted higher levels of dihydrotestosterone, which is connected to sexual dysfunction [153].

Anorexia nervosa (AN) is defined by three fundamental features: persistent energy intake restriction resulting in significantly low body weight relative to age, sex, developmental trajectory, and physical health; intense fear of gaining weight or becoming fat, or persistent behavior that interferes with weight gain; and a disturbance in self-perceived weight, shape, or pursuit of thinness [14]. Further, AN tends to have a long-lasting, chronic course, significant functional impairments, and high suicidality and mortality rates [14]. The subtypes differentiate between predominantly restricting or binge/purging type at current diagnostic evaluation, as the individual may migrate across subtypes or diagnoses over time [14, 189]. Although amenorrhea is no longer a defining diagnostic criterion of AN due to its exclusion of males, prepubertal and postmenopausal females, as well as females taking hormonal contraceptives, it may ensue as a physiological sequela of AN in some individuals [190].

The relationship between severity of low weight and sexual dysfunction is unclear, but worsened sexual dysfunction is evidenced among individuals with AN compared to healthy controls [186, 187, 191]. As a result of hypogonadism and emaciation [192] individuals with AN experience decreased sexual interest; once weight is restored, libido tends to increase [193]. Low libido, commonly observed in AN, is linked to both low concentrations of circulating sex hormones and psychological factors, such as body dissatisfaction and depleted self-esteem [183]. Zemishlany and Weizman [9] highlight that patients with AN suffer from low sexual interest, inhibited sexual behavior, sexual disgust, and intimacy fears. The authors [9] observe a pattern of normal or advanced sexual development in adolescence prior to the manifestation of AN, and a significant decline in sexual interest and need for intimacy during AN. Non acceptance of their sexuality, low sexual desire, sexual aversion, and anorgasmia likely continue post AN recovery [9]. Moreover, sexual dysfunction may ensue due to the physiological effects of starvation seen in AN and/or development of depressive symptoms [191] and fertility problems [183].

A few studies demonstrate AN subtype differences in sexuality, with decreased sexual drive [187, 194] and limited sexual fantasy [192] among restricting anorectics compared to purging anorectics. Also, purging anorectics have higher rates of multiple sexual partners than restricting subtype anorectics [187]. Further, Castellini et al. [187] suggest that varying levels of sexual dysfunction correspond with pathological eating behavior , as restricting anorectics report lower arousal, lubrication, orgasm, satisfaction, and more pain, compared to purging type AN and BN.

The essential features of bulimia nervosa (BN) include recurrent episodes of uncontrollable binge eating and repeated inappropriate compensatory behaviors to prevent weight gain (purging), accompanied by self-evaluation that is disproportionately driven by body shape and weight [14]. Notably, a subset of individuals with BN continue to engage in binge eating, but discontinue purging behaviors—resulting in a change in diagnosis to BED or other category [14, 182].

Sexual dysfunction in BN is correlated with impulsive behaviors, including excessive drinking, sexual disinhibition, bullying, truancy, and binge/purge practices [183]. Indeed, individuals with EDs who have low self-control and emotional dysregulation reported increased impulsive and chaotic sexual functioning [194]. Similarly to results for binge/purging subtype anorectics, individuals with BN also had higher rates of multiple sexual partners compared to restricting anorectics [187]. Further, individuals with BN display increased risk for induced abortion compared to controls [183]. Gonidakis and colleagues [191] indicate that sexual functioning in BN is associated with level of depression.

The novel inclusion of binge eating disorder (BED) in DSM-5 allows for the diagnosis of recurrent episodes of uncontrollable binge eating, causing marked distress, without engagement in any repeated inappropriate compensatory behavior [14, 182]. Individuals with BED commonly experience social role adjustment issues, reduced health-related quality of life, increased healthcare utilization, and poor life satisfaction, along with higher morbidity and mortality compared to BMI-matched controls [14].

Provided that BED is a relatively new diagnosis, the research on BED is often grouped with findings on obesity, with expectations of similar sexual functioning impairments [183, 185]. Individuals with BED are at elevated risk for weight gain and developing obesity, which has been demonstrated to have multiple effects on sexual functioning [195]. The role of weight or perception of body shape and size may be critical in sexual functioning for individuals with BED, as BMI modification has been hypothesized to affect sexual dysfunction within individuals with BED [183]. In the same vein, research shows that post-bariatric surgery weight loss was associated with significantly improved hormonal profiles and sexual functioning in both males [196] and females [197]. Notably, diagnosis of BED is correlated with higher risk of miscarriage [183].