Changes in sexual behaviors are commonly described in patients with dementia [1]. Diminished sexual interest is one of the most common symptoms in dementia patients, but this will not be the focus of this chapter. Among changes in sexual behaviors, inappropriate sexual behaviors (ISB) are particularly difficult to deal with. In dementia, ISB may be the only, or most readily apparent, manifestation of concomitant medical issues. ISB are probably more frequent than what has been described in the literature, while frequently overlooked in these patients because all such behaviors tend to be attributed to the dementia process. Caregivers may have difficulties speaking about the problem, especially informal caregivers, when patient and caregiver are relatives or a close relation exists. A taboo often arises, enrooted in stigma-related issues. Additionally, families and caregivers usually also attribute these symptoms to the cognitive disorder itself. As a consequence, they frequently do not even ask for help from the clinician in charge.

Over the chapter, unless otherwise specified, the term “caregiver” is used to denote both informal and formal caregivers. Concerning ISB, both types of caregivers face challenging situations. However, it must be acknowledged that the reaction of each caregiver is shaped by cognitive and emotional appraisals that may be utterly different. No doubt, a son or daughter of the patient will react differently from their father or mother, as the patient’s spouse. No doubt, a formal caregiver will tend to react otherwise, probably in a more neutral way, but not necessarily in a more constructive or empathic one. Different formal caregivers will also differ in their reactions (one determinant may be how they displace their own relationship to their father, mother, spouse, etc. unto the patient, in the context of sometimes embarrassing situations).

On the other hand, clinicians frequently overlook the approach to sexual behavioral changes in patients with dementia throughout the clinical interview. Doctors may be afraid to ask specifically about sexual behaviors. Medical training, even among dementia specialists, does not include specific training in how to deal with sexual behaviors and ISB in particular. Therefore, doctors might be limited (sometimes unconsciously) by their own convictions or societal and cultural stereotypes. In addition, the number of studies on ISB is not large, and we need a greater evidence base to inform our general approach and management of these clinical problems. The lack of standardized and very specific guidelines makes the evaluation of ISB in a patient with dementia even more difficult [2].

A recent review addressed controversial issues on sexuality in aging and dementia [1], while others have targeted ISB in dementia [3–6]. We aim to provide a clinical perspective regarding ISB in neurodegenerative disorders manifesting with cognitive decline. The chapter mainly takes the perspective of a clinical neurologist (the first author) but also addresses broader, multidisciplinary issues. Here we will focus on ISB in patients with dementia, mostly taking into account what puzzles clinicians and how to address it in practice. After reading this chapter, it is expected that readers will systematically search for etiological factors in ISB and feel more comfortable handling the situation.

As highlighted above, sexual behavioral changes are described in persons with dementia, either within the context of other behavioral problems or in isolation. Frequently, there is diminished sexual interest [1], but its impact is not usually disruptive in family and social relations, as opposed to hypersexuality or other ISB. These include type of sexual language used or content and sexual acts implied or even overtly expressed. According to the International Psychogeriatric Association (IPA) [2], inappropriate (physical and verbal) sexual behaviors (that are also designed as sexual disinhibition or hypersexuality) involve persistent, uninhibited sexual behaviors directed at oneself or at others. However, the understanding of what is considered inappropriate can vary according to several factors including societal, cultural, or religious beliefs, or even educational levels, so we lack an uncontentious definition. Moreover different terms have been used, for instance, “hypersexual behavior” [7], “improper sexual behaviors” [8], or “sexual disinhibition” [9]. A distinction must be made regarding normal sexual behaviors within an abnormal context [2, 3], which can appear in the context of other dementia symptoms, e.g., impaired judgment. For instance, false recognition of the partner/spouse can lead to unexpected familiarity and attempts to interact with someone else. Taking another real-world example, in a nursing home, lying down in another patient’s bed (or just entering another patient’s bedroom by mistake) can be misinterpreted as ISB, while actually reflecting cognitive impairment only.

This is why a recent clinical review emphasized the need for great caution in what concerns “pathologizing” appropriate sexual behaviors in cognitive impairment, only because patients are older or have dementia [3], or attributing a sexual meaning to inappropriate behaviors otherwise unrelated to sex.

The prevalence of ISB in dementia varies widely (2–25 %) [2–5]. Although some authors report higher rates in nursing homes [4], others describe a higher frequency of at least some of the manifestations in community settings [6]. This apparent contradiction in data may be partly explained by different appraisals or by reporting bias in samples, related e.g., to being either a caregiver or a health-social professional, or not. In nursing home settings, health-care professionals may be more prone not only to identify but also to signal abnormal behaviors. Additionally, using different ISB definitions may contribute to these discrepancies.

Overall, these ISB are more frequently described in men than in women [6]. Some drugs are associated with a higher risk of ISB, e.g., dopamine agonists, amantadine, benzodiazepines, and selective serotonin reuptake inhibitors (SSRI). Alcohol consumption can also be associated with ISB. It is uncertain whether previous personality traits or personality disorder can be associated with frequency or shaping of ISB. It is also unclear if there is a relation between previous mental disorders and frequency, severity, and type of ISB.

Although it is consensual that ISB are more frequent in more severe stages of dementia, they have been also described in mild forms of cognitive decline [6].

A review by Ozkan and coworkers described the ways in which different brain systems may be involved in the pathophysiology of ISB [4]. The authors focused on four brain systems: the frontal lobes, the temporo-limbic system, the striatum, and the hypothalamus, each of them likely associated with specific patterns of behaviors. Several neurotransmitters and other modulators are potentially implicated in ISB, as pointed out by a comprehensive review available on the neurobiology of sexual function [10]. However the exact changes and interactions among them regarding ISB in subjects with dementia are not yet understood. This issue is far beyond the scope of this chapter.

As explained in previous sections, the most frequent sexual behaviors described across all types of dementia are loss of affection and reduced initiation of sexual activity, not ISB. One interesting finding is that “hyposexual” behavior and ISB can coexist or even alternate in the same patient, and this is also true for the different types of dementia.

Regarding ISB, it is unclear whether they are more frequent in any specific type of dementia.

Alzheimer’s disease (AD) patients are affected by some degree of decline in sexual activity, but the manifestation differs regarding, for instance, frontotemporal dementia (FTD) patients, in the sense that AD patients usually maintain the ability of being affectionate and accepting affection from the partner. Alagiakrishnan and colleagues reported that in AD (comparing to FTD and vascular dementia), a smaller proportion of patients exhibit hypersexuality or other ISB [6]. Notwithstanding, inconsistencies regarding the available evidence overall suggest a strong need for further high-quality research.

FTD usually starts at a younger age comparing to other neurodegenerative dementias. The potential interference of sexually disturbed behaviors in couple relations at an earlier phase of the life cycle can be highly relevant to the interpretation of clinical findings. Taking into consideration the high frequency of behavioral changes in FTD, it is usually assumed that patients frequently develop concomitant disinhibited forms of sexual behavior. In fact, some reports support that association [11]. However, it was recently found that the most common sexual behavior changes in FTD patients were decrease of initiation, decrease of response to the initiatives of the partner, and reduced affection toward the partner, with decreased frequency of sexual relations on the whole [12]. In this same study, only a minority of FTD patients exhibited hypersexual and aberrant behaviors [12].

In our experience, vascular dementia (VD) is more prone to be associated with ISB, a finding supported by only very few studies [6, 13], and a more severe stage of vascular dementia is usually associated with more frequent and severe ISB.