Adults with intellectual disability have reduced access to healthcare services, and healthcare specialists in particular, compared to the general population [1–4]. In a meta-analysis by MG Mazza, A Rossetti, G Crespi and M Clerici [5] the overall reported prevalence of psychiatric disorders among adults with intellectual disability was 34%. The same study concluded that the elevated risk of psychiatric disorders underlines the significance of identifying such disorders in adults with intellectual disability.However, people with intellectual disability and mental health problems have experienced restricted availability of psychiatric evaluation, therapy, and support [6, 7]. Some of these challenges emerged after the closure of centralised institutions for people with intellectual disability in Norway [8]. Institutional healthcare has been reduced across many countries since the normalization movement in the 1970s, and people with intellectual disability consequently more often reside in community settings [9, 10]. In Norway, the municipalities inherited the task of providing services to individuals with intellectual disability from county administration in 1991. By 1996, all institutions serving people with intellectual disability were closed [11, 12]. As a result, specialised habilitation services were developed in all counties of Norway to provide physical and mental health care to people with intellectual disability. Habilitation services are administered within the specialist health services and provide outpatient and inpatient care for people with intellectual disability. The habilitation services work in close collaboration with primary health services where the general practitioner (GP) refers patients to habilitation [13].
All Norwegian citizens are entitled to healthcare, including specialised services, as part of the universal health coverage financed by taxes [14]. Still, Norwegian authorities have addressed the need for further improvement in the health services offered to people with intellectual disability in national reports [15] after service violations were found in more than 80% of the municipalities inspected. A Norwegian green paper report identified challenging behavior in combination with mental health problems as particularly challenging. In this report, managers in the municipalities described a lack of available medical expertise, and access to psychiatrists in particular, and the need for the strengthening of psychiatric and inpatient services for people with mental health problems, intellectual disabilities, and challenging behavior [16]. These reports resulted in the development of national guidelines, referred to as "Good health and care services for people with Intellectual disabilities", that are currently being implemented in the services [17].
Limited research has been conducted on how the utilization of mental healthcare services is associated with levels of intellectual disability. However, previous studies have found disparities, including a scarcity of psychiatric services for people with more severe intellectual disability [18, 19]. People with intellectual disability have a higher prevalence of medical conditions [20] that have an impact on their overall well-being and mental health [21]. This reduced well-being will sometimes be communicated through behavior by people with intellectual disability and concurrent difficulties expressing discomforts [22].
H Costello, N Bouras and H Davis [23] reported that psychiatrists' comprehension and expertise concerning mental health problems in people with intellectual disability was inadequate in England. The study concluded that specific knowledge of this population's unique requirements with regard to psychiatric assessment, diagnosis, and therapeutic approaches is essential [23].
Co-occurring mental illnesses may have serious consequences when it comes to treatment and health care service access for people with intellectual disability [5]. A scoping review by EL Whittle, KR Fisher, S Reppermund, R Lenroot and J Trollor [24] pointed out that the elevated risk of mental illness does not seem to correspond with the utilization of mental healthcare services among people with intellectual disability.
People with intellectual disability may encounter obstacles preventing them access to mental healthcare services [25, 26]. When access to healthcare or health consequences brought about by treatment (health outcomes) are varying among populations [27], there is a potential for health disparities [28]. Accessing services may be more complicated for adults with intellectual disability due to communication issues and limitations in social support [29]. Individuals who have more severe levels of intellectual disability may find it difficult to communicate their requirements and needs [30]. In addition, challenging behaviour has been described as behaviour that may drastically restrict or deny the individual from accessing otherwise open community facilities [31]. Challenging behaviours have also been reported by healthcare professionals to be a barrier when providing services to people with intellectual disability [32]. Recognising mental illnesses in this particular demographic is a multifaceted matter that relies on variables that include the level of intellectual disability, the clinical competence of mental healthcare specialists, the existence or nonexistence of complicating factors like challenging behaviours, and additional factors like the location of residence and the structure of the healthcare services [33].
Frequent use of psychiatric services has been found to be associated with the use of psychotropic medication [34]. The use of psychotropic medication is common among people with intellectual disability, challenging behaviour and mental health problems [35, 36] and other interventions from mental health services may be considered less often [37]. Furthermore, a previous Norwegian study found the presence of a challenging behaviour to be a common indication of psychotropic prescriptions and that as few as half of all psychotropic prescriptions were indicated by a diagnosis of mental illness. Further, assessments of medications and adverse reactions by psychiatrists were scarce, and therapeutic alternatives were seldom considered [38].
There appears to be a lack of recent studies examining factors associated with the use of mental health services by adults with intellectual disability [24] and previous Nordic studies have mainly focused on older people [39–41]. This may hinder the establishment and assessment of policies and measures to enhance effective service use. The purpose of this study was to address the knowledge gap regarding the use of mental healthcare services among adults with intellectual disability in Norway.