As indicated above, numerous studies investigate the outcomes of specific health literacy levels. Still, there is a lack of scientific health literacy studies, which evaluate the group of people with intellectual disabilities [10
]. It is estimated that there are approximately 978 million people worldwide with disabilities. Approximately 1–3% of the global population have an intellectual disability—as many as 200 million people. Due to the lack of definitions and the lack of measuring instruments, the number of people with intellectual disabilities can only be estimated very roughly [11
People with intellectual disabilities are people with an innate low IQ (below 70) who have an increased need for support due to this reduction in intelligence. They do not suffer from a psychological illness or a physical disability. A health literacy concept for people with intellectual disabilities in addition to one of these diseases would have to be discussed differently.
The group of people with intellectual disabilities is at an increased risk of chronic diseases, cardiovascular diseases, and obesity [12
]. Additionally, the life expectancy of people with intellectual disabilities increased in the last decades, and hence, an increased presence for age-related diseases in this group can be verified [12
]. There is also evidence that people with intellectual disabilities tend to experience specific health problems like incontinence, difficulty swallowing, sensory loss, and adaptability losses [13
], as well as oral motor problems and dental problems, fractures, fatigue, arthritis, musculoskeletal deformities, decreased walking ability, progressive cervical degeneration, and a higher risk of developing osteoporosis [14
]. Due to the high risk for diseases and chronical illness described above, people with intellectual disabilities have a particularly high need for support and care [12
]. Evidence from curative education and nursing research shows that people with intellectual disabilities have major problems in the field of language [16
]. Particularly, a reduced understanding of speech and a reduced ability to communicate are stated. A reduced ability to communicate is characterized by short and incomplete sentences and altered semantics [17
]. It has long been known that this has an impact on the access to information and leads to a lack of health-related knowledge [19
]. These issues cause problematic access to understandable health-related information and cause difficulties with regard to self-directed decision-making in health promotion and disease prevention in people with intellectual disabilities [20
]. For these reasons, high sensitivity of caregivers is required. So far, caregivers play a major role in health-related decision-making [22
]. However, nurses or caregivers are usually not trained to provide understandable health-related information in a corresponding manner. These aspects indicate that people with intellectual disabilities are a vulnerable group in terms of health, health literacy, health care, and everyday life support. Therefore, it is urgently necessary to include these people in the discussion about health literacy.
The concept of health literacy influences various levels. At a political level, the United Nations Convention for the Rights of People with Disabilities [23
] (UN-CRPD) demands empowerment in the health sector based on informed self-determination. As already described, we assume that empowerment is related to health literacy and consider whether it can be strengthened by targeting health literacy in this group (at in the individual and also within professionals, among others health service providers, and care givers). Moreover, health literacy is also formulated as a political goal in national action planning [1
]. At the individual level, strengthened health literacy could lead to more informed choices and could have a lasting impact on compliance and health care provision for people with intellectual disabilities [24
]. At the social level, the strengthening of health literacy and empowerment could address the inequalities of people with intellectual disabilities [25
] (It has to be discussed to what extent a specific health literacy concept for people with intellectual disabilities actually leads to health equality, or on the contrary, leads to increased health differences due to a lack of comparability. This should be an urgent part of future research.). These represent manifold arguments why health literacy is highly relevant for people with intellectual disabilities and why strengthening it is crucial for targeting health inequalities in this vulnerable group. Nevertheless, due to the particularities of people with intellectual disabilities described above, we question whether the application of common health literacy understanding to people with intellectual disabilities without further consideration or testing is feasible. Moreover, there is a lack of scientific evidence for a target group-specific conception of health literacy within this group. Afterwards, further scientific studies could be carried out to investigate expected health literacy outcomes such as decision-making or the effects on health equality. Therefore, scientific knowledge must be generated that takes into account people with intellectual disabilities in their particularities.