A scoping review of studies on physical activity and nutrition health promotion interventions for individuals with intellectual disabilities was conducted. Searches included MEDLINE, PsycINFO, and CINAHL databases from 1986 through July 2006. The final number included 11 articles comprising 12 studies. Generally, this review indicated some evidence for fitness and psychosocial benefits of community-based physical activity and exercise programs for adults with intellectual disabilities. When combined with a more comprehensive health behavior education program incorporating exercise and nutrition information, some evidence exists for reductions in weight.
Individuals with intellectual disabilities have a higher risk than does the general population of developing secondary conditions at younger ages, due to the confluence of biological factors related to syndromes and associated developmental disabilities, access to adequate health care, and lifestyle and environmental issues. They have lower fitness levels, poorer nutrition, higher rates of obesity, and are more sedentary (Draheim, Williams, & McCubbin, 2002; Fernhall & Pitetti, 2001; Yamaki, 2005).
Closing the Gap: A National Blueprint to Improve the Health of Persons With Mental Retardation
In this document (U. S. Surgeon General, 2002), the authors recommended broad-based health promotion programs, including physical activity and nutrition interventions that would improve health and fitness among adults with intellectual disabilities (U. S. Department of Health and Human Services, 2002). In the present paper we used scoping review methods to look at the research literature on physical activity and nutrition health promotion interventions for adults with intellectual disabilities.
Both in the United States and other developed countries, many researchers have reported high rates of overweight and obesity in adults with intellectual disabilities living in the community (reviewed in Haveman et al., 2009; Yamaki, 2005). Using the National Health Interview Survey in the United States, Yamaki found that during the period of 1997–2000, the rate of obesity was 34.6% in persons with intellectual disabilities and 20.6% in the general population. Among adults with intellectual disabilities living in group homes and in family homes, the rate went up to 47.5% and 37.5%, respectively. Draheim et al. (2002) found in their study that individuals with intellectual disabilities who are overweight or have abdominal obesity are 3 to 10 times more likely to have elevated cardiovascular disease risk factors, such as hypertension, hypertriglyceridemia, hyperinsulinemia, and low high-density lipoprotein (bad) cholesterol levels than those who are not overweight or who do not have abdominal obesity.
Across studies of physical activity of adults with intellectual disabilities, Stanish, Temple, and Frey (2006) found that only between 17.5% to 33% of these adults engaged in the standard recommended amount of physical activity (30 min of moderate intensity physical activity on most days of the week) and these investigators tended to focus on relatively young and healthy volunteers with mild to moderate limitations.
In addition to sedentary behavior and lack of education and health promotion programs, poor nutrition is likely to play a role in the development of obesity among adults with intellectual disabilities living in the community. These individuals tend to consume diets that are high in fat and low in fruit and vegetable intake (Braunschweig et al., 2004; Draheim, Stanish, Williams, & McCubbin, 2007; Lindemann, 1991; Mercer & Ekvall, 1992). Across these studies results indicate that only 0 to 6% of the residents of group homes consumed the recommended five or more fruits and vegetables per day, and 15 (30%) consumed the recommended calories from fat (< 30%). Numerous studies have highlighted the high rates of overweight and obesity in people with intellectual disabilities compared to the general population.
Low levels of physical activity, poor nutrition, and obesity are highly related to such chronic conditions as cardiovascular diseases, high blood pressure, and diabetes. Among adults with intellectual disabilities, Draheim et al. (2002) found that those who were overweight or had abdominal obesity were 3 to 10 times more likely to have higher cardiovascular disease risk factors, such as hypertension, hypertriglyceridemia, hyperinsulinemia, and low high-density lipoprotein cholesterol than those who are not overweight or who do not have abdominal obesity. Although the health problems related to physical inactivity are well understood for persons with intellectual disabilities, less is known about the role of physical activity as a health promotion approach.
Physical activity and nutrition health promotion interventions could result in increased physical activity and better nutrition leading to better fitness, better health, and in improved quality of life as well as greater community participation of people with intellectual disabilities. Such interventions can also potentially reduce health care costs through prevention of secondary conditions. Although there are no data specific to the costs of poor health due to health behaviors for persons with intellectual disabilities, the World Health Organization (2003) estimated that health care costs due to inactivity of the general population is $75 billion per year. In addition, the Centers for Disease Control (2004) estimated that individuals with intellectual disabilities have an average lifetime economic cost over $1,000,000 per person, which is the highest per person cost of individuals with any type of developmental disability.
Traci, Seekins, Szalda-Petree, and Ravesloot (2002) suggested that by increasing physical activity in individuals with developmental disabilities, secondary health conditions can be lowered, thereby reducing overall health care costs and improving quality of life. Although much evidence exists for the benefits of physical activity and nutrition health promotion programs for the general population, we are just beginning to develop and implement empirically based health promotion programs designed for people with intellectual disabilities.
The genesis of this review was a mandate by the National Institute on Disability and Rehabilitation Research, U.S. Department of Education to The Rehabilitation Research and Training Center (RRTC) on Health and Wellness at Oregon Health & Science University to identify interventions that promote health and wellness and minimize the occurrence of secondary conditions for persons with disabilities (Federal Register, 2004). The RRTC on Health and Wellness convened a national expert panel to conduct a scoping review to characterize the status of the field of health promotion for people with disabilities and to begin the process of identifying the interventions with evidence to support their effectiveness (Seekins et al., 2010). In the present article we build on the findings of the scoping review by examining in greater detail the health promotion interventions in the review that were focused on physical activity and nutrition among adults with intellectual disabilities. We organized our review using health promotion topics and considered the following questions: (a) What type of intervention is effective (with significant findings) on what outcomes, including physical and psychosocial outcomes? (b) What approaches (including protocols and curricula) were used? (c) What is the type of design (ranging from qualitative to quasi-experimental to randomized control trials? (d) What are promising approaches (e.g., ones that show some evidence but require further research)?
Scoping Review Method
Scoping reviews and systematic reviews use rigorous scientific methods incorporating specific protocols to identify, appraise, and synthesize information in order to eliminate the bias found in many general literature reviews (Arksey & O'Malley, 2005; Cameron, Tsoi, & Marsella, 2008; Hempel, Norman, Goider, Aguiar-Ibanex, & Eastwood, 2008; Petticrew & Roberts, 2006). Scoping reviews can produce preliminary assessments of the research to date, when the area of inquiry (such as health promotion and intellectual disability) is relatively new and emerging or lacks uniformity in study design and outcome measurement (Hempel et al., 2008). It can also be helpful in determining the feasibility of undertaking a full systematic review (Arksey & O'Malley, 2005; Cameron et al., 2008). Systematic reviews are more appropriate when the field is more established and narrowly focused, with some consistency in methods and measurement (Arksey & O'Malley, 2005; Cameron et al., 2008); whereas scoping reviews are typically broader assessments of a particular field, better suited than highly specified systematic reviews to overview the literature landscape of the field.
The RRTC on Health and Wellness Scoping Review (Seekins et al., 2010) used scoping review procedures to obtain literature on community-based health promotion interventions for adults with disabilities. English-language peer-reviewed primary literature and review articles in which authors examined health promotion interventions among adults (aged 18 to 65) with disabilities were included in the review. Community-based was defined as an intervention that was delivered in community or home settings (in contrast with an intervention delivered in hospital as part of in-patient rehabilitation). For the full scoping review, disability was defined a mobility, sensory, or cognitive impairment. Mental health disabilities, although important, were not included in this review.
Subject heading searches identified citations from MEDLINE, PsycINFO, and CINAHL databases from 1986 through July 2006. Subject headings were compiled to identify the population with disabilities relevant to intellectual disability. The search terms for intellectual disability were cognitive disabilities, intellectual disabilities, mental retardation, developmental disabilities, mental handicap, and learning disabilities. Other subject headings were autism, chromosomal abnormality, Down syndrome, fetal alcohol syndrome, phenylketonuria (PKU), cerebral palsy, neural tube defects, and spina bifida combined with two sets of subject headings used to identify health promotion interventions (relevant to physical activity and nutrition). Search terms were health education, health promotion, nutrition, exercise, and health behavior. The electronic search resulted in a total 3,987 citations. The expert panel also nominated 10 seminal health promotion articles as a quality control check for the electronic search. Upon cross-reference, all nominated seminal articles were included in the electronic search results, indicating appropriate breadth of the search. The table of contents for each issue of two journals identified by the panel (Disability and Rehabilitation and Archives of Physical Medicine and Rehabilitation) were also scanned for relevant articles. Issues published between 2001 and 2006 contributed 110 articles to be reviewed, for a total of 4,078 articles identified across sources.
We used a rigorous, systematic exclusion process to arrive at the final scoping review article set (Petticrew & Roberts, 2006). The project staff excluded articles at the abstract level if they met the following exclusion criteria: not disability-related, not health promotion-related, medically oriented treatment studies, descriptive studies, discussion articles, or program descriptions, set in clinical setting as part of clinical treatment or rehabilitation, not English language, published before 1986, all study participants younger than 18 or older than 65, and nonpeer reviewed publications (i.e., dissertations, chapters, conference presentations). A subset of the abstracts was independently reviewed by two reviewers, who reviewed all discrepancies again to reach resolution. Interobserver agreement on abstract exclusion averaged 95%. This resulted in the exclusion of 3,638 articles from further consideration, leaving 330 articles that were reviewed at the full-text level. Two reviewers discussed a subset of articles that they reviewed at the full-text level, and a third reviewer served as an arbitrator for 16 of the articles for which a clear inclusion decision could not be reached. Of the 330 reviewed at the full-text level, 253 articles were excluded, resulting in 77 remaining articles. The process of article selection is displayed in Figure 1.
Secondary Analysis Selection Criteria
Although the scoping review included a wide variety of disabilities, our review here is limited to intellectual disabilities. We coded full-text articles as having a study population of individuals with intellectual disability if functional limitations were described (e.g., limitation in intellectual functioning, mental retardation) or diagnoses reported as characterizing the population were consistent with intellectual disability (e.g., Down syndrome). Using this disability criterion, we had 19 articles on intellectual disability in the scoping review database.
In the next level of review of these 19 articles by project staff, 8 articles were excluded after the reviewers indicated that the studies were not focused on physical activity or nutrition, were case reports, or were school-based interventions. The final number of included studies was 11. One article (Marshall, McConkey, & Moore, 2003) contained two separate substudies, so the number of studies reported in the Results is 12. (See Figure 2 for the abstraction processed used in this study.)
As can be seen in Table 1, the types of interventions included 11 studies with a component on exercise/physical activity and 5 with a nutrition component. Some of the studies included more than one component, and these were coded in both categories. Physical activity studies referred to those focused on increasing physical activity, exercise, weight loss, or fitness. Nutrition interventions were on nutrition improvement, diet, weight loss, dietetics, and diet therapy studies.
Among the 11 articles identified as related to physical activity as a component of a health promotion program, the following outcomes were noted in the majority of the articles reviewed: improved fitness (balance, strength, aerobic capacity), weight reduction (e.g., lower body mass index [BMI]), fewer maladaptive behaviors, reduced functional decline expected with aging, better attitudes toward exercise (self-efficacy, expected outcomes, cognitive–social barriers), and improved life satisfaction for persons with intellectual disabilities. Actual changes in health behaviors or improvements in health status were not measured in all of the studies. As an example, in the Heller et al. (2004) study, attitudinal and psychosocial factors changed in a positive direction, but the health outcomes were not reported.
Only 3 of the 11 studies (Fisher, 1986; Heller et al., 2004; Rimmer, Heller, Wang, & Valerio, 2004) had a control group or comparison group in the study design, limiting the validity of the findings in most of the studies. Also, the Fisher (1986) study had a very small sample size. To further limit what can be generalized from these findings, none of the researchers indicated that intervention programs could be implemented over a long period of time; that achieved gains could be maintained beyond the intervention period, other than a short-term 4 week follow-up in the Fisher study; and none demonstrated behavioral changes that lead to long-term improvements in important health outcomes. Also, 2 of these studies were limited to adults with Down syndrome with mild to moderate intellectual disabilities.
The 5 studies that included a nutrition component also had a screening component (Marshall, McConkey, & Moore, 2003), health behavior education that included both nutrition and exercise information (Ewing et al., 2004; Heller et al., 2004; Mann, Zhou, McDermott, & Poston, 2006), and home visits (Ewing et al., 2004; Mann et al., 2004). The 4 studies that included health behavior education also had a physical activity component. A major outcome of the nutrition studies was a change in the participants' BMI or weight. This included lower BMI and weight loss for those who were overweight (Ewing et al., 2004; Mann et al., 2006; Marshall et al., 2003) and increased weight for those who were underweight (Evers et al., 1991; Hogan & Evers, 1997). The interventions that were most effective in reducing obesity were those with health behavior education incorporating both healthy eating and exercise components (Heller et al., 2004; Mann et al., 2006) and home visits (Mann et al., 2004). These curricula included Exercise and Nutrition Health Education Curriculum for Adults with Developmental Disabilities (Heller, Marks, & Ailey, 2001; Marks, Sisirak, & Heller, 2010) and Steps to Your Health (Mann et al., 2006). Advice-giving and screening alone were not effective in reducing obesity (Marshall et al., 2004). In the Marshall study, only 34% of overweight participants who received health screens, referral to a general practitioner, and advice followed up with actions to reduce weight.
Other outcomes included participants' increased knowledge of nutrition and self-reported healthier diet (Mann et al., 2006) and improved life satisfaction (Heller et al., 2004). In both of these studies, the investigators also included health behavior education and physical activity components.
The most common research design for the nutrition studies was a repeated measures design, without any comparison groups. The two exceptions were Heller et al. (2004) and Fisher (1986), who used a randomized control group. Most of the studies included no longer term follow-up, with the exception of the 4-week follow-up in the Fisher study and the first phase of Marshall et al. (2004), who conducted 3-month follow-ups to assess the degree to which actions were taken on referrals.
Generally, in this review we found some evidence for fitness and psychosocial benefits of community-based physical activity and exercise programs for adults with intellectual disability. Outcomes of physical activity programs include improved fitness weight reduction, fewer maladaptive behaviors and improved adaptive behaviors, better attitudes toward exercise, and improved life satisfaction. Although the findings measured vary across social–psychological and metabolic outcomes, there were too few studies in any specific area to summarize differently. What has been demonstrated in these studies, similar to investigations of adults without disabilities, is that physical activity interventions can indeed lead to important health outcomes. What is missing is the ability to develop, implement, and sustain programs and health benefits over time. Nutrition studies show some weight reduction for those who are overweight. However, when both exercise and nutrition interventions are combined with a more comprehensive health behavior education program that incorporates exercise and nutrition information, stronger evidence exists for reductions in weight. One limitation of studies in which researchers combine both components is that it is difficult to determine the impact of the nutrition component separately from the physical activity component.
Key challenges for addressing this population include developing programs that take into account intellectual limitations (e.g., difficulty understanding, lack of knowledge), other cognitive and social emotional barriers (e.g., lack of motivation, lack of self-efficacy, poor outcome expectations), and issues of accessibility (e.g., transportation, accessibility of equipment, money) (Heller et al., 2004; Stanish et al., 2006). Agency structure, such as policies and staffing ratios along with limited opportunities, can also impact involvement in health promotion activities. Lack of staff motivation to promote physical activity (Temple & Walkley, 2003a) and a lack of physical activity counseling (Frey et al., 2006) have been reported to be constraints to active physical participation of adults with intellectual disabilities.
Based on the numerous descriptive studies that have documented low levels of physical activity and high levels of obesity in this population, a significant need exists for community-based interventions that lead to improved health outcomes. For example, programs incorporating balance and strength training can affect mobility and be important in preventing the onset of functional decline as adults with intellectual disabilities age. Promising programs that include comprehensive health behavior education curricula geared to adults with intellectual disabilities, such as the Exercise and Nutrition Health Education Curriculum for Adults with Developmental Disabilities (Heller et al., 2004; Marks et al., 2010) and Steps to Your Health (Mann et al., 2006) show promise as interventions that can improve the health of people with disabilities. However, neither of the studies that included these curricula resulted in evidence of long-term health benefits. Although group health behavior education can be helpful in reducing weight for some people with intellectual disabilities and can improve the fitness and attitudinal and psychosocial factors in the short-term, these programs are more likely to be effective in the long-term through the addition of on-going community-based programs.
We need to develop and test interventions that address issues of staff training, knowledge and motivation of people with intellectual disabilities regarding health promotion, and ways to increase the organizational capabilities of community-based organizations to promote healthy behaviors and health promotion programs.
In the future researchers need to use appropriately powered representative samples with validated measures that objectively assess physical activity directly (such as pedometers, accelerometers, or direct observations) and that monitor dietary intake. This could include use of informants, such as staff members and families, and better measures for self-report. Furthermore, a need exists for more research, including randomized control groups with longer term follow-up, to assess adherence over time.
Overall, the studies reviewed show that health promotion interventions incorporating physical activity, better nutrition, and health behavior education can have some positive impacts on the health and function of adults with intellectual disabilities. However, the interventions need more rigorous testing because the evidence to date, while promising, lacks a strong empirically tested evidence base.
Tamar Heller, PhD (e-mail: firstname.lastname@example.org), Professor and Head, Department of Disability and Human Development, University of Illinois at Chicago, 1640 W. Roosevelt Rd., MC 626 Chicago, IL 60608-1336. Jeffrey A. McCubbin, PhD, Executive Associate Dean and Distinguished Professor, Oregon State University, Department of Nutrition and Exercise Sciences, Corvallis, OR 97331. Charles Drum, JD, PhD, Professor, Director, Institute on Disability, University of New Hampshire, 10 W. Edge Dr., Durham, NH 03824. Jana Peterson, PhD, Coordinator of Health Disparities Research, Institute for Human Development, University of Missouri, 215 W. Pershing Rd., 6th floor, Kansas City, MO 64108.
Editor-in-Charge: Steven J. Taylor