Taken together, these findings suggest the evidence base about services for adults with an ASD is underdeveloped and can be considered a field of inquiry that is relatively unformed. Extant research does not reflect the demographic or impairment heterogeneity of the population, the range of services that adults with autism require to function with purposeful lives in the community, or the need for coordination across services.
We found a lack of attention to SEP in ASD research. This was surprising because impoverishment is common in the general population and is associated with decreased access to services and adverse developmental outcomes in non-ASD populations. For instance, as of 2009, 1 in 5 US children aged 17 years or younger were living below the federal poverty line. Given an ASD prevalence rate of 1 per 110, this translates into about 163 000 children aged 17 years or younger with an ASD in the United States who were living in poverty. As these children age toward adulthood, it will be important to determine how poverty influences developmental trajectories in those with an ASD, the related impact on need for supportive services as adults, and access to services in adulthood.
Research on poverty and ID has documented 2 distinct processes that can increase the risk that adults with an ID will have low SEP.33
First, the process of raising a child with an ID takes a cumulative toll on a family’s financial well-being, both directly (for example, through out-of-pocket expenditures for interventions) and indirectly (for instance, if one parent forgoes wage earning to stay home to care for the child). Second, having an ID is associated with an increased risk, relative to those without an ID, for unemployment as an adult and a subsequent lowering of earning power. These processes are not mutually exclusive, and suggest similar lines of inquiry for research related to ASDs.
Including measures of SEP in future ASD services research can open a door to 3 general types of research question.34
First, stratification of estimates of access to services by SEP measures will enable the description and monitoring of inequities in service use across strata. Second, SEP measures can be used for statistical adjustment to obtain conditional estimates of the association between non-SEP factors (for example, impairment severity) and measures of service access and related outcomes. Third, including SEP measures in research can enable the examination of underlying mechanisms that may give rise to unequal access and outcomes.
We also found a relative neglect of issues related to ethnoracial diversity. This stands in contrast to Canada and the United States becoming increasingly more demographically diverse. Further, the past decade has seen a steadily expanding body of evidence about racial disparities in health outcomes and access to health services across a wide range of health conditions and service systems. The connections among race, service access, and health outcomes are complex, historically contingent, and vary across countries.36
Nonetheless, some useful general frameworks for inquiry have emerged.
A landmark report in the United States posited that racial health disparities need to be examined at 2 main levels: the systemic level of organizations, laws, and policies; and the individual level of patients and providers.37
The report emphasized the importance of gathering and disseminating basic descriptive information about the extent of disparities as a tool for justifying and motivating change at all levels. This would be an important starting point for ASD services research, which has often neglected racial differences.
Attention to issues of service costs and efficiency is also lacking. The recent global economic recession has increased pressure on publicly funded systems of care to do more with less.38
Social welfare mechanisms for the support of aging citizens are becoming more financially strained as the ratio of current workers to retirees shrinks. Thus the growing number of adults with autism is occurring in a broader and adverse sociopolitical context of declining financial resources that are available for the support of aging citizens. To increase relevance to policy-making, future research must examine the cost and efficiency of service provision because these factors tend to be highly influential with policy-makers.39
The heterogeneity of both abilities and challenges exhibited by people on the autism spectrum is vast. Severity of impairment and the presence of comorbid conditions have significant implications for service needs. 40
However, few of the reviewed studies examined the implications of this heterogeneity for service provision, nor did most studies adequately characterize the heterogeneity of their participants. Moving services research forward will entail characterizing the wide diversity of service needs in this heterogeneous population and careful thinking of ways to target services accordingly.
Most of the reviewed studies focused on adults aged 29 years or younger. Future research on services for adults with an ASD needs to more consistently reach into middle and older adulthood, as the needs and intervention models for these groups are likely to be different than for those who are in their 20s.
The reviewed research also failed to note that the nature and meaning of aging from adolescence to adulthood has undergone a significant historical shift in recent decades, resulting in a new stage of psychosocial development called emerging adulthood. In the early 1990s, Arnett41
suggested that the transition from adolescence to adulthood is no longer best represented by a normative sequence of social role transitions, such as ending formal schooling, moving out of the parental home, getting married, or having children—which are now more often achieved in a gradual, disordered fashion.41–43
Instead, he identified 3 criteria defining the transition to adulthood that could be measured in future services research: independence in decision making, being responsible for one’s own person, and financial independence. 44
Not a single reviewed study examined patterns of service use across multiple service providers or sectors. However, ASDs are pervasive (by definition) regarding how many areas of development and function are affected. People with an ASD often need various kinds of support from multiple service providers and across different sectors and systems of care.45
Future ASD research needs to investigate the prevalence, management, and consequences of simultaneous engagement in multiple types of services. A particular emphasis is needed on the issues of care coordination, the extent to which families and individuals need support navigating complex multi-sectoral systems of care, and research on the effectiveness of models for supporting care navigation.
Most of the reviewed studies focused on life functioning in the area of employment. Gerhardt6
noted a similar predominant focus on employment topics related to transition planning. However, work is but one dimension of adult life. Future research needs to examine services aimed at supporting positive functioning in a wider array of adult social roles and settings.
Few reviewed studies were explicitly anchored in a conceptual model of disability or human development. Several ideas from the broader field of disability research could be useful for this area of research. The capability approach is rooted in the seminal work of Nobel economist Amartya Sen and has been adapted by others to address disability-related issues.46–53
From this perspective, promoting positive human development means expanding choices for all people to achieve higher quality of life and well-being. Capability is based on a convergence of individual abilities, an enabling socioeconomic context that fosters multiple options, and the freedom to make choices for oneself. In turn, having capabilities can translate into achieved functioning through agency in areas such as health, mental health, social role attainment (having a job, going to school), and social participation. This framework suggests the broad aim of service provision is to improve capabilities so that people can attain more positive achievements in multiple domains of life functioning.
Capability approach’s simultaneous focus on individual abilities and the social context imply that interventions, at either level, can have potential for positive impact on achievements. The related implication is that intervening only at the level of individual abilities cannot, by itself, lead to enduring positive achievements at the population level. Intervention must also occur at the level of the social environment to achieve enduring population-level change.
Another useful conceptual model of disability is the World Health Organization’s ICF.54
The model acknowledges the influence of personal and environmental contextual factors on how disability is experienced by an individual, and how the confluence of all these factors forms the disability experience. The ICF uses a biopsychosocial model of disability, combining elements of both biomedical and social perspectives of disability. An advantage of the ICF is that it provides a detailed system of classification for activity participation and limitation indicators that could be used by programs for the sake of individual assessment and intervention goal setting, as well as for program evaluation and performance measurement at the agency and community levels.
In addition to these conceptual models, future research on services for adults with an ASD should also draw from the ideas and methodologies of the more fully formed field of health services research, which often organizes research questions into aims related to effectiveness, equity, efficiency, and access.55–57
Effectiveness research aims to build an evidence base of what works in real-world settings. Equity research puts the focus on questions of disparate access and outcomes stratified by race, ethnicity, sex, and SEP. Efficiency research highlights issues of cost and finding ways to make the most of finite financial resources. Access to services can be usefully defined along 5 dimensions: availability (do services exist?), affordability (are they affordable?), accessibility (are they geographically and physically accessible?), acceptability (what are the attitudes of youths and families toward currently available options?), and accommodation (how are the currently available options organized?). Future research on services for adults with an ASD needs to address this broad set of potential aims.