In contrast to studies on ‘individuals’, however, only a very small percentage of literature over the past 2 years has focused on ‘families’ of offspring with developmental disabilities. Table 1 shows the numbers and percentages of family articles across five different groups: autism, intellectual disabilities, other developmental disabilities, genetic syndromes, and psychiatric disorders. On the basis of the total number of studies in each diagnostic group, family studies capture, on an average, just 3% of published work in these disorders.

The uneven distribution between individual versus family studies is both predictable and unsettling. On the one hand, technological advances are facilitating a remarkable growth of new insights into the genetic and neurobiological mechanisms of many specific IDDs [7^■]. Such work requires increasingly specialized expertise and technology, as well as interdisciplinary research that enable linkages between neurobiological, genetic, developmental, and phenotypic data.

On the other hand, this remarkable progress appears to be accomplished at the expense of studies on the families in which affected individuals live and grow. However, two qualifications to this assertion are in order. First, while families are certainly studied, it is typically through the lens of parental risk factors that potentially contribute to child outcomes. Such studies focus, for example, on parental genetic or epigenetic contributions, or other factors (e.g. age, infections, and exposures during pregnancy) that may have a causal link to offspring with developmental disabilities.

Second, a body of critically important work has examined children living in adverse, toxic, or impoverished families or institutions, providing unique insights into brain plasticity, stress, and developmental trajectories [8^■]. Research on extreme environmental conditions, including children exposed to abuse, violence, or neglect, points to actionable risk factors and social policies that can improve outcomes for all children, including those with developmental disabilities.

Genetic factors and extreme family or environmental conditions aside, what do the 173 family studies noted in Table 1 address?

The 173 recently published articles generally affirm previous work showing considerable stress in parents of children with disabilities, and at much higher levels than parents of typically developing children. These articles differentially address one or more of the following themes:

Maternal coping and mental health: These include maternal emotional, problem-solving, avoidant and other coping styles, as well as anxiety, depression, sleep, optimism, hope, satisfaction, health, mental health, well-being, broader autism phenotype in parents or siblings.

The majority of the 173 family publications (64%) applied the themes noted above to parents of children with ASD. As shown in Table 1, remaining articles were equally spread between intellectual and developmental disabilities, with fewer studies on families of children with genetic syndromes or psychiatric disorders.

Several factors likely contribute to the predominance of studies on families of children with ASD. Certainly, the rising prevalence of children diagnosed with ASD, now approximately 1% of the child population [2], partially explains these trends. As well, there continues to be considerable federal and private foundational funding for research on ASD relative to other disabilities. Studies on the broader autism phenotype in first-degree relatives could also inflate study numbers, but just four of the 110 family autism studies addressed this issue.

The predominance of family studies in autism is consistent with a recent analysis of which neurodevelopmental disorders get studied. Bishop [9] found that both National Institutes of Health (NIH) funding and publications favored rare, clinically severe conditions. However, two prevalent disorders were major exceptions to this rule – autism and attention deficit hyperactivity disorder? – with each showing substantial increases in funding and publications.

While a research and funding focus on rare, clinically severe disorders may apply to affected ‘individuals’, this trend does not appear to hold up in studies of ‘families’ of affected individuals. Indeed, very few recent studies examined the families who care for children with psychiatric disorders, genetic syndromes, or severe intellectual disabilities [10].

Consistent with current practices, family studies often used the global term ‘developmental disabilities’ to describe their samples with heterogeneous causes. Although the Tables aimed to represent each disorder as distinctly as possible, diagnostic overlap exists. As such, these Tables should be viewed as painting broad strokes of the family literature. For example, the 22 family studies in developmental disabilities included those with sensory, motoric, or medical disabilities who may or may not have also had co-occurring cognitive impairments.

Historically, the prevalence rate of intellectual disabilities has varied between 1 and 3%, with a recent international meta-analysis reporting intellectual disabilities in 1% of the population [3]. Thus, even though intellectual disabilities are as prevalent as ASDs, disproportionately fewer studies focused on the concerns of parents raising children with intellectual disabilities as opposed to ASD. Bishop [9] noted a similar trend in the literature, albeit with individuals, not families, in which publications on intellectual disabilities fell below the level predicted by either the prevalence or severity of these disabilities.

The majority of studies on families of children with intellectual and developmental disabilities were conducted abroad. As shown in Table 2, just one study on families of children with intellectual disabilities was conducted in the USA, and 18 abroad. In contrast, families of children with autism accounted for 80% of family studies published in the past 2 years. Studies abroad were better distributed across disability types, with autism being a focus in 40% of international family studies.

Probing these findings further, 24 different countries contributed to the past 2 years of family and disability literature. Australia, the UK, and Canada collectively accounted for 44% of international family publications, and 17% were from India, China, or Greece. The remaining 39% originated from countries that varied considerably in their levels of economic development. Overall, then, researchers in the USA are more likely to publish study families of children with autism than families of offspring diagnosed with other developmental disabilities.

Having thoroughly described families, we now need to translate this work into meaningful interventions that help families. Strikingly, however, Table 3 shows that just 20 articles (11%) of the 173 family publications over the past 2 years were devoted to interventions aimed at reducing parental stress or enhance their well-being. An additional four articles outlined therapeutic models to guide future intervention [11]. Intervention studies were only included in this tally if there was some measure of parental outcome; not included were studies that provided parent training in order to impact specific child outcomes. Sometimes, however, parent training that targets child functioning may also have indirect or downstream salutatory effects on parent stress [12]. Articles that formally measured such indirect effects were counted among the 11%.

The types of interventions tested in these 20 studies are summarized in Table 4. Of note is that the vast majority of interventions were psychoeducational in nature. These approaches generally combined teaching, modelling, or sharing specific disability-related information (e.g. transitioning youth with ASD, behavior problems in young children), with additional curriculum on parent coping skills or tips for stress reduction [13^■,14–16]. Psycho-educational groups were generally effective, with participants reporting more parenting confidence and emotional support and, at times, reduced stress.

Three of the 20 intervention studies assessed the impact of respite care on families [17^■,18^■,19]. These studies report positive effects, including improved marital relations and less distress after taking a welcomed reprieve from care giving duties. A concern, however, is that these short breaks do not necessarily teach parents new skills or strategies to promote their healthy development once the break is over. Good responses to marriage or family counseling were also reported in couples with children on the autism spectrum [20]; however, just a few case reports and theoretical issues were described.

An additional three studies took a different approach by implementing groups of mindfulness-based stress reduction with parents of children with autism and other disabilities [21^■,,22,23^■,]. The salutatory effects of mindfulness practices have a strong evidence base, and are increasingly used in medical and psychiatric patients, educational settings, and in the general population. Two of these studies used a wait list control design [21^■,,22], and one also included special education teachers – a group at high risk for professional burn out [22]. The third study – a randomized trial of 243 mothers – compared mindfulness-based stress reduction to positive psychology interventions aimed at promoting healthy adult development [23^■].

At post-treatment, all three mindfulness studies reported improved parental outcomes in stress and depressive symptoms, and one [21^■] noted modest spill over effects of parental improvements on children’s ADHD symptoms. The comparative effectiveness study [23^■] also followed participants up to 6 months after treatment. On average, improvements were sustained in the post-treatment follow-up period in sleep, well-being, stress, depression, and anxiety. Further, whereas both treatments had positive effects, those in the mindfulness group showed steeper and more rapid improvements, and those in the positive adult development arm reported increased well-being during follow-up.

The comparative study also successfully tested a peer-mentor model of treatment delivery [23^■]. Prior to co-leading treatment groups, parents of children with disabilities went through in-depth training in intervention curricula, research ethics, and the peer-mentor role; they also received clinical supervision throughout the study. This approach took advantage of naturally occurring rapport between parents in the disability community, and showed considerable promise for reaching at-risk families who may not otherwise seek professional services.

Strikingly, less than 1% of recent studies of children with psychiatric disorders addressed the stress, adjustment, and coping of parents raising these children. This gap is an important one to fill. Parents of children with psychiatric disorders face similar challenges as parents of children with autism or other IDDs. These include managing significant child behavioral or emotional problems, advocating for their child, organizing medical, behavioral and other therapies, coping with stigma and isolation, and oftentimes, continuing their direct care giving role with adult children. Just one intervention study of parents of children with psychiatric illness was conducted in Eastern Asia [24^■]. Positive effects of empowering parents and rejecting stigma were found but tempered somewhat by cultural views and expectations. It is puzzling that family genetic or epigenetic contributions to psychiatric illness are of keen research interest, whereas parental stress and challenges in caring for these children are understudied, including interactions between stressful households and disease expression.

Although the sibling literature is gaining momentum, researchers often overlook these family members. Indeed, just 2% of the family studies reviewed addressed the adjustment of siblings living with a brother or sister with developmental disabilities. Even so, siblings have increasingly important care-giving roles as the population of adults with disabilities ages, and parents are no longer able to assume care-giving roles. Two recent studies of siblings of brothers or sisters with schizophrenia identify key elements that propel siblings to or from a care-giving role [25^■,26]. Other work found lower than expected levels of anxiety in siblings of brothers or sisters with autism [27^■], and several beneficial effects of family respite care for siblings [17^■].

Only a handful of family studies have used bio-markers to index levels of stress and distress in parents of children with disabilities. Disturbingly, these parents show blunted diurnal cortisol trajectories [28^■,29], accelerated telomere shortening [30], and compromised immune function in response to vaccination [31]. All are indices of stress chronicity. These and other biomarkers should be used to complement parental self-report as outcomes in future trials or interventions.