Methodological challenges and opportunities when studying the course of autism.

Longitudinal research in autism has contributed a wealth of knowledge about etiological factors, development from childhood through adulthood, life course changes and needs, as well as longer-term adult outcomes for individuals on the spectrum and their family members. This research is essential to better understand the needs of individuals as they age. However, along with the as yet unrealized opportunities to understand an individual in more nuanced ways across time, there are challenges to utilizing this research design that should be considered. These include sample and measurement diversity, retention, outcome measures, analysis, and funding considerations. This article outlines some of the most pressing challenges together with potential solutions to maximize the value of longitudinal research designs that can help address questions that are of high priority to the autism community.Lay AbstractLongitudinal research has been critical to understand the life course of people with autism, including factors which increase the probability of an autism diagnosis, the emergence of early markers, co-occurring psychiatric conditions, predication of future educational and support needs across childhood and adulthood, and understanding what makes each person unique and contributes to the well-being of autistic people and their families. However, these studies take time, patience, investment of families and individuals, scientists and are challenging to all involved. This article will outline some of the issues that have occurred in the past and provide potential solutions to improve the quality of these studies to both the scientific and autistic communities. They include sample and measurement diversity, retention, outcome measures, analysis, and funding considerations. This understanding of the field is important for both scientific research and community engagement in the studies that include the autistic community.