Systemic approaches are therapies that look at a person within their relationships and settings, such as family, partner or workplace, rather than only at the individual.
Family therapy and couples therapy are the best-known examples. The idea is that difficulties often come from the pattern between people as much as from one person, so changing the pattern helps everyone in it.
This approach is useful for ADHD and autism. In a household where one partner has undiagnosed ADHD, the other partner often takes on more and more of the planning, and both become frustrated. Understanding the ADHD changes how both partners understand that pattern.
For autistic adults, systemic work can mean adjusting the environment and how people around them communicate, rather than asking the autistic person to adapt alone.