Like ASD, the prevalence of ADHD has increased significantly in the past 2 decades. A critical analysis examines the factors, and many of them can be applicable to the increase in the rise of autism diagnoses: increased diagnosis in adults, looser diagnostic criteria, and untrained professionals making the diagnoses. While they are not of course the same, listen to some of their arguments and read their comments (link below) to see if you agree with my assessment.

https://onlinelibrary.wiley.com/doi/epdf/10.1002/jclp.23348