An overview of developments in research on persons with intellectual disabilities.

Matson et al. (2009) counted every paper on intellectual disability published from 1975 to 2005.

They used library tools, not lab tools. No kids were tested. The team simply asked, "What are we studying and who is doing the studying?"

Genetics papers topped the list every single year.

Yearly output almost doubled, but the topic mix stayed the same.

Behavioral intervention studies stayed a small slice. Most pages were about genes, brain scans, or medication.

Oliver (2014) later showed the field is finally shifting toward cognitive-process work and long-term studies. That update supersedes the 2009 snapshot.

Naaldenberg et al. (2013) looked only at health-promotion trials and also found weak methods. Together the two reviews reveal a second gap: even when we do test interventions, the designs are shaky.

Logan et al. (2000) saw the same male, university-based authorship pattern a decade earlier. The club has not grown much.

If you write grants, choose dissertation topics, or teach literature-review skills, this map is your starting point. It tells you where the crowd is not. Fewer genetics labs need BCBA partners; more behavioral labs do. Point your students toward intervention, participation, or executive-function studies—areas the field still under-serves.