Researchers at the Kennedy Krieger Institute in Baltimore, MD recently found that boys diagnosed with ADHD scored lower on motor coordination tests than their female counter parts or control groups. The study, published in Neurology, tested skills like tapping feet to a rhythm and balancing in young people between 7 and 15 years old. The results now have researchers wondering why boys with ADHD seem so much more delayed.
To get a better understanding of the research I contacted the study’s author, E. Mark Mahone, PhD, who has been quoted in the media saying that the conclusions build on current knowledge about brain development and ADHD. “In our previous work, we found that children with ADHD had difficulties with motor speed and coordination. In typically developing children, we found that motor development improved earlier in girls than in boys. Thus, we wanted to see if this difference extended to children with ADHD.”
Dr. Mahone went on to say, “Girls brains, particularly the part of the brain that supports motor development, develop earlier than boys.” However there are some things about the study that do raise questions. If there were a causal link between ADHD and these delays in coordination, why don’t they effect boys and girls equally? In other words, why does it seem that ADHD slows down boys motor development but doesn’t do the same for girls?
Dr. Mahone explained that all the participants of the study were screened heavily. Participants and Parents had structured psychiatric interviews and parents and teachers filled out questioneers on student behavior. Participants with other neurological disorders or those who take psychotropic medications (not including stimulants commonly used by children diagnosed with ADHD) were screened out.
The problems with the study come in with the things that were not controlled for, particularly media intake and weight issues. Lets look at some numbers on media intake or screen time from Tracie A. Barnett, Ph.D. a professor and researcher from Montreal.
- 52 percent of boys/26 percent of girls reported average total screen-time levels above 42 hours per week;
- 52 percent of boys and 39 percent of girls reported average levels of TV/video use above 23 hours per week;
- 24 percent of boys and 7 percent of girls reported average levels of computer/Internet use of almost 30 hours per week.
- Approximately 73 percent of girls and 48 percent of boys were in the ‘low’ total screen-time group, corresponding nevertheless to between 18 and 22 hours of screen-time per week.
Clearly boys overdose on TV, games, and the net at much higher levels than girls. The significance here is a high percentage of boys are spending all that time not doing other things like playing basketball, riding bikes, or learning to juggle. The delays these boys are experiencing in coordination or attention clearly could be positively linked to screen time.
The other possible issue the Kennedy Krieger study failed to screen for was obesity. Well into the 1990s the obesity rate for boys and girls stayed right about at the same level. However, in the last few years the numbers have changed. A CDC study finished in 2000 found that boys 6 to 11 had a 16% obesity level compared to 14.5% in girls. In the teenage year the numbers even out between boys and girls, but that disparity at younger ages could definitely lead to delays in dexterity or coordination. All of these issues with weight are further complicated by the previously found connections between weight and ADHD. This past Summer, U.S. News & World Report published a story on weight and ADHD. Young people with ADHD are 50% more likely to be overweight and also more likely to be underweight.
Dr. Mahone’s study clearly tells us more about the condition of kids with diagnosed with ADHD. Boys with ADHD do seem to show pronounced delays in physical adeptness. The question now is, “what does it mean?“ As scientists try to figure out what ADHD is neurologically and psychologically they can begin to try and zero in on how it affects different aspects of human development. But ADHD is not the only issue affecting youth development in the world today and some say it is more of a symptom than a disease.
