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Dennis J. Baumgardner, MD

Geographic Analysis of ADHD in Children: Milwaukee County

Contributors: 
Dennis Baumgardner MD

Dennis J. Baumgardner, MD, Professor in the Department of Family Medicine on the Milwaukee Campus (Aurora UW Medical Group and Center for Urban Population Health), served as primary investigator for the Geographic Analysis of ADHD in Children: Milwaukee County study, funded by a small grant from the UW-Department of Family Medicine. He was assisted by Jonathan Weimer, a UW-M undergraduate student, and Andrea Schreiber, MA, a GIS expert with the Center for Urban Population Health.

Attention deficit hyperactivity disorder (ADHD) is a prevalent neurodevelopmental disorder of childhood. Older studies have shown that male gender, low income, and family dysfunction increase the incidence of ADHD, without apparent relationship to geographic region, socioeconomic status, or environmental factors. A recent study (2001) has suggested a higher screening prevalence of ADHD in African-American students than white students, but no variation by geographic region or socioeconomic status. A 2004 study suggested that green outdoor settings decrease ADHD symptoms.

ADHD Map

We performed a pilot GIS (Geographic Information Systems) study to determine if there is a non-random geographic distribution of ADHD in Milwaukee County. Street addresses and demographic data of all children aged five through seventeen receiving continuity care at three Family Medicine Clinics in Milwaukee who did, or did not, have ADHD were geocoded with Map Marker Plus and were mapped using GIS technology.

In univariate analysis, all non-white ethnicities were less frequently diagnosed with ADHD, and 75% of children diagnosed with ADHD were male. In multivariate analysis, zip code of residence and gender were significant factors, but not race/ethnicity. ADHD cases were over represented in southern and western suburban school districts, compared to the City of Milwaukee, and particularly in a zip code adjacent to the major airport.

First it is important to remember that the results are associations, not cause and effect! A possible explanation for the overrepresentation of cases in suburban school districts is that such districts may be more "aggressive" or have more resources to identify children with possible ADHD and see that they follow through with diagnosis. Perhaps some school personnel are more likely to seek a medical diagnosis (ADHD) to explain disruptive behavior in a student rather than other psychosocial factors. Given that another study found a higher ADHD screening positivity rate in African-American children, could we be seeing a health diagnosis disparity?

The community adjacent to the airport may have the highest case density ratio because that school district is particularly "efficient" regarding referral for ADHD diagnosis, rather than any contribution from airport noise. Again, these results are associations, not cause and effect.

A weakness of this study is the relatively small size and lack of subject interviews (subjects may have lived somewhere else most of their lives). Further studies are needed to determine if the geographic distribution of ADHD patients can be partially explained by differential efficiency of referral for diagnosis by school districts and/or environmental factors such as noise corridors.