Childhood Lead Exposure and Attention-Deficit/Hyperactivity Disorder Symptoms: A Meta-Analysis

Childhood Lead Exposure and Attention-Deficit/Hyperactivity Disorder Symptoms: A Meta-Analysis by Megan Glenn Brown MS, Mississippi State University, 2008 BA, Utica College of Syracuse University, 2005 Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Clinical Psychology Walden University May 2018 Abstract Lead exposure during childhood is a significant global public health concern as the potential effects of exposure can result in the need for long-term treatment, diminished productivity in society, and financial strain on the health care system. There is strong evidence of a relationship between lead exposure and attention-deficit/hyperactivity disorder (ADHD); however, there is a gap in the current literature regarding the relationship between lead exposure and specific symptoms of ADHD and the strength of that relationship. The purpose of this meta-analysis was to examine and help quantify this relationship. Cohen’s d was used as the standardized mean effect size measure for this study, and allowed for comparison of 2 groups on a specific measure. For the final analysis 20 studies were included that provided a comparison between lead exposure and overall ADHD, inattentive, or hyperactive/impulsive symptoms. The magnitude of the effect size of childhood lead exposure on ADHD symptoms was significant and of medium strength. There was significant variability in the research results for inattentive and hyperactive/impulsive symptoms, and it was hypothesized that this variability may be due to factors related to lead levels and covariates known to affect ADHD symptoms.Lead exposure during childhood is a significant global public health concern as the potential effects of exposure can result in the need for long-term treatment, diminished productivity in society, and financial strain on the health care system. There is strong evidence of a relationship between lead exposure and attention-deficit/hyperactivity disorder (ADHD); however, there is a gap in the current literature regarding the relationship between lead exposure and specific symptoms of ADHD and the strength of that relationship. The purpose of this meta-analysis was to examine and help quantify this relationship. Cohen’s d was used as the standardized mean effect size measure for this study, and allowed for comparison of 2 groups on a specific measure. For the final analysis 20 studies were included that provided a comparison between lead exposure and overall ADHD, inattentive, or hyperactive/impulsive symptoms. The magnitude of the effect size of childhood lead exposure on ADHD symptoms was significant and of medium strength. There was significant variability in the research results for inattentive and hyperactive/impulsive symptoms, and it was hypothesized that this variability may be due to factors related to lead levels and covariates known to affect ADHD symptoms. Study results may contribute to positive social change by providing health care practitioners with a greater understanding of the effect of childhood lead exposure on ADHD symptoms, which they may use to achieve advancements in prevention and treatment. Improved prevention programs for lead exposure and early identification and treatment of related concerns may decrease negative outcomes, as well as the occurrence of ADHD symptoms on a population level, thus improving public health. Childhood Lead Exposure and Attention-Deficit/Hyperactivity Disorder Symptoms: A Meta-Analysis by Megan Glenn Brown MS, Mississippi State University, 2008 BA, Utica College of Syracuse University, 2005 Dissertation Submitted in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy Clinical Psychology Walden University May 2018 Dedication This dissertation is dedicated to my father, Dr. Thomas Glenn Brown, who passed away prior to its completion. Without his support and encouragement I would not have begun nor completed my doctoral degree, and his memory has kept me committed to this goal even when I felt discouraged. Acknowledgments I would like to thank Dr. McBride for his continued support and guidance throughout this process. I would also like to thank Dr. Little and Dr. Cabiria for their feedback and assistance.