Analysis of Heavy Metals in the Hair of Children with Attention-Deficit Hyperactivity Disorder and Tourette's Syndrome

ABSTRACT

OBJECTIVES: The purpose of this study was to examine the association of exposures to heavy metals with positive diagnosis for attention-deficit hyperactivity disorder (ADHD) and Tourette's syndrome (TS). METHODS: Study participants included 27 children diagnosed with ADHD (9.9+/-2.9 years of age), 21 diagnosed with Tourette's disorder (10.7+/-2.2 years of age), and 45 normal control children (9.6+/-0.5 years of age). A Perkin-Elmer mass spectrometer was used to measure the concentrations of 5 heavy metals (Pb, Cd, U, Be, Hg) in hair samples obtained from each participant. Each heavy metal concentration was compared among the groups by use of a Kruskal-Wallis test. RESULTS: The levels of lead (p=.006) and cadmium (p=.037) observed in the hair of children diagnosed with ADHD were significantly higher than those found in the control subjects. There were no significant differences observed for heavy metal levels when comparing TS and control subjects. CONCLUSION: We confirmed that lead exposure is a risk factor for ADHD. We also identified that cadmium may be a new candidate risk factor for manifestation of ADHD. We did not find an association between heavy metals and manifestation of TS.