| Cognitive Deficits and Magnetic Resonance Spectroscopy in Adult Monozygotic Twins with Lead Poisoning Marc G. Weisskopf,1 Howard Hu,1,2,3 Robert V. Mulkern,4 Roberta White,1,5,6 Antonio Aro,1,2 Steve Oliveira,2 and Robert O. Wright1,2,7 1Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA; 2Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA; 3Center for Occupational and Environmental Medicine, Northeast Specialty Hospital, Braintree, Massachusetts, USA; 4Department of Radiology, Children's Hospital Boston, Boston, Massachusetts, USA; 5Veterans Affairs Boston Healthcare System, Boston, Massachusetts, USA 6Department of Environmental Health, Boston University School of Public Health, Boston, Massachusetts, USA; 7Department of Pediatrics, Children's Hospital Boston, Boston, Massachusetts, USA Abstract
 |  |  |  |  |  |  | Harvard School of Public Health,
Harvard Medical School,
Northeast Specialty Hospital,
Children's Hospital,
Boston University School of Public Health,
and Veterans Affairs Boston Healthcare System |
Seventy-one-year-old identical twin brothers with chronic lead poisoning were identified from an occupational medicine clinic roster. Both were retired painters, but one brother (J.G.) primarily removed paint and had a history of higher chronic lead exposure. Patella and tibia bone lead concentrations measured by K-X-ray fluorescence in each brother were 5-10 times those of the general population and about 2.5 times higher in J.G. than in his brother (E.G.) . Magnetic resonance spectroscopy (MRS) studies examined N-acetylaspartate:creatine ratios, a marker of neuronal density. Ratios were lower in J.G. than in his brother. Scores on neurocognitive tests that assess working memory/executive function were below expectation in both twins. Short-term memory function was dramatically worse in J.G. than in his brother. These results demonstrate some of the more subtle long-term neurologic effects of chronic lead poisoning in adults. In particular, they suggest the presence of frontal lobe dysfunction in both twins, but more dramatic hippocampal dysfunction in the brother with higher lead exposure. The MRS findings are consistent with the hypothesis that chronic lead exposure caused neuronal loss, which may contribute to the impairment in cognitive function. Although a causal relation cannot be inferred, the brothers were genetically identical, with similar life experiences. Although these results are promising, further study is necessary to determine whether MRS findings correlate both with markers of lead exposure and tests of cognitive function. Nevertheless, the results point to the potential utility of MRS in determining mechanisms of neurotoxicity not only for lead but also for other neurotoxicants as well. Key words: lead poisoning, magnetic resonance spectroscopy, monozygotic, neuropsychological tests, paint, twins. Environ Health Perspect 112:620-625 (2004) . doi:10.1289/ehp.6687 available via http://dx.doi.org/ [Online 8 January 2004]
Address correspondence to M.G. Weisskopf, Harvard School of Public Health, Occupational Health Program, Landmark Center, 401 Park Dr., P.O. Box 15697, Boston, MA 02215 USA. Telephone: (617) 384-8872. Fax: (617) 384-8994. E-mail: mweissko@hsph.harvard.edu We are indebted to the steadfast and patient cooperation of J.G. and E.G., the two study participants who were the focus of this investigation. The KXRF instrument used in this work was originally developed by ABIOMED, Inc. (Danvers, MA) with support from the National Institutes of Health (NIH) (ES03918) . This research was supported by NIH grants R01-ES05257, K23-ES000381, General Clinical Research Center grant RR02635, and Center grant ES00002. The contents of this report are solely the responsibility of the authors and do not necessarily represent the official views of the NIH. The authors declare they have no competing financial interests. Received 20 August 2003 ; accepted 8 January 2004.
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