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Comment & Response
June 2017

Could the Adoption of Unleaded Gasoline in the 1970s Play a Role in the Precipitous Decline in Dementia Prevalence?

Author Affiliations
  • 1Factor-Inwentash Faculty of Social Work, Cross-appointed to the Department of Family and Community Medicine, Faculty of Nursing and Institute for Life Course & Aging, University of Toronto, Toronto, Canada
  • 2University of Toronto, Institute of Health Policy, Management and Evaluation, Toronto, Canada
JAMA Intern Med. 2017;177(6):892-893. doi:10.1001/jamainternmed.2017.1074

To the Editor We read with great interest the article in a recent issue of JAMA Internal Medicine by Langa et al, “A Comparison of the Prevalence of Dementia in the United States in 2000 and 2012.”1 This study provides additional support for the emerging evidence that the prevalence and incidence of dementia may have decreased substantially in recent decades in the United States and other developed countries. We propose that the removal of lead from gasoline 4 decades ago may play a role in this precipitous decline. It should be noted that our proposal is a hypothesis that would have to be tested. Whether our hypothesis would explain findings about the prevalence of dementia at the population level is entirely speculative but worthy of further study.