Honglei Chen, MD, PhD

Dr. Chen is a Professor at the Department of Epidemiology and Biostatistics of Michigan State University. His research focuses on studying environmental causes of neurodegenerative diseases with the ultimate goal of disease prevention and healthy aging.

 

PRIMARY RESEARCH INTERESTS 

• Search for the environmental causes of Parkinson’s disease and neurodegeneration. Genes and environmental factors, alone or in combination, contribute to the pathogenesis of Parkinson's disease. Over the past decade, Dr. Chen’s research has contributed to a better understanding of the role of environmental factors in Parkinson's etiology.
• Understand the complexity of prodromal neurodegeneration and the roles of the environment. Parkinson’s disease and dementia may take decades to develop, and by the time of diagnosis, it is generally too far gone to intervene. Over the past decades, it has become clear that various nonspecific symptoms (e.g., poor olfaction, dream enacting behaviors) may develop years, if not decades, before the disease’s clinical diagnosis. Dr. Chen studies these prodromal symptoms with two important goals: first to characterize populations at-risk, and second to identify the environmental triggers and modifiers of prodromal neurodegeneration, both critical for disease prevention.  
• Study poor olfaction as “miner’s canary” foretelling deteriorating health in older adults. Besides Parkinson’s disease and dementia, poor olfaction in older adults has been robustly linked to higher mortality. When examining how much of this could be explained by neurodegenerative diseases, Dr. Chen’s team found only ~22%. This suggests most of the health consequences of poor olfaction in older adults remain unknown. Given the high prevalence of poor olfaction in older adults, Dr. Chen is interested in assessing the potential profound health implications of poor olfaction in older adults.

Importantly, these research interests are interconnected and may synergistically improve our understanding of major health issues in older adults and identify preventive strategies. The olfactory system is uniquely positioned at a host-environment interface, and olfaction may thus be a sensitive “sentry” reflecting both intrinsic physiological aging and cumulative damages from environmental insults. Therefore, a comprehensive research program involving environmental risk factors, poor olfaction, and neurodegeneration may significantly advance our understanding of the environmental causes of neurodegenerative diseases in the context of aging.

 

MAJOR RESEARCH PROJECTS

 

• Airborne pollutants as triggers of Parkinson's Disease via the olfactory system - This is a multi-PI project supported by the US Department of Defense (9/2017-8/2022), supplemented by funding from the Parkinson Foundation. In this project, we have objectively assessed the sense of smell of ~3,400 women, ages 50-79, from the NIEHS Sister Study. The primary goal of this project is to assess the roles of air pollutants in olfactory impairment and their relevance to Parkinson’s disease.
• Pesticides, olfaction, and neurodegeneration among US farmers - In this R01 project (2/2019 – 1/2024), we aim to investigate the roles of pesticides in olfaction impairment and their relevance to prodromal neurodegeneration. We have tested the sense of smell of ~2,500 farmers from the Agricultural Health Study. Currently, we are conducting virtual clinical exams on selected participants to further assess their cognitive and motor functions more accurately.
• Poor olfaction and the health of older adults - In this R01 project (6/2022 – 2/2027), we aim to answer two novel and clinically-significant questions: 1) What adverse health outcomes can a poor sense of smell in older adults potentially herald, in addition to neurodegenerative diseases? 2) Is poor olfaction a marker of accelerated aging? We will conduct secondary data analyses in the Health ABC and ARIC studies.

These projects support the team’s research interests and approach. With these valuable and complementary resources from well-established longitudinal cohorts, Dr. Chen aims to decipher the codes of poorly understood poor olfaction, prodromal neurodegeneration, environmental causes, and beyond.

 

BIOGRAPHY

Dr. Chen earned his M.D. (equivalent) from TianJin Medical University in TianJin, China, and Master's degree from the Chinese Academy of Preventive Medicine in Beijing, China. In 2001, he earned his Ph.D. in Nutritional Epidemiology from Tufts University in Boston, MA, and then worked as a Research Fellow and Instructor at the Harvard School of Public Health. From 2005-2016, Dr. Chen worked at the Epidemiology Branch of the National Institute of Environmental Health Sciences and received his Tenured Senior Investigator appointment from NIH in 2013. Dr. Chen joined Michigan State University in 2016 as a professor in the Department of Epidemiology and Biostatistics, and was recognized with the MSU Foundation Professorship in 2021 for his excellence in research.

 

PRESS RELEASE

1. Can Poor Sense of Smell in Older Adults Lead to Chronic Diseases?
2. Chen Named MSU Foundation Professor
3. Poor olfaction and pneumonia risk
4. Olfaction predicts risk of death
5. MSU lands 5 million NIH grant to connect dots between pesticides and Parkinson’s
6. High pesticide exposure event linked to poor olfaction
7. DoD funding to study air pollution and Parkinson’s prodromal risk
8. Olfaction predicts Parkinson’s risk

 

SELECTED PUBLICATIONS

 

• Cao Z, Yang A, White AJ, Purdy F, Li C, Luo Z, D'Aloisio AA, Suarez L, Deming-Halverson S, Pinto JM, Chen JC, Werder EJ, Kaufman JD, Sandler DP, Chen H. Ambient Air Pollutants and Olfaction among Women 50-79 Years of Age from the Sister Study. Environ Health Perspect 2023 Aug;131(8):87012. doi: 10.1289/EHP12066. Epub 2023 Aug 18. PMID: 37594315
• Yuan Y, Shrestha S, Luo Z, Li C, Plassman BL, Parks CG, Hofmann JN, Beane Freeman LE, Sandler DP, Chen H: High Pesticide Exposure Events and Dream-Enacting Behaviors Among US Farmers Mov Disord. 2022 Feb 13. doi: 10.1002/mds.28960. Online ahead of print; PMID: 35152487
• Yuan Y, Luo Z, Li C, Pinto JM, Shiroma EJ, Simonsick EM, Chen H: Poor olfaction and pneumonia hospitalisation among community-dwelling older adults: a cohort study. Lancet Healthy Aging May 21, 2021, 2(5): e275
• Liu B, Luo Z, Pinto JM, Shiroma EJ, Tranah GJ, Wirdefeldt K, Fang F, Harris TB, Chen H. Relationship Between Poor Olfaction and Mortality Among Community-Dwelling Older Adults: A Cohort Study. Ann Intern Med. 2019 May 21;170(10):673-681. doi: 10.7326/M18-0775. Epub 2019 Apr 30. PubMed PMID: 31035288.
• Shrestha S, Kamel F, Umbach DM, Freeman LEB, Koutros S, Alavanja M, Blair A, Sandler DP, Chen H. High Pesticide Exposure Events and Olfactory Impairment among U.S. Farmers. Environ Health Perspect. 2019 Jan;127(1):17005. doi:10.1289/EHP3713. MID: 30648881.
• Palta P, Chen H, Deal JA, Sharrett AR, Gross AL, Knopman D, Griswold M, Heiss G, Mosley TH. Olfactory Function and Neurocognitive Outcomes in Old Age: the Atherosclerosis Risk in Communities Neurocognitive Study (ARIC-NCS). Alzheimers Dement 2018 pii: S1552-5260(18)30073-6. doi: 10.1016/j.jalz.2018.02.019. PMID: 29605223
• Chen H, Shrestha S, Huang X, Jain S, Guo X, Tranah GJ, Garcia ME, Satterfield S, Phillips C, Harris TB; Health ABC Study. Olfaction and incident Parkinson disease in US white and black older adults. Neurology 2017 Sep 6. pii: 10.1212/WNL.0000000000004382. PMID: 28878051.
• Dong J, Pinto JM, Guo X, Alonso A, Tranah G, Cauley JA, Garcia M, Satterfield S, Huang X, Harris T, Mosley TH Jr, Chen H. The Prevalence of Anosmia and Associated Factors Among U.S. Black and White Older Adults. J Gerontol A Biol Sci Med Sci. 2017 Aug 1;72(8):1080-1086. doi: 10.1093/gerona/glx081. PMID: 28498937. 
• Liu R, Young MT, Chen JC, Kaufman JD, Chen H. Ambient Air Pollution Exposures and Risk of Parkinson Disease. Environ Health Perspect. 2016 Nov;124(11):1759-1765. Epub 2016 Jun 10. PMID: 27285422; PMC5089873.
• Alonso A, Huang X, Mosley TH, Heiss G, Chen H. Heart rate variability and the incidence of Parkinson’s disease: the ARIC study: Ann Neurol. doi: ;77(5):877-83. doi: 10.1002/ana.24393, 2015. PMID: 25707861
• Liu R, Umbach D, Peddada S, Tröster AI, Huang X, Chen H. Potential sex differences in non-motor symptoms in early drug-naive Parkinson disease: Neurology, 2015, PMID: 25925983