Three years ago, an international study commissioned by the Lancet listed 12 modifiable factors that increased dementia risk, including three new ones: binge drinking, head injury, and air pollution.
Written in the May 2, 2023 edition of the Journal of Alzheimer’s diseaseA team of researchers, led by scientists at the University of California, San Diego, explains in more detail how exposure to the last of these new factors – ambient air pollution, such as car exhaust and emissions from power plants electrical) is associated with an increased risk of developing dementia over time.
Lead author William S. Kremen, PhD, professor of psychiatry and co-director of the Center for the Behavioral Genetics of Aging at UC San Diego School of Medicine, and colleagues examined baseline cognitive assessments of approximately 1,100 men participating in the study. of Vietnam-era twins in the process of Aging. The mean initial age was 56 years, with 12 years of follow-up.
They also analyzed measures of exposure to particulate matter (PM2.5) in the air and nitrogen dioxide (NO2), which is created when fossil fuels are burned, and assessments of episodic memory, executive function, verbal fluency, brain processing speed, and APOE genotype.
APOE is a gene that provides instructions for making a protein crucial for transporting cholesterol and other fats in the bloodstream. A version or allele of APOE called APOE-4 has been identified as a strong risk factor gene for Alzheimer’s disease.
The researchers found that participants with higher levels of PM2.5 and NO2 exposure in their 40s and 50s showed worse cognitive functioning in verbal fluency between ages 56 and 68. And people with the APOE-4 allele seemed even more sensitive, with people exposed to higher levels of PM2.5 showing worse outcomes for executive function and those with higher NO2 exposure showing worse outcomes related to episodic memory.
Executive function refers to the higher-level cognitive abilities used to plan, control, and coordinate behaviors and mental acts. Episodic memory is the ability to recall and re-experience distinct and specific past events.
“The 2020 Lancet report concluded that modifying 12 risk factors, including others such as education and midlife depression, could reduce the incidence of dementia by up to 40%,” said first author Carol E. Franz, PhD, professor of psychiatry and coauthor. director of the Center for the Behavioral Genetics of Aging.
“That report placed ambient air pollution as a greater risk of Alzheimer’s and related dementias than diabetes, physical activity, hypertension, alcohol use and obesity. Our findings underscore the importance of identifying modifiable risk factors as earlier in life as possible, and that the processes by which air pollution affects the risk of cognitive decline in later life begin earlier than previous studies suggest.”
Coauthors include: Daniel E. Gustavson, University of Colorado Boulder; Jeremy A. Elman, Christine Fennema-Notestine, Donald J. Hagler, Jr., Xin M. Tu, Tsung-Chin Wu, and Nathan Whitsell, all at UC San Diego; Aaron Baraff, VA Puget Sound Health Care, Seattle; Jaden DeAnda, UC San Diego and San Diego State University; Asad Beck and Joel D. Kaufman, University of Washington; Caleb E. Finch and Jiu-Chiuan Chen, University of Southern California; and Michael J. Lyons, Boston University.
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