Heart Failure Plus Pollution Appears to Increase Dementia Risk, Study Indicates
Almost 70% of the world’s population could be living in urban areas, being continuously exposed to air pollution, by 2050, while cases of dementia are expected to triple. Recent study results highlight the link between cardiovascular disease and dementia, as mediated by long-term exposure to air pollution.
Sixty-eight percent of the world’s population could be living in urban areas, being continuously exposed to air pollution, by 2050, while cases of dementia are expected to triple.
"Air pollution is an established risk factor for cardiovascular health and because CVD accelerates cognitive decline, we believe exposure to air pollution might negatively affect cognition indirectly,"
Overall results show that heart failure and ischemic heart disease increased the risk of dementia and that stroke was a likely reason behind the development of close to 50% of cases of air pollution—related dementia.
Study participants, who were from the Kungsholmen district of Stockholm, were already enrolled in the ongoing
International Statistical Classification of Disease and Related Health Problems, Tenth Revision, criteria were used to classify the CVDs, and Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision, criteria were used to define dementia. Pollution levels were measured at the participants’ residential addresses,and calculated every 5 years (1990, 1995, 2000, 2005, and 2011).
During follow-up, 364 of the study participants developed dementia, the risk of which increased the most per interquartile (IQR) range difference in the previous 5 years for both levels of pollutants measured (HR for difference of 0.88 μm/m3 PM2.5, 1.54 [95% CI, 1.33-1.78]; HR for difference of 8.35 μm/m3 NOX, 1.14 [95% CI, 1.01-1.29]). When heart disease was investigated for its role in dementia development, these numbers were even higher:
- Heart failure had a hazard ratio for PM2.5 of 1.93 (95% CI, 1.54-2.43) and for NOX of 1.43 (95% CI, 1.17-1.75)
- Ischemic heart disease had a hazard ratio for PM2.5 of 1.67 (95% CI, 1.32-2.12) and for NOX of 1.36 (95% CI, 1.07-1.71)
As for stroke’s relationship to dementia and pollution, the results showed a 26% greater risk of stroke per IQR difference at higher levels of PM2.5, and the odds of developing dementia were 3.8 times greater following a stroke.
“Cardiovascular disease appeared to amplify the negative association of air pollution. In particular, heart failure and ischemic heart disease seemed to enhance the dementia risk, whereas stroke seemed to be an important condition between air pollution and dementia,” the authors concluded. “Interestingly, the higher [pollution] limit reported herein is not only below the current European limit for fine particulate matter but also below the US standard.”
Reference
Grande G, Ljungman PLS, Eneeroth K, Bellander T, Rizzuto D. Association between cardiovascular disease and long-term exposure to air pollution with the risk of dementia [published online March 30, 2020]. JAMA Neurol. doi: 10.1001/jamaneurol.
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