Background: Alzheimer’s disease, the most common cause of dementia among the elderly, is
a progressive and irreversible neurodegenerative disease. Exposure to air pollutants is known to have
adverse effects on human health, however, little is known about hydrocarbons in the air that can trigger
a dementia event.
Objective: We aimed to investigate whether long-term exposure to airborne hydrocarbons increases the
risk of developing dementia.
Method: The present cohort study included 178,085 people aged 50 years and older in Taiwan. Cox
proportional hazards regression analysis was used to fit the multiple pollutant models for two targeted
pollutants, including total hydrocarbons and non-methane hydrocarbons, and estimated the risk of dementia.
Results: Before controlling for multiple pollutants, hazard ratios with 95% confidence intervals for the
overall population were 7.63 (7.28-7.99, p <0.001) at a 0.51-ppm increases in total hydrocarbons, and
2.94 (2.82-3.05, p <0.001) at a 0.32-ppm increases in non-methane hydrocarbons. The highest adjusted
hazard ratios for different multiple-pollutant models of each targeted pollutant were statistically significant
(p <0.001) for all patients: 11.52 (10.86-12.24) for total hydrocarbons and 9.73 (9.18-10.32) for
Conclusion: Our findings suggest that total hydrocarbons and non-methane hydrocarbons may be contributing
to dementia development.