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Written By Zeran Zhang, Co-VP for Music For Dementia
Here is the link to the full article: https://doi.org/10.1016/j.envint.2018.12.054 (Wei et al., 2019).
This is a paper published in 2019 in the Environmental International Journal about a 11-year study that analyzes data collected from New England dementia patients and seasonal and temporal fluctuations in seasonal temperatures for each New England zip code to find the associations between seasonal temperature and dementia-associated hospitalizations in New England.
The study is impactful because it sheds light on how human-induced climate change is also a public health issue, where it can directly impact the well-being of large and vulnerable populations and indirectly burden families, the healthcare system, and the economy, by increasing costs due to to hospitalization, caregiving, and decreased productivity.
Human-induced climate change has been accelerating in the past 10 years and the results from the study show that cooler-than-average temperatures and higher temperature variability increase the risk of dementia-associated hospital admissions. It is important to note that this study was conducted from 2001-2011 and examines the effects of long-term temperature fluctuations on the health of the elderly population, because there has already been research done to support that short-term temperature extremes such as heat and cold waves are associated with adverse health effects.
Based on previous animal studies that show memory improvement in mice when ambient, or room temperature, is increased, and the fact that body temperature decreases with increasing age as thermoregulation becomes unbalanced, the hypothesis focused on the association between dementia-related hospitalizations and greater temperature variability. The study restricted human subjects to older than 65 residing throughout New England, and those whose dementia diagnosis is a principal diagnosis or secondary diagnosis. As mentioned before, seasonal temperatures and characterized spatial differences and temporal fluctuations in seasonal temperatures were estimated for each New England zip code by using a satellite-based prediction model, and potential confounding variables, such as the risk factors for dementia and individual-level variants such as sex, race, age, income etc. were taken into account during data collection and analysis.
The main results of the study show that every 1.5 °C increase in summer mean temperature was significantly associated with a 12% increased hazard of dementia-associated hospital admission. There was also a significant increased risk of dementia admission every 0.5 °C increase in standard deviation of summer temperature (HR = 1.07; 95% CI: 1.05, 1.09). The association between higher winter temperature variability and increased risk of dementia admissions (HR = 1.03; 95% CI: 1.00, 1.06) was not highly statistically significant. It is also interesting that the researchers acknowledge that participants who had more access to medical care, air conditioning etc. could have been less impacted by climate change and suffer less health costs.