Outdoor Temperature Influences Blood Pressure

By Richard Shank

It has been 40 years since the discovery of seasonal variations in blood pressure. Subsequent research demonstrated that these variations were directly related to outdoor temperature, where blood pressure decreased with higher outdoor temperatures and increased with lower temperatures.

Very little is known about how this relationship impacts older adults. Before the present time, only one large study attempted to examine how temperature-related changes in blood pressure differed by age; however, this study did not include adults over the age of 64. Recent research, published in the Archives of Internal Medicine, attempted to shed light on this issue.

The Three-City Study (3C Study) is a population-based longitudinal study whose primary focus is on the relationship between dementia and vascular disease. Data from this study allowed researchers to examine the impact that outdoor temperature had on the arterial blood pressure of adults 65 and older.

The researchers suggest that older adults face elevated risks associated with temperature-related changes in blood pressure. This population often has a diminished capacity to regulate blood pressure and faces a greater chance of cardiovascular-related morbidity during extreme weather events. They find it important to consider how weather temperature influences blood pressure, since older adults who live in extreme hot or cold conditions, or who experience wild fluctuations in air temperature, will be at the greatest risk of illness and death.

This research found that both systolic and diastolic blood pressure differed significantly between all four seasons of the year, in that systolic blood pressure decreased with increasing temperature. Temperature-related changes in blood pressure were greatest among research participants 80 years and older.

This research implies that older adults need increased blood pressure monitoring during the winter and summer months as well as during periods of extreme hot or cold.

Source: Alperovitch, A. Lacombe, J-M., Hanon, O. et al. 2009. Relationship between blood pressure and outdoor temperature in a large sample of elderly individuals: The Three City Study. The Archives of Internal Medicine 169(1): 75–80.

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