Extreme changes in outdoor temperature can have a significant effect on an older adult's BP, particularly if he's over age 80. In a study of 8,801 men and women age 65 and older, French researchers found a strong correlation between baseline BP readings and outdoor temperature during follow-up exams. The variations were seasonal, with the highest BP readings occurring in the coldest weather and the lowest in hot weather.
An outdoor temperature drop of 59[degrees] F (15[degrees] C) was associated with a systolic BP increase of about 5 mm Hg in subjects age 80 and older, compared with a 0.8-mm Hg change in those ages 65 to 74. Conversely, an outdoor temperature increase of the same degree was associated with systolic BP decreases of about 14 mm Hg and 10 mm Hg in the two age-groups.
Researchers noted that increased BP raises the risk of stroke and other vascular events and decreased BP may be associated with syncope, falls, and heat-related illness. They concluded that "during periods of extreme temperatures, a careful monitoring of blood pressure and antihypertensive treatment could contribute to reducing the consequences of blood pressure variations in the elderly."
Sources: Alperovitch A, Lacombe JM, Hanon O, et al. Relationship between blood pressure and outdoor temperature in a large sample of elderly individuals: the Three-City study. Arch Intern Med. 2009;169(1):75-80; Hendry J. Elders' blood pressure varies with outdoor temps. Reuters Health. January 12, 2009.