Elderly more at risk of heart attack in cold weather

Cold weather may raise blood pressure in elderly. In new research French are suggesting that elderly people may be more at risk of suffering a stroke, heart attack or kidney failure in winter because cold weather may raise their blood pressure.

The researchers from the National Institute of Health and Medical Research in Paris say four decades of research has shown that blood pressure changes with the seasons, but very little has looked specifically at old people.

According to Dr. Annick Alperovitch and colleagues, even though their study does not demonstrate a causal link between blood pressure and external temperature, the observed relationship nevertheless has potentially important consequences for blood pressure management in the elderly.

Billions of adults around the world suffer from hypertension which increases a person's risk for stroke, heart failure, heart attack and kidney failure.

For their study the French team looked at the relationship between blood pressure and temperature in more than 8,800 men and women aged 65 or older from three French cities - they had their blood pressure measured at regular intervals in 1999 and again two years later - outdoor temperatures on the day of measurement were obtained from local meteorological offices.

The researchers found that both systolic and diastolic blood pressures differed across the four seasons and during varying outdoor temperatures and high blood pressure was detected in about a third of the volunteers during winter and a quarter in summer.

High blood pressure is defined as a systolic reading of 160 or higher or a diastolic reading above 95.

The researchers say on average, each person's blood pressure fell between the initial and follow-up measurements and the decrease was strongly linked to outdoor temperature, with the average systolic blood pressure 5 millimetres higher in winter than in summer.

These differences over time were larger in participants age 80 and older.

The researchers say the higher the temperature, the greater the decrease in blood pressure and they suspect the reason for this might be a hormone linked to stress that is released in cold weather possibly raises blood pressure by speeding up the heart rate and decreasing the responsiveness of blood vessels.

The team say elderly people may be particularly susceptible to temperature-related variations in blood pressure and they suggest that doctors should consider a closer monitoring of elderly patients on high blood pressure medicine when the temperature falls.

They say their study may help explain well-established seasonal variations in illness and death from stroke, aneurysm ruptures and other vascular diseases.

The research is published in the current issue of the Archives of Internal Medicine.