The weather is believed to influence your health in a number of ways. Seasonal affective disorder affects people when seasons change. Those with arthritis say that decreases in air pressure and temperature increase joint pain. Weather changes can be triggers for people that suffer from migraines. Thunderstorms can lead to asthma attacks.
Heart attacks can be added to the list of health concerns as it gets colder outside, according to a study published in JAMA Cardiology on Wednesday. It looked at all the heart attacks occurring in one country with corresponding weather station data, according to the one of the study's authors, Dr. David Erlinge.
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"The main findings where an increase in heart attacks in low temperature, strong wind, low sunshine duration and low atmospheric pressure," said Erlinge, who is also head of the department of cardiology at Lund University in Sweden.
The authors found that there was a higher risk of heart attack on a day that was colder than zero degrees Celsius -- 32 degrees Fahrenheit -- rates of heart attacks declined as temperatures got above 3 degrees C or 4 degrees C.
"When minimum temperature decreases from +20° to 0° (68°F to 32°F) the risk of suffering a heart attack increased by 14%," Erlinge said in an email.
In fact, they reported that an increase of 7.4 degrees C in the minimum air temperature was associated with a 2.8% reduction in the risk of heart attack in the 274,029 patients in the study.
"Often weather conditions have been considered to increase the risk of a heart attack, and we realized that the Swedish registers gave us a unique possibility to test this," said Erlinge.
The study, looked at the relationship between acute myocardial infarction -- or heart attacks -- and the weather using data from SWEDEHEART, a Swedish registry that tracks everyone admitted to coronary health centers, and a government weather tracking database.
Although the researchers considered lags in exposure to the cold weather, they could have benefited from looking at longer periods according to Hong Chen, a research scientist at the Population Studies Division of Health Canada. "There is growing literature showing prolonged effect of cold temperature on cardiovascular health which remains pronounced even 2 to 3 weeks after exposure," he said in an email. Chen, who was not involved in the study, added that the findings about moderate cold temperatures were notable:
"The observation of a stronger association of moderate cold temperature and [myocardial infarction] suggests that while climate change will bring more hot days, the effect of cold temperature on public health will likely persist into the future. In addition, climate change may intensify the effects of the jet streams position, causing more severe cold winters."
The authors reported that "seasonal analyses showed more pronounced association of air temperature during warmer seasons."
"It's the largest study that brings to the public square information about an association between lower air temperature and a higher risk of heart attack," said Dr. Ivor Benjamin, president of the American Heart Association. He was not involved in the new study.
Benjamin stressed that only associations were being made in the research, something that the authors also acknowledged.
An association does not necessarily mean causation," said Benjamin, who is also a professor of medicine and director of the Cardiovascular Center at the Medical College of Wisconsin in Milwaukee. "Now they can only speculate about the mechanisms that might contribute to the higher number of heart attacks."
The study suggests reasons for the increase could include known risk factors, such as flu, during cold weather months.
Cold weather activities, such as shoveling snow, could also be the reason for an uptake in heart attacks, according to the American Heart Association.
Benjamin suggests staying indoors or reducing physical activity when the weather cools down to reduce heart attack risk. It's also important to check on loved ones, especially those who live alone.