Vive la différence. This playful French phrase refers to biological distinctions between the sexes—but there’s nothing whimsical about the different rates of heart attack (myocardial infarction, or MI) between men and women. A new study led by Craig Atwood, PhD, associate professor, Geriatics and Gerontology, in conjunction with the Wisconsin Longitudinal Study (WLS), headed by Pamela Herd, PhD, professor, LaFollett School of Public Affairs, has identified important differences in risk factors associated with heart attack between the sexes. The analysis using datasets from the WLSmay help guide measures to prevent MI, which 715,000 people in the US suffer from each year.

Dr. Atwood’s team, headed by Tina Gonzales, MS, associate research specialist, Department of Sociology, utilized WLS survey data collected over 60 years from a cohort of individuals who graduated from high schools in Wisconsin in 1957. Participants completed periodic surveys assessing thousands of environmental, health, social and behavioral factors as they aged, and provided samples for genetic analysis of 77 single nucleotide polymorphisms (SNPs). To identify factors associated with MI, data from a total of 6,198 WLS participants (2,938 men and 3,260 women) were analyzed by Dr. Atwood’s team. The researchers identified two WLS groups: those that had a MI before the age of 72, and those who had a MI between the ages of 65 and 72 years. “This allowed us to look at factors associated with MI at any point in one’s lifetime up to age 72, versus factors associated with a MI in ‘older age’ (65 to 72)," said Dr. Atwood. Strikingly, the biggest risk factors diverged between women and men.

Researchers used recursive partitioning and random forest analyses, followed by logistic regression and chi-squared analyses, to identify factors associated with MI. As expected, more men (18.1 percent) than women (7.5 percent) reported an MI by age 72. But whereas the biggest risk factors for men were (in order) stroke, high cholesterol, diabetes, and hypertension, for women it was diabetes that topped the list of risk factors, followed by hypertension, high cholesterol, and being dissatisfied with their financial situation.

Dr. Atwood’s team also identified divergent risk factors for MI in men versus women when they focused on the “older age” phase of life (65 to 72). For men, the effect of high cholesterol and hypertension weakened between the ages of 65 and 72, while the stroke and diabetes association remained high. For women between 65 and 72, the biggest associations were diabetes and whether they had previously been exposed to dangerous work conditions in mid-life (by the age of 54).

Additionally, the team found differing combinations of factors between the sexes that greatly influenced the likelihood of MI. For example, high cholesterol, smoking and being diabetic were associated with higher MI prevalence in men, but for the subset of men who completed more than 5.5 years of college, prevalence of MI dropped to 0.0 percent compared to those completing less than 5.5 years of college, whose MI prevalence was an astounding 53.3 percent. For women, exercise played a more protective role against MI than in men, particularly for women under the age of 65. While different SNPs were identified as risk factors in men and women, the genotypes that the team assessed had less of an impact than environmental, health, social and behavioral factors.

“We believe that this study holds value for identifying different major risk factors and combinations of factors for MI between men and women, and for identifying a previously unrecognized risk factor (being exposed to dangerous conditions at work). It also guides our understanding of how risk changes with age. While the social-factor homogenities and limited genetic data of this cohort indicate that further study is needed, this is an important step toward understanding differential patterns of MI risk factors with aging in men and women,” said Dr. Atwood.

Resources:

• Gonzales TK, Yonker JA, Chang V, Roan CL, Herd P, Atwood CS. 2017. Myocardial infarction in the Wisconsin Longitudinal Study: the interaction among environmental, health, social, behavioural and genetic factors. BMJ Open. 27(1):e011529