JP Stroke Foundation

With over 80 million individuals affected by stroke worldwide, many believe that gender differences play a role in the experience of stroke and the probability of suffering from its debilitating effects. Scholars took charge in unveiling such claims and discovered shocking results!

To begin with, stroke is one of the leading causes of chronic disability in the world. With the steady increase of elderly people in the population, along with an increasing incidence of stroke with age, there is a clear sense of urgency to identify other groups of people at risk for stroke. Looking at sex differences in stroke, the mortality (death) rate for women ages 25-44 years is slightly lower than men. The difference significantly increases at the ages of 45-74 year, with women at a much lower mortality rate than men. However, for ages 85 and above, women suffer from significantly higher mortality rates after a stroke than men [5]. So why the sudden shift in mortality rates between these two genders?

Studies show that women get the worse end of the stick when it comes to strokes. For instance, women live longer than men and, since stroke events increase with age, women experience more severe effects after a stroke. Women (who live longer than men) experience a higher incidence of stroke, and a mortality rate, in their later years of life. Many studies claim that gender differences in stroke cause fatality but do not provide substantial evidence to support such claims [5]. Researchers of such studies assert that females suffer from a higher stroke case fatality, thus pointing towards a sex-specific difference as the cause. However, after accounting for factors such as stroke severity, age, blood pressure, among others, researchers concluded that these observed differences in case fatality rates were not caused by a gender disparity.

Many risk factors contribute to the increased probability of stroke. Although men and women can have the same risk factors for stroke, there is an imbalance. Women are more likely to suffer from atrial fibrillation and hypertension, both of which significantly increase the probability of stroke. Atrial fibrillation is an irregular and rapid heart rate and hypertension is a condition where the individual has abnormally high blood pressure. Some studies indicate that oral contraceptive use for women almost triples the risk of ischaemic stroke. On the other hand, men are more likely to have a history of heart disease, diabetes, metabolic syndrome, alcohol, and tobacco use. Additionally, diabetes and metabolic syndrome are widely known to increase chances of stroke. The abnormal excess fat, high blood pressure, and high blood sugar, can cause blood vessels to constrict and reduce/block blood flow to the brain, ultimately leading to a stroke. For males with type 2 diabetes, the risk of stroke doubles. A quite worrisome finding is that women with type 2 diabetes saw their risk of stroke increase even higher than men with type 2 diabetes.  Even more unfortunate, the effect of metabolic syndromes on women greatly increases their risk of a type of stroke called ischemic stroke, while males with the same condition were not affected.

Interestingly, ischemic strokes tend to have a genetic component to them. As you may have guessed already, the heritability of stroke differs for females and males. Female stroke patients are more likely to have a family history of stroke in comparison to males. Not only that, but the family history of stroke seems to be more prevalent in mothers than in fathers. As you can see, there are many different factors that can play a role in increasing your risk of having a stroke. Pregnant women run a great risk of suffering from a stroke event for up to 6 weeks following childbirth. This can be partly explained by the rapid changes in hormones and the massive decrease in blood volume [3]. Other common disorders related to pregnancy can also elevate the risk of stroke such as eclampsia and pre-eclampsia. Both disorders are characterized by high blood pressure and hypertension, two main risk factors for the development of a stroke.

Additionally, elderly women tend to live alone and are socially isolated, which plays a role in determining their quality-of-life post-stroke. Women are institutionalized more often prior to their first stroke episode and this can lead to disability issues after the stroke occurs [5]. Institutionalized women are often widowed or unmarried, do not benefit from enough social support and suffer from depression. Rehabilitation can become an additional challenge to overcome. Doctors that complete medical assessments after the stroke takes place concur that women are less likely to have an average verbal score, using the Glasgow Coma scale, to retain their ability to walk unaided post-stroke, and to lift both arms off the bed. According to Sue-Min et al, females with stroke also faired worse in the Camden test, which is a scale used to assess one’s mental ability. On average, women are more severely handicapped 3-months after a stroke, but why?

A possible explanation for gender differences in stroke outcomes relates to the sex hormone, estrogen. Scientists suggest that this hormone plays a role in promoting dilation of blood vessels and maintaining good blood flow in pre-menopausal women [5]. This is important because it helps prevent any blockages of blood going to the brain, thus reducing the risk of stroke. Estrogen has protective effects against cardiovascular diseases. On the other hand, its male counterpart, testosterone produces opposite effects, allegedly conferring an advantage to females. Knowing this, why do females still receive a poor prognosis? Unfortunately, post-menopausal women have lower levels of estrogen and do not benefit from the preventative effects of the hormone. To make matters worse, post-menopausal women also have a poorer brain response than age-matched men following changes in blood flow to the brain. So, due to women having decreased estrogen, their brain’s ability to process changes in blood flow is diminished. This puts them at higher risk of developing a stroke event and a worse stroke outcome.

Another plausible cause of higher disability rates in women is the disparity in the administration of treatment interventions when compared to men. According to Di Carlo et al, the researchers demonstrated that gender plays a discriminatory role in the use of therapeutic interventions. Women were less likely to undergo carotid surgery, which consists of restoring blood flow in clogged arteries. Furthermore, women were less likely to undergo brain imaging techniques and other diagnostic resources, despite their heightened likelihood of suffering from severe stroke complications. 77 female patients and 50 male patients died within the first 48 hours following a stroke event. Shockingly, when researchers analyzed this group, 66% of male patients had received brain imaging prior to their deaths while only 37.7% of female patients were lucky enough to receive the same treatment [2]. This helps demonstrate that the lack of interventions for female patients might contribute to their worse prognosis.

Author: Jean Paul Sabat

[1] Boehme, A. K., Siegler, J. E., Mullen, M. T., Albright, K. C., Lyerly, M. J., Monlezun, D. J., Jones, E. M., Tanner, R., Gonzales, N. R., Beasley, T. M., Grotta, J. C., Savitz, S. I. & Martin-Schild, S. (2014). Racial and gender differences in stroke severity, outcomes, and treatment in patients with acute ischemic stroke. Journal of Stroke and Cerebrovascular Diseases 23(4), 255-261 https://doi.org/10.1016/j.jstrokecerebrovasdis.2013.11.003.

[2] Di Carlo, A., Lamassa, M., Baldereschi, M., Pracucci, G., Basile, A. M., Wolfe, C. D., Giroud, M., Rudd, A., Ghetti, A., Inzitari, D., & European BIOMED Study of Stroke Care Group (2003). Sex differences in the clinical presentation, resource use, and 3-month outcome of acute stroke in Europe: data from a multicenter multinational hospital-based registry. Stroke, 34(5), 1114–1119. https://doi.org/10.1161/01.STR.0000068410.07397.D7

[3] Kittner, S. J., Stern, B. J., Feeser, B. R., Hebel, R., Nagey, D. A., Buchholz, D. W., Earley, C. J., Johnson, C. J., Macko, R. F., Sloan, M. A., Wityk, R. J., & Wozniak, M. A. (1996). Pregnancy and the risk of stroke. The New England journal of medicine, 335(11), 768–774. https://doi.org/10.1056/NEJM199609123351102

[4] Petrea, R. E., Beiser, A. S., Seshadri, S., Kelly-Hayes, M., Kase, C. S., & Wolf, P. A. Gender differences in stroke incidence and poststroke disability in the Framingham heart study. Stroke 40(4), 1032–1037 https://doi.org/10.1161/STROKEAHA.108.542894

[5] Reeves, M. J., Bushnell, C. D., Howard, G., Gargano, J. W., Duncan, P. W., Lynch, G., Khatiwoda, A., & Lisabeth, L. (2008). Sex differences in stroke: epidemiology, clinical presentation, medical care, and outcomes. The Lancet. Neurology, 7(10), 915–926. https://doi.org/10.1016/S1474-4422(08)70193-5

[6] Sue-Min, L., Duncan, P. W., Dew, P. & Keighley, J. (2005). Sex differences in stroke recovery. Preventing Chronic Disease, 2(3), A13.