Our chances of contracting an illness or disease vary immensely from person to person based on risk factors — traits that increase the likelihood of developing a disease. Many of these risk factors don't very from person to person — for example, anyone who smokes cigarettes has a higher likelihood of getting lung cancer, period. But there are some diseases that have totally different risk factors for women, and we all need to be aware of what those are.
This may come as a surprise to most people, but much of what we know about medicine in general comes from studies that only tested on men. Until 1993, women were not allowed to be used as test subjects in the U.S. because of potential risks to their fertility, and this means that the diagnostic criteria for a number of illnesses doesn't take into account the different biological realities for people who are female. That means that we're only just beginning to see that many diseases have sex-specific elements — and that when it comes to your risk of certain illnesses, your sex may play a bigger role than you thought. It's important to know this for your own health, and to contradict assumptions that all risks are the same and all illnesses affect different sexes in the same way. Spoiler: they don't, and here are five diseases where the risks look very different.
A study released in 2018 in Scientific Reports revealed that when it comes to a type of brain cancer tumor called glioma, which is one of the most common types, the genetic risk factors are radically different for men and women. Researchers previously knew that gliomas, particularly glioblastoma, affect different sexes differently, but they didn't know why. The new study discovered that certain genes highlight a bigger risk for developing a glioma, but that the genes are sex-specific — in other words, that the genes that raise the risk for brain cancer in men are different to those that raise it in women.
And the new research shows that there's an entire area of the female genome that we didn't know had anything to do with brain cancer risk. That bit of the genome is related to how old you are when you get your first period, and the researchers think that women who have their periods later have a lower risk of glioma, because estrogen exposure seems to help to protect against it. Why? No idea. There are still a lot of questions to be answered.
Risks of stroke in women, according to a new study, have their own unique element: how much exposure you've had to various reproductive hormones. Women have more strokes than men, and according to the new data, they're at higher risk if they get their first period early, start menopause early, take oral or hormonal contraceptives for a long period, and have low levels of a steroid hormone called dehydroepiandrosterone, which gets converted into estrogen and testosterone. They only raise risk minimally, but they're definitely factors.
While this study observed transgender women who underwent hormone therapy and concluded that those hormones did not seem to increase stroke risk, a different study that looked specifically at the experience of transgender women, and found that hormone therapy did appear to increase this risk. More study in this area is needed.
It's been known for a while that being a carrier of a particular gene — the apolipoprotein E ε4 allele — means women are at a higher risk of Alzheimer's disease, one of the primary causes of dementia. And a study released in 2018 has clarified exactly when that risk occurs. The presence of ApoE4, as it's called, makes women more likely to develop Alzheimer's when they're between the ages of 65 and 75. Before that, they have about the same likelihood of developing it as men of the same age.
There are a lot of other risk factors for Alzheimer's; the Alzheimer's Society explains that many more women than men over the age of 65 have it, and it's thought that the lack of estrogen after menopause might contribute to this imbalance too.
There are a lot of different risk factors for developing melanoma skin cancers, including sun exposure, but researchers in 2009 discovered one that's specific to women — and it seems to be particularly important for women under 50. It's a genetic variant on a gene called MDM2, and it looks like it raises melanoma risk in women. The variant is particularly toxic in women who have higher levels of estrogen, which seems to "activate" it in ways that make melanomas more likely.
This is particularly important for women who are in their 20s and 30s, but even if you don't have the genetic variant, tanning is still off-limits; that's one of the other major risk factors for young women when it comes to melanoma.
Risk factors for cardiovascular disease can be sex-specific. While smoking, alcohol and obesity increase risk in both men and women, it's more likely that you'll develop cardiovascular illnesses as a woman if you experienced diabetes or complications during pregnancy and have gone through menopause, with its corresponding lowering of hormone levels. 2017 research from Harvard also found that, for women, high blood lipids and diabetes are more likely to increase risk of heart disease in women than they are in men, because of genetic and lifestyle factors that are unique to us.
Just because there are different risk factors for certain illnesses doesn't mean everybody knows about them. If you believe you have the symptoms of an illness or are at high risk, do your research on sex-specific risk factors and you and your GP can work together on the best way forward.