Epidemiology 101
by Nandini Maharaj
Age effect: change in the rate of a condition by age, independent of calendar time and birth cohort.
No one ever tells you that you’re going to get your period when you’re ten years old and you’re on a field trip to Six Flags with your fifth-grade class. And you have to tie Mr. Reid’s flannel shirt around your waist like you’re a child of the 90s. And you figure this out just as you get off the Viper and Tina is the first one to see the red spot on your jeans but you swear her to secrecy threatening to tell everyone about the time she kissed Corey Evans, you know, always-has-a-nosebleed-Corey.
Cohort effect: change in the rate of a condition by year of birth, independent of calendar time and age.
No one ever tells you that you’re going to spend your 16th birthday in the principal’s office pleading with her not to expel your best friend Kayla who came to Winter Formal drunk and maybe a little high—you’re not sure what she took. And your school has a zero-tolerance policy about alcohol on school grounds and she wasn’t even that drunk. And Tina who told everyone about you getting your period at Six Flags could barely stand up and didn’t even get into trouble. And because this happened again at Spring Formal, school dances are now banned.
Period effect: change in the rate of a condition due to a global shift or trends that affect an entire population, independent of age and birth cohort.
And no one ever tells you that you’re going to reconnect with Kayla because the boredom from being housebound has rendered you utterly vacuous, yet full of dread and self-loathing. And it’s been 13 years since you spoke to Kayla. And you messaged her first. And she and Keith Evans (yeah nosebleed-Corey’s hot older brother) are now married with two boys, Blake and Harper. And this sick feeling comes over you while scrolling through old posts. And you realize the emptiness of your life after seeing the video from January 19 of their gender-reveal party as Kayla and Keith pop a gold balloon and pink confetti rains down all over their grinning faces.
These are the things no one ever tells you.
Nandini Maharaj is a writer, dog mom, and human-animal bond researcher. She has a PhD in public health and counselling psychology. Her work has been featured in HuffPost Canada, the Super Awesome Science Show, and The River. She can be found on Twitter @NandiniMaharaj_.
