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The week before chemotherapy began, I sat in a brightly lit exam room with an oncology nurse. She handed me a stack of papers and pulled up a chair.

“So,” she began. “You should read through these to get all the side effects, but some are more common than others.”

I sat through her ten-minute spiel about mouth sores and how they’re so painful that some patients need feeding tubes inserted. Nausea. Partial hearing loss. Peripheral neuropathy. Hair loss, duh. I listened, not bothering to read through the papers, which still felt hot from the printer. Never did she say anything about chemo brain.

I was first diagnosed with hepatoblastoma, a rare form of liver cancer, when I was 23. My surgeons removed it and gave me the option of chemo, which — like any 20-something given the option of chemo — I declined. But when it returned, two years later, I didn’t have a choice. Not only did I have to undergo chemotherapy, I needed a regimen that my oncologist called “spicy.” (It was more like “burn-your-gums-off.”)

The side effects were, for the most part, brutal but bearable. But none of them accounted for my sudden stupidity. I first noticed it at work. As a beauty editor for a magazine, my primary job was to write. A few weeks into chemo, I began to make odd mistakes. I switched similar-sounding words, like “with” and “which.” Sometimes, I’d find random half-sentences in my stories, and I’d quickly backspace, backspace, backspace before anyone noticed. Once in a while, I just wrote nonsensical stuff, like “hair blow dryer could possibly what.”

Before long, the weird stuff began happening all the time. I lost my oven mitt in my 400-square-foot apartment. (It was in the garbage.) I poured boiling water into my bottle of multivitamins instead of the mug I’d readied. I wished my best friend happy birthday a full three days after her actual birthday — not because I’d forgotten, but because I truly believed her birthday fell on April 28. I wrapped up a day at work and left without my purse (and keys, and wallet). Another day, I toted my yoga mat halfway to the office before I wondered why I was dragging a yoga mat to the office.

I thought I was losing my mind — which is why I was relieved when an on-staff psychiatrist at my cancer hospital mentioned chemo brain, a common side effect among cancer patients. Chemo brain makes you hazy, forgetful, and — at least in my case — especially prone to Spoonerisms (in which you accidentally switch the first consonants of two words, like “lad buck” instead of “bad luck”). Finally, I had an explanation for everything that had been happening. And a bonus: Just saying “chemo brain” makes people feel so bad for you that they won’t say anything when you hand in a draft littered with spelling errors.

The good news, sort of, is that at least it wasn’t all in my head: Recent research has discovered a scientific basis for chemo brain. In a study published earlier this year in the journal Brain Imaging and Behavior, researchers conducted brain scans and neuropsychology tests on 92 women. Roughly a third of the participants had had surgery for breast cancer and were waiting to begin chemo, another third had had surgery for breast cancer of the same severity and were awaiting radiation only, and the remainder were healthy, age-matched women who served as the control group.

The study authors focused on the subjects’ verbal working memory, testing it at three different points: one month before the chemotherapy group began treatment, one month after chemotherapy had begun, and 12 months after the first session (which was also seven months after the chemotherapy group had finished their treatment).

While the radiation patients and control group saw improvements over the course of the study, the chemotherapy patients saw their verbal memory decline over time. Throughout the study, members of the chemotherapy group also showed signs of variability in neural efficiency that, over time, became statistically significant compared to the participants. According to study co-author Marc Berman, Ph.D., the director of the Environmental Neuroscience Laboratory at University of Chicago, the inconsistency of neural function can lead to deficits in memory, attention, planning, and decision-making.

Multiple factors may contribute to chemo brain, which can kick in before treatment even starts (in this study, the chemo group performed the worst in verbal memory even at the first test). “The distress of receiving a cancer diagnosis can harm cognitive and affective processes, making it hard to concentrate,” Berman says. “In some sense, we’re identifying pre-chemo brain.” Secondly, the drugs used in chemotherapy are so powerful that they could potentially alter brain physiology, both during and after treatment. Plus, a major side effect of chemo is extreme fatigue, which can cause mental sluggishness.

To add insult, this doesn’t even end when chemo stops. “This fatigue likely persists for a while after treatment,” says Berman. “It takes a while to regain one’s mental and physical strength.” Post-treatment, patients may worry about cancer returning, and the stress and anxiety of this can have lasting brain and behavioral effects. (There’s even a word among cancer survivors called “scanxiety,” the panicky feeling of wanting to throw up before, during, and after your scans for fear that they’ll reveal a recurrence.)

But there are steps one can take to mitigate chemo brain. Literal steps, outside. “Other work has demonstrated that interacting with nature, like a walk in a park, can benefit individuals who have been recently diagnosed with cancer,” Berman says. “It suggests that interacting with natural environments could help to restore attentional abilities, particularly for those under mental fatigue.” Meditation may offer similar benefits, too.

Fortunately, my commute at the time took me on a walk though a park. I also adapted to my new mental fuzziness. I went through my work with a fine-toothed comb. Sometimes, I’d ask a co-worker to double-check a draft before I sent it to my editor. I wrote so. Many. Lists.

I finished chemo two years ago. But to this day, I struggle with those Spoonerisms, and I still swap similar-sounding words. I even did it while writing this essay — so meta! But I can’t complain. Isn’t a brain that functions at half-mast better than a brain that doesn’t function at all?

And, on the bright side, I didn’t get a single mouth sore.