Mostly, it was subtle.

A word on the tip of my tongue that I couldn’t find.

A name I couldn’t remember.

But sometimes it was much more obvious.

I’d forget the stove was on and leave the house.

I’d mix up words or change them entirely.

I’d easily lose focus and often couldn’t multi-task.

When I began chemotherapy treatment for breast cancer, I knew there would be many physical changes. I wasn’t expecting the cognitive ones. But the things I’ve just listed are all side effects I experienced known as "chemo brain."

The condition has been described as a "mental fog" and that’s really what it felt like, particularly in the days immediately following chemotherapy.

I’d hear myself mess up words in a sentence and wonder how it happened. For example, I might mean to say: "I wanted to go for a hike but it was raining." What would instead come out was: "I wanted to go for a rike but it was haining."

Sometimes I would swap words in a sentence so the placement was incorrect or accidently use the same word twice. I didn’t know if I should laugh or cry! While people outside my family may not have noticed the slip-ups, my daughter says during the five months I underwent chemo, I was making verbal mistakes like this on a daily basis. And the "fog" didn’t go away just because chemo had ended. (By the way, some cancer patients not undergoing chemotherapy also report experiencing the same symptoms.)

Kristin Campbell, an associate professor in the department of physical therapy at UBC and cancer researcher, started hearing about chemo brain a number of years ago.

"We were doing studies with cancer patients around exercise for other things and they were reporting all their cognitive changes, they were telling us this is a problem," Campbell said.

She said previous studies have shown that with every chemo treatment, patients report a real decline in cognitive function.

"Right now if you complain of these symptoms, there are not a lot of treatment options available that we know are effective," she said.

Campbell is hoping her new research might change that.

She’s teaming up with the Canadian Cancer Society to look at cognitive function after chemotherapy and whether exercise during chemotherapy or after makes a difference.

The 3,800 Club

She says it’s already been shown that exercise can help older adults having challenges with their memory so "maybe this is an intervention that would help with cognitive changes cancer patients are experiencing too."

The study will follow 80 women between Vancouver and Ottawa for a year. Some will do exercise throughout their treatment and others will begin after. The study will finish in mid-2021.

"Exercise does have a lot of other benefits during or after cancer treatment so I think it’s worth seeing if this also helps with cognitive related changes," she told me.

Exercise was important to me during chemotherapy. I always felt less nauseated if I was outside and moving. But did it help fight off more severe symptoms of chemo brain or make my recovery shorter? That I do not know. But I do know that the "mental fog" has finally lifted and it’s a huge relief!

If you’re a cancer patient and feel like you’re still in the "fog," give yourself time. Campbell says for most people, it appears chemo brain is only temporary. As your body heals after treatment, so too will your mind.