The two-year brain fog that turned out to be one number

The David moment

I was on a call with a colleague named David when I forgot his name. Not the tip-of-the-tongue kind, where you can feel the shape of it. The kind where the slot in my head where his name should have been was just empty, and I had to wait until he signed off so I could check the meeting invite. It was a Tuesday morning in October. I was 32. I had been like this for almost two years.

Before that, I had been the kind of person who remembered every PIN, every birthday, every license plate of every car I'd ever owned. I remembered my high school locker combination and the names of the dogs on my paper route in 1998. People used to make small jokes about it. Then for two years they didn't, because I had stopped being that person, and nobody had wanted to be the one to point out the moment I changed.

The list of suspects

Visit one was about three months in. My doctor at the time ordered TSH and free T4 and told me, kindly, that thyroids were the usual culprit when otherwise healthy women in their thirties came in saying they felt off. The numbers came back unremarkable. She said it was probably stress. I had a stressful job. I left feeling vaguely embarrassed for having come in.

Visit two was six months later, with a different doctor, because the first one had moved practices. This one added B12, folate, and ferritin to the panel. Ferritin came back at 28, which she called borderline-low and said might explain the tiredness. I bought iron at the drugstore and took it for four months. The fog did not lift. The ferritin went up, eventually, and the fog stayed where it was.

Visit three was a year in. The doctor that day, going through what was now a small thicket of normal results, suggested gently that this might be anxiety, and would I consider seeing someone. I did. The therapist, after two sessions, said this didn't sound like anxiety to her. She said it sounded like something else, but she couldn't tell me what. She sent me back to a doctor with the most polite shrug I have ever received.

The almost-missed test

Visit four was almost an accident. I had moved cities and needed a new primary. The PCP I picked off a list took my chart, scrolled through it for what felt like a long minute, and then said: I don't see vitamin D in here. Should be in here.

I had not asked for it. In two years of trying to figure out what was wrong with me, vitamin D had not crossed my mind once. It is the kind of thing that lives in the foreground of supplement aisles and the background of medical attention, and I had walked past it the same way most people do.

She added vitamin D to the panel. The result came back a week later: 14 ng/mL. I had to look up what 14 meant, because nobody had told me there was a number to begin with. Above 30 was sufficient, by most labs. Mine was not sufficient.

The first eight weeks

I started supplementing the next week. The doctor told me what to take and how often, and I won't get into the dose, because doses are between people and their doctors, and mine was not anyone else's.

For the first four weeks, nothing. I had braced myself for nothing, because by then I had learned to brace myself, but it was still a quiet kind of disappointment to be doing the thing and not feeling the thing.

Week five, I made dinner without checking the recipe. Chicken and rice, nothing complicated. I noticed it standing at the stove, halfway through, holding a wooden spoon. I had not memorized the recipe. I had remembered it. The two are not the same, and I had been making this distinction without knowing it for a long time.

Week six, I sat through a meeting I had been dreading and was not, for once, hollowed out by it. A colleague came up afterward and said something, and her name arrived in my head when I needed it, and I noticed that too.

By week eight, words were coming back when I reached for them. Not always. More than before. I stopped writing things down on Post-its quite so often. I still write things down. I still have days when the fog rolls back in for an afternoon and I cannot say why. The change was not a switch. It was a tide that had started coming in.

What I'm not saying

Low vitamin D is not the answer to brain fog. It was the answer to mine. There are people walking around with vitamin D in the single digits who feel fine. There are people with brain fog whose vitamin D looks textbook-perfect.

Brain fog is a cluster, not a diagnosis. It can be sleep, hormones, depression, autoimmune, B12 issues that hide behind a normal serum B12 and only show up on methylmalonic acid testing, or a hundred other things, alone or in combinations. Some of those have answers. Some don't. Some have answers nobody has found yet.

What I'm saying is what happened to me. The question that opens the door, sometimes, is whether anyone has checked vitamin D recently. The question doesn't always get a yes. When it does, the number is what the number is, and the next part is between a person and their doctor.

Where the number is now

Two years after the first 14, my vitamin D sits around 47 ng/mL. I still supplement through the winter. I forget sometimes. I always know when it's been a few weeks, because the words start to take longer, and I have come to recognize the texture of that.

My TSH is still normal. My B12 is still normal. My ferritin is up to 65, which the new doctor calls a respectable number for a person who doesn't think about iron.

The thing I keep coming back to is that the body had been telling me something for two years. It just wasn't telling me in words I had been trained to listen for. The signal was there. The receiver was tuned somewhere else. Once I found the right frequency, everything that had been static became information.

It is a Tuesday morning. I am on a call with a colleague named Sam. He says good morning and I say his name back, and the slot where his name lives is full, and I don't make too much of it. Most days I don't. The fact that I can, on the days I do, feels like enough.