It starts with something you can brush off: the standard Where in this enormous mall parking lot did I leave the damn car?! Happens to everyone, no big deal, a brain fart. Until you realize it wasn’t just today at the mall; you’ve somehow spent most of your week feeling as if you’ve made major decisions behind a smokescreen. As if those brain farts were fogging up the place.
“Brain fog is an inability to really punch through,” says Mady Hornig, MD, associate professor of epidemiology at Columbia University Medical Center in New York City. “It’s a vague sense of what you’re trying to retrieve, but you can’t focus in on it,” she says, “and the effort to harness the thought can be as draining as physical activity.”
Remember how impossibly exhausting it was to run your board meeting the last time you came to work sick? (Please, please stop doing that, by the way.) Brain fog is a lot like that, except it persists. A fog can linger for several days, sometimes even weeks.
Its impermanence is the big difference between what we know as brain fog and actual dementia, says rheumatologist Robert Lahita, MD, PhD, chairman of medicine at Newark Beth Israel Medical Center and professor of medicine at Rutgers University in New Jersey. Brain fog might cause you to forget where you parked that car at the mall, but dementia might make it impossible to get there in the first place, he says.
There’s not a lot of scientific evidence to explain what’s going on when the clouds roll in. Researchers haven’t really found a way to measure or test for brain fog like they have dementia. “Everybody knows what it is,” Lahita says, “but at the same time, it is so unknown.”
If you’re sure you’ve been getting enough sleep—because who isn’t in a daze when sleep deprived; It’s probably a good idea to bring up brain fog with your doctor if you start to feel seriously off. “If you’re not feeling like your normal self, that might suggest something’s going on,” says neuropsychologist Kelly Ryan, PhD, clinical assistant professor of psychiatry at the University of Michigan, especially if it lasts for a week or two, Lahita says. At the very least, your doctor can perform tests to reassure you it’s not dementia.