Every mom knows the feeling of fog rolling in, clouding even the most simple of thoughts until suddenly you’ve left your keys in the fridge, your milk in the car and your baby in a onesie he grew out of a month ago.

That’s mommy brain for you. Never experienced it? Either you’re not a mom or you happen to have bionically bred, says Aprile Miller, Lawrence parent of two and one in the oven.

“It kind of feels like Alzheimer’s. You’re acting as if you’re old. I mean I’m 26, this shouldn’t be happening,” says Miller, even though her mother-in-law warned her about “mommy brain” before she got pregnant. “She was like, ‘Those babies … the umbilical cord is attached to your brain, and they just suck it out.’ And we’d all laugh about it and stuff, but nope, it’s pretty true. She says she’s never recovered from it and we’d always laugh about it, but now it’s a scary prospect. What if you don’t come back from it, you know?”

From Pulitzer to parenting

That’s exactly the reason that Katherine Ellison waited to have kids until her biological ticker had nearly conked out. The lifetime journalist had been worried about losing her Pulitzer Prize-winning mind right along with her pre-baby belly. So, after having her sons, she decided to take up the challenge of figuring out if the mental fatigue that had come along with her kids was real or if it was truly all in her head.

The result is “The Mommy Brain,” a book she published in 2005, in which she argues that motherhood actually makes women smarter.

Yep, smarter.

Ellison explains that after talking to the experts, it’s clear that the anecdotal evidence she saw in her own life was true: Motherhood stretches a woman’s brain in ways previously unseen in her lifetime. Suddenly she has to take care of a tiny, helpless creature on very little sleep after going through what amounts to the physical equivalent of a biologically beautiful train wreck.

So, what accounts for the mental fog and lost keys if not dulled neurons?

“I suspect it comes down to sleep deprivation much more than anything else, plus the huge new learning demands, which we’re hard-wired to accept,” says Ellison, who won a Pulitzer in 1986 doing international reporting for the San Jose Mercury News. “I looked and looked and looked and found no clear smoking gun for any hormonal impact.”

Miller can attest that adding a new member is liable to affect everyone in the household. She even diagnoses her husband, Brandon, with having, ahem, “mommy brain,” too — locking the kids in the car with the engine running being just one example of his own daddy-induced slip-ups.

All about mom

Which begs the question: Why are mothers saddled with the “mommy brain” tag and dads, even stay-at-home dads, aren’t? Ellison says that’s because “mommy brain” wasn’t even a phenomenon until it began poking up in feminist literature during the women’s movement in the middle of the last century.

“I think our culture conditions us to think that motherhood is dumb work rather than smart work, when the reality is that the cerebral demands on parents are increasing all the time. So this blame is very dangerous,” Ellison says. “It may stem from a combination of factors, including traditional sexism, plus to a great extent some of the unfortunate messages of the feminist revolution, when we were all intent on breaking down the doors to get into professions and at times maybe unthinkingly disparaged the work of motherhood as a consequence.”

And what’s worse is if moms are told that they’re going to be dumber after kids, they’ll think it’s true, even if it isn’t.

“It’s a self-fulfilling prophesy, and there’s research to back that up too,” Ellison says. “When elderly people are told that old people are dumb before they take a test, they do worse on that test. Same thing with moms, I’m sure.”

So, in what ways does motherhood make you noticeably smarter? Miller says that although she feels forgetful all the time, she admits that she has a lot more to remember than when she didn’t have two kids under the age of 4 and a husband to worry about. In fact, she has identified several areas where she’s upped her smarts quotient since becoming a mom.

“Anticipation, I think, is heightened, and also your ability to problem solve is greater when you’re a mom,” Miller says. “I’m braver, I’m more confident in who I am, so there’s some emotional maturity, I guess, that comes with it.”