We all know the husband who forgets his wedding anniversary is a bad cliché, but it may be true that guys just have a harder time remembering things.

A new study published in JAMA Neurology found that memory generally starts declining for both sexes after age 30—and then plummets after age 40 for men.

For the study, researchers looked at 1,246 men and women between the ages of 30 and 95. Study subjects were all cognitively healthy when selected and went through PET scans, MRI scans, and some memory testing protocols—all in the name of measuring the size of their brain's hippocampus, levels of peptides typically associated with Alzheimer's, and levels of learning and memory performance.

Over time, everyone's hippocampal volume progressively worsened, but it shrunk the most in men over the age of 60. And overall age-related memory decline was most dramatic in men, even before any kind of abnormal PET scan showed up.

Such differences between the sexes could be happening for a number of reasons, from simple developmental causes to hormone defenses (thanks, estrogen!) to lifestyle-related differences. Still, researchers have yet to dig deeper to discover the true reason behind the cognitive gap.

You might be tempted to scan your spouse's noggin to find out just what exactly is (and isn't) going on in there, but since you can't just submit him for research, try to realize that a memory lag may not be his fault. So don't get mad if (when?) he forgets the date you two tied the knot. Just leave him a little note to serve as a friendly reminder, and hope he remembers the gift.