If you forget where you put your car keys, don’t fret. It’s probably not a sign that you’re developing Alzheimer’s.

And yes, ladies, you aren’t imagining. Your husband’s memory is worse than yours.

Those are two of the many facts presented in a study published this morning in JAMA Neurology.

Dr. Clifford R. Jack Jr. of the Mayo Clinic and Foundation in Minnesota said the purpose of the study is to let people know some memory loss is a natural byproduct of getting older.

“It’s an unpleasant feature of normal aging, but it doesn’t necessarily mean you’re getting dementia,” Jack told Healthline in an interview. “A decline in memory is something that happens to everyone.”

Jack and other researchers examined brain structure and activity in 1,246 people between the ages of 30 and 95 with normal cognitive function.

They concluded that overall memory declines steadily from age 30 through 95. They also discovered the hippocampus region of the brain shrinks gradually from the age of 30 through the mid-60s and then decreases more dramatically in volume after that.

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The hippocampus is the area of the brain that forms, organizes, and stores memories. Jack explained that as that region shrinks, it’s natural that it won’t function as well. He added humans also tend to lose neurons and neuron connections as they age. That also results in memory loss.

“This type of decline happens in other organs of the body, so why shouldn’t it happen with the brain?” he said.

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The researchers also concluded that memory is worse in men, especially after age 40. They discovered the volume of the hippocampus in men’s brains was lower than in women’s, especially after age 60.

Jack noted men tend to score lower than women on verbal mental tests even as teenagers. That advantage seems to hold until at least middle age when women hit menopause.

Jack said we don’t know why men’s brains tend to decline more rapidly, but he added the difference probably has to do with the chemical makeup of a woman’s body. He said a chemical such as estrogen may help women’s brains stave off neuron damage.

The researchers also noted that amyloid accumulation in the brain, a factor in Alzheimer’s disease, is relatively low in most people before age 70, but it increases after that.

People who carry a gene called APOE ɛ4, which is a risk factor for Alzheimer’s, showed signs of amyloid accumulation at a median age of 57. Those without the gene showed that accumulation, on average, at 64.

Jack said the importance of this study for the average person is to help ease fears of dementia.

He said with the rising public awareness of Alzheimer’s, people have started to become concerned about dementia whenever they forget something.

“In middle age, if you are experiencing losses in memory, it’s normal,” he said.

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