HealthDay News — A new study finds that nearly everyone will suffer more memory lapses as they age, with men being more vulnerable to failing memory than women.
The study also reported that people’s memory skills and brain volume typically decline with age — and, surprisingly, it seems to have little to do with the buildup of brain “plaques” that mark Alzheimer’s disease, the study suggests.
The researchers said their findings challenge a prevailing view on the aging brain.
Experts have speculated that when older adults start having memory lapses, it may be a sign of early Alzheimer’s disease — and likely related to abnormal clumps of a protein called beta-amyloid that accumulate in the brain.
“But our findings suggest that memory actually declines in almost everybody, and well before there is any amyloid deposition in the brain,” said Clifford Jack, Jr., MD, a researcher at the Mayo Clinic in Rochester, Minn., who led the study.
Overall, both memory and brain volume gradually declined from age 30 to the mid-60s. But few people showed any amyloid buildup during that time. It wasn’t until around age 70 that there was a substantial increase in the number of people who were “amyloid positive” on PET scans, the researchers reported in JAMA Neurology.
The results are based on over 1,200 adults from one county in Minnesota. All were between the ages 30 and 95, and had no symptoms of dementia. They all took standard memory tests and underwent two types of brain scan: an MRI to measure the volume of the hippocampus, a brain structure involved in memory; and a PET scan to look for amyloid buildup.
Beta-amyloid deposits — commonly called plaques — are still a hallmark of Alzheimer’s disease, Jack said. But the new findings suggest that they do not “initiate” the disease process, and instead enter the picture later.
“There seems to be a profound effect of aging, itself, on memory — independent of amyloid,” Jack said. “We think that [amyloid] pathology tends to arise late in life, to accelerate a pre-existing decline in memory.”
According to Jack, that offers some good news.
“The memory decline that people often experience as they get older is usually not an indicator of underlying Alzheimer’s pathology,” he said. “So it in no way means you’re inevitably going to become demented.”
Jack CR, et al. Age, Sex, and APOE ε4 Effects on Memory, Brain Structure, and β-Amyloid Across the Adult Life Span. JAMA Neurol. doi:10.1001/jamaneurol.2014.4821.