CHICAGO — “SuperAgers” who stay robust and mentally healthy into their 80s have bigger brain cells than their peers who are more likely to develop dementia, a new study reveals.
A team from Northwestern University says neurons responsible for memory are larger in these individuals than in people who are 20 to 30 years younger. They lie in a region known as the entorhinal cortex and could hold the key to preventing Alzheimer’s.
The discovery opens the door to a screening program and earlier diagnoses and therapy. So far, drugs trials have failed to cure dementia because doctors prescribe them too late — once the disease takes hold.
“The remarkable observation that SuperAgers showed larger neurons than their younger peers may imply that large cells were present from birth and are maintained structurally throughout their lives,” says lead author Tamar Gefen, an assistant professor of psychiatry and behavioral sciences at the Northwestern University Feinberg School of Medicine, in a media release. “We conclude that larger neurons are a biological signature of the SuperAging trajectory.”
Here’s why SuperAgers avoid the main symptom of dementia
The new study found SuperAger neurons do not harbor tau proteins, which tangle into plaques that disrupt brain cells and are the hallmark symptom of dementia. For reasons that remain unknown, cells in the entorhinal cortex are specifically vulnerable during normal aging and in the early stages of Alzheimer’s.
“In this study, we show that in Alzheimer’s, neuronal shrinkage (atrophy) in the entorhinal cortex appears to be a characteristic marker of the disease,” Gefen says.
“We suspect this process is a function of tau tangle formation in the affected cells leading to poor memory abilities in older age,” the researcher continues. “Identifying this contributing factor (and every contributing factor) is crucial to the early identification of Alzheimer’s, monitoring its course and guiding treatment.”
With no cure in sight, there is an increasing focus on SuperAgers, who prove that mental deterioration is not inevitable for the elderly. This special group can recall events well into their 80s with the same clarity as those in their 20s, studies have discovered.
Increasing age is often accompanied by cognitive decline that can lead to full blown dementia and the devastating symptoms of confusion. The new findings are based on 24 people who donated their brains to medical science. Six were members of the Northwestern SuperAging Research Program. It studies people over 80 who demonstrate exceptional memory that is at least as good as people in their 50s.
What does a SuperAger’s brain look like?
Postmortem analysis compared their organs to those of seven cognitively average peers, six individuals who were two to three decades younger, and five who died during the early stages of dementia.
“To understand how and why people may be resistant to developing Alzheimer’s disease, it is important to closely investigate the postmortem brains of SuperAgers,” Gefen adds. “What makes SuperAgers’ brains unique? How can we harness their biologic traits to help elderly stave off Alzheimer’s disease?”
The team measured the entorhinal cortex because it controls memory and is one of the first regions affected by cognitive decline. It has six layers of neurons packed on top of each other. The second, in particular, is a crucial hub — receiving information from other memory centers.
It was here that SuperAgers had bulkier, healthier neurons than the other three groups. They were also spared from the formation of tau tangles. The results suggest brain cells can maintain their structural integrity well into old age, while tau leads to them wasting away.
An estimated 40 percent of people over 60 suffer from some degree of memory loss. The figures get higher with age. Dr. Gefen now wants to examine how and why neurons survive in SuperAgers, probing the cellular environment in particular.
“What are the chemical, metabolic or genetic features of these cells that render them resilient?” Gefen asks.
Dr. Gefen also plans to investigate other hubs along the brain’s memory circuit to better understand the spread of Alzheimer’s, or resistance to it. Finding ways to combat shrinkage in these networks could help tackle memory loss in older people.
“We expect this research to be amplified and more impactful through a $20 million expansion of the SuperAging Initiative now enrolling five sites in the U.S. and Canada,” says Emily Rogalski, associate director of the Mesulam Center for Cognitive Neurology and Alzheimer’s Disease at Northwestern University Feinberg School of Medicine.
Estimates project that the number of cases of people living with Alzheimer’s and other forms of dementia will triple to more than 150 million by 2050 because of aging populations.
The findings appear in The Journal of Neuroscience.
South West News Service writer Mark Waghorn contributed to this report.
