SUPER-SIZED NEURONS IN THE AREA OF THE BRAIN RESPONSIBLE FOR MEMORY KEEP SUPER-AGERS SHARP
Some of us stay mentally sharp well into our 80s and it could be due to the size of our brain cells
Super-agers have long puzzled scientists. Despite being in their 70s and 80s, they have the physical ability and cognitive function of people much younger. Now, researchers at Northwestern University in Illinois may have discovered one of the reasons super-agers are able to stay so mentally sharp: the neurons in their entorhinal cortex, the part of the brain responsible for storing memories, are much larger than those of their cognitively average peers.
Furthermore, these neurons show no sign of tau tangles, the abnormal accumulations of protein that collect inside neurons and limit the communication between them, which are a tell-tale sign of Alzheimer’s disease.
“To understand how and why people may be resistant to developing Alzheimer’s disease, it’s important to closely investigate the postmortem brains of super-agers,” said lead researcher Tamar Gefen, an assistant professor of psychiatry and behavioural sciences at Northwestern University. “By learning what makes super-agers’ brains unique, it may be possible to harness these biological traits to help elderly people stave off Alzheimer’s disease.”
To make the discovery, the researchers examined the brains of six super-agers, seven cognitively average elderly individuals, six young individuals and five individuals in the early stages of Alzheimer’s disease.
“It’s important to closely investigate the postmortem brains of super-agers”
“The remarkable observation that super-agers showed larger neurons than their younger peers may imply that large cells were present from birth and are maintained structurally throughout their lives. We conclude that larger neurons are a biological signature of the super-ageing trajectory.”
The researchers concentrated their studies on the entorhinal cortex as it’s one of the first locations to be affected by Alzheimer’s disease. The entorhinal cortex is made up of six layers of neurons stacked on top of one another, and the second of these layers is known to be a particularly important hub that receives information from other memory centres in the brain.
The neurons that form this second layer were found to be bigger in super-agers than in all of the other groups in the study, even those who were 20 to 30 years younger. They were also found to be free from tau tangles.
“In this study, we show that in Alzheimer’s disease, neuronal shrinkage [atrophy] in the entorhinal cortex appears to be a characteristic marker of the disease,” Gefen said.
“We suspect this process is a function of tau tangle formation in the affected cells leading to poor memory abilities in older age. Identifying this contributing factor – and every contributing factor – is crucial to the early identification of Alzheimer’s, monitoring its course and guiding treatment.” The researchers are now planning further studies to try and figure out why super-agers have such large neurons.