SuperAger brains have the 'super neurons'

Neurons in an area of the brain responsible for memory were significantly larger in SuperAgers compared to cognitively average peers, individuals with early-stage Alzheimer's disease and even individuals 20 to 30 years younger than SuperAgers — who are aged 80 years and older, reports a new Northwestern Medicine study.

These neurons did not harbor tau tangles, a signature hallmark of Alzheimer's disease.

The study of SuperAgers with exceptional memory was the first to show that these individuals carry a unique biological signature that comprises larger and healthier neurons in the entorhinal cortex that are relatively void of tau tangles (pathology).

The Northwestern SuperAging Research Program studies unique individuals known as SuperAgers, 80+ year-olds who show exceptional memory at least as good as individuals 20 to 30 years their junior. In the study, scientists show that SuperAgers harbor large, healthier neurons in layer II of the entorhinal cortex compared to their same-aged peers, individuals with early stages of Alzheimer's disease and even individuals 20 to 30 years younger. They also showed that these large layer II neurons were spared from the formation of tau tangles.

Taken together, the findings suggest that a neuron spared from tangle formation can maintain its structural integrity (i.e., remain healthy and large). The inverse also seems to be true: Tau tangles can lead to neuronal shrinkage.

Participants in the SuperAger study donate their brains for research.

For the study, scientists examined the brains of six SuperAgers, seven cognitively average elderly individuals, six young individuals and five individuals with early stages of Alzheimer's. Then they measured the size of neurons in layer II of the entorhinal cortex (compared to layers III and V). They also measured the presence of tau tangles in these cases.

For reasons that remain unknown, cell populations in the entorhinal cortex are selectively vulnerable to tau tangle formation during normal aging and in early stages of Alzheimer's.

Reference:

Tamar Gefen et al,Neuronal Integrity in SuperAging,JNeurosci