What is different about the brains of "SuperAgers"

We all probably know some people well into their 80's and 90's who seem to maintain crystal clear intelligence, presence, and memory. A group of collaborators at Northwestern University has studied a group of such individuals, and was able to do postmortem anatomy of the brains of five them. Compared with average elderly individuals, they found fewer Alzheimer-type neurofibrillary tangles and an increased packing density of von Economo neurons, especially in the anterior cingulate. Von Economo neurons, large spindle shaped cells distinctive to humans and great apes, are located in only two parts of the brain: the anterior cingulate cortex, deep in the center of the brain, and the frontoinsular cortex, located inside the frontal lobes. In humans, both of these structures appear to be involved in aspects of social cognition such as trust, empathy, and feelings of guilt and embarrassment.

This human study is based on an established cohort of “SuperAgers,” 80+-year-old individuals with episodic memory function at a level equal to, or better than, individuals 20–30 years younger. A preliminary investigation using structural brain imaging revealed a region of anterior cingulate cortex that was thicker in SuperAgers compared with healthy 50- to 65-year-olds. Here, we investigated the in vivo structural features of cingulate cortex in a larger sample of SuperAgers and conducted a histologic analysis of this region in postmortem specimens. A region-of-interest MRI structural analysis found cingulate cortex to be thinner in cognitively average 80+ year olds (n = 21) than in the healthy middle-aged group (n = 18). A region of the anterior cingulate cortex in the right hemisphere displayed greater thickness in SuperAgers (n = 31) compared with cognitively average 80+ year olds and also to the much younger healthy 50–60 year olds (p < 0.01). Postmortem investigations were conducted in the cingulate cortex in five SuperAgers, five cognitively average elderly individuals, and five individuals with amnestic mild cognitive impairment. Compared with other subject groups, SuperAgers showed a lower frequency of Alzheimer-type neurofibrillary tangles (p < 0.05). There were no differences in total neuronal size or count between subject groups. Interestingly, relative to total neuronal packing density, there was a higher density of von Economo neurons (p < 0.05), particularly in anterior cingulate regions of SuperAgers. These findings suggest that reduced vulnerability to the age-related emergence of Alzheimer pathology and higher von Economo neuron density in anterior cingulate cortex may represent biological correlates of high memory capacity in advanced old age.