A recent study published in the Journal of Neuroscience has shed light on the brain’s white matter health in a group of elderly individuals known as “superagers.” These are older adults whose memory performance rivals that of people decades younger. The research reveals that superagers maintain better white matter microstructure in their brains compared to typical older adults, which may help explain their remarkable memory retention.
The study’s primary aim was to understand why some older adults can retain superior episodic memory, the ability to recall personal experiences, well into their 80s and beyond. This is particularly important given that episodic memory decline is one of the earliest and most prominent features of Alzheimer’s disease, the leading cause of dementia. By studying superagers, researchers hoped to uncover insights into how certain individuals can age without experiencing significant memory impairment.
“The study of superagers — elderly individuals over 80 years old with the episodic memory of a person 30 years younger — is an exceptional paradigm to explore preventive strategies for memory deterioration with age. Therefore, the characterization of the superager phenotype (including brain, lifestyle, etc.) is of great importance given the increasing incidence of Alzheimer’s disease,” said study author Marta Garo-Pascual, a biomedical researcher at the Laboratory for Clinical Neuroscience at Universidad Politécnica de Madrid.
“In this study, we put our attention to the characterization of cerebral white matter in a population of superagers and controls with normal memory for their age. White matter is the basic component of the nervous system that functions as the wires that carry information between different parts of the brain. White matter connects different parts of the brain to ensure an appropriate response to the inputs we receive. We were interested to know if there is something special about the preservation of white matter over time in superagers.”
The researchers selected participants from the Vallecas Project, an ongoing study based in Madrid, Spain, focusing on brain health in the elderly. The sample included 64 superagers and 55 typical older adults, all of whom were over 80 years old. Superagers were identified based on their performance in episodic memory tests, where they scored as well as individuals 20-30 years younger. Typical older adults had memory scores typical for their age.
The study used advanced neuroimaging techniques to examine the participants’ brains. Magnetic Resonance Imaging (MRI) was used to measure the volume of white matter and the extent of white matter lesions, which are small areas of damage that appear as bright spots on certain MRI scans. The researchers also used diffusion tensor imaging, a type of MRI that can assess the microstructural integrity of white matter by measuring how water molecules move through the brain’s tissues.
The researchers found significant differences in the white matter health of superagers compared to typical older adults. Superagers had better-preserved white matter microstructure, particularly in the frontal regions of the brain. This was evidenced by higher fractional anisotropy (FA) values, indicating more directionally organized water diffusion in the brain, and lower mean diffusivity (MD) values, reflecting less overall water movement and suggesting more intact tissue structure.
Interestingly, while both superagers and typical older adults had similar total white matter volumes and white matter lesion loads, the superagers showed a slower rate of decline in white matter microstructure over time. This suggests that the cognitive resilience of superagers may be partly due to their brains’ ability to resist the typical age-related deterioration in white matter health. This resistance was observed across several white matter tracts, including the anterior thalamic radiation and association fibers, which are crucial for cognitive functions such as memory and executive function.
The study also revealed that the differences in white matter health between superagers and typical older adults were not established early in life but rather developed later. This finding supports the hypothesis that the superager phenotype is characterized by a resistance to age-related changes rather than an early developmental advantage. The longitudinal data indicated that superagers and typical older adults had similar white matter properties around age 75, but superagers’ cognitive and structural brain advantages became more pronounced as they aged.
“We have found that the cerebral white matter of superagers is better preserved over time compared to controls with normal memory for their age and this can be interpreted as superagers being resistant to some extent to brain age,” Garo-Pascual told PsyPost.
While the findings are promising, the study has limitations. The use of neuroimaging, though non-invasive and highly informative, provides only indirect measures of tissue properties. More detailed insights would require histological studies, which can only be performed postmortem. Additionally, the study’s sample was drawn from a specific cohort, potentially limiting the generalizability of the findings.
Looking forward, Garo-Pascual and her colleagues aim to explore whether there is a genetic basis for the superager phenotype. Understanding the genetic factors could offer deeper insights into the mechanisms underlying healthy cognitive aging and potentially inform strategies for preventing age-related cognitive decline.
The study, “Superagers resist typical age-related white matter structural changes,” was authored by Marta Garo-Pascual, Linda Zhang, Meritxell Valentí-Soler, and Bryan A. Strange.