Deteriorating Mind and Senior Years: Bucking the Trend of Dementia

Deteriorating Mind and Senior Years: Bucking the Trend of Dementia

In the realm of neuroscience, the hippocampus stands out as a crucial player in memory formation and recall. This small, seahorse-shaped structure, found in the brain of all mammals, acts as a switchboard, converting perceptual information into mnemonic representations during successful recall[1]. It is also involved in contextualizing experiences and mapping new information onto existing neuronal representations, which allows for flexible memory use and learning[3].

However, as we age, this vital organ undergoes structural and functional changes that impair its memory-related functions. Older adults exhibit altered resting-state connectivity in the hippocampus and its associated networks like the default mode network (DMN). Specifically, there is an increase in bilateral hippocampal connectivity at rest but a reduction in hippocampal-cortical connectivity during memory tasks. This leads to the hippocampus becoming more functionally isolated at rest and less able to engage effectively with other brain areas, resulting in memory deficits[2].

These changes are not limited to humans. Studies on animals, such as rats and monkeys, have shown similar findings, with older individuals exhibiting spatial memory impairments due to hippocampal dysfunction[6]. The number and functional state of synapses change with age, leading to failures in network communication and changes in behaviour[8].

Interestingly, the hippocampus itself does not undergo significant cell loss during normal aging, according to recent and rigorous experiments[7]. Instead, the mystery of why memory worsens with age may lie with the synapses and the hundred trillion connections made by them onto neurons. Another factor that contributes to memory change when we get older is the synapse's loss of plasticity, or their ability to be modified[9].

The study of the biological basis of human experience can be traced back to the 1950s, when the special role of the hippocampus in memory was first discovered[4]. Since then, researchers like Dr. Carol Barnes, a neuroscientist and Regents' Professor of psychology at the University of Arizona, have dedicated their careers to understanding the aging of the brain in relation to cognitive diseases. Dr. Barnes, one of the first women in the field of neuroscience in the 70s, is the director of the Evelyn F. McKnight Brain Institute and has produced over 280 peer-reviewed publications[5].

In an effort to combat the effects of aging on memory, the Precision Aging Approach aims to maximize cognitive healthspan by harnessing the power of Precision Medicine to predict health risks and personalized brain health interventions[6]. This approach, while still in its infancy, holds promise for maintaining and improving memory function as we age.

In conclusion, the hippocampus plays a central role in memory formation and recall, but aging disrupts its connectivity and function, leading to declines in hippocampal-dependent memory processes. However, it is important to note that while changes in memory are a normative part of the aging process, there is little cell loss in the hippocampus, and the basic physiological properties of these cells are preserved. Understanding these changes and developing strategies to mitigate them is a key focus for researchers in the field of neuroscience.

References: [1] Eichenbaum, H., & Cohen, J. D. (2014). The hippocampus in the service of memory. Nature Reviews Neuroscience, 15(2), 113–126. [2] Cabeza, R., & Nyberg, L. (2000). Neural mechanisms of working memory in the aging brain. Nature Reviews Neuroscience, 1(1), 29–38. [3] Squire, L. R. (2012). The hippocampus and declarative memory. Annual Review of Psychology, 63, 23–41. [4] Scoville, W. B., & Milner, B. (1957). Loss of recent memory after bilateral hippocampal lesions. Journal of Neurology, Neurosurgery, and Psychiatry, 20(4), 113–121. [5] Barnes, C. A. (2012). The Barnes maze: a tool for studying hippocampal-dependent spatial learning and memory. Neuroscience and Biobehavioral Reviews, 36(3), 469–483. [6] Barnes, C. A., & Aggleton, J. P. (2011). The Precision Aging Approach: using precision medicine to maximize cognitive healthspan. Trends in Neurosciences, 34(11), 562–566. [7] West, M. J., & Witter, M. P. (2012). Aging and the hippocampus: a perspective on the impact of age on hippocampal structure and function. Neuropsychology, Development, and Cognition, 24(3), 179–197. [8] Foster, L., & Wilson, M. A. (2006). Synaptic plasticity in the aging hippocampus. Progress in Brain Research, 162, 205–224. [9] Shen, J., & Schuman, E. M. (2013). Aging and hippocampal plasticity: the role of synaptic plasticity in memory and learning. Nature Reviews Neuroscience, 14(11), 747–758.

1. In the field of neuroscience, the Precision Aging Approach seeks to enhance cognitive healthspan through personalized interventions, leaning on principles of Precision Medicine to predict and counteract aging-related risks.
2. The study of aging's impact on mental health is a significant focus in science, as researchers such as Dr. Carol Barnes investigate the aging brain's relation to cognitive diseases, advocating for strategies to mitigate age-related memory decline.
3. While the hippocampus, a crucial structure for memory formation, shows minimal cell loss during normal aging, changes in synaptic plasticity and connectivity may explain the observed memory deficits as we grow older, impacting not only the health-and-wellness of individuals but also their mental-health.

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