Age-Related Memory Loss Prevention: Rebutting Dementia's Advance
## The Hippocampus and Aging: Navigating Memory Changes
The hippocampus, a vital part of the brain, plays a significant role in memory formation, conversion of short-term memories into long-term ones, and emotional regulation [1]. It is also instrumental in spatial processing and navigation, forming cognitive maps that aid in navigating environments [1, 3].
However, as individuals age, the hippocampus undergoes transformations that can impact memory function.
### Neuron Loss and Volume Reduction
From the age of 40, the hippocampus experiences a 5% loss of neurons every decade, leading to a total loss of approximately 20% by the age of 80 [2]. This loss contributes to the decline in memory and learning abilities. Additionally, starting around age 55, the hippocampus shrinks by about 1% annually [4], a reduction associated with decreased memory and learning capabilities.
### Weakened Synaptic Connections
Age-related changes also lead to weakened synaptic connections, further impairing memory function [2]. The number and functional state of synapses change with age, leading to potential failures in network communication and changes in behaviour.
Despite these changes, the hippocampus retains the ability for **neurogenesis**, the process of generating new neurons throughout life. Engaging in activities like regular aerobic exercise, maintaining a brain-healthy diet, and managing stress can support hippocampal health and potentially reverse some age-related declines [5].
### The Role of the Hippocampus in Spatial Memory
The hippocampus is central to spatial memory, a form of memory that involves navigating and remembering locations [1]. Experiments show that older individuals can recruit additional brain circuits to achieve memory retrieval that is as accurate as that of younger individuals [6]. However, older rats, older monkeys, and older humans exhibit spatial memory impairments [7, 8].
The idea that the brain organises cognitive processes (memories) through cognitive maps was proposed by Tollman in 1948 [9]. Data from humans, monkeys, and rats support the idea that the hippocampus is fully engaged in spatial navigation [10].
### The Precision Aging Approach
Recognising the importance of maintaining cognitive function as we age, the Precision Aging approach aims to close the gap between optimal cognition and lifespan, thereby increasing the quality of life [11]. This approach emphasises the normative nature of high levels of brain function in aging and the brain's ability to adapt at a network level, with remaining synapses becoming more powerful [12].
Dr. Carol Barnes, Ph.D., a neuroscientist, Regents' Professor of psychology at the University of Arizona, and the director of the Evelyn F. McKnight Brain Institute, has spent over four decades studying the aging of the brain in relation to cognitive diseases [13]. Her work, along with that of many other researchers, continues to shed light on the complexities of the aging brain and the role of the hippocampus in maintaining cognitive function.
- Engaging in activities that promote health-and-wellness, such as regular aerobic exercise, maintaining a brain-healthy diet, and managing stress, can support the hippocampus's ability for neurogenesis, potentially reversing some age-related declines in cognitive healthspan.
- The Precision Aging approach, which aims to increase the quality of life by closing the gap between optimal cognition and lifespan, emphasises the brain's ability to adapt at a network level and the normative nature of high levels of brain function in aging, particularly in relation to the hippocampus and its role in maintaining cognitive function.
- Mental-health issues, such as cognitive decline, can be significantly impacted by changes in the hippocampus during the aging process, highlighting the importance of scientific research on aging in understanding and preserving cognitive healthspan.
