Memory at Midlife

Early brain development may lay an essential foundation.

Posted Jan 09, 2019

Aging is associated with alterations in thinking abilities. Whereas not all of these changes are detrimental—for example, vocabulary and knowledge increase over the lifespan and into older age—it is the thinking abilities that decline with age that grab our attention

Compared to younger persons, midlife and older adults are slower to process information, learn new information somewhat less efficiently, and may also experience changes in problem solving and decision making

Data published by Cacciaglia and colleagues shed new light on age-related changes in memory. In 463 midlife adults, the investigators measured the size of different brain regions and determined, in part, if bigger brains are better. That is, they sought to determine if there were associations between the sizes of various brain regions and memory performance.

Remarkably, there is not a great deal of research on brain size and cognition in healthy aging. Most studies focus on links between brain activity and cognition, rather than on the size of various brain regions.

The investigators found that remembering new information was associated with smaller sizes of several brain regions.  This is a counterintuitive finding.  Would not bigger brain regions foster better memory? 

The authors had a viable explanation. That is, they suggest that smaller volumes of some brain structures are the result of successful brain development very early in life.  Part of early brain development involves pruning—or natural loss—of brain connections, in order to optimize brain networks and communication pathways. Smaller brain volumes of some brain structures might be the end result of healthy brain development and thus support better memory performance.

Further, the smaller brain regions that were linked with better learning and memory are known to be “turned off” when successful learning and memory occur. Activity in some brain regions support new learning, whereas inactivity in these particular brain regions support new learning. 

It is as if the brain needs to stop engaging in some activities in order to focus resources on the task at hand. Just as multitasking is hard and generally a bad idea—just consider texting while driving—so too goes the functionality of the brain. 

Some things need to be turned off—the text can wait —while resources are focused on a demanding task. 

This work is fascinating and important in linking ideas about early brain development and memory performance at midlife, as well as highlighting how brain regions are turned on and off during cognitive tasks.  The data will be even more valuable as the midlife adults are followed into older adulthood and changes in memory and brain structure and function can be further tracked.

References

Cacciaglia, R., Molinuevo, J. L., Sanchez-Benavides, G., Falcon, C., Gramunt, N., Brugulat-Serrat, A., … Huguet, J. (2018). Episodic memory and executive functions in cognitively healthy individuals display distinct neuroanatomical correlates which are differentially modulated by aging. Human Brain Mapping, (11), 4565. https://doi.org/10.1002/hbm.24306

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