WASHINGTON, D.C.: The ability to remember details, such as the location of objects, inevitably starts to decline in early midlife, the 40s. But it may be the result of a change in what information the brain focuses on during memory formation and retrieval, instead of a decline in brain function, according to a study by McGill University researchers.
Senior author Natasha Rajah, Director of the Brain Imaging Centre at McGill University’s Douglas Institute and Associate Professor in McGill’s Department of Psychiatry, says this reorientation could impact daily life.
Brain changes associated with dementia are now thought to arise decades before the onset of symptoms. So a key question in current memory research concerns which changes to the aging brain are normal and which are not.
But Dr. Rajah says most of the work on aging and memory has concentrated on understanding brain changes later in life, rather than midlife memory decline.
In this study 112 healthy adults ranging in age from 19 to 76 years were shown a series of faces. Participants were then asked to recall where a particular face appeared on the screen (left or right) and when it appeared (least or most recently).
The researchers used functional MRI to analyze which parts of brain were activated during recall of these details.
Rajah and colleagues found that young adults activated their visual cortex while successfully performing this task. As she explains,
“They are really paying attention to the perceptual details in order to make that decision.”
On the other hand, middle-aged and older adults didn’t show the same level of visual cortex activation when they recalled the information.
Instead, their medial prefrontal cortex was activated. That’s a part of the brain known to be involved with information having to do with one’s own life and introspection.
Even though middle-aged and older participants didn’t perform as well as younger ones in this experiment, Rajah says it may be wrong to regard the response of the middle-aged and older brains as impairment.