According to a study by McGill University researchers, the inability to remember details that begins in early midlife (the 40s) may be the result of a change in what information the brain focuses on during memory formation and retrieval, rather than a decline in brain function.

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, identifies that a key question in current memory research concerns which changes to the aging brain are normal and which are not, and that most of the work on aging and memory has concentrated on understanding brain changes later in life. This research was aimed at addressing what happens at midlife in healthy aging and how this relates to findings in late life.

In the study, 112 healthy adults ranging in age from 19 to 76 years were shown a series of faces and were asked to recall where a particular face appeared on the screen (left or right) and when it appeared (least or most recently). Researchers then used functional MRI to analyze which parts of brain were activated during recall of these details.

Dr Rajah and colleagues found that young adults activated their visual cortex while successfully performing this task, while 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.

Even though middle-aged and older participants didn’t perform as well as younger ones in this experiment, Dr Rajah suggests that it may be wrong to regard the response of the middle-aged and older brains as impairment, but rather that it may reflect changes in what adults deem important information as they age. Researchers also concluded that middle-aged and older adults might improve their recall abilities by learning to focus on external rather than internal information.

Dr Rajah is currently analyzing data from a similar study to discern if there are any gender differences in middle-aged brain function as it relates to memory, noting that women go through a lot of hormonal change at midlife. The question is, how much of these results is driven by postmenopausal women?

The study, “Changes in the modulation of brain activity during context encoding vs. context retrieval across the adult lifespan,” was published in the October 2016 issue of Neuro-Image.

This research was supported by the Canadian Institutes of Health Research and by a grant from the Alzheimer’s Society of Canada.