Elderly who are tested at their optimal time of day (the morning), not only perform better on demanding cognitive tasks but also activate the same brain networks responsible for paying attention and suppressing distraction as younger adults, researchers said.
The study has yielded some of the strongest evidence yet that there are noticeable differences in brain function across the day for older adults.
"Time of day really does matter when testing older adults. This age group is more focused and better able to ignore distraction in the morning than in the afternoon," said lead author John Anderson, a PhD candidate with the Rotman Research Institute at Baycrest Health Sciences and University of Toronto, Department of Psychology.
"Their improved cognitive performance in the morning correlated with greater activation of the brain's attentional control regions - the rostral prefrontal and superior parietal cortex - similar to that of younger adults," said Anderson.
Anderson recommended that older adults try to schedule their most mentally-challenging tasks for the morning time.
Those tasks could include doing taxes, taking a test (such as a driver's license renewal), seeing a doctor about a new condition, or cooking an unfamiliar recipe.
In the study, 16 younger adults (aged 19-30) and 16 older adults (aged 60-82) participated in a series of memory tests during the afternoon from 15 pm.
The tests involved studying and recalling a series of picture and word combinations flashed on a computer screen.
Irrelevant words linked to certain pictures and irrelevant pictures linked to certain words also flashed on the screen as a distraction.
During the testing, participants' brains were scanned with fMRI which allows researchers to detect with great precision which areas of the brain are activated.
Older adults were 10 per cent more likely to pay attention to the distracting information than younger adults who were able to successfully focus and block this information.
The fMRI data confirmed that older adults showed substantially less engagement of the attentional control areas of the brain compared to younger adults.
Indeed, older adults tested in the afternoon were "idling" showing activations in the default mode (a set of regions that come online primarily when a person is resting or thinking about nothing in particular) indicating that perhaps they were having great difficulty focusing.
The study was published in the journal Psychology and Ageing.