Brain imaging and age-related changes in cognition

Although there is currently some debate as to the degree of structural chan ges in the brain that occur with age, there is little doubt that such chang es occur. There also are physiological changes in many areas that could hav e implications for cognitive function in the elderly. One way to study the impact of these age-related changes in the brain on cognition is to use neu roimaging techniques to examine brain activity during the performance of va rious tasks, and determine how this activity differs between young and olde r individuals. This approach has been used to study functions such as memor y, perception, and attention, and it has generally been found that older in dividuals utilize different areas of the brain than do young subjects when carrying out the same cognitive task. This has lied some researchers to sug gest that older persons utilize different functional brain networks, perhap s to compensate for reductions of efficiency in some brain areas. The areas of the brain most often found to be more active during cognitive tasks in the elderly are the frontal lobes. Studies that have directly examined the functional networks utilized during cognition have found that older people do indeed have different functional interactions involving he frontal lobes , and therefore, utilize different functional networks. In some cases this differential activity has been accompanied by cognitive performance in the older participants that is equivalent to that. seen in the young, suggestin g that greater reliance on this brain region is related in some way to the maintained ability of the older individuals to perform the task. However, d ata collected to date on this issue are still limited, so although the evid ence is intriguing, the definitive interpretation of these findings must aw ait further experiments. (C) 1998 Elsevier Science Inc.