ScienceDaily (Sep. 8, 2009) — The belief that healthy older brains are substantially smaller than younger brains may stem from studies that did not screen out people whose undetected, slowly developing brain disease was killing off cells in key areas, according to new research. As a result, previous findings may have overestimated atrophy and underestimated normal size for the older brain.
As long as people stay cognitively healthy, the researchers believe that the gray matter of areas supporting cognition might not shrink much at all. "If future longitudinal studies find similar results, our conception of 'normal' brain aging may become more optimistic," said lead author Saartje Burgmans, who is due to receive her PhD later this year.
The findings should caution scientists about drawing conclusions from brain studies that don't screen participants over time, using precise and objective definitions, the authors added.