Imaging hippocampal function across the human life span: is memory decline normal or not?
Memory function commonly declines in later life. Whether memory decline represents a disease process or whether it is part of normal aging remains unknown. Here we answer this question by assessing the function of multiple subregions that make up the hippocampal circuit across the human life span. A newly developed MRI approach--designed to detect functional changes in individual hippocampal subregions--was used to assess the hippocampal circuit in 70 subjects between 20 and 88 years of age. Using strict parametric criteria, analysis revealed that function in two hippocampal subregions--the subiculum and the dentate gyrus--decline normally with age. In contrast, function in the entorhinal cortex declines pathologically. Single-subject analysis revealed that hippocampal dysfunction, found in 60% of elders was selectively correlated with memory decline. These results show that memory decline is caused by different mechanisms and suggests how memory decline should be approached clinically.
Small
Scott A
SA
The Taub Institute on Alzheimer's Disease and the Aging Brain, Deparment of Neurology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA. sas68@columbia.edu
Tsai
Wei Yann
WY
DeLaPaz
Robert
R
Mayeux
Richard
R
Stern
Yaakov
Y
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology* / Q000523:psychology*; D018891:Dentate Gyrus / Q000502:physiology; D018728:Entorhinal Cortex / Q000503:physiopathology; D005260:Female; D006624:Hippocampus / Q000502:physiology* / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008568:Memory; D008569:Memory Disorders / Q000503:physiopathology / Q000523:psychology*; D008875:Middle Aged; D012016:Reference Values