The influence of age and mild cognitive impairment on associative memory performance and underlying brain networks.
Associative memory is essential to everyday activities, such as the binding of faces and corresponding names to form single bits of information. However, this ability often becomes impaired with increasing age. The most important neural substrate of associative memory is the hippocampus, a structure crucially implicated in the pathogenesis of Alzheimer's disease (AD). The main aim of this study was to compare neural correlates of associative memory in healthy aging and mild cognitive impairment (MCI), an at-risk state for AD. We used fMRI to investigate differences in brain activation and connectivity between young controls (n = 20), elderly controls (n = 32) and MCI patients (n = 21) during associative memory retrieval. We observed lower hippocampal activation in MCI patients than control groups during a face-name recognition task, and the magnitude of this decrement was correlated with lower associative memory performance. Further, increased activation in precentral regions in all older adults indicated a stronger involvement of the task positive network (TPN) with age. Finally, functional connectivity analysis revealed a stronger link of hippocampal and striatal components in older adults in comparison to young controls, regardless of memory impairment. In elderly controls, this went hand-in-hand with a stronger activation of striatal areas. Increased TPN activation may be linked to greater reliance on cognitive control in both older groups, while increased functional connectivity between the hippocampus and the striatum may suggest dedifferentiation, especially in elderly controls.
Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Marburg, Germany. C.S.Oedekoven@sussex.ac.uk.|School of Psychology, University of Sussex, Brighton, BN1 9QH, UK. C.S.Oedekoven@sussex.ac.uk.
Christiane S H
CS
Oedekoven
Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Marburg, Germany.
Andreas
A
Jansen
School of Psychology, University of Sussex, Brighton, BN1 9QH, UK.
James L
JL
Keidel
Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Marburg, Germany.
Tilo
T
Kircher
Department of Psychiatry and Psychotherapy, Philipps-University Marburg, Marburg, Germany.
Dirk
D
Leube
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001245:Association Learning / Q000502:physiology*; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D060825:Cognitive Dysfunction / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology*; D008875:Middle Aged; D009434:Neural Pathways / Q000503:physiopathology; D009483:Neuropsychological Tests; D055815:Young Adult
Aging; Functional connectivity; Hippocampus; Mild cognitive impairment (MCI); Task positive network (TPN)