Dedifferentiation of caudate functional connectivity and striatal dopamine transporter density predict memory change in normal aging

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 115; no. 40; pp. 10160 - 10165
• Main Authors: Rieckmann, Anna, Johnson, Keith A., Sperling, Reisa A., Buckner, Randy L., Hedden, Trey
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 02.10.2018
• Subjects: Adolescent; Adult; Adults; Age; Aged; Aged, 80 and over; Aging; Aging - physiology; Biological Sciences; Cerebral Cortex - diagnostic imaging; Cerebral Cortex - physiology; Cognitive ability; Corpus Striatum - diagnostic imaging; Corpus Striatum - physiology; Decoupling; Density; Dopamine; Dopamine Plasma Membrane Transport Proteins - metabolism; Dopamine transporter; Emission measurements; Female; Functional magnetic resonance imaging; Hippocampus; Humans; Life span; Magnetic Resonance Imaging; Male; Memory; Memory - physiology; Middle Aged; Neostriatum; Neural networks; Older people; Performance prediction; Positron emission; Positron emission tomography; Reduction; Tomography; Trigeminal Caudal Nucleus - diagnostic imaging; Trigeminal Caudal Nucleus - metabolism; functional connectivity; memory; aging; striatum; dopamine
• ISSN: 0027-8424; 1091-6490; 1091-6490
• DOI: 10.1073/pnas.1804641115

Age-related changes in striatal function are potentially important for predicting declining memory performance over the adult life span. Here, we used fMRI to measure functional connectivity of caudate subfields with large-scale association networks and positron emission tomography to measure striatal dopamine transporter (DAT) density in 51 older adults (age 65–86 years) who received annual cognitive testing for up to 7 years (mean = 5.59, range 2–7 years). Analyses showed that cortical–caudate functional connectivity was less differentiated in older compared with younger adults (n = 63, age 18–32 years). Unlike in younger adults, the central lateral caudate was less strongly coupled with the frontal parietal control network in older adults. Older adults also showed less “decoupling” of the caudate from other networks, including areas of the default network (DN) and the hippocampal complex. Contrary to expectations, less decoupling between caudate and the DN was not associated with an age-related reduction of striatal DAT, suggesting that neurobiological changes in the cortex may drive dedifferentiation of cortical–caudate connectivity. Reduction of specificity in functional coupling between caudate and regions of the DN predicted memory decline over subsequent years at older ages. The age-related reduction in striatal DAT density also predicted memory decline, suggesting that a relation between striatal functions and memory decline in aging is multifaceted. Collectively, the study provides evidence highlighting the association of age-related differences in striatal function to memory decline in normal aging.