Brain Changes in Older Adults at Very Low Risk for Alzheimer's Disease

Research Group for Lifespan Changes in Brain and Cognition, Department of Psychology, University of Oslo, 0317 Oslo, Norway, Multimodal Imaging Laboratory and Department of Neurosciences, University of California, San Diego, California 92093, and Department of Radiology, University of California, San Diego, California 92103.
The Journal of Neuroscience : The Official Journal of the Society for Neuroscience (Impact Factor: 6.34). 05/2013; 33(19):8237-42. DOI: 10.1523/JNEUROSCI.5506-12.2013
Source: PubMed


Alzheimer's disease (AD) has a slow onset, so it is challenging to distinguish brain changes in healthy elderly persons from incipient AD. One-year brain changes with a distinct frontotemporal pattern have been shown in older adults. However, it is not clear to what extent these changes may have been affected by undetected, early AD. To address this, we estimated 1-year atrophy by magnetic resonance imaging (MRI) in 132 healthy elderly persons who had remained free of diagnosed mild cognitive impairment or AD for at least 3 years. We found significant volumetric reductions throughout the brain. The sample was further divided into low-risk groups based on clinical, biomarker, genetic, or cognitive criteria. Although sample sizes varied, significant reductions were observed in all groups, with rates and topographical distribution of atrophy comparable to that of the full sample. Volume reductions were especially pronounced in the default mode network, closely matching the previously described frontotemporal pattern of changes in healthy aging. Atrophy in the hippocampus predicted change in memory, with no additional default mode network contributions. In conclusion, reductions in regional brain volumes can be detected over the course of 1 year even in older adults who are unlikely to be in a presymptomatic stage of AD.

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    • "The MTL also shows accelerated volume loss during aging (Raz et al., 2004; Fjell et al., 2013) and is known to be the initial site of histopathological changes in Alzheimer's disease (Greicius et al., 2004). Evidence from a recent longitudinal study suggests that in older adults free of dementia, the MTL shows the greatest volumetric reductions, followed by the prefrontal cortex (Fjell et al., 2013). Further, the structural and functional changes in the MTL have been linked to cognitive decline in older adults (Persson et al., 2012). "
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