Brain beta-Amyloid and Atrophy in Individuals at Increased Risk of Cognitive Decline

: Martikainen IK, Kemppainen N, Johansson J, Teuho J, Helin S, Liu Y, Helisalmi S, Soininen H, Parkkola R, Ngandu T, Kivipelto M, Rinne JO

Publisher: AMER SOC NEURORADIOLOGY

: 2019

: American Journal of Neuroradiology

: AMERICAN JOURNAL OF NEURORADIOLOGY

: AM J NEURORADIOL

: 40

: 1

: 80

: 85

: 6

: 0195-6108

DOI: https://doi.org/10.3174/ajnr.A5891(external)

BACKGROUND AND PURPOSE: The relationship between brain beta-amyloid and regional atrophy is still incompletely understood in elderly individuals at risk of dementia. Here, we studied the associations between brain beta-amyloid load and regional GM and WM volumes in older adults who were clinically evaluated as being at increased risk of cognitive decline based on cardiovascular risk factors.MATERIALS AND METHODS: Forty subjects (63-81 years of age) were recruited as part of a larger study, the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability. Neuroimaging consisted of PET using C-11 Pittsburgh compound-B and T1-weighted 3D MR imaging for the measurement of brain beta-amyloid and GM and WM volumes, respectively. All subjects underwent clinical, genetic, and neuropsychological evaluations for the assessment of cognitive function and the identification of cardiovascular risk factors.RESULTS: Sixteen subjects were visually evaluated as showing cortical beta-amyloid (positive for beta-amyloid). In the voxel-by-voxel analyses, no significant differences were found in GM and WM volumes between the samples positive and negative for beta-amyloid. However, in the sample positive for beta-amyloid, increases in 11C Pittsburgh compound-B uptake were associated with reductions in GM volume in the left prefrontal (P = .02) and right temporal lobes (P = .04).CONCLUSIONS: Our results show a significant association between increases in brain beta-amyloid and reductions in regional GM volume in individuals at increased risk of cognitive decline. This evidence is consistent with a model in which increases in beta-amyloid incite neurodegeneration in memory systems before cognitive impairment manifests.